Peace through practical, proved civil defence for credible war deterrence
  • Please see also post linked here, and our summary of the key points in Herman Kahn's much-abused call for credible deterrence, On Thermonuclear War, linked here.

  • Hiroshima's air raid shelters were unoccupied because Japanese Army officers were having breakfast when B29s were detected far away, says Yoshie Oka, the operator of the Hiroshima air raid sirens on 6 August 1945...

  • In 1,881 burns cases in Hiroshima, only 17 (or 0.9 percent) were due to ignited clothing and 15 (or 0.7%) were due to the firestorm flames...

  • Dr Harold L. Brode’s new book, Nuclear Weapons in ...

  • 800 war migrants drowned on 22 April by EU policy:...

  • Photographed fireball shielding by cloud cover in ...

  • Nuclear weapons effects "firestorm" and "nuclear w...

  • Proved 97.5% survival in completely demolished houses ...

    "There has never been a war yet which, if the facts had been put calmly before the ordinary folk, could not have been prevented." - British Foreign Secretary Ernest Bevin, House of Commons Debate on Foreign Affairs, Hansard, 23 November 1945, column 786 (unfortunately secret Cabinet committees called "democracy" for propaganda purposes have not been quite so successful in preventing war). Protection is needed against collateral civilian damage and contamination in conventional, chemical and nuclear attack, with credible low yield clean nuclear deterrence against conventional warfare which, in reality (not science fiction) costs far more lives. Anti scientific media, who promulgate and exploit terrorism for profit, censor (1) vital, effective civil defense knowledge and (2) effective, safe, low yield air burst clean weapons like the Mk54 and W79 which deter conventional warfare and escalation, allowing arms negotiations from a position of strength. This helped end the Cold War in the 1980s. Opposing civil defense and nuclear weapons that really deter conventional war, is complacent and dangerous.

    War and coercion dangers have not stemmed from those who openly attack mainstream mistakes, but from those who camouflage themselves as freedom fighters to ban such free criticism itself, by making the key facts seem taboo, without even a proper debate, let alone financing research into unfashionable alternatives. Research and education in non-mainstream alternatives is needed before an unprejudiced debate, to establish all the basic facts for a real debate. “Wisdom itself cannot flourish, nor even truth be determined, without the give and take of debate and criticism.” – Robert Oppenheimer (quotation from the H-bomb TV debate hosted by Eleanor Roosevelt, 12 February 1950).

    “Apologies for freedom? I can’t handle this! ... Deal from strength or get crushed every time ... Freedom demands liberty everywhere. I’m thinking, you see, it’s not so easy. But we have to stand up tall and answer freedom’s call!” – Freedom Kids

  • Tuesday, August 01, 2006

    U.K. Home Office Scientific Advisory Branch 'Protect and Survive' civil defence research

    Home Office Scientific Advisory Branch full time civil defence research scientists Frank H. Pavry and George R. Stanbury at Monte Bello, measuring the effects of Britain's first nuclear weapon test, Operation Hurricane, in collaboration with Penney's Atomic Weapons Research Establishment, October 3, 1952.

    Above: film of the Effects of Nuclear Weapons, beginning by debunking the radiation myths of Hiroshima. The 1977 edition of the Effects of Nuclear Weapons book, by Glasstone and Dolan, gives further data showing that there is evidence for "threshold" doses below which no negative effects occur:

    "From the earlier studies of radiation-induced mutations, made with fruitflies [by Nobel Laureate Hermann J. Muller and other geneticists who worked on plants, who falsely hyped their insect and plant data as valid for mammals like humans during the June 1957 U.S. Congressional Hearings on fallout effects], it appeared that the number (or frequency) of mutations in a given population ... is proportional to the total dose ... More recent experiments with mice, however, have shown that these conclusions need to be revised, at least for mammals. [Mammals are biologically closer to humans, in respect to DNA repair mechanisms, than short-lived insects whose life cycles are too small to have forced the evolutionary development of advanced DNA repair mechanisms, unlike mammals that need to survive for decades before reproducing.] When exposed to X-rays or gamma rays, the mutation frequency in these animals has been found to be dependent on the exposure (or dose) rate ...

    "At an exposure rate of 0.009 roentgen per minute [0.54 R/hour], the total mutation frequency in female mice is indistinguishable from the spontaneous frequency. [Emphasis added.] There thus seems to be an exposure-rate threshold below which radiation-induced mutations are absent ... with adult female mice ... a delay of at least seven weeks between exposure to a substantial dose of radiation, either neutrons or gamma rays, and conception causes the mutation frequency in the offspring to drop almost to zero. ... recovery in the female members of the population would bring about a substantial reduction in the 'load' of mutations in subsequent generations."

    - Samuel Glasstone and Philip J. Dolan, The Effects of Nuclear Weapons, 3rd ed., 1977, pp. 611-3.

    Update on 19 October 2009: PhD research student Melissa Smith of the Centre for the History of Science, Technology and Medicine at the University of Manchester, has just had published a vital new scholarly paper on the role of the British Home Office Scientific Advisory Branch nuclear test research programme in shaping the 'Protect and Survive' advice (one fragment of which was actually published as a paper in the little read 1965 U.S. National Academy of Sciences civil defense compendium, Proceedings of the symposium on protective structures for civilian populations, giving experimental data on the 1.25 MeV mean gamma Co-60 radiation protection factors for emergency 'core shelters' inside typical British homes):

    Melissa Smith, 'Architects of Armageddon: the Home Office Scientific Advisers' Branch and civil defence in Britain, 1945–68', British Journal for the History of Science (published by Cambridge University Press), 8 October 2009.

    'In 1948, in response to the perceived threat of atomic war, the British government embarked on a new civil defence programme. By the mid-1950s, secret government reports were already warning that this programme would be completely inadequate to deal with a nuclear attack. The government responded to these warnings by cutting civil defence spending, while issuing apparently absurd pamphlets advising the public on how they could protect themselves from nuclear attack. Historians have thus far sought to explain this response with reference to high-level decisions taken by policymakers, and have tended to dismiss civil defence advice as mere propaganda. This paper challenges this interpretation by considering the little-known role of the Home Office Scientific Advisers' Branch, a group of experts whose scientific and technical knowledge informed both civil defence policy and advice to the public. It explores both their advisory and research work, demonstrating their role in shaping civil defence policy and showing that detailed research programmes lay behind the much-mocked government civil defence pamphlets of the 1950s and 1960s.'

    This paper is an expanded version of the essay awarded the Singer Prize of the British Society for the History of Science for 2008:
    Ms Melissa Smith wins 2008 Singer Prize

    The BSHS Singer Prize judging panel has selected the essay entitled "Architects of Armageddon: Scientific advisers and civil defence in Britain, 1945-68" by Ms Melissa Smith (CHSTM, University of Manchester), as the winner of the 2008 Singer Prize. The judges were impressed by the flair and ambition of the essay, by its critical engagement with the existing literature on post-war British science and government, and by its extensive use of primary archival sources. They found the essay original, well written, engaging and informative.

    As we explain below, the government should have published its nuclear weapons effects research based on the nuclear test data in order to substantiate the scientific basis for civil defense. Hiding the factual scientific evidence for public civil defense advice behind a solid wall of secrecy is a guaranteed way to allow the advice to be falsely ridiculed and ignored by ignorant 'scientists' with a political agenda, thereby maximising the scale of tragedy in the event that civil defense is needed in a disaster. Allowing the popular media to wrongly discredit civil defence also increases the risk of war by encouraging dictators and terrorists to spend money trying to get hold of weapons of mass destruction in the belief that there is no effective defense against such weapons. It's vital to publish the facts!

    “The obsession with secrecy ensured that almost all the public information on nuclear attack was provided by the government’s opponents.”

    - Matthew Grant, After the Bomb: Civil Defence and Nuclear War in Britain, 1945-68, Palgrave Macmillan, London, 2010, page 197.

    My father was a Civil Defence Corps instructor in Colchester the 1950s. After the local basic instructor course, for the advanced instructor course he attended the government Civil Defence College, Easingwold (which still exists, now named the Emergency Planning College). At the time he left in 1957 (when he had to work abroad for 12 years until 1969), Britain's Civil Defence Corps was at its largest size since the wartime Blitz. Civil defence Corps membership peaked at 336,265 by May 1956 (reported in The Times, 2 May 1956, page 6). This would have been enough to make a large difference in the event of a war or disaster. However, my father found that even when he left in 1956, the British Civil Defence Corp was doomed by secrecy. The American fallout fiasco at the 15 megaton Castle-Bravo Bikini Atoll surface burst on 1 March 1954 (when they didn't evacuate inhabited atolls directly downwind for two days, and also failed to warn or spot a Japanese ship directly downwind) was being exploited by Soviet Union "peace" propaganda, far-left wing political groups, and genuine but ignorant pacifist groups.

    Despite the fact that the BBC still fakes all nuclear explosion films with the sound of the blast falsely superimposed on the explosion flash, to make civil defense duck and cover seem stupid (actually, like thunder after lightning, the blast wave travels slower than light so the flash occurs in silence until the blast arrives, which can be many seconds later for the case of large areas of devastation from a nuclear explosion, giving plenty of time for “duck and cover” action to avoid flying glass when the blast finally arrives), the BBC did make one honest film about the Soviet Union’s “peace offensive” propaganda lies, the four-part 1995 “Messengers from Moscow” documentary. This documentary provides essential evidence of Soviet KGB and related "World Peace Council" propaganda lies discussed in an earlier blog post. Dimitri K. Simes reviewed “Messengers from Moscow” in the 1 June 1995 issue of Confirmation Time:
    “The end of Soviet communism has given Westerners unprecedented access to Moscow's historical resources. Various archives have been opened and living witnesses to history are suddenly prepared to tell their stories, even in front of foreign television cameras. ... the four-part documentary series Messengers from Moscow, shown in the United States by PBS and in Britain by the BBC, represents a powerful blow to two fundamentals of the liberal dogma - namely, that the Cold War resulted from a Western overreaction to largely defensive, even if rather heavy-handed, Soviet policies and that the preoccupation with the communist menace inside Western democracies amounted to a vicious witch hunt. The series, ably directed by Daniel Wolf and produced by Eugene B. Shirley with Herbert E. Ellision as chief consultant, is based on numerous on-camera interviews with Soviet insiders ranging from Stalin’s second-in-command Vyacheslav Molotov to Brezhnev’s personal physician. The accounts they present are sobering. Molotov, in a 1972 taped conversation with poet Felix Chuyev, stated point blank that expanding Soviet borders “as far as possible” was his official duty. In Molotov's view, “there could not be a peaceful Germany unless it takes a socialist path.” But he cautioned that it had to be accomplished “carefully,” without provoking a war with the West.”

    After President Nixon’s Watergate scandal and failure in Vietnam, to deflect media attacks from Nixon, America began to press ahead with negotiations with the Soviet Union for SALT treaties just when the Soviet threat was reaching parity with the Western arms stockpile, and when Soviet civil defense was being transferred from civilian control to military control with vastly increased spending. If the arms race had been stopped, the Soviet Union might have survived instead of going effectively bankrupt when Reagan manipulated oil prices in the 1980s. In 1975, America signed the Helsinki Act, for the first time agreeing to the borders of the Soviet Union and its Warsaw Pact in Europe. This officially handed over those countries and people to Soviet control. After it was signed, the Chairman of the Soviet KGB (secret police), Yuri Andropov, stated in a letter to the Soviet Central Committee on 29 December 1975: “It is impossible at present to cease criminal prosecutions of those individuals who speak out against the Soviet system, since this would lead to an increase in especially dangerous state crimes and anti-social phenomena.” After a succession of appeasers, President Reagan finally spelled out some of the problems in his famous "evil empire" speech, much to the frustration and amusement of the communists who clearly wanted to encourage "peaceful" invasions and war, at the expense of liberty.

    Above: Soviet civil defense posters on improvised shelters and animal decontamination from 1987, ideas which Kearny's team at Oak Ridge National Laboratory field-tested against high overpressures in explosions, after translating 1960s and 1970s Soviet Union civil defense manuals, leading to Kearny's 1979 Nuclear War Survival Skills. In the 1986 Chernobyl nuclear disaster the Soviet civil defense organization measured radiation and organized the rapid, large-scale evacuation.

    Our government had the facts from British nuclear tests, but even in 1956 every piece of information such as scientific British nuclear test data and even basic pamphlets of civil defence countermeasures against biological and chemical warfare of relevance to civil defence and of any value in convincing the public and the next generation Civil Defence Corp members that planning and training was based on hard facts, was either Restricted or Official Use Only. A propaganda war ensued, in which all convincing Western nuclear test data was withheld, so that enemy anti-civil defence lies was allowed to go unopposed. The Civil Defence Corp gradually declined and was closed in 1968. The secrecy did not increase security. Enemies armed with nuclear weapons were testing their weapons, and had their own supply of nuclear effects data; in any case secrecy failed to stop the atom spies like Fuchs giving the blueprints of nuclear weapons to the Soviet Union even before Hiroshima! The idea that the public is best-served by keeping civil defence validation data secret is therefore crazy. It's very interesting to look at the Soviet Union's Cold War civil defence history. Until 1971, the Soviet civil defence organization was under control of the Ministry of Internal Affairs, but that year (coinciding with the Soviet nuclear missile program approaching parity with the West, the failure of American efforts in Vietnam, and the American decision to withdraw 2,100 Davy Crockett tactical nuclear weapons from Western Europe), it was put under the control of the Soviet Ministry of Defence, and it had a vastly increased budget from 1973.

    Physics and mathematics professors John Dowling and Evans M. Harrell's 1987 American book Civil Defense: A Choice of Disasters (American Institute of Physics, New York) states in Table 1 on page 119 the following per capita expenditures for civil defence (defense for Americans), which shows how the Soviet Union was investing in civil defence for war preparedness (the Soviet figure is what it would cost a democratic country to duplicate the Soviet civil defence preparedness; obviously the Soviet system was not democratic but socialist, so it didn't involve the same actual costs that it would take for a democracy, i.e. the Soviets did not pay out the same wages and tended to less democratic methods to make its citizens train in civil defence):

    France: $0.15
    U. S.: $0.75
    U. K.: $1.15
    Italy: $2.00
    Denmark: $6.50
    U. S. S. R.: $11.30
    Switzerland: $33.00

    The tardy progress of American civil defense against EMP is emphasized on page 43 of that 1987 Dowling and Harrell book: "Some 2,771 commercial radio and TV stations are to be selected from the more than 9,000 stations participating in the emergency broadcast system. ... As of the start of FY85, 641 stations had been protected against fallout, but only 110 had EMP protection." By contrast, the Soviet Union had been investigating the damaging EMP effects of high altitude nuclear explosions during Operation K in October 1962 before America even knew the exact mechanism for why streetlights had gone out in Hawaii on 9 July 1962. Russia was EMP-hardening its infrastructure way ahead of us.

    (Note that at the same time that the Soviet Union was transferring its civil defense organization from civilian to direct military control with massively increased resources in the early 1970s when the Soviet Union's nuclear missile stockpile and main battle tank collection was beginning to rival Western military capabilities to defend Western Europe, America transferred its civil defense from military control to a civilian agency. At the same time, as discussed elsewhere, President Nixon was pressed into détente with the Soviet Union in order to deflect media harrassment over his personal involvement in the Watergate controversy. The transfer of American civil defence from control by the Pentagon to a civilian agency had actually been recommended in several research reports on civil defence by nuclear weapons effects researchers in the late 1960s, in the belief that it would reduce secrecy problems. Actually, it increased secrecy problems because civilian agencies tended to have greater numbers of uncleared personnel who had to be kept out of discussions involving classified data, so that the flow of key information was seriously impeded, and being out of the Pentagon they were physically more removed from discussions of the problems with others who were doing very similar analyses.)

    Above: the British Government's 1957 civil defence poster on The Hydrogen Bomb (U.K. National Archives, reference INF 13/281) grossly exaggerates the effects of nuclear weapons, due to errors in Dr Glasstone's June 1957 edition of The Effects of Nuclear Weapons on thermal radiation transmission, blast and cratering. Thermal transmission was wrongly assumed to be about 50% for all distances beyond 10 miles. The crater size was quoted as 1 mile diameter for the 10 megaton Mike test on the water wave innundated, saturated porous coral reef around Elugelab Island of Eniwetok Atoll in 1952; the correct crater diameter for a 10 megaton surface burst on dry soil is just 0.11 miles as finally discovered from gravitational potential energy considerations in 1991. Notice that the poster, just like the British civil defence handbooks, omitted all the scientific British nuclear test data. The incompetently produced 1964 film version (below) falsely states that the radiation level at 2 days is 100 times less than "at first", which is pseudoscience: at two days the level is 10 times less than at 7 hours, 100 times less than that at 1 hour, 1000 times less than that at 9 minutes, and according to Glasstone and Dolan's Effects of Nuclear Weapons 3rd ed., 1977, (1 + tseconds)-1.2 decay rate formula (in the chapter on radio and radar interference effects), at times less than a fraction of a second, the dose rate is about 2,000,000 greater than that at 2 days. The film also fails to show the physical nature of radioactive fallout particles (as distinct from dust), and then falsely claims that fallout is undetectable by human senses. It's a real masterpiece of time-wasting, obfuscating pseudoscience:

    U.K. Government, House of Lords debate entitled "Nuclear Weapons: Review of Effects" on 13 November 1984, published in Hansard, vol. 457 cc211-3:

    § 2.51 p.m.

    § Lord Renton My Lords, I beg leave to ask the Question standing in my name on the Order Paper.

    § The Question was as follows:

    § To ask Her Majesty's Government when they hope to publish the Home Office review of the casualty and damage effects of nuclear weapons.

    § The Minister of State, Home Office (Lord Elton) My Lords, we intend to publish this review early next year. [Actually, the report was only finished in 1986 by Home Office scientists Dr S. Hadjipavlou and Dr G. Carr-Hill, a brief description of which is published in the article, 'A Revised Set of Blast Casualty Rates for Civil Defence Use: An Overview' by S. Hadjipavlou and G. Carr-Hill, Journal of the Royal Statistical Society, Series A (Statistics in Society), vol. 152, No. 2 (1989), pp. 139-156. The main 1986 report, A review of the blast casualty rules applicable to U.K. houses, U.K. Home Office Scientific Research and Development Branch, Publication 34/86, was never published but remained a Home Office internal publication unavailable from H. M. Stationery Office.]

    § Lord Renton My Lords, while I thank my noble friend for that reply, may I ask him whether he is aware of the serious conflicts of evidence and the consequent misunderstandings with regard to this vital matter? Will he therefore ensure that publication of the report is given the highest priority and the widest possible circulation when it is published?

    § Lord Elton My Lords, the report will rest on very thorough research. It will be published as an official document available to the public and a copy will be placed in your Lordships' Library.

    Lord Shinwell My Lords, with great respect to the noble Lord, Lord Renton, may I ask the noble Lord the Minister how it is possible to estimate or determine the casualties that are likely to result from the use of nuclear weapons when the nuclear weapons have not been used? Do we not have to wait for what happens, and when it happens shall we not know what is going to happen? We shall be destroyed.

    § Lord Mishcon My Lords, will the noble Lord the Minister agree that the public of this country deserve a full, frank and simple account of what the Government feel, on scientific advice, to be the effects of nuclear war, in so far as one can carry that hypothesis through? Does the Minister feel that that may well encourage people to support, in so far as is practicable, a civil defence policy, whereas if the Government are not frank people will disbelieve?

    § Lord Elton My Lords, it is the purpose of the report to reveal what we believe the effects of certain nuclear weapons would be if they were used. That will no doubt contribute to the understanding of the public of the need for civil defence, as the noble Lord rightly suggests. ...

    § Lord Jenkins of Putney My Lords, is it not the case that the fortunate people in such an event would be not the survivors but those of us who were lucky enough to catch the full benefit of the blast? ...

    § Lord Renton My Lords, with regard to the question—if I may say so, the shrewd question—raised by the noble Lord, Lord Shinwell, is my noble friend aware that there have been nuclear tests in various parts of the world and that a great deal of scientific evidence has been accumulated as a result of those tests which would give us some indication of what could be done to help people who were not damaged by a direct hit by a nuclear bomb, but were on the wide perimeters of such an attack?

    On 10 November 1980, Home Secretary Brittan stated in a written answer in the House of Commons that 150,000 copies of nuclear civil defence pamphlet Protect and Survive had been printed at a cost of £9,758 (the price of the published booklet was 50p and it was placed on sale in May 1980). In the event of the imminent threat of nuclear war, it would have been reprinted for free issue to all householders. Therefore, the gross turnover from the first print run of Protect and Survive was £75,000. On 27 July 1981 Mayhew stated in a written answer to a question in the House of Commons that 81,000 copies of Protect and Survive had been sold up to that time, i.e. over a period of 14 months. On 5 March 1981, Mayhew had stated in response to a question about EMP wiping out all "radio and computer networks" to a 2,500 km radius, that Protect and Survive advice on using radio receivers was valid because: "We are advised that domestic transistor radios with internal aerials are substantially immune from damage by electromagnetic pulse. Precautions will be taken to reduce the risk of damage to wartime broadcasting service transmitters." Mayhew was referring to the Home Office EMP experimental research by A. D. Perryman which was published in its Restricted journal Fission Fragments, Issue No. 21, April 1977, page 25, EMP and the Portable Transistor Radio.

    On 16 January 1984, Home Secretary Hurd stated in a written answer in the House of Commons: "The booklet Protect and Survive will be replaced by further publications in due course. The scientific rules for assessing casualties from nuclear explosions are being reviewed and the results will be published as soon as the work is completed."

    On 19 January 1984, Hurd was asked "... does the Minister accept that these calculations fail to take account of the additional radiation arising from the blast destruction of buildings?" John Newman had examined effects of fallout blown into a buildings, due to blast-broken windows, in Health Physics, vol. 13 (1967), p. 991: ‘In a particular example of a seven-storey building, the internal contamination on each floor is estimated to be 2.5% of that on the roof. This contamination, if spread uniformly over the floor, reduces the protection factor on the fifth floor from 28 to 18 and in the unexposed, uncontaminated basement from 420 to 200.’ But measured volcanic ash ingress, measured as the ratio of mass per unit area indoors to that on the roof, was under 0.6% even with the windows open and an 11-22 km/hour wind speed as reported in U.S. Naval Radiological Defense Laboratory report USNRDL-TR-953, 1965. The main gamma hazard is from a very big surrounding area, not from trivial fallout nearby! Hence, the gamma radiation that needs to be shielded is not that from fallout under your feet. Even if the roof is blown off a building, since 90% of the fallout gamma radiation dose is from direct gamma rays (not Compton effect air scattered gammas) any walls or indeed pile of rubble will shield the long range direct gamma rays which are coming to you almost horizontally.

    Home Secretary Hurd replied: "We are updating our estimates and information and that will be published. One of the difficulties about this subject is the way in which some people persist in believing that the only possibility worth considering is a massive nuclear attack. That is simply not so. Civil defence planning and training must deal with a whole range of possibilities, including, of course, conventional attack."

    Mr. Neil Thorne then stated:

    "Will my right hon. Friend please make it clear that a increasing number of countries are capable of joining the nuclear powers and therefore any hostilities of this sort could come from one of those, which would create a very different scale of casualties from that following action by one of the super powers? Therefore, it would be quite wrong to reject civil defence purely and merely because some people believe that a major confrontation is quite incomprehensible."

    Home Secretary Hurd replied:

    "I have never understood the argument that because not every one could be saved, no attempt should be made to save anyone."

    On 20 December 1984, the Home Secretary stated to the House of Commons that: "Work is in hand on a replacement for Protect and Survive. It cannot be finalised until the review of the blast and radiation effects of nuclear weapons is available." He was then asked "whether he will include information on the properties of and protection against chemical weapons in any revised edition of Protect and Survive." He replied: "It will be included when this work is complete. ... It will cover those areas of civil defence which would be of direct relevance to the public including the action the public could take for protection against the effects of hostile attack and information on these effects and the complementary action that would be taken by local and central Government."

    (For fairly up-to-date civil defense countermeasures against chemical and biological terrorism, see the 2004 U. S. Department of State publication No. 11162, Responding to a Biological or Chemical Threat in the United States, while for convincing scientific data on casualty predictions see G. O. Rogers et al., Evaluating Protective Actions for Chemical Agent Emergencies, Oak Ridge National Laboratory for FEMA and the U. S. Army, ORNL-6615, 1990. Other useful information can be found here, here, here, here and here. The Hague Declaration of 1899 Concerning Asphyxiating Gases supposedly “banned” the use of “projectiles the sole object of which is the diffusion of asphyxiating or deleterious gases.” Despite this 1899 ban on poison gas, all sides used it extensively in World War I. So much for trusting security to making written promises. In his 1923 book The World Crisis, Winston Churchill summarised the wishful thinking of people towards warfare including chemical warfare in 1911: “It is too foolish, too fantastic to be thought of in the twentieth century ... No one would do such things. Civilisation has climbed above such perils. The interdependence of nations in trade and traffic, the sense of public law, the Hague Convention, Liberal principles, the Labour party, high finance, Christian charity, common sense have rendered such nightmares impossible.” Despite the wishful thinking of the 1899 Hague Convention banning chemical warfare, chemical warfare was used by both sides in World War I, and was used in gas chambers in World War II.)

    Above: the Home Office Scientific Advisory Branch forerunner during World War II ensured that every civilian and soldier had a reliable gas mask, which deterred Hitler from using nerve gases tabun and sarin (discovered in the late 30s by German chemists) against England. He was not being a nice guy: he was deterred by the fact that in highly dispersed form, nerve gas inhalation (not merely skin contact, which requires far larger doses and far more nerve gas to overcome disperson by the wind) is prevented by the activated charcoal absorbers in the cannisters of standard gas masks! If Hitler had used nerve gas, it would have been largely ineffective and would have led to a retaliation with mustard gas against Germany, which did not have enough gas masks due to a rubber shortage. (In Britain, rubber was stockpiled for gas masks long before war broke out and by September 1939, no less than 38 million gas masks had been issued to civilians.) Civil defence thereby helped to negate weapons of mass destruction.

    Above: school girls skipping in Britain during a World War II gas mask drill (such drills had to apply to sports recreation outdoors, as well as indoor activities). Cynical, evil anti-civil defence propaganda by falsely claims that because gas masks helped to negate the threat of, and thus deter, gas attacks, they 'were never used and therefore a waste of time and money; no more use than home fire insurance in a year when your home doesn't burn down'. Such people miss the whole point: civil defence is not just like a worthwhile insurance policy, but it actually helps to deter the enemy from attacking because it undermines the gains to be had from making an attack! If America had better aircraft security and defences against terrorists prior to 9/11, and the terrorists had been thus deterred, then we can envisage that terrorism-supporting anti security propaganda would doubtless have cynically and nefariously claimed that the defence measures were a 'waste of time and money' because they were never needed. The gas masks that deterred Hitler from using weapons of mass destruction were successful because they were never used against gas, they were successful because they were used as a deterrent; similarly nuclear weapons in the cold war were not a waste of time because they were never dropped, they were a success, in combination with some civil defence planning, for deterring the Soviet Union from launching an invasion of the West through nuclear intimidation.

    Above: this picture answers the question 'why didn't Hitler use his nerve gas against Britain in World War II?' Britain's comprehensive issue of gas masks for all civilian situations - including babies, children, telephone operators, the unconscious and people with acute breathing disorders - meant that Nazi nerve gas production was rendered impotent and obsolete; for it was simply inadequate to gas Britain. The LDt50 (i.e., the air concentration and exposure time product which has units of dosage*time/volume, and which gives rise to 50% lethality) for skin exposure to Nazi tabun and sarin nerve gases were 3,700 and 3,100 times the inhalation LDt50's, respectively. Issuing gas masks increased the amount of nerve gas needed by a factor of 3,700 for tabun and 3,100 for sarin. To overcome dispersion by the weather, the Nazis would have had to drench the country with nerve gas to get it on people's skin assuming people were out of doors, but they simply couldn't make enough nerve gas to do this. Thus, because of Britain's civil defence - which didn't even know about nerve gas, although they did know that the pores in activated charcoal absorbers will absorb any dangerously reactive molecules apart from carbon monoxide - the Nazis were effectively deterred from making what would have been an ineffective attack inviting effective retaliation. These scientific facts are totally ignored in evil anti-civil defence propaganda which ignores the fact that simple civil defence countermeasures in Britain successfully averted weapons of mass destruction during World War II.

    From the official British World War II History volume on Civil Defence, by Terence H. O'Brien, H. M. Stationery Office, London, 1955 (now out of the 50 years government copyright, and therefore scanned in and linked here in British A4 PDF format, page 81):
    “Early in 1937 some [anti-civil defence] scientific workers at Cambridge University, who described themselves as the ‘Cambridge Scientists’ Anti-War Group’ and their function as that of acting as ‘a technical and advisory body to national and international peace movements’, published a book attacking the Government's A.R.P. [Air Raid Precautions/civil defence] plans. This body had studied the official advice about the 'gas-proofing' of rooms, the civilian mask, and extinguishing incendiary bombs, and then conducted some experiments. It claimed to have shown that the measures officially proposed were ineffective or inadequate, and implied that these constitued deception of the public [this was precisely repeated in the 1980s when SANA/ ‘Scientists Against Nuclear Arms’ published a lying smear campaign against the U.K. Government’s Home Office Scientific Advisory Branch civil defence data; all of the problem in both instances was caused by official secrecy on weapons effects and countermeasures research, i.e. the published official handbooks omitted all of the very extensive experimental scientific data from the detailed research reports upon which they were based, leaving them scientifically unsubstantiated as presented and thus open to ‘ridicule’]. ... The Government’s reply was that the experiments were academic (in the sense of removed from reality), and based on fallacious assumptions about the conditions likely to be met in actual warfare.”

    A very important point about the role of effective asymmetrical civil defence in preventing attacks by gas is made by O’Brien on pages 329-330, where he states that although 44 million people in Britain had been issued a gas mask by the outbreak of war in September 1939, only 12 million gas masks had been issued to German civilians, due to the rubber shortage in Germany:

    “The data available to experts had suggested that a high degree of protection could only be achieved by equipping every civilian with a gas-mask. ... How far did Britain's [gas mask] defence on the outbreak of war and later deter Germany from using this weapon [gas] against her? It will be assumed throughout this volume that Hitler and Goering's restraint in using any weapon cannot be attributed to motives of humanity [they used gas in gas chambers], but solely to fear of reprisals or calculation that the aircraft and crews available could be used to better advantage in some other way. On this assumption, and taking into account Allied investigations after the war [where it was discovered that Germany had invented the nerve gases tabun, sarin, and soman in 1936, 1938 and 1944, stockpiling 12,000 tons of tabun as a war gas between April 1942 and May 1945], it would seem that the deterrent effect was considerable to the point, perhaps, of being decisive.”

    If you make an attack unlikely to succeed in the first place, and you don’t keep this fact top secret but explain it clearly with scientific evidence to back up the explanation, it is less likely that such an attack will ever be made, and you will be ready to handle it if it is made. This required a strategy of ongoing vigilance against gas attacks from the Nazis throughout WW II. For example, in 1940 all of the British black-coloured gas mask cannisters were modified by the taped-on addition of the small green coloured "contex" end filter to improve protection against arsine particles (designed to bounce around through the charcoal without undergoing absorption, and then induce vomiting and the removal of the mask), as O'Brien explains on page 332:

    “Early in 1940 the Government received reports that the Germans had found a method of using arsine gas (arseniurretted hydrogen) in the aerial bombardment of civilians. Since only the Service [military] masks offered full protection against this gas, the Government ordered the supply of 70,000,000 filters of an improved type for Civilian Duty, civilian and children's masks. In May the first of these - known as ‘contex’ since they formed small extensions to existing containers - were distributed to local authorities, and wardens began the considerable task of fitting them to the millions of masks in the possession of the public.”

    Above: the 1 cm thick green “contex” filter cartridges taped on to the front of all 70,000,000 issued and stockpiled (reserve) 1938 gas masks in 1940 to provided added protection against toxic arsine smoke particles. These gas masks, contrary to Cold War propaganda against civil defence, were not an “unneeded” or “token” countermeasure, but valuably helped to deter chemical warfare by credibly negating the Nazi chemical warfare threat, which included 12,000 tons of stockpiled tabun nerve gas, discovered by the Allies in 1945. Terrorists exploit vulnerability; they don't choose to attack using means that can be effectively countered. In this sense, the gas masks proved their worth.

    Above: the 1963 Civil Defence Handbook No. 10, Advising the Householder on Protection against Nuclear Attack, was cynically written by the Central Office of Information for either the illiterate or the inmates of lunatic asylums, and contained no justification or nuclear test experience to substantiate the crazy-sounding advice it offered. It quickly led to the closure of the Civil Defence Corps when it was held up and ridiculed in the House of Commons. It teaches the lesson that for civil defence, it is no good to dictatorially hand out 'official' nonsense-sounding advice, while keeping the facts that justify it secret. That is what communist and fascist dictatorships do, on the false grounds of 'secrecy' and 'national security' (in fact, some dictatorships are more open to their citizens that this). Instead of patronising citizens by refusing to reveal the solid scientific evidence for each protective measure, the facts must be disclosed to forestall cynical anti-civil defense propaganda. By contrast, the 1950 edition of the U.S. Department of Defense Effects of Atomic Weapons, edited by Dr Glasstone, on pages 392-9 justifies each protective action:

    'If a person is in the open when the sudden illumination is apparent, then the best plan is instantaneously to drop to the ground, while curling up so as to shade the bare arms and hands, neck and face with the clothed body. ... A person who is inside a building or home when a sudden atomic bomb attack occurs should drop to the floor, with the back to the window, or crawl behind or beneath a table, desk, counter, etc.; this will also provide a shield against splintered glass due to the blast wave. The latter may reach the building some time after the danger from radiation has passed, and so windows should be avoided for about a minute, since the shock wave continues for some time after the explosion. ... planning will be necessary to avoid panic, for mass hysteria could convert a minor incident into a major disaster.'

    It is estimated that Mongol invaders exterminated 35 million Chinese between 1311-40, without modern weapons. Communist Chinese killed 26.3 million dissenters between 1949 and May 1965, according to detailed data compiled by the Russians on 7 April 1969. The Soviet communist dictatorship killed 40 million dissenters, mainly owners of small farms, between 1917-59. Conventional (non-nuclear) air raids on Japan killed 600,000 during World War II. The single incendiary air raid on Tokyo on 10 March 1945 killed 140,000 people (more than the total for nuclear bombs on Hiroshima and Nagasaki combined) at much less than the $2 billion expense of the Hiroshima and Nagasaki nuclear bombs! Non-nuclear air raids on Germany during World War II killed 593,000 civilians.

    J. K. S. Clayton (formerly with the Weapons Department of the RAE Farnborough which he joined in 1946), as Director of the Home Office Scientific Advisory Branch oversaw Thatcher’s brilliant ‘Protect and Survive’ era civil defence assault on the Soviet Union (which was controversial because it presented facts about how to protect against nuclear weapons blast, heat and fallout without giving the nuclear test data which validated those facts). Clayton wrote about the basis of Protect and Survive policy in his lengthy and brilliant introduction, 'The Challenge - Why Home Defence?', to the Home Office 1977 Training Manual for Scientific Advisers:

    'Since 1945 we have had nine wars - in Korea, Malaysia and Vietnam, between China and India, China and Russia, India and Pakistan and between the Arabs and Israelis on three occasions. We have had confrontations between East and West over Berlin, Formosa and Cuba. There have been civil wars or rebellions in no less than eleven countries and invasions or threatened invasions of another five. Whilst it is not suggested that all these incidents could have resulted in major wars, they do indicate the aptitude of mankind to resort to a forceful solution of its problems, sometimes with success. ...

    'Let us consider what a nuclear attack on the United Kingdom might mean. It will be assumed that such an attack will only occur within the context of a general nuclear war which means that the UK is only one of a number of targets and probably by no means the most important. It follows that only part of the enemy's stock of weapons is destined for us. If the Warsaw Pact Nations constitute the enemy - and this is only one possible assumption - and if the enemy directs the bulk of his medium range and intermediate range weapons against targets in Western Europe behind the battle front, then Western Europe would receive about 1,000 megatons. Perhaps the UK could expect about one fifth of this, say 200 Mt. Let us assume rather arbitrarily that this would consist of 5 x 5 Mt, 40 x 2 Mt, 50 x 1 Mt and 100 x 1/2 Mt.

    'An attack of this weight would cause heavy damage over about 10,000 square kilometres, moderate to heavy damage over about 50,000 square kilometres, and light damage over an additional 100,000 square kilometres. (Light damage means no more than minor damage to roofs and windows with practically no incidence of fire.) We can compare the heavy damage to that suffered by the centre of Coventry in 1940. This will amount to approximately 5% of the land area of the UK. Another 15% will suffer extensive but by no means total damage by blast and fire; another 40% will suffer superficial damage. The remaining 40% will be undamaged. In other words, four-fifths of the land area will suffer no more than minor physical damage. Of course, many of the undamaged areas would be affected by radioactive fallout but this inconvenience would diminish with the passage of time.

    'Policy to meet the Threat

    'The example just given of the likely severity of the attack - which is, of course, only one theoretical possibility - would still leave the greater part of the land area undamaged and more people are likely to survive than to perish. Government Home Defence policy must therefore be aimed to increase the prospects of the survivors in their stricken environment.'

    Clayton's booklet Protect and Survive was first prepared and printed in 1976, but was only used for training purposes until it was published and placed on sale in May 1980. It was justified by Dr Carl F. Miller’s work on fallout radiation at the CASTLE, REDWING and PLUMBBOB nuclear test series in 1954, 1956 and 1957; the research he directed explained the nature and radiation properties of fallout, which is especially easy to shield for the case of 'dirty' bombs with U-238 casings, because much of the gamma radiation from these weapons in the period of hours to weeks after burst is very low energy (easily shielded) gamma rays from neutron induced isotopes like Np-239 (resulting from neutron capture in U-238) and U-237 (resulting from neutron capture in U-238 followed by double neutron emission, the n,2n reaction first discovered by Professor Kenjiro Kimura, who used this reaction to discover Uranium-237, and later found this isotope in the CASTLE-BRAVO fallout that landed on Japanese fishing boat 'Lucky Dragon' on 1 March 1954).

    The British Home Office report reviewing in great detail Dr Carl F. Miller's 1963 Stanford Research Institute vital report Fallout and Radiological Countermeasures is: HO 227/74 Home Office: Scientific Adviser's Branch and successors: SA/PR Reports Series, Fallout and radiological counter-measures, Former reference (Department) SA/PR 74. Dr Miller's report was a complete chemical, physical and radiological model of the fallout process, and answered all of the Home Office Scientific Advisory Branch concerns about:

    (1) the physical and chemical nature (solubility, stickiness, etc.) of fallout,

    (2) the actual mass (kilograms per square metre) of deposited fallout (to sweep up and decontaminate) associated with given radioactivity intensities,

    (3) the fractionation of fission products as a function of the distance from the detonation (the most hazardous large fallout particles near ground zero are seriously lacking in soluble, ingestible fission products like iodine-131, strontium-90 and caesium-137, because these isotopes have either gaseous precursors or are volatile with a low boiling point, so they only 'plate out' on to the surfaces of the still-present tiny particles of solidified fallout after the fireball has cooled to low temperatures in the last stages of fallout formation, and those tiny particles take a long time to fall out, being deposited globally not locally), and

    (4) the radioactive decay rate as modified by fractionation of different fission product decay chains in the hot, condensing fireball and also the vital effect of neutron induced activities like U-239, Np-239, U-240, Np-240 and U-237 on the decay rate and the gamma ray spectra of fallout radiation, which of course determines the penetrating ability of the gamma radiation from fallout and the protection afforded by simple expedient countermeasures against it, particularly at times of 2 hours to 2 weeks after burst when sheltering is most important because the intensity is greatest; low-energy or soft gamma rays from fractionated local fallout fission products and in particular from neutron-induced activities such as Np-239 and U-237 formed by neutron capture in the casings of dirty fission-fusion-fission 3-stage thermonuclear weapons with U-238 jackets, are much more easily shielded than the harder gamma ray spectrum from unfractionated fission products as a whole.
    (For additional data on fallout see the earlier posts here and here.)

    Clayton's decisive civil defence actions based on the Miller fallout data were later strongly supported by British Prime Minister Margaret Thatcher (a former research chemist, unlike most scientifically ignorant politicians) who - despite her widely perceived domestic policy failings as a right-wing woman - backed the morality of civil defence and on foreign policy issues stood up to terrorist state dictator Leonid Brezhnev, echoing Clayton's pragmatic outlook on war in her address to the United Nations General Assembly on disarmament on 23 June 1982, when she pointed out that in the years since the nuclear attacks on Hiroshima and Nagasaki, 10 million people were killed by 140 non-nuclear conflicts, so:

    ‘The fundamental risk to peace is not the existence of weapons of particular types. It is the disposition on the part of some states to impose change on others by resorting to force against other nations ... Aggressors do not start wars because an adversary has built up his own strength. They start wars because they believe they can gain more by going to war than by remaining at peace.’

    On 29 October 1982, Thatcher stated of the Berlin Wall:

    ‘You may chain a man, but you cannot chain his mind. You may enslave him, but you will not conquer his spirit. In every decade since the war the Soviet leaders have been reminded that their pitiless ideology only survives because it is maintained by force. But the day comes when the anger and frustration of the people is so great that force cannot contain it. Then the edifice cracks: the mortar crumbles ... one day, liberty will dawn on the other side of the wall.’

    Leonid Brezhnev fortunately died on 10 November 1982, while Reagan and Thatcher challenged the Soviet Union's nuclear superiority with increased civil defence efforts coupled to military expenditure in a successful effort to bankrupt and reform the corrupt Soviet terrorist system.

    On 22 November 1990, she was able to declare: ‘Today, we have a Europe ... where the threat to our security from the overwhelming conventional forces of the Warsaw Pact has been removed; where the Berlin Wall has been torn down and the Cold War is at an end. These immense changes did not come about by chance. They have been achieved by strength and resolution in defence, and by a refusal ever to be intimidated.’

    'The case for civil defence stands regardless of whether a nuclear deterrent is necessary or not. ... Even if the U.K. were not itself at war, we would be as powerless to prevent fallout from a nuclear explosion crossing the sea as was King Canute to stop the tide.' - U.K. Home Office leaflet, Civil Defence, 1982.

    ABOVE: excellent nuclear test evidence-based civil defence protection film by the U.S. Navy, Nuclear Effects at Sea. Robert Jungk's book, Children of the Ashes, Heinemann, London, 1961, cites a report in Hiroshima by American psychologist Woodbury Sparks called Panic Among A-Bomb Casualties at Hiroshima which showed that due to their surprise at the effects of the nuclear explosion, only 26 percent (153 out of a random sample of 589 bomb survivors in Hiroshima) gave any assistance at all to anybody else after the explosion. Seeing that the majority of the people in each city survived and that a major cause of death was the burning of blast damaged wooden houses containing persons trapped by blast debris, a lot more could have been done if people had been prepared. This is one of the civil defence lessons from Hiroshima: the emotional shock prevented proper action. Effective civil defence training in the solid, unvarnished facts about nuclear effects phenomenology can avert this shock, enabling help to be given more efficiently where and when practical to save lives and minimise injury.

    Above: Morrison steel table indoor shelter which survived the debris load of a collapsed house, and a badly damaged Anderson garden shelter which nevertheless did its job and saved lives of three children when their house was wrecked during World War II bombing.

    Overall lifesaving civil defence effectiveness in Britain and Germany during World War II

    German bombing damaged or destroyed 2 million houses in Britain during World War II, but the 60,595 people killed from bombing in Britain was 0.030 persons killed per house destroyed or damaged. In London alone, 1,200,000 houses were damaged or destroyed, and 29,890 were killed by bombing, 0.025 persons killed per house destroyed or damaged. Without civil defence, the ratio of the number of people killed per house destroyed could have been much greater than 0.025-0.030. Assuming just 2 persons per house, this means that the assumption of 100% killed per damaged or destroyed house exaggerates deaths from bombing by a factor of 2/0.025 to 2/0.030 or 67 to 80.

    In Germany, where there were firestorms in medieval wooden areas of Dresden and Hamburg, 300,000 people were killed and 3,600,000 houses were destroyed, a ratio of 0.083 persons killed per house destroyed. 7,500,000 people were made homeless, so there had been roughly 2 persons living in each house destroyed. Hence, the assumption of 100% killed in destroyed houses would exaggerate deaths by a factor of 2/0.083 = 24 times.

    Above: some of Penney's 1970 published data for the attenuation of peak blast overpressure by the act of causing destruction in Hiroshima and Nagasaki, which lowers the peak overpressure in a city relative to that over unobstructed terrain. This effect means that the desert nuclear test-validated cube-root distance scaling law severely exaggerates peak overpressures at large distances from nuclear weapons exploding in or over cities. The very first edition of Glasstone's nuclear effects handbook, The Effects of Atomic Weapons, 1950, on page 57 has a section written by John von Neumann and Fredrick Reines of Los Alamos (it is attributed to them in a footnote) stating factually:

    "... the structures ... have the additional complicating property of not being rigid. This means that they do not merely deflect the shock wave, but they also absorb energy from it at each reflection.

    "The removal of energy from the blast in this manner decreases the shock pressure at any given distance from the point of detonation to a value somewhat below that which it would have been in the absence of dissipative objects, such as buildings."

    This was removed from future editions. This isn't speculative guesswork: it's down to the conservation of energy. I emailed Dr Harold L. Brode and other experts about why it isn't included in American nuclear weapons effects manuals. Dr Brode kindly replied with some relevant and interesting facts about non-radial energy flows in Mach waves and the transfer of energy from the blast wave to flying debris (which, alas, travels slower than the supersonic shock front because the blast wind is always slower than the shock front velocity). It is true that the energy loss from the blast wave near ground level is partially offset by downward diffraction of energy from the diverging blast wave at higher altitudes. However, this downward diffraction process is not a 100% efficient compensator for energy loss, particularly for the kinetic energy of the air (the dynamic pressure or wind drag effect). The dynamic pressure (which in unobstructed desert or ocean nuclear tests makes the blast more hazardous for higher yield weapons) is an air particle effect not a wave effect so it does not diffract like a wave, and it is cut down severely when transferring its energy to building debris. Even if every house absorbs just 1% of the incident energy per unit of area incident to the blast, then the destruction of a line of 100 houses cuts the blast energy down to 0.99100 = 0.366 of what it would be over a desert surface. Basically, this chops down the collateral blast damage from large yield weapons detonated in cities and affects the usual scaling laws, making nuclear weapons even less dangerous than predicted by the textbook equations and curves.

    A. D. Perryman's 1964 Home Office Scientific Advisory Branch report CD/SA 117, Experimental determination of protective factors in a semi detached house with or without core shelters, National Archives document HO 225/117, is the key document behind Protect and Survive. A concise illustrated summary of it was published in the report by D. T. Jones, The Protection Against Fallout Radiation Afforded by Core Shelters in a Typical British House, published on pages 298-303 of the U.S. Proceedings of the Symposium held at Washington, D.C. April 19-23, 1965 by the Subcommittee on Protective Structures, Advisory Committee on Civil Defense, U.S. National Research Council, Protective Structures for Civilian Populations (available freely as a PDF download from Google is linked here). Jones' report states that a survey of protective factors (fallout gamma radiation dose rate reduction factors) in 11 districts of Britain in 1958 showed that, with no protection other than windows being blocked (with say sandbags) to the same mass per unit area as the walls, some 36% of houses had protective factors of 1-25, 28% had protection factors of 25-39, 29% had 40-100 and 7% had over 100. In the summer of 1963, the benefit from "core shelters" in houses of the easily improvised Protect and Survive sort were measured for radiation shielding efficiency at the Civil Defense School, Falfield park, Gloucestershire. The measured protection factor of 21 in the house was increased to 39 inside the Protect and Survive "lean to" shelter consisting of simply doors piled with bags of matter leaning against an inner wall.

    It is vitally important to stress that all such measurements using say 1.25 MeV mean energy gammas from Co-60 or similar standard radioactive sources, massively underestimate protection factors from the most threatening types of fallout hazard, i.e. those from the U-238 encased thermonuclear bombs, due to low gamma ray energy caused by fractionation and neutron induced non-fission activities like U-239, Np-239, U-240, and U-237 in the U-238 casing, as explained by Dr Terry Triffet (fallout characterization project officer for Operation REDWING) at the 22-26 June 1959 Congressional Hearings on the Biological and Environmental Effects of Nuclear War. Dr Triffet on pages 61-111 of those published hearings and also in weapon test report WT-1317 co-authored with Philip D. LaRiviere showed that at 1 week after burst, the mean gamma ray energy of fractionated fallout 8 statute miles downwind on Bikini Lagoon barge YFNB 29 due to 5.01 Mt burst 87% fission REDWING-TEWA in 1956 was just 0.25 MeV (4.5 grams per square foot of fallout was deposited there, giving a peak dose rate on the barge of 40 R/hr at 2.7 hours after burst), while at 60 statute miles on ship LST 611 downwind it was 0.35 MeV (due to less depletion of high energy fission products at greater distances, a fractionation effect) where only 0.06 gram/square foot of fallout was deposited giving a peak dose rate of 0.25 R/hr at 14 hours after burst. On page 205 of the June 1959 hearings on the Biological and Environmental Effects of Nuclear War, Dr Triffet explained that the low gamma ray energy makes most of the radiation very easy to shield by improvised emergency countermeasures:

    'I thought this might be an appropriate place to comment on the variation of the average energy. It is clear when you think of shielding, because the effectiveness of shielding depends directly on the average energy radiation from the deposited material. As I mentioned, Dr Cook at our [U.S. Naval Radiological Defense] laboratory has done quite a bit of work on this. ... if induced products are important in the bomb [dirty bombs with U-238 jackets], there are a lot of radiations emanating from these, but the energy is low so it operates to reduce the average energy in this period and shielding is immensely more effective.'

    George R. Stanbury of the Home Office Scientific Advisory Branch investigated the contribution of low-energy Np-239 to fallout radiation for civil defence purposes in his 1959 report The contribution of U239 and Np239 to the radiation from fallout, National Archives document HO 226/75 (beware: Stanbury makes a calculating error in the computation of the contribution from U-239, but that is not as important as the Np-239 which is accurate). The Home Office gained a detailed confirmation of this from Dr Carl F. Miller's Fallout and Radiological Countermeasures, vol. 1, in 1963, which merited a lengthy review report, National Archives document HO 227/74. (Page 432 of the 1962/64 editions of Glasstone's Effects of Nuclear Weapons also confirmed Stanbury's estimate that non-fission neutron induced activities in U-238 cased bomb fallout contribute up to about 40% of the gamma radiation about 4 days after detonation.)

    In 1932, former and future Prime Minister Stanley Baldwin had falsely told the House of Commons:

    "I think it is well for the man in the street to realise that there is no power on earth that can protect him from being bombed. Whatever people may tell him, the bomber will always get through. The only defence is in offence, which means that you have to kill more women and children more quickly than the enemy if you want to save yourself."

    However, in March 1938 the British Home Secretary Samuel Hoare issued to every household in Britain the 38-page long booklet The Protection of Your Home Against Air Raids. (Available in full here.) Key pages from this booklet are reproduced below:

    "... history is apparently not among the areas of expertise claimed by IPPNW [international physicians for the prevention of nuclear war]. Its spokesmen have yet to comment on the Washington Naval Treaty of 1922, the Kellogg-Briand Pact of 1928 (for which Kellogg and Briand received the Nobel Peace Prize), the Oxford Peace Resolution of 1934, the Munich Agreement of 1938, or the Molotov-Ribbentrop Pact of 1939, and on the effectiveness of these measures in preventing World War II. ...

    "Sir Norman Angell (also a Nobel Peace Prize winner), in his 1910 best-seller entitled The Great Illusion, showed that war had become so terrible and expensive as to be unthinkable. The concept of ‘destruction before detonation’ was not discovered by Victor Sidel (Sidel, V. W., ‘Destruction before detonation: the impact of the arms race on health and health care’, Lancet 1985; ii: 1287-1289), but was previously enunciated by Neville Chamberlain, who warned his Cabinet about the heavy bills for armaments: ‘even the present Programmes were placing a heavy strain upon our resources’ (Minutes of the British Cabinet meeting, February 3, 1937: quoted in Fuchser, L. W., Neville Chamberlain and Appeasement: a Study in the Politics of History, Norton, New York, 1982). ...

    "Psychic numbing, denial, and ‘missile envy’ (Caldicott, H., Missile envy: the arms race and nuclear war, New York: William Morrow, 1984) are some of the diagnoses applied by IPPNW members to those who differ with them. However, for the threats facing the world, IPPNW does not entertain a differential diagnosis, nor admit the slightest doubt about the efficacy of their prescription, if only the world will follow it. So certain are they of their ability to save us from war that these physicians seem willing to bet the lives of millions who might be saved by defensive measures if a nuclear attack is ever launched.

    "Is this an omnipotence fantasy?"

    - Jane M. Orient, MD, ‘INTERNATIONAL PHYSICIANS FOR THE PREVENTION OF NUCLEAR WAR: MESSIAHS OF THE NUCLEAR AGE?’, The Lancet (British medical journal), 18 November 1988, pp.1185-6. (See also link here.)

    British civil defence research in Hiroshima and Nagasaki, 1945

    Above: the British Mission to Japan in 1945 evaluated the nuclear explosion damage at Hiroshima and Nagasaki, producing a report called The Effects of the Atomic Bombs at Hiroshima and Nagasaki (linked here, 42.5 MB pdf file). The purpose of the British Mission was for ten British Home Office bomb damage scientists to directly compare the British bomb damage assessment criteria from German air raids upon British cities with conventional bombs to the effects of nuclear weapons. Page 6 states:

    "Photographs in this report and elsewhere show great areas of destruction in which, rising here and there like islands, there remain reinforced concrete buildings showing few signs of external damage. There were in fact many reinforced concrete buildings in Hiroshima and a number in Nagasaki. ... These observations make it plain that reinforced concrete framed buildings can resist a bomb of the same power detonated at these heights, without employing fantastic thicknesses of concrete."

    On page 8, the report finds that Japanese wood-frame houses collapsed out to a ground range of 2.0 km in Hiroshima (at this range, 50% of the wood-frame houses were subsequently burned out by the fire storm, due to the blast wave displacement of breakfast cooking charcoal braziers and flammable traditional bamboo/paper screen furnishings in the wooden houses; at 2.6 km only 10% were burned out and at 1.0 km about 90% were burned out) and 2.4 km in Nagasaki, while typical brick type British type only collapsed out to an average distance of 910 metres (at 1.6 km they were standing but irrepairably cracked, at 2.4 km they needed repair before habitation and there was minor damage from 3.2-4.0 km). Page 9 states:

    "The provision of air raid shelters throughout Japan was much below European standards. Those along the verges of the wider streets in Hiroshima were comparatively well constructed: they were semi-sunk, about 20 ft. long, had wooden frames, and 1 ft. 6 ins. to 2 ft. of earth cover. One is shown in photograph 17. Exploding so high above them, the bomb damaged none of these shelters.

    "In Nagasaki there were no communal shelters except small caves dug in the hillsides. Here most householders had made their own backyard shelters, usually slit trenches or bolt holes covered with a foot or so of earth carried on rough poles and bamboos. These crude shelters, one of which is shown in photograph 18, nevertheless had considerable mass and flexibility, qualities which are valuable in giving protection from blast [better protection is provided by "earth arching", where a weak arched structural support is used during construction to hold up a mound of packed earth, but the earth acts to deflects the load around the weak support when hit by a blast wave]. Most of these shelters had their roofs forced in immediately below the explosion; but the proportion so damaged had fallen to 50 per cent. at 300 yards from the centre of damage, and to zero at about 1/2 mile.

    "These observations show that the standard British shelters would have performed well against a bomb of the same power exploded at such a height. Anderson shelters [1.5 million of which were assembled in Britain by September 1939, each sleeping 6 people], properly erected and covered, would have given protection. Brick or concrete surface shelters with adequate reinforcement would have remained safe from collapse. The [indoor] Morrison shelter is [a steel table type shelter] designed only to protect its occupants from the debris load of a [collapsing] house, and this it would have done. Deep shelters such as the refuge provided by the London Underground would have given complete protection."

    Page 11: "There were cases where a clump of grass or the leaf of a tree had cast a sharp shadow on otherwise scorched wood. Therefore the most intense flash from the ball of fire had ended in a time less than that required to shrivel vegetation. On the other hand, since direct injuries to the eye-ball were not common, the heat radiation may be presumed to have required a perceptible time to build up to its maximum intensity, during which some people had closed their eyes."

    Above: U.S. Army photo showing how a mere leaf of Fatsia japonica attenuated the heat flash enough to prevent scorching to the bitumen on an electric pole near the Meiji Bridge, 1.3 km range, Hiroshima. It didn't even vaporize the leaf before the pulse ended, let alone did it ignite the wooden pole (most photos claiming to show thermal flash radiation effects in Hiroshima and Nagasaki show effects from the fires set off by the blast wave overturning cooking stoves, which developed 30 minutes to 2 hours later).

    Page 12: "In general, even thin clothing protected from flashburn. There were a few exceptions, when the skin was burnt through uncharred fabric where the latter was stretched tightly, say over the point of the shoulder. On other occasions, equally rare, clothing caught fire without burning the skin [the flames were easy to put out when the thermal pulse subsided]."

    Above: photos of a Hiroshima woman (left) with flash burns where the dark pattern lines printed on tight-fitting clothing conducted heat to the skin, and a Nagasaki man (right) with the shadow of his vest burned on his skin; from Figure 1.3 in the January 16, 2009 manual, Planning Guidance for Response to a Nuclear Detonation, developed by the U.S. Homeland Security Council Interagency Policy Coordination Subcommittee for Preparedness & Response to Radiological and Nuclear Threats.

    Page 14: "The Japanese had provided fuel for the fires [in buildings] by introducing a mass of wooden detail [also paper screens and bamboo furnishings] into otherwise fireproof buildings. Photograph 20 shows the interior of one of the reinforced concrete buildings of the hospital in Nagasaki, 1/2 mile from the centre of damage. Having resisted the blast, these buildings and their services were denied to the city at a critical time because they were filled with such material as that shown in the photograph: a false lath and plaster ceiling hung on heavy timbers, a wooden floor raised on wooden beams, and plaster walls on battens and laths.

    "As a result, about half the occupants were killed or were trapped and died in the fires which broke out nearly everywhere among this material It is a very plain lesson that a fireproof building should not be converted into a major fire risk and a trap for its tenants by ill-chosen fittings."

    In order to estimate the casualty rate curve, the British Mission to Japan on page 18 uses detailed survival records from a group of 15,000 Hiroshima school children working throughout the city on the construction of fire breaks and other tasks when the bomb fell in the early morning. Scaling the data to the London population density of 45 people per acre, they calculated on page 19 that 65,000 people would be killed in a British city without evasive action, or 50,000 allowing for the fact that some people would be indoors inside brick rather than wooden buildings. Assuming 15 houses per acre of ground, they then calculated that 30,000 houses would be beyond repair after an Hiroshima type attack on a British city, with another 35,000 needing extensive repair. The British Home Office bombing effects scientists who had seen the destruction at Hiroshima and Nagasaki stated on page 13 of the Home Office Civil Defence Manual of Basic Training, Vol. 2 Pamphlet No. 6, Atomic Warfare (H. M. Stationery Office, 1950):

    "If the people in our cities were caught, as were the Japanese, without [credible] warning, before any evacuation had taken place, and with no suitable shelters, the casualties caused by a [Hiroshima or Nagasaki type] high air burst would be formidable [thermal effects would be reduced severely in a surface or low air burst by shadowing due to structures blocking the line-of-sight to the fireball before the blast wave arrival time, and by loss of energy due to crater throwout, etc.]. The British Mission to Japan estimated that under these circumstances as many as 50,000 people might lose their lives in a typical British city with a population density of 45 persons to the acre. Much can be done, however, to mitigate the effects of the bomb and to save life, and it is certain that with adequate advance preparations, including the provision of suitable [WWII type] shelters and with good Civil Defence services, the lives lost could be reduced to a fraction of the number estimated by the British Mission."

    That statement had been personally approved in June 1950 by no less than the then British Prime Minister, Clement Attlee, who contributed a page-long personally signed Foreword to that "Atomic Warfare" pamphlet, explaining concisely that Civil Defence was needed to combat the proliferation of nuclear weapons (click on images for larger view):

    ABOVE: a 1950s British Civil Defence Corps poster, explaining that civil defence is important in peacetime emergencies, such as the 1953 floods in England, just as it is important in war.

    ABOVE: a 1950s British Civil Defence Corps poster, explaining evacuation planning and organization in September 1939 when war was declared, which is also needed in case of nuclear hostilities.

    ABOVE: a 1950s British Civil Defence Corps poster, showing rescue of trapped people. The whole point of civil defence is precisely the problem that enormous numbers of houses can be destroyed in either massive enemy conventional bombing raids, or a single nuclear explosion: either way, the conventional peacetime energency services such as the fire brigade would not be able to cope with the tremendous (but not unlimited) scale of destruction in a built up area. This is the reason why hundreds of thousands of civil defence volunteers were trained in rescue, first aid, the effects of various weapons including chemical, biological, nuclear and conventional weapons, and the emergency feeding and evacuation measures which are important for any kind of emergency including natural ones like floods. Civil defence membership peaked at 336,265 by May 1956 (The Times, 2 May 1956, p 6). This would have been enough to make a large difference in the event of a war or disaster.

    ABOVE: (click on image for larger view) 1958 British Civil Defence Corps poster (29 inches wide x 23 inches high, printed by Her Majesty's Stationery Office), extrapolating damage in the wood frame inflammable cities of Hiroshima and Nagasaki to a British city with brick, concrete and steel-frame buildings. This poster shows the severe damage such as building collapse at 0.5 mile from ground zero after a 20 kt air burst at an altitude of 1760 feet, or at equivalent scaled distances (to brick houses which diffraction-vulnerable overpressure targets) from a 10 megaton burst. (The posters came in a set of eight, namely 1 & 1a, 2 & 2a, 3 & 3a , and 4 & 4a, showing four typical streets both before and after the explosion, thus illustrating typical complete destruction, heavy damage, moderate damage and light damage. They are based on data from Hiroshima and Nagasaki nuclear attacks on brick and concrete structures corresponding to U.K. type housing, as well as a Nevada nuclear test on brick houses in 1955, and a wealth of conventional bombing experience on London and other U.K. cities from World War II. We will just show the "after" posters, because the "before" posters are show typical terraced streets of houses, shops and multistorey buildings of the types still dominant throughout London today, a half century later.)

    ABOVE: a 1958 British Civil Defence Corps poster, showing damage at 0.67 mile from ground zero after a 20 kt air burst at an altitude of 1760 feet, or at equivalent scaled distances (to brick houses which diffraction-vulnerable overpressure targets) from a 10 megaton burst.

    ABOVE: a 1958 British Civil Defence Corps poster, showing damage at 0.85 mile from ground zero after a 20 kt air burst at an altitude of 1760 feet, or at equivalent scaled distances (to brick houses which diffraction-vulnerable overpressure targets) from a 10 megaton burst.

    ABOVE: a 1958 British Civil Defence Corps poster, showing damage at 1.3 mile from ground zero after a 20 kt air burst at an altitude of 1760 feet, or at equivalent scaled distances (to brick houses which diffraction-vulnerable overpressure targets) from a 10 megaton burst.

    ABOVE: a 1950s British Civil Defence Corps poster, showing warden equipped with anti-contamination protective clothing, a pen-like quartz fibre dosimeter to measure integrated gamma radiation dose and a RADIAC (radioactivity detection, identification and computation) survey meter to measure the varying dose rate of beta and gamma radiation (a hinged aluminium flap on the base of the instrument could be opened to measure beta plus gamma, and shut to measure gamma radiation only; the dosimeters and the RADIAC Survey Meter No. 2 instruments were checked for calibration accuracy and rugged reliability against real nuclear bomb fallout at the four British-Australian nuclear tests in Maralinga, Operation Buffalo, in 1956).

    ABOVE: a selection of random 1950s British Civil Defence Corps posters, focussing on the aspects of civil defence which are common to not just nuclear attack, but also to the experience of civil defence during World War II, when attacks on London occurred repeatedly by large numbers of aircraft, V1 cruise missiles and V2 rocket missiles. In 1950, the Top Secret British Home Office Scientific Advisory Branch report SA/16 (HO225/16 in the UK National Archives), 'The number of atomic bombs equivalent to the last war air attacks on Great Britain and Germany', concluded:

    ‘The wide publicity given to the appalling destruction caused by the atomic bombs at Hiroshima and Nagasaki has possibly tended to give an exaggerated impression of their effectiveness. Perhaps the best way to counteract this impression, and to help to get the atomic bomb to scale, is to consider the numbers of atomic bombs that would have to be dropped on this country and on Germany to have caused the same total amount of damage as was actually caused by attacks with high explosive and incendiary bombs.

    ‘During the last war a total of 1,300,000 tons [i.e. 1.3 MEGATONS of bombs] were dropped on Germany by the Strategic Air Forces [of Britain and America]. If there were no increase in aiming accuracy, then to achieve the same amount of material damage (to houses, industrial and transportational targets, etc.) would have required the use of over 300 atomic bombs together with some 500,000 tons of high explosive and incendiary bombs for targets too small to warrant the use of an atomic bomb… the total of 300,000 civilian air raid deaths in Germany could have been caused by about 80 atomic bombs delivered with the accuracy of last war area attacks, or by about 20 atomic bombs accurately placed at the centres of large German cities...’

    This report, SA/16, was kept Top Secret for 8 years, and then Restricted for another 22 years. It was never published, and civil defence was gradually undermined by the exaggeration of nuclear weapons effects by political groups such as CND, the full facts remaining secret.

    Before Mr Pseudoscience of CND makes the claim that the Home Office miss-divided 1.3 megatons of bombs into 20 kilotons, adding that "everyone can see that 1.3 Mt is just 65 times 20 kt", it should be pointed out, as explained in the comments at and, that blast damage radii for overpressure diffraction damage scale at most as the cube-root of yield (or more slowly than the cube-root if allowance for blast attenuation by the work energy used in destroying houses while the blast knocks down successive houses in a radial line from ground zero is included in the calculations). Areas of damage scale as the square of the ground range, or the two-thirds of yield at most.

    Hence, the 1.3 megatons of small bombs dropped as mentioned in this blog post is not anywhere remotely equivalent to a single 1.3 megaton nuclear bomb. It turns out that 1.3 megatons as a single explosive is only the equivalent of 4.64 kilotons of 100 kg bombs, because efficiency is greater for smaller bombs.

    (This is the reason that America stopped designing very high yield thermonuclear weapons after the 1954 nuclear tests of Operation Castle, and the mean yield of the 4,552 nuclear warheads and bombs in the deployed 1.172 Gt or 1,172 Mt U.S. nuclear stockpile is only 0.257 Mt or 257 kt. 257 kt is just 12 times the yield of the Nagasaki bomb, so by the cube-root scaling law the blast destruction radii for the mean yield of 257 kt is just 2.27 times the blast destruction radii in Nagasaki. Because there are no flimsy wood-frame inflammable cities in the West, the actual effects of typical stockpiled nuclear weapons today would be less severe than they were in Nagasaki.)

    Because the average bomb size of conventional (chemical) high explosive bombs was under 100 kg in WWII, they were far more efficient than a megaton nuclear bomb: relative area damaged = number of bombs * {bomb yield}2/3

    Hence to get the same area damaged by 100 kg TNT bombs as by a 1 Mt nuclear bomb, you would need only 1/(10-7)2/3 = 46,400 conventional 100 kg bombs, a total of just 46400*0.0001 = 4.64 kilotons of bombs doing the same area destruction as a single 1 megaton bomb. To emphasise this non-linear addition law:

    1 megaton of TNT as a single explosion = 4.64 kt of 100 kg bombs in an air raid

    The relative efficiency of the single 1 Mt nuclear bomb in this example is only 0.464% compared to conventional small TNT explosive bombs.

    Hence, heavy conventional high explosive bombing raids with hundreds of aircraft in WWII produced the same destruction as a relatively large thermonuclear weapon. The fact that easily mitigated effects (such as delayed fallout and thermal radiation which is easily avoided by ducking and covering skin) were absent in the high explosive attacks, where the energy wasn't wasted but mainly went into blast wave damage, made conventional warfare far more dangerous.

    Above: All that happened to the Anderson shelters 400 yards from the 25 kt Hurricane nuclear test on 3 October 1952 was that a few sand bags were blown off by the arrival of the blast wave, but by that time the initial nuclear radiation and thermal radiation pulses were already over, so the sandbags had shielded the radiation. Frank H. Pavry, who as part of the British Mission to Japan had observed the surviving air raid shelters near ground zero in both Hiroshima and Nagasaki in 1945, organized the construction of 15 Anderson shelters. In World War II, two types of shelters were issued by the U.K. government to householders: the 'Morrison' (a steel table designed to resist the debris load from the collapse of a house, which was introduced in March 1941 and named after the Home Secretary, Herbert Morrison), and the 'Anderson' which was an outdoor shelter supplied to 2,100,000 householders (a 14-gauge corrugated steel arch shelter, 2 m long, 1.4 m wide and 1.8 m high, designed to accommodate 6 people and to be sunk to 1.2 metre depth and covered by at least 40 cm of earth; it was invented in 1938 and named after Sir John Anderson, who was in charge of U.K. Air Raid Precautions/Civil Defence).

    Frank H. Pavry's report, Operation HURRICANE: Anderson Shelters, Atomic Weapons Research Establishment, AWRE-T17/54, was originally classified 'Secret - Atomic'. The 15 Anderson shelters had survived very well. Nearest to the bomb ship, they survived a peak overpressure of 55 psi or 380 kPa without internal damage: sand bags on the outside were hurled off when the blast wave arrived, but by that time they had done their job of shielding the initial neutron and gamma radiation. (They could have been replaced before fallout arrived.) At a peak overpressure of 12 psi or 83 kPa, even the sandbags on the outside remained intact. (Pavry had used sand bags instead of the recommended packed earth as a convenience.)

    This rightly gave conviction to the British Home Office civil defence effects team. The bomb ship HMS Plym, can be seen moored in 40 feet of water 400 yards off Trimouille Island, Monte Bello group. The public information film on Operation Hurricane states: 'At Montebello the advance party is already at work: 200 Royal Engineers had arrived in April to find an empty wilderness of salt, bush and spinifex ... Within the danger zone they erected the familiar [World War II British civilian] Anderson shelters, well-protected by sandbags ... These tests would influence the pattern of civil defence against some future atomic attack. ... On shore, they find many of the Anderson shelters have survived the ordeal remarkably well – better than some of the concrete-block houses.' (The full report on the Anderson shelters exposed at Operation Hurricane is 'Operation Hurricane: Anderson Shelters', Atomic Weapons Research Establishment, Aldermaston, report AWRE-T17/54, 1954, UK National Archives reference ES 5/19 and also duplicated at DEFE 16/933. See also 'Penetration of the gamma flash into Anderson shelters and concrete cubicles', AWRE-T20/54, 1954, UK National Archives ref ES 5/22 duplicated at DEFE 16/935.)

    Here again are some extracts from the civil defence chapter in the 1962/64 edition of The Effects of Nuclear Weapons:

    'At distances between 0.3 and 0.4 mile from ground zero in Hiroshima the average survival rate, for at least 20 days after the nuclear explosion, was less than 20 percent. Yet in two reinforced concrete office buildings, at these distances, almost 90 percent of the nearly 800 occupants survived more than 20 days, although some died later of radiation injury.

    'Furthermore, of approximately 3,000 school students who were in the open and unshielded within a mile of ground zero at Hiroshima, about 90 percent were dead or missing after the explosion. But of nearly 5,000 students in the same zone who were shielded in one way or another, only 26 percent were fatalities. ... survival in Hiroshima was possible in buildings at such distances that the overpressure in the open was 15 to 20 pounds per square inch. ... it is evident ... that the area over which protection could be effective in saving lives is roughly eight to ten times as great as that in which the chances of survival are small.'

    Page 645 (1962/4 edition):

    'The major part of the thermal radiation travels in straight lines, so any opaque object interposed between the fireball and the exposed skin will give some protection. This is true even if the object is subsequently destroyed by the blast, since the main thermal radiation pulse is over before the arrival of the blast wave.

    'At the first indication of a nuclear explosion, by a sudden increase in the general illumination, a person inside a building should immediately fall prone, and, if possible, crawl behind or beneath a table or desk or to a planned vantage point. Even if this action is not taken soon enough to reduce the thermal radiation exposure greatly, it will minimise the displacement effect of the blast wave and provide a partial shield against splintered glass and other flying debris.

    'An individual caught in the open should fall prone to the ground in the same way, while making an effort to shade exposed parts of the body. Getting behind a tree, building, fence, ditch, bank, or any structure which prevents a direct line of sight between the person and the fireball, if possible, will give a major degree of protection. If no substantial object is at hand, the clothed parts of the body should be used to shield parts which are exposed. There will still be some hazard from scattered thermal radiation, especially from high-yield weapons at long ranges, but the decrease in the direct radiation will be substantial.'

    A person on the ground whose clothes ignite (which is only a risk under extremely high thermal exposure to dark coloured clothing) can immediately extinguish the clothes by simply rolling over to starve the flames of oxygen. Page 653 (1962/4 edition):

    'Some, although perhaps not all, of the fallout in the Marshall Islands, after the test explosion of March 1, 1954, could be seen as a white powder or dust. This was due, partly at least, to the light color of the calcium oxide or carbonate of which the particles were mainly composed. It is probable that whenever there is sufficient fallout to constitute a hazard, the dust will be visible.'

    Below are some extracts from the British Home Office civil defence booklet, The Hydrogen Bomb (published by Her Majesty's Stationery Office, London, 1957, 32 pages). The frontispiece to the booklet is a quotation from Sir Winston Churchill: 'The hydrogen bomb has made an outstanding incursion into the structure of our lives and thoughts.' Page 3 states:

    'Knowledge of the effects of this weapon should be widespread. Terrible as these effects are, they can be exaggerated, and the information given in this booklet shows that much can be done to reduce them and to save lives. ... The publication of this summary does not mean that the Government think war likely. As the 1957 White Paper on Defence made clear, the existence of nuclear weapons and of the means to use them is a safeguard against aggression and a deterrent to war. But everyone should know what these weapons could do, and have some idea of how their effects could be reduced.'

    It is impressive (in comparison to more 'modern' pamphlets) due to the way it conveys the facts by direct examples from thermonuclear weapons tests and from the nuclear weapon attacks on Hiroshima and Nagasaki. For example, the chapter on 'The danger from heat' (pages 8-11) draws directly on the experience of the Home Office authors (George R. Stanbury and others attended British nuclear tests at Monte Bello and elsewhere during the 1950s):

    'With an atomic bomb similar [20 kilotons] to the one used at Nagasaki, the "heat flash" lasts for only about one and a half seconds, and most of it is over in half a second. With the [15 megatons] hydrogen bomb, heat is radiated for twenty seconds or more, most of it in the first ten seconds.


    'What would happen to anyone in the open directly exposed to the heat? People have gained some inkling from nuclear tests. At one test, for example, the device exploded was rather more powerful than the bombs dropped in Japan. The day was clear, which favoured the radiation of heat, and the observers were six miles away. Even at this distance, their eyes would have been temporarily blinded, if not permanently injured, had they not worn very dark glasses [when staring directly at the fireball]. As the fireball rapidly expanded, they felt as if an oven door had been opened only a few feet away. If the distance had been only one or two miles, their skin would have been severely burned. At half a mile, they would have been killed.

    'With a hydrogen bomb these distances would be increased, though not as much as might be expected. The "heat radiation" from a hydrogen bomb lasts longer. On a fine cloudless day, it might be felt as far as fifty miles away, but without injury to the skin. ... Mist or fog would reduce the range of the heat. They act as a barrier against heat rays, just as they do against the rays of the sun [water molecules have band absorption spectra covering the infrared radiation wavelengths].

    'Anything that keeps off the sun's heat will help to give protection against the heat of a nuclear bomb. At Hiroshima, for instance, a painted surface was scorched except where it was in the shadow of a wheel. ... At Hiroshima some Japanese women, who had on white cotton dresses with a darker pattern, suffered burns only beneath the pattern. The skin under the white material escaped. This was because white or light-coloured material reflects heat while dark material absorbs it. Colour apart, woolen clothes would be less likely to catch fire than cotton. If clothing did catch fire and there was no time to throw it off, the best way to put out the flames would be to roll over and over on the ground.

    'All this applies only to people caught in the path of the heat rays. Any solid substance would give full protection against this danger. ... In built-up areas, the lower storeys would probably be shielded by other buildings. Here a householder would need to pay particular attention to the upper floors with a full view of the sky ...'

    ABOVE: U.S. Army photo showing how a mere leaf of Fatsia japonica attenuated the heat flash enough to prevent scorching to the bitumen on an electric pole near the Meiji Bridge, 1.3 km range, Hiroshima. It didn't even vaporize the leaf before the pulse ended, let alone did it somehow ignite the wooden pole (most photos claiming to show thermal flash radiation effects in Hiroshima and Nagasaki purely show effects from the fires set off by the blast wave overturning cooking stoves, which developed 30 minutes to 2 hours later): 'Even blades of grass cast permanent shadows on otherwise badly scorched wood. The [Hiroshima nuclear bomb heat] flash lasted less time than it took the grass to shrivel.' - Chapman Pincher, Into the Atomic Age, Hutchinson and Co., London, 1950, p. 50.

    ABOVE: the heat flash radiation which causes the scorching is so unscattered or unidirectional that any shading from the fireball source stops it even if you are exposed to the scattered radiation from the rest of the sky: shadows still present in October 1945 in the bitumen road surface of Yorozuyo Bridge, 805 m SSW of ground zero, Hiroshima, pointed where the bomb detonated (U.S. Army photo).

    Pages 18-19 of the 1957 British Home Office booklet The Hydrogen Bomb introduce the protected 'refuge room' against fallout gamma radiation from large contaminated areas outside and on the roof (small areas of fallout contamination, such as indoor contamination, are negligible by comparison because most of the gamma dose rate comes almost horizontally from large distances across a uniformly contaminated plane rather than vertically upwards from the small amount of fallout under your feet or nearby, so the ingress of fallout into buildings makes no siugnificant difference unless the wall protection factors are so pathetically low it is not much help anyway):


    'The three factors which count in gaining protection are the distance from the radioactive dust, the weight of material in between, and the time for which one remains protected while the radioactivity decays.

    'A slit trench with overhead cover of two or three feet of earth would give very good protection against fall-out, as well as protection against blast, but the occupants would have to remain in the trench for forty-eight hours or more while the radioactivity surrounding them decayed.

    'A prepared refuge room inside a house could be made to give good protection against fall-out (although not so good as a covered slit trench) and it would also be much less uncomfortable for a period of two days or more. A cellar or basement would be by far the best place for a refuge room; next best would be the room with the fewest outside walls and the smallest windows. The windows would need to be blocked with solid material, to the thickness of the surrounding walls at least. It would help if the walls themselves were thickened, not necessarily to their full height, with sandbags, boxes filled with earth, or heavy furniture. The occupants of the refuge roof would have to remain in it until told that it was safe to come out - perhaps for a period of days - and the room would have to be prepared and equipped accordingly.

    'In some places it might be practicable to make good use of both an outdoor slit trench and an indoor refuge room, using the first for protection against blast, and the second, if the house survived the blast, for subsequent protection against fall-out.'

    This advice about a refuge room against fallout is actually an extension of advice in the 1938 British Home Office booklet The Protection of Your Home Against Air Raids, 38 pages. (See also the collection of official civil defence public handouts here.) Page 1 of that 1938 booklet contains a Foreword signed by Samuel Hoare (the Home Secretary of the British Government at that time), stating:


    'If this country were ever at war the target of the enemy's bombers would be the staunchness of the people at home. We all hope and work to prevent war but, while there is risk of it, we cannot afford to neglect the duty of preparing ourselves and the country for such an emergency. This book is being sent out to help each householder to realise what he can do, if the need arises, to make his home and his household more safe against air attack.'

    Page 3 states (in italics):

    'On board ship, both crew and passengers are instructed where to go and what to do, not when danger threatens, but beforehand. The captain considers it a matter of ordinary routine and everyday precaution that everything is in readiness for a shipwreck which he hopes will never happen. If the head of the house will consider himself as "the captain of the ship" and put these air raid precautions in to effect, the principal object of this book will have been achieved.'

    Page 4 states:

    'If air raids ever came to this country, every home should have a refuge specially prepared in which the whole household could take cover. Every shop and office, or other place of work or business, would require a place similarly prepared for those engaged on its premises.

    'Every householder, or head of a family or business, should learn now how to protect, in war-time, his own people and home from the effects of explosive bombs, incendiary bombs, and poison gas. This applies to those who live in large centres of population. In more remote districts the dangers would no doubt be less, though the need for protection and precautions would still exist.

    Page 8 states:


    'Almost any room will serve as a refuge-room if it is soundly constructed, and if it is easy to reach and to get out of. Its windows should be as few and small as possible, preferably facing a building or blank wall, or a narrow street. If a ground floor room facing a wide street or a stretch of level open ground [where bombs could fall] is chosen, the windows should if possible be specially protected. The stronger the walls, floor and ceiling are, the better. Brick partition walls are better than lath and plaster. ... An internal refuge will form a very good refuge room if it can be closed at both ends.'

    Both 'Morrison' indoor refuge-room shelters (basically a steel table designed to take the weight of the house collapsing on top of it, under which people could take protection against blast damage) and 'Anderson' outdoor earth-covered corrugated steel arch shelter were used for blast protection during World War II. Tube stations were used as communal air raid shelters. The first experiment set up by George R. Stanbury and others from the Home Office who attended the British 'Operation Hurricane' nuclear weapons test at Monte Bello in 1952, was to set up Anderson shelters to see the effects of nuclear weapons against World War II style civil defence. The shelters stood up very well indeed cutting down thermal and nuclear radiation and protecting against blast, although the longer duration of the nuclear blast wave relative to the bombs used in World War II meant that at the same high overpressure levels, the air drag effect of wind pressure tended to blow some sandbags off in the case of the nuclear explosion (but not in the case of the conventional low yield chemical explosives).

    The final British civil defence booklet was prepared for the Home Office by the Central Office of Information in 1976 and was first published by Her Majesty's Stationery Office in May 1980:

    Protect and Survive

    This booklet tells you how to make your home and family as safe as possible under nuclear attack


    If the country were ever faced with an immediate threat of nuclear war, a copy of this booklet would be distributed to every household as part of a public information campaign which would include announcements on television and radio and in the press. The booklet has been designed for free and general distribution in that event. It is being placed on sale now for those who wish to know what they would be advised to do at such a time.

    May 1980

    If Britain is attacked by nuclear bombs or by missiles, we do not know what targets will be chosen or how severe the assault will be.

    If nuclear weapons are used on a large scale, those of us living in the country areas might be exposed to as great a risk as those in the towns. The radioactive dust, falling where the wind blows it, will bring the most widespread dangers of all. No part of the United Kingdom can be considered safe from both the direct effects of the weapons and the resultant fall-out.

    The dangers which you and your family will face in this situation can be reduced if you do as this booklet describes.

    Challenge to survival


    Fall-out is dust that is sucked up from the ground by the explosion. It can be deadly dangerous. It rises high in the air and can be carried by the winds for hundreds of miles before falling to the ground.

    The radiation from this dust is dangerous. It cannot be seen or felt. It has no smell, and it can be detected only by special instruments. Exposure to it can cause sickness and death. If the dust fell on or around your home, the radiation from it would be a danger to you and your family for many days after an explosion. Radiation can penetrate any material, but its intensity is reduced as it passes through - so the thicker and denser the material is, the better.

    Planning for survival

    Plan a Fall-out Room and Inner Refuge

    The first priority is to provide shelter within your home against radioactive fall-out. Your best protection is to make a fall-out room and build an inner refuge within it.

    First, the Fall-out Room

    Because of the threat of radiation you and your family may need to live in this room for fourteen days after an attack, almost without leaving it at all. So you must make it as safe as you can, and equip it for your survival. Choose the place furthest from the outside walls and from the roof, or which has the smallest amount of outside wall. The further you can get, within your home, from the radioactive dust that is on or around it, the safer you will be. Use the cellar or basement if there is one. Otherwise use a room, hall or passage on the ground floor.

    Even the safest room in your home is not safe enough, however. You will need to block up windows in the room, and any other openings, and to make the outside walls thicker, and also to thicken the floor above you, to provide the strongest possible protection against the penetration of radiation. Thick, dense materials are the best, and bricks, concrete or building blocks, timber, boxes of earth, sand, books, and furniture might all be used.


    If you live in a block of flats there are other factors to consider. If the block is five stories high or more, do not shelter in the top two floors. Make arrangements now with your landlord for alternative shelter accommodation if you can, or with your neighbours on the lower floors, or with relatives or friends.

    If your flat is in a block of four storeys or less, the basement or ground floor will give you the best protection. Central corridors on lower floors will provide good protection.


    Bungalows and similar single-storey homes will not give much protection. Arrange to shelter with someone close by if you can do so.

    If not, select a place in your home that is furthest from the roof and the outside walls, and strengthen it as has been described.


    If you live in a caravan or other similar accommodation which provides very little protection against fall-out your local authority will be able to advise you on what to do.

    Now the Inner Refuge

    Still greater protection is necessary in the fall-out room, particularly for the first two days and nights after an attack, when the radiation dangers could be critical. To provide this you should build an inner refuge. This too should be thick-lined with dense materials to resist the radiation, and should be built away from the outside walls.

    Here are some ideas:

    1. Make a 'lean-to' with sloping doors taken from rooms above or strong boards rested against an inner wall. Prevent them from slipping by fixing a length of wood along the floor. Build further protection of bags or boxes of earth or sand - or books, or even clothing - on the slope of your refuge, and anchor these also against slipping. Partly close the two open ends with boxes of earth or sand, or heavy furniture.

    2. Use tables if they are large enough to provide you all with shelter. Surround them and cover them with heavy furniture filled with sand, earth, books or clothing.

    3. Use the cupboard under the stairs if it is in your fall-out room. Put bags of earth or sand on the stairs and along the wall of the cupboard. If the stairs are on an outside wall, strengthen the wall outside in the same way to a height of six feet.

    Essentials for survival in your Fall-out Room

    1 Drinking Water

    You will need enough for the family for fourteen days. Each person should drink two pints a day - so for this you will need three and a half gallons each.

    You should try to stock twice as much water as you are likely to need for drinking, so that you will have enough for washing. You are unlikely to be able to use the mains water supply after an attack - so provide your drinking water beforehand by filling bottles for use in the fall-out room. Store extra water in the bath, in basins and in other containers.

    Seal or cover all you can. Anything that has fall-out dust on it will be contaminated and dangerous to drink or to eat. You cannot remove radiation from water by boiling it.

    2 Food

    Stock enough food for fourteen days.

    Choose foods which can be eaten cold, which keep fresh, and which are tinned or well wrapped. Keep your stocks in a closed cabinet or cupboard.

    Provide variety. Stock sugar, jams or other sweet foods, cereals, biscuits, meats, vegetables, fruit and fruit juices. Children will need tinned or powdered milk, and babies their normal food as far as is possible. Eat perishable items first. Use your supplies sparingly.

    In the open

    If you are in the open and cannot get home within a couple of minutes, go immediately to the nearest building. If there is no building nearby and you cannot reach one within a couple of minutes, use any kind of cover, or lie flat (in a ditch) and cover the exposed skin of the head and hands.

    Light and heat from an explosion will last for up to twenty seconds, but blast waves may take up to a minute to reach you. If after ten minutes there has been no blast wave, take cover in the nearest building.

    What to do after the Attack:

    After a nuclear attack, there will be a short period before fall-out starts to descend. Use this time to do essential tasks. This is what you should do.

    Do not smoke.

    Check that gas, electricity and other fuel supplies and all pilot lights are turned off.

    Go round the house and put out any small fires using mains water if you can.

    If anyone's clothing catches fire, lay them on the floor and roll them in a blanket, rug or thick coat.

    If the mains water is still available also replenish water reserves.


    The danger from fall-out is greatest in the first forty-eight hours. During that time you must stay in the fall-out room and as far as possible within your inner refuge. If you leave the room to dispose of waste or to replenish food or water supplies, do not stay outside it for a second longer than is necessary.

    Above: The car-over-trench expedient fallout shelter from G. A. Cristy and C. H. Kearny, "Expedient Shelter Handbook", Oak Ridge National Laboratory, August 1974, report AD0787483, 318 pages. In place of a car, doors, felled logs, or planks of wood heaped with soil can be used instead, depending on the resources to hand.

    The most important for emergency use (where rapid protection is desirable) are the "car over trench shelter" (dig a trench the right size to drive your car over, putting the excavated earth to the sides for added shielding, then drive your car over it), "tilt up doors and earth" shelter (if your house is badly damaged, build a fallout shelter against any surviving wall of the house by putting doors against it and piling earth on top in accordance to the plans), and the "above ground door-covered shelter" (basically a trench with excavated earth piles at the sides, doors placed on top, then a layer of earth piled on top of the doors).

    All these shelters can be constructed very quickly under emergency conditions (in a time of some hours, e.g., comparable to the time taken for fallout to arrive in the major danger area downwind from a large nuclear explosion). For the known energy of gamma rays from fallout including neutron induced activities with low energy gamma ray emission (Np-239, U-237, etc.), a thickness of 1 foot or 30 centimetres of packed earth (density 1.6 grams per cubic centimetre) shields 95% of fallout gamma radiation, giving an additional protective factor of about 20. A thickness of 2 feet or 60 centimetres of packed earth provides a protective factor of about 400. Caravans have a protective factor of 1.4-1.8, single storey modern bungalows have a protection factor of 5-6, while brick bungalows have a protective factor of 8-9. British brick multi-storey buildings have protection factors of 10-20, while British brick house basements have protective factors of 90-150. These figures can easily be increased by at least a factor of 2-3 by making a protected ‘inner core’ or ‘refuge’ within the building at a central point, giving additional shielding:

    Dr Saad Z. Mikhail's report, Beta-Radiation Doses from Fallout Particles Deposited on the Skin (Environmental Science Associates, Foster City, California, report AD0888503, 1971) quantified the beta contact hazard for fallout particles while they are descending in the open:

    'A fission density of 10 to the 15th power fissions per cubic centimeter of fallout material was assumed. Comparison of computed doses with the most recent experimental data relative to skin response to beta-energy deposition leads to the conclusion that even for fallout arrival times as early as 1000 seconds (16.7 minutes post-detonation), no skin ulceration is expected from single particles 500 micron or less in diameter. Absorbed gamma doses calculated for one particle size (100 microns) show a beta-to-gamma ratio of about 15. Dose ratio for larger particle sizes will be smaller. Doses from arrays of fallout particles of different size distributions were computed, also, for several fallout mass deposition densities; time intervals required to accumulate doses sufficient to initiate skin lesions were calculated. These times depend strongly on the assumed fallout-particle-size distribution. Deposition densities in excess of 100 mg per square foot of the skin will cause beta burns if fallout arrival time is less than about three hours, unless the particles are relatively coarse (mean particle diameter more than 250 microns).'

    Keeping the highly visible particles off the skin by wearing clothing, or removing them quickly by brushing or washing after contamination, eliminates the beta burn hazard, as demonstrated by the examples of Marshallese Islanders who washed after fallout contamination.

    Manual of Civil Defence, Volume 1, Pamphlet No. 1, Nuclear Weapons, published for the Home Office and Scottish Home Department by Her Majesty's Stationery Office, 1956, 55 pages. This publication was written by the Scentific Advisory Branch of the Home Office, including Dr R. H. Purcell (the Home Office Chief Scientific Advisor) and his scientists Frank H. Pavey who had been in the British Mission to Japan in 1945, surveying Hiroshima and Nagasaki to examine the effects of nuclear weapons, and George R. Stanbury who (with Frank Pavey) had travelled to the Monte Bello Islands in Australia to measure the heat, blast and fallout effects as the Civil Defence Study Team at the Australian-British 25 kt nuclear test Hurricane on 3 October 1952 (including many Anderson and Morrison type World War II shelters, which stood up to the nuclear explosion very well indeed). Stanbury retired in 1967 but continued advising the Scientific Advisory Branch until his death in 1974, while Frank Pavry retired aged 65 in 1976. The 'Nuclear Weapons' 1956 report is with respect to firestorm hazards and other effects generally the best overall treatment of the problem and was influenced by Glasstone's 1950 Effects of Atomic Weapons which was based on empirical observations rather than guesses.

    As with The Effects of Nuclear/Atomic Weapons (1950, 1957, 1962, 1964, 1977), the 2nd (1959) and 3rd (1974) editions of the British publication Nuclear Weapons moved away from Hiroshima, Nagasaki, and nuclear test data and more towards theoretical discussions of hypothetical problems which has not been seen in practice.


    To explain the history of the British Home Office's Scientific Advisory Branch, here are quotations from Scientist in Civil Defence written by George R. Stanbury, published in two parts in Fission Fragments magazine (part 1 in issue 17, June 1971, edited by P. R. Bentley and part 2 in issue 18 of January 1972, the first issue of Fission Fragments to be edited by M. J. Thompson):

    'The use of scientists in Civil Defence had its origin in a circular (how appropriate!) issued by the Home Office in July 1935 in which local authorities were told that the Government would issue general instructions on air raid precautions, based on expert study of the problems, and the first of the official ARP [air raid precautions] handbooks [handbook "No. 2" because of a delay, the "No. 1" handbook also concerned with gas was not issued until August 1936!], concerned with measures against gas attack, was issued with commendable alacrity at the end of the same month (Porton having been working on the problems for almost 10 years!).

    'On the structural side [damage from blast effects of TNT bombs], a Bombing Tests Committee which which had been formed in 1934 as a sub-committee of the Committee of Imperial Defence, was reconstituted in 1935 to work closely with the Home Office, and the Superintendent of Experiments at Shoeburyness was put in charge of the experimental work. A Structural Precautions Committee was appointed by the Home Secretary in February 1936 to report on the nature of material damage likely to result from air attack and on appropriate countermeasures. An interim report based on trials carried out by the research Department at Woolwich provided the information for Handbook No. 6 on Air Raid Precautions in Factories and Business Premises, and the fact that the final report was not issued until 1939 is an indication of the lack of relevant information at the time which had to be made good by a rapid expansion of testing facilities at the Building Research Station, the Road Research Laboratory, and elsewhere.

    'In the last quarter of 1938 [e.g. the time of the Munich Crisis of September 1938 when Britain's Prime Minister Chamberlain had to visit Hitler in Germany to sign a peace pact on paper in a desperate effort to avert the impending war by appeasement of pacifist sentiments] the menacing political situation quickened interest in civil defence, and there was a rapid increase in the rating of civil defence research. ... In February 1939, therefore, the Research and Experiments Branch of the ARP Department was set up with Dr (later Sir) R. E. Stradling (the Director of the Building Research Station) as the Chief Adviser. The new branch started in two rooms in Horseferry House but soon moved across to Cleland House, where there was a staff of 24 at the outbreak of war in 1939. ... before the end of the war, over 600 people had been used in one capacity or another. ... in May 1939 a Civil Defence Research Committee was set up to advise on the formulation and execution of a programme of research by the branch [Chaired by Dr E. V. Appleton, FRS, and including such famous scientists as J. D. Bernal FRS, C. G. Darwin FRS, R. V. Southwell FRS, and G. I. Taylor FRS, the mathematician who - as part of this committee - in a famous paper predicted the blast wave and fireball growth rate for a nuclear explosion successfully ahead of the Trinity nuclear test in 1945; a paper which was only published openly in 1950 due to secrecy]. ...

    'When it was decided to issue helmets to fire watchers the Department had the greatest difficulty in gaining acceptance of the idea that the metal crown should be several inches above a supporting cradle to allow any pressure from a suddenly applied load to be spread over the whole head instead of being concentrated into one place. [This is now the standard design for not just wartime use against the risk of falling bricks, but also a legal requirement for construction workers on building sites.] ...

    'A similar difficulty was experienced by prof. (now Sir John) Baker and his colleagues in gaining acceptance of the idea that a shelter should be designed to absorb some part of the applied energy in its own partial collapse; complete resistance was far too costly and even unnecessary. The Morrison table shelter was an excellent example of this. It was designed to withstand the debris load of a house by its own partial collapse, whilst still giving adequate protection to the occupants. Sir John recalls with relish the long argument he had with the PM [prime Minister] before the latter was convinced about this and he still believes that it was only accepted eventually because it could also be used as a dining table! ... [End of Part 1; the following is from Part 2.]

    'The British Mission to Japan with profcessor W. N. Thomas (later the Senior Regional Scientific Adviser in Wales) as its Scientific Director, had brought back to this country a vast amount of data on the effects of atomic bombs on Hiroshima and Nagasaki, and this now had to be analysed and translated into the very different [not predominantly frammable wood-frame, but brick and concrete] conditions of British cities.

    'The members of the Mission were mainly drawn from the staff of the R and E Department (including Mr F. H. Pavry) whose accumulated experience in the field was now found to be invaluable. In 1946 an open report was published which served as the basis for all future Civil Defence training in this field and shortly afterwards, detailed reports were prepared on special aspects of the Mission's studies which likewise served as the basis of most of our subsequent appreciations in Scientific Advisory Branch of the effects of atomic bomb attacks on British cities.

    'Reactivation of Civil Defence

    'In 1948, in view of the uncertain international situation, the Home Office decided to reactivate civil defence, and appointed Dr E. T. Paris from the Ministry of Supply as its Scientific Adviser. Dr Paris had a staff of 5 scientists under Mr E. Leader Williams and Mr J. W. Martin and a small clerical staff still trying to cope manfully with the Bomb Census and the War Damage Commission, and the [bomb damage] records which were pouring in from the Regions and the various war-time out-stations of the Department. ... One interesting outcome of the study of debris problems initiated by the Working Party was ... that any incipient fires in this [blast devastated brick or concrete building] area would be crushed out by the collapse of the buildings, the fire zone being confined to the annular ring beyond this where building structure was still identifiable.

    'Operation Hurricane

    Above: Anderson shelters (which survived the explosion, with merely a few sandbags blown off by the blast wave after they had done their essential job of screening out the initial nuclear radiation flash, but long before fallout arrived) near the bomb ship HMS Plym, Monte Bello, 1952. The ship carrying the bomb can be seen moored in 40 feet of water 400 yards off the island (Trimouille Island, Monte Bello group). The public information film on Operation Hurricane states:

    'At Montebello the advance party is already at work: 200 Royal Engineers had arrived in April to find an empty wilderness of salt, bush and spinifex... Control points and test buildings rise from the wasteland but the only local materials are sand and rock for making concrete. There wasn't even a jetty until this one was built by an Airfield Construction Unit of the Australian Air Force. ... Within the danger zone they erected the familiar Anderson shelters, well-protected by sandbags, and there too they built concrete structures of varying sizes and strengths to test the impact of blast and the penetration of gamma ray. These tests would influence the pattern of civil defence against some future atomic attack. This was one of the problems Montebello would help to decide. ... survey boats set out on patrol to find and chart the limits of contamination in the island waters before anyone can dare approach the shore. In due course recovery teams land on the stricken beach. On shore, they find many of the Anderson shelters have survived the ordeal remarkably well – better than some of the concrete-block houses.'

    (The full report on the Anderson shelters exposed at Operation Hurricane is 'Operation Hurricane: Anderson Shelters', AWRE-T17/54, 1954, UK National Archives refences ES 5/19 and also duplicated at DEFE 16/933. See also 'Penetration of the gamma flash into Anderson shelters and concrete cubicles', AWRE-T20/54, 1954, UK National Archives ref ES 5/22 duplicated at DEFE 16/935.) The photos below show the effects of Operation Hurricane.

    'In 1952, Scientific Advisory Branch were invited to participate in the first British atomic explosion at Monte Bello - Operation Hurricane. [Dr William Penney, in charge of the test, had witnessed the Nagasaki explosion and the base surge contamination from the Baker underwater test at Bikini Atoll in 1946, and decided that the first British test should be predominantly concerned with checking the civil defence effects of a terrorist burst of a nuclear bomb smuggled into a harbour inside the hull of a ship and detonated in shallow water. Hence, he gave civil defence special consideration at Operation Hurricane.]

    'Our particular interests at the time were the resistance of reinforced concrete structures to atomic [long duration] blast, the performance under practical field conditions of the range of radiac instruments which had just been developed by AERE Harwell for the use of civil defence and the Services, the performance of ground zero indicators and the contamination of food packages by deposited fallout. The small team consisted of myself and Mr Pavry, with Mr Westbrook from the Ministry of Works. The Task Force itself was under the Command of Rear Admiral A. D. Torlesse CB who later became the Regional Director for Civil Defence in No. 3 Region. Sir William (later Lord) Penney was the chief scientist.

    'The Royal Engineers erected 3 specially designed reinforced concrete box-like test structures under Mr Westbrook's direction at appropriate distances from HMS Plym, which was anchored in the nearby lagoon and which was to house the device. The front face of the closest box was completely stove in, the second received only minor damage, and the third none at all.

    'As there were no other substantial structures on the island, and the camp on the shore was completely blown away, there was little else to prove to an outsider that the thing had actually gone off except a photograph of this front box, and this was in fact one of the first things shown to the PM [Winston Churchill] by Sir Wm. Penney on his return.

    'As I was one of those who, a few years earlier, had recommended the Home Office to spend several millions on radiac [radioactivity detection, identification and computation] equipment, I was naturally very interested in their performance. [The Home Office ordered the manufacture of 20,000 of the 0-300 R/hr No. 2 version Radiac survey meters for civil defence fallout survey work in the 1950s. By 1990 when Cold War stockpiles of equipment peaked, Britain's Home Office Emergency Planning Division had stockpiled 100,000 digital 0-300 cGy/hr PDRM82 fallout survey meters, 1,000,000 pen-sized quartz fibre electrometer self-reading dosimeters with ranges of up to 0-500 cGy, and 66,000 dosimeter chargers of four types. A further 2,000 portable military PDRM82s and 2,000 fixed-type PDRM82Fs - which used an external probe in an above ground housing above Royal Observer Corps monitoring post fallout shelters - have been sold off since the Royal Observer Corps was stood-down at the end of the Cold War. ] On one occasion I was in a contaminated area for 20 minutes where the dose rate as measured on a No. 2 Survey meter was 10 r/hr; I must say I was quite relieved to find at the end, that according to my personal dosemeter I had just clocked up slightly over 3 r! Such are the wonders of science! ...

    'At later dates, a number of other members of Scientific Advisory Branch staff together with representatives from Training Division attended British atomic trials in Australia and gained much useful experience. We were always kept fully in touch with these trials and had ready access to all the results of weapons effects tests which were gradually incorporated into our doctrine and training. ...

    'The period from 1954 onwards for a few years was one of intense activity in the Branch now removed to the Home Office Building in Whitehall. Dr Paris had retired and his place was taken by Dr R. H. Purcell from the Admiralty Research Laboratory.

    'The first thermonuclear device had been exploded and the whole problem of heavy fallout was beginning to rear its ugly head. Sir John Hodsoll resigned from his post as Director General of Civil Defence and was appointed Civil Defence Adviser to NATO where he soon persuaded the Civil Defence Committee to set up a Scientific Working Party for the exchange of weapons' effects data between member countries, which became a useful source of information for many years. ... conferences were being held with the Americans under various auspices at which information on weapons' effects obtained from atomic trials was exchanged and digested. The staff were augmented to cope with this flood of activity.

    'Early in 1957 at one of the NATO Civil Defence Scientific Working Party Meetings an address was given by Dr Willard F. Libby [discoverer of carbon-14 dating] of the US Atomic Energy Commission based on an advance proof copy of the Effects of Nuclear Weapons which he had before him. I asked him afterwards how long it would be before we received copies, and without hesitation he gave me his own. On my return the book was broken down into Chapters so that members of Scientific Advisory Branch could burn the midnight oil over them to the exclusion of everything else. for a few months at least, until the book was published, we held the lead over other Departments and Agencies in the United Kingdom and established an advanced knowledge in this field which we never really lost. ENW was of course followed by ENW Revised [1962, 1964, and 1977] so that we have much to thank our American colleagues for. ...

    'In 1962 Dr Purcell left us to be replaced by Mr H. A. Sargeaunt. The exciting period of adventure and development of the previous 8 years was coming to a close and we were entering a period of consolidation.

    'One of the most important functions of any scientific establishment is the maintenance of an adequate library of relevant records and reports. We never had any difficulty in getting stuff in; the problem was almost how to keep it out! We were on the circulation lists of most of the service establishments working directly or indirectly in fields of interest to use, and we had a large intake from most of the corresponding establishments in the United States and Canada.

    'Even today, after some recent severe pruning and the destruction of all duplicates, we are still left with 125 feet of closely packed shelving with corresponding card indexes and summary sheets. Early in Dr Purcell's time we found that we were spending so much time reading reports that there was hardly any time left to do any work ... The supply of new material I believe is now just beginning to fall off which is just as well as the staff has likewise been decimated. Our American friends seem to have developed the custom of paying some of their research agencies according to the thickness of the reports produced and this is taxing our resources of manpower and shelf space to the limit.

    'The Birth of 'Fission Fragments'

    'In 1961 we started to issue this magazine Fission Fragments [edited by Mr Greenhalgh who joined the Scientific Advisers Branch in 1959] for Scientific Intelligence Officers. ... So far 18 editions have been published at approximately 6-month intervals. The early productions looked rather poverty stricken, but since 1968 we have been allowed to produce something rather more stylish which we hope has been found useful. There was always some danger of Scientific Advisers Branch becoming a closed shop, but Dr Purcell and Mr Sargeaunt were always keen for us to use every possible opportunity of passing information on.'

    According to the originally 'Restricted' classified U.K. Home Office Scientific Adviser's Branch journal Fission Fragments, W. F. Greenhalgh, Editor, London, Issue Number 3, August 1962, page 2: '... Dr R. H. Purcell, who has been Chief Scientific Adviser to the Home Office for the past eight years, took up a new post as head of the Royal Naval Scientific Service at the beginning of April. Dr Purcell was only the second holder of the post of C.S.A., which was created in 1948 [from 1939-45 the Research and Experiments Department of the Ministry of Home Security was headed by its Chief Scientific Adviser Sir Reginald Stradling, and from 1945-8 the Scientific Adviser's Branch of the Ministry of Works was responsible for assessments of nuclear and high explosive weapons], and he took office at a critical time when Civil Defence philosophy was being re-oriented away from the nominal A-bomb and towards the H-bomb.' His immediate successor, Mr Sargeaunt, was more interested in broadening the branch activities into areas such as helping the police service, prison service and fire service with scientific problems, not just focussing on civil defence - the Civil Defence Corps was closed by the Labour Government in 1968.

    There was a resurgence of interest in civil defence in the 1970s and early 1980s. Mr J. D. Culshaw replaced Mr Sargeaunt as Director of the Scientific Advisory Branch, and in 1972 when Mr J. K. S. Clayton, BA, became the Assistant Director of the Scientific Advisory Branch of the Home Office, London. Culshaw as Director of Scientific Advisery Branch wrote an interesting article on pages 9-15 of issue No. 19 (September 1972) of Fission Fragments, stating:

    'Apart from those who don't want to know or can't be bothered, there seem to be three major schools of thought about the nature of a possible Third World War involving the use of strategic nuclear, bacteriological or chemical weapons ...

    * 'The first group think of something like World War II but a little worse ['a period of tension will precede the outbreak of war so allowing time for the implementation of emergency civil defence measures'],

    * '... the second of World War II but very much worse ['the idea that one's enemy will deliver a massive attack without warning at a time calculated to cause maximum damage ... although there may be many different ways of delivering an attack this represents the worst that the enemy can do and therefore is the most likely ... this concept makes passive civil defence look very unattractive compared to having a powerful second strike capability sufficient to inflict as much or more damage on the would be enemy so as to deter him'],

    * 'and the third group think in terms of a catastrophe ['Armageddon - upset the balance of ecology in favour of predator insects etc.'] ...

    'When the Armageddon concept is in favour, the suggestion that such [unobserved, indirect nuclear war guesswor like brick and concrete buildings burning in mass firestorms, nuclear winter, etc.] problems exist leads to "way out" research on these phenomena, and it is sufficient to mention a new catastrophic threat to stimulate research into the possibilities of it arising. The underlying appeal of this concept is that if one could show that the execution of all out nuclear, biological or chemical warfare would precipitate the end of the world, no one but a mad man would be prepared to initiate such a war.'

    Clayton was soon appointed Director after Culshaw. J. K. S. Clayton was formerly with the Weapons Department of the RAE Farnborough which he joined in 1946, and oversaw the Protect and Survive publicity campaign of British civil defence, which was controversial because it presented facts about how to protect against nuclear weapons blast, heat and fallout without giving the nuclear test data which validated those facts. The booklet Protect and Survive was first prepared and printed in 1976, but was only used for training purposes until it was published and placed on sale in May 1980. J. K. S. Clayton wrote in his lengthy and brilliant introduction, The Challenge - Why Home Defence?, to the 1977 Home Office Scientific Advisory Branch Training Manual for Scientific Advisers:

    'Since 1945 we have had nine wars - in Korea, Malaysia and Vietnam, between China and India, China and Russia, India and Pakistan and between the Arabs and Israelis on three occasions. We have had confrontations between East and West over Berlin, Formosa and Cuba. There have been civil wars or rebellions in no less than eleven countries and invasions or threatened invasions of another five. Whilst it is not suggested that all these incidents could have resulted in major wars, they do indicate the aptitude of mankind to resort to a forceful solution of its problems, sometimes with success. ...

    'Let us consider what a nuclear attack on the United Kingdom might mean. It will be assumed that such an attack will only occur within the context of a general nuclear war which means that the UK is only one of a number of targets and probably by no means the most important. It follows that only part of the enemy's stock of weapons is destined for us. If the Warsaw Pact Nations constitute the enemy - and this is only one possible assumption - and if the enemy directs the bulk of his medium range and intermediate range weapons against targets in Western Europe behind the battle front, then Western Europe would receive about 1,000 megatons. Perhaps the UK could expect about one fifth of this, say 200 Mt. Let us assume rather arbitrarily that this would consist of 5 x 5 Mt, 40 x 2 Mt, 50 x 1 Mt and 100 x 1/2 Mt.

    'An attack of this weight would cause heavy damage over about 10,000 square kilometres, moderate to heavy damage over about 50,000 square kilometres, and light damage over an additional 100,000 square kilometres. (Light damage means no more than minor damage to roofs and windows with practically no incidence of fire.) We can compare the heavy damage to that suffered by the centre of Coventry in 1940. This will amount to approximately 5% of the land area of the UK. Another 15% will suffer extensive but by no means total damage by blast and fire; another 40% will suffer superficial damage. The remaining 40% will be undamaged. In other words, four-fifths of the land area will suffer no more than minor physical damage. Of course, many of the undamaged areas would be affected by radioactive fallout but this inconvenience would diminish with the passage of time.

    'Policy to meet the Threat

    'The example just given of the likely severity of the attack - which is, of course, only one theoretical possibility - would still leave the greater part of the land area undamaged and more people are likely to survive than to perish. Government Home Defence policy must therefore be aimed to increase the prospects of the survivors in their stricken environment.'

    Above: J. K. S. Clayton as Director of the Scientific Advisory Branch of the British Home Office (formerly with the Weapons Department of the RAE Farnborough which he joined in 1946), oversaw the Protect and Survive publicity campaign of British civil defence, including a booklet of that name and the films above on how it is easy to shield radiation from fallout while it rapidly decays.

    I should also quote here a note on page 39 of the Scottish Home and Health Department Scientific Advisers' Operational Handbook, H.M. Stationery Office, Edinburgh, 1979:

    'The density of initial ignitions in the main fire zone, for UK houses, is likely to be very roughly one house in thirty, with a fire-spread factor of about 2 [i.e., the total number of house fires is 2 times the initial number of house fires]. About one house in fifteen is expected to become burnt out. This situation would not constitute a "firestorm" or "mass fire", and the number of fire casualties should be small.'

    (We will consider in great detail the very solid evidence for this claim which has provided by Stanbury, later in this blog post.)

    Clayton's decisive civil defence actions were later strongly supported by British Prime Minister Margaret Thatcher, who echoed his pragmatic outlook on war in her address to the United Nations General Assembly on disarmament on 23 June 1982, when she pointed out that in the years since the nuclear attacks on Hiroshima and Nagasaki, 10 million people were killed by 140 non-nuclear conflicts, so:

    ‘The fundamental risk to peace is not the existence of weapons of particular types. It is the disposition on the part of some states to impose change on others by resorting to force against other nations ... Aggressors do not start wars because an adversary has built up his own strength. They start wars because they believe they can gain more by going to war than by remaining at peace.’

    On 29 October 1982, Thatcher stated of the Berlin Wall:

    ‘You may chain a man, but you cannot chain his mind. You may enslave him, but you will not conquer his spirit. In every decade since the war the Soviet leaders have been reminded that their pitiless ideology only survives because it is maintained by force. But the day comes when the anger and frustration of the people is so great that force cannot contain it. Then the edifice cracks: the mortar crumbles ... one day, liberty will dawn on the other side of the wall.’

    On 22 November 1990, she was able to declare: ‘Today, we have a Europe ... where the threat to our security from the overwhelming conventional forces of the Warsaw Pact has been removed; where the Berlin Wall has been torn down and the Cold War is at an end. These immense changes did not come about by chance. They have been achieved by strength and resolution in defence, and by a refusal ever to be intimidated.’

    Above: The two posters on the left and the leaflet on the right were printed by the British Government in January 1964 and stockpiled in case of a repetition of the Cuban missiles crisis or similar escalation of the nuclear arms race. The idea was to evacuate all children under 15 with their mothers, children between 15-18 either alone or accompanied by a parent, expectant mothers, and all invalids to safe areas well away from potential targets like major cities, before war broke out. These people would have been billeted (by defence regulations laws, pertaining to a national state of emergency) on the rural population, which would be paid an allowance for the accommodation provided. (This evacuation plan was abandoned after the civil defence corps was abolished in 1968.)

    In Britain, after being stood down in 1945, civil defence was restarted from 1948-68 with the voluntary Civil Defence Corps including rescue, warden, ambulance, and welfare sections. There were also a separate Auxiliary Fire Service (which was equipped with 1,000 Green Goddess fire engines for use in nuclear war or even by military personnel during firemen's strikes), the Royal Observer Corps (which existed from 1925-95, operating during World War II to identify enemy aircraft and generate air raid warnings - since radar could not identify friend or foe - and during the Cold War it was ready to detect and record information on nuclear explosions and fallout, which is now fully automated by computerised detectors called AWDREY, Atomic Weapons Detection, Recognition, and Estimation of Yield, which detects and analyses the long-range EMP and light flash signatures from a nuclear explosion), and National Hospital Service Reserve.

    Ignoring these other volunteer run organizations organized by the Government, and just focussing on the numbers of recruits in the basic Civil Defence Corps, statistics are available which show that the number of members increased from 24,649 by May 1950 (according to the The Times 4 May 1950, p 8) to 205,392 by August 1952 (The Times 15 August 1952, p 3), and peaked at 336,265 by May 1956 (The Times, 2 May 1956, p 6). Membership remained over 300,000 at the time of the Cuban missiles crisis in October 1962, but dropped below 300,000 in 1963, was only 211,570 in November 1964 (The Times, 26 November 1964, p 8), and reached 122,000 by December 1966 (The Times, 15 December 1966, p 6). The Civil Defence Corps was closed in 1968.

    The first edition (1956) of Nuclear Weapons is based on scientific facts from Hiroshima and Nagasaki, and scientific facts from nuclear tests. The later editions are full of speculations and assertions followed by vague statements that the assertions have no real validity, such as speculation on the radiation recovery rate being 10 roentgens/day to the bone marrow irrespective of the dose rate or time after exposure. Anyone can see clearly that in fact recovery will be slower at higher dose rates than at lower dose rates, because of increasing damage to the biological repair mechanisms, and that the recovery rate will also not be a constant but vary with time and will decrease to a minimum when the white blood cell count is most depressed, which occurs about 30 days after exposure for humans. Another speculation consists of various political doctrines about what types and sizes of nuclear detonation a hypothetical enemy will use in a hypothetical war, and other completely speculative rubbish. For example, if to begin with you speculate that any nuclear war will involve enough nuclear weapons of high enough yield to totally wipe out everything, then you can forget the science altogether and get on with the more important business of brainwashing everyone that civil defence is a joke and surrender is worth while.

    Many of the vital scientific facts based on observations of nuclear explosions in wars and in weapon trials were deleted from later editions of Nuclear Weapons and the American Effects of Atomic Weapons to make way for speculative theorising and political doctrines about procedures. I'll give examples below. (I've already given examples for The Effects of Nuclear Weapons in a previous post on this blog; 1950 fallout maps of the Baker underwater test and Trinity air burst upwind fallout data were removed and not replaced in later editions, etc.)
    Nuclear Weapons is clear and concise with just four well-organised informative chapters:

    • Features of Nuclear Explosions (Types of Burst: air bursts, surface bursts, underwater bursts, etc.)

    • The Fire Risk (Thermal radiation; Effects on people; Primary fires; Secondary fires; Firestorms)

    • Nuclear Radiation Hazards (Types of radiation; Initial nuclear radiation; Neutron induced activity; Fallout; Decay rates of fallout; Distance and shielding to reduce dose, Decontamination of clothing, vehicles, streets, etc.)

    • Blast (Height of burst in relation to blast damage; Cratering and ground shock; casualties)

    Pages 2-4: TYPES OF BURST

    Air burst

    'When the explosion takes place in the air, light and heat and the nuclear radiations are radiated outwards through the air in all directions and their effects at a distance are felt almost instantaneously [although the duration of the pulse is long and it takes 1 second for the final peak in thermal power to be reached by a 1 megaton low altitude burst] because they travel at the speed of light (186,000 miles per second). The blast takes the form of a pressure wave in air which travels at [a minimum of] the speed of sound 1,100 ft. (one-fifth of a mile) per second [the speed is much higher initially as the shock wave heats the air isothermally and this increases the initial speed way beyond sound speed, but it slows down and degenerates into a sound wave quickly]; this is accompanied by a powerful blast wind of short duration. Close to the explosion the pressure produced ... drops rapidly as the blast wave moves outwards. It is this pressure and the accompanying wind that are responsible for most of the damage caused to structures. ...

    'When it has reached its full size the fireball is extremely light, only a tiny fraction of the density of the air surrounding it [hence initial gamma radiation is less shielded by the air causing a second gamma radiation pulse when the fireball density falls during expansion; this is 'hydrodynamic anhancement']; it therefore shoots upward very rapidly [like a hot air balloon at immense temperature], quickly losing its brilliance as it cools by [radiation of energy, by] expansion, and by turbulent mixing with the surrounding air. ... The immense suction created as the fireball rises, draws up water droplets and dust from the surrounding atmosphere into the base of the ascending mass where they mix with the products of the explosion. ...

    Ground surface burst

    'If the explosion takes place close to the ground about a third of the total heat produced may be lost by absorption into the ground itself. [Photo of fireball in the 1953 Australian-British Totem-1 nuclear test just 30 metres above ground level.] If, in addition, the explosion takes place in a built-up area there is a considerable reduction in heat effects because of the shielding provided by buildings which have not yet been reached by blast.

    'Some of the immediate nuclear radiation is also absorbed into the ground and again the shielding of buildings on the remainder is considerable.

    'The blast wave through the air is reduced in power because some of the energy is used up in producing a crater and in sending a shock wave through the ground itself. The reinforcing effect of the reflection (Mach) wave which is a feature of the air burst is reduced. ...

    'The result is that the cloud contains much more solid matter than with an air burst and this increases the fall-out of radioactive material immediately downwind, the heavier particles falling out first and the lighter particles later, producing a residual radiation hazard to people on the ground. The seriousness of the hazard depends on the amount of fall-out deposited in a given area and this is more dependent on the closeness of the burst to the ground than on the power of the weapon.

    An underground burst (nuclear 'earth penetrator' against hardened targets)

    'In this case a large part of the heat radiation and the immediate nuclear radiation is absorbed in the crater [photos of Nevada 1951 shallow underground nuclear test Uncle and Nevada 1955 deeper underground nuclear test Ess shown] produced by the explosion, and the surrounding buildings provide considerable shielding against the remainder.

    'Much of the blast energy goes into the production of a shock wave in the earth, a feature which is absent from the air burst and less important when the burst is on or near the ground. This shock will cause damage to underground structures and services as well as to buildings above ground, but the power of the blast wave in the air above is reduced.

    'A greater proportion of the radioactivity is trapped in the debris of the crater, mingling with the material which spills out around the crater and immediately downwind. This gives rise to a serious but more localised residual radiation hazard; the radioactive fall-out beyond is less widely distributed.

    An underwater burst (terrorist attack by trawler, cargo ship or submarine)

    'The United States authorities caried out a test of this kind at Bikini in 1946 from which most of he information about such explosions has been obtained [photos of American 1946 Crossroads-Baker test and also Australian-British 1952 Hurricane nuclear underwater test at Monte Bello are shown]. The explosion took place well below the surface of a lagoon 200 ft. deep.

    'The effects of light and heat, and immediate nuclear radiation were almost entirely absent since the fireball was still below the surface at its most brilliant stage. As the fireball reached the surface, however, water was thrown up with great force in a gigantic hollow cylinder of spray. Gases from the fireball were vented through this column, forming the typical mushroom shaped cloud at the top. As the water from the column fell back to the surface, a rapidly moving surge of mist, known as the base surge, travelled outwards. This was highly radioactive mist since much of the radioactive material of the explosion had been trapped in it.

    'The explosion was accompanied by a strong shock wave through the water. The remaining pressure energy appeared as a blast wave through the air, but the range of its effectiveness was about 40 per cent. less than that from a surface burst.

    'The explosion also produced big surface waves which would have added to the damage to harbour works and installations if the explosion had taken place in a harbour with a similar depth of water.'

    Pages 5-9: THE FIRE RISK

    Thermal radiation

    'For convenience both the visible radiation and the radiation in the infra-red part of the spectrum (the "light and heat" ...) will be referred to as thermal radiation, since they both heat surfaces into which they are absorbed.

    'With the nominal [20 kt] bomb the pulse of thermal radiation from the fireball lasts for only about 1.5 seconds though most of the energy is radiated in about half a second; because it is so transient, this pulse has been called the "heat flash". With a 10 megaton bomb the thermal radiation lasts much longer and can hardly be described as a "flash"; it may persist for 20 seconds or more though most of its energy will be radiated in the first 10 seconds.

    'The heat rays from the fireball are similar to those from the sun. They travel in straight lines with the speed of light and heat up surfaces into which they are absorbed, although the degree of absorption depends upon the colour of the surface because a large proportion of the radiation is in the visible range. Just as some surfaces appear dark because they reflect little of the heat of the sun's light into the eyes, so a dark surface reflects little of the heat radiated from the explosion, most of it being absorbed to produce a rise in temperature. On the other hand, just as some substances appear white because they reflect most of the sun's rays to the eye, so a white substance reflects mos of the heat radiation and consequently absorbs little into its surface. Light coloured objects are less likely, therefore, to catch fire than dark coloured ones.

    'In a clear atmosphere the intensity of the thermal radiation falls off according to the inverse-square law. Thus when the distance from the source is doubled, the intensity is reduced to a quarter. In a misty atmosphere some of this radiation may be scatered out of the direct beam, but any reduction from this cause is not as great as was at one time supposed. On the other hand, whatever may be the effect of scattering, some reduction in distance results from the fact that part of the energy of the thermal rays - especially in the infra red [infrared is strongly absorbed by both water vapour and carbon dioxide in the atmosphere] - is actually absorbed in heating the atmosphere.

    Effects on people

    'People directly exposed to the heat flash from an air burst nominal [20 kt] bomb within 2.5 miles of ground zero would receive burns on exposed skin; even at a distance of 5 miles it would feel as though an oven door had suddenly been opened nearby. The nearer to ground zero the greater is the danger to life, and those directly exposed within 0.5 mile of ground zero [unshielded by white paper or anything opaque] would undoubtedly be killed because of serious burns, if not from other causes. Severe third degree burns (charring) would result up to about a mile, second degree burns (blistering) up to about 1.5 to 2 miles, and first degree burns (reddening) up to about 2.5 miles.

    'It is relatively easy to gain protection, since [because atmospheric scattering of thermal radiation has been found to be trivial compared to absorption] one has only to be out of the direct path of the rays from the fireball. Complete protection from heat-burn could be achieved if everyone took cover [just get out of the fireball line-of-sight from windows and skylights]...

    'The clothing of exposed people, though it may itself catch fire, affords some degree of protection to the skin underneath at ranges greater than 0.5 mile, paricularly if the clothing is not in close contact with the body, and provided that the burning clothing can quickly be removed or the flames extinguished. The risk of ignition is reduced if the outer garments ... are of light rather than of a dark colour. One of the reasons for the heavy burn casualties in Japan [Hiroshima and Nagasaki nuclear attacks, 6 and 9 August 1945] was the fact that most people were only wearing thin cotton garments [another reason is that people were out of doors at the times - morning commuting hour for Hiroshima and lunch time for Nagasaki - and most who suffered the worst facial burns had actually stood watched the B-29 bombers drop the nuclear bombs, totally unaware of any danger at their distance, let alone of the fact they could have avoided urns by turning away or 'duck and cover'].

    'The importance of covering as much of the skin as possible is illustrated by the fact that the risk of death from burns depends on the proportion of the area of the body burnt. ... Even with 50 per cent. of the body area burnt the chance of recovery with young people is 50 per cent.

    Primary fires

    'Many strong buildings near the centre [in Hiroshima and Nagasaki] which survived the blast were gutted by fires started earlier by the heat flash which had entered through windows and open doors and ignited combustible contents [paper screens, bamboo furniture, etc.]. Fires started in this way are usually referred to as "primary fires".

    Secondary fires

    'There is also a risk of fires resulting from damage caused by the blast, e.g. the collapse of buildings on to domestic fires [the overturning of breakfast time and lunchtime charcoal cooking braziers in paper screen and bamboo furniture filled Japanese wooden houses caused the firestorms], the breaking of gas pipes and short-circuiting of electrical wiring. These fires are called "secondary fires". The risk can be reduced by such simple precautions as shutting up stoves, covering open fires with sand or earth, and by turning off gas and electricity at the main [modern circuit breaker switch boxes which replace old fuse boxes reduce the electrical fire risks].

    'Research into the causes of fire in Hiroshima and Nagasaki, combined with a study of the secondary fire risk from the flying bomb [V1 and V2] damage in this country during the last [1939-45] war has shown that with nuclear attack the secondary risk is likely to be small compared with the primary risk ofdirect ignition by thermal radiation.

    Fire precautions

    'Although the fire risk even from a nominal [20 kt] bomb is always serious, targets in this country, where the great majority of buildings are of brick, stone or concrete, are less vulnerable to fire than were those Japan, where most of the buildings were of wood. ... since the thermal radiation has no great penetrating power, any opaque screen, especially a white one, will keep it out ...

    'Another obvious fire precaution is the removal of all readily combustible material from the direct path of any heat radiation that could possibly enter windows or other openings.

    'Both these precautions apply only to those windows and other openings that have a direct view of some part of the sky. In a built-up area they would apply more particularly to the windows of upper floors; even for an air burst, in a closely built-up area one building shields another to a considerable extent.

    The probable fire situation in a British city

    '... most Japanese houses are constructed of wood and once they were set on fire they continued to burn even when knocked over. In this country only about 10 per cent. of all the material in the average house is combustible, and under conditions of completecollapse, where air would be almost entirely excluded, it is doubtful whether a fire could continue on any vigorous scale. The main fire zone will be around this central area of heavy destruction, in the region where buildings are damaged but standing sufficiently to allow free burning ... The range of ignition is affected to some extent by the state of the atmosphere and on a dull misty day will be reduced ...

    The possibilities of a fire storm

    'The chief feature of a fire storm is the generation of high winds which are drawn into the centre of the fire area to feed the rising column of hot air and flames. These in-rushing winds prevent the spread of fire outwards, but ensure the almost complete destruction by fire of everything within the fire area. This inevitably increases the number of casualties, since it becomes impossible for people to escape by their own efforts because they succumb to the effects of suffocation and heat stroke.

    'The Hiroshima bomb (but not the Nagasaki one) caused a fire storm. A fire storm occurred in [the medieval multistorey wooden building region of] Hamburg and possibly also in several other German cities as a result of accurate and very dense attacks with incendiary and high explosive bombs by the R.A.F. ... it has been fairly well established that during these particular raids on Germany half the buildings in the target area were set on fire in about half an hour. ...

    'Whether a fire storm develops depends also on the nature of the target; where there are tall buildings closely packed together with plenty of combustible material to burn, the risk is much greater than in areas less densely built up.

    'It seems unlikely from the evidence available that an initial density of fires equivalent to one in every other building would be started by a nuclear explosion over a British city. Studies have shown that a much smaller proportion of buildings than this would be exposed to thermal radiation and even then it is not certain that continuing fires would develop. Curtains may catch fire, but it does not necessarly follow that they will set light to the room; in the last war it was found tha only one incendiary bomb out of every six that hit buildings started a continuing fire.

    'Moreover after a nuclear explosion the large and almost completely flattened central area would counteract the development of a fire storm, since one essential requirement seems to be a continuous mass of fire over a large area. ... For a 10 megaton bomb, with its longer lasting thermal radiation, it takes about 20 calories per square centimetre to start fires [contrasted to 5 calories per square centimetres for a 20 kt low air burst] because so much of the heat (spread out over the longer emission) is wasted by conduction into the interior of the combustible material and by convection and re-radiation whilst the temperature of the surface is being raised to the ignition point. ...

    'For a ground burst bomb, however, several other factors contribute to a further reduction in the fire range. Apart from an actual loss of heat by absorption into the ground and from the pronounced shielding of buildings [due to the much lower elevation of the fireball in the sky at the time of peak radiating power], the debris from the crater [some of which which gets melted to form glassy, spherical fallout particles like tiny marbles] tends to reduce the radiating temperature of the fireball and a greater proportion of the energy is consequently radiated in the infra red region of the spectrum - this proportion being more easily absorbed by the atmosphere [both carbon dioxide and water vapour in the air absorb the infrared]. ...

    'An important point in relation to personal protection against the effects of hydrogen bomb explosions is that because the thermal radiation lasts so long there is more time for people who may be caught in the open, and who may be well beyond the range of serious danger from blast, to rush to cover and so escape some part of the exposure. For example, people in the open might receive second degree burns (blistering) on exposed skin at a range of 16 miles from a 10 megaton ground burst bomb. If, however, they could take cover in a few seconds they would escape this damage. Moreoer, at this range the blast wave would not arrive for another minute and a haf so that any effects due to the blast in the open (e.g. flying glass, etc.) could be completely avoided.



    'Whatever the size or nature of a nuclear explosion the material in the fireball is highly radioactive, emitting radiations which are referred to as either nuclear or ionising radiations. They are called nuclear because thet arise from disturbances taking place in the central nuclei of the atoms, and ionising because they possess the property of producing electrically charged atoms or molecules called ions in the materials through which they pass.

    'Nuclear radiations consist of alpha rays, beta rays, gamma rays, and neutrons.

    Alpha rays

    'The alpha particle is now known to be identical with the nucleus of the helium atom, i.e. a helium atom which has been stripped of its two planetary electrons, leaving it positively charged. Alpha particles pass through only a few inches of air before losing all their energy by collisions with atoms. Those produced at the time of the explosion are all absorbed in the fireball itself; from the point of view of the immediate dager they can be disregarded. Any unfissioned uranium or plutonium that is subsequently deposited on the ground would radiate alpha particles, but since they cannot penetrate the skin they become a hazard only if the materials emitting them are taken into the body.

    Beta rays

    'These are streams of particles, called beta particles, which are identical in almost every respect with electrons. The electron is 1/1800 of the weight of a hydrogen atom and 1/7200 of the weight of an alpha particle. Because of its small mass the beta particle can travel several yards in air before its energy is used up in collisions producing ionisation. This range is so small that from the point of view of the immediate danger be disregarded; their contribution to the hazard from deposited radioactivity is discussed [later].

    Gamma rays

    'These contribute the chief danger of all nuclear radiations, and so are discussed in detail [later].


    'These are uncharged particles, each equal in weight to a hydrogen atom, but very penetrating, since - being uncharged - they can pass close to the electrically charged nuclei of the atoms of the material through which they travel without being defected and thereby losing energy. They are discussed further [later].

    The immediate danger from nuclear radiation

    'There is a continuing emission of gamma rays as the fireball expands and cools, but in rapidly decreasing intensity. It is not until the cloud moves into the upper air [the radiation shielding of the full atmosphere is equivalent vertically to a water shield 10 metres thick] that the immediate danger can be said to be over. Whatever the power of the bomb, this time may be taken to be about a minute.

    'The explosion products continue to emit nuclear radiations for a long time, and wherever they are subsequently deposited as fall-out the radiation hazard from them persists.

    'Gamma rays ... are similar in their general nature to X-rays although they are usually shorter in wavelength and more penetrating. They travel at the speed of light and are scattered by atoms of oxygen and nitrogen in the air. At each encounter [a Compton collision between a gamma ray and an orbital electron of an air molecule, leading to the ejection of the electron and the re-emission of the gamma ray in a slightly different direction; the Compton effect mathematics treats the gamma ray as a particle not as a wave, so it interacts with the electron simply like one billiard ball striking another] the direction of the rays is changed, charged ions are produced, and some of the energy is lost [as the kinetic energy of the electron].

    'Although at any one place most of the radiation comes in the direct beam from the fireball, an appreciable proportion arrives from every other part of the sky, just as in strong sunlight a room which faces north [away from the sun, which is confined to the southern hemisphere of the observer] still receives light from the visible sky, and by reflection from other objects. The mechanism of scattering is somewhat different in the two cases, but the results are similar. ...

    'The amount of gamma radiation absorbed in agiven time is usually referred to as the "dose" of radiation ... While gamma rays of themselves have no effect on the shielding materials through which they pass and do not make them radioactive, they do have a harmful effect on the human body or any living tissue because of the property of ionization already referred to. Ionisation produces chemical changes which are harmful to the body cells and eventually to the organs which are made up of these cells. ... Some of the effects do not appear for some time. Delays are due to the fact that different body cells have diferent life spans which vary from several days to several weeks, and although some of the cells are affected in such a way that they can no longer reproduce themselves, they go on living for some time. ... In buildings the dose inside would only be a small percentage of that in the open ...

    'Neutrons ... are ... gradually slowed down and lose their energy as a result of continual collisions with light atoms of the same size in their path, just as for example one billiard ball will lose a lot of its energy in striking another of the same size, but will bounce almost unaffected off a much larger object. The nuclei of atoms of hyrogen, since they are the same weight as neutrons, are particularly effective in this way ...

    'Neutrons are occasionally captured by nuclei of some of the atoms with which they collide, making them unstable and radioactive. This "induced radioactivity", as it is called, may be quite strong in the area immediately around ground zero, but the range of neutrons in air from a nominal [20 kt] bomb explosion is not much greater than about half a mile, and beyond this distance there will be little radioactivity from this cause. Induced radioactivity takes the form of the emission of gamma and beta rays similar to those from the explosion products.

    Effect of neutrons on living organisms

    'Neutrons do not cause ionization directly, but because they may collide with the nuclei of light atoms in the body they can produce ionisation indirectly and are therefore harmful.

    The delayed danger from residual nuclear radiation

    Fall-out and induced radioactivity

    'Some of the products of the explosion (which are still radioactive) settle on the ground at the point of burst; some may spill over into the immediate area around and downwind; and some are carried into the upper air to be deposited eventually perhaps much further from ground zero, depending on the winds prevailing up to the height to which the products first ascend. Any such settling, spill over, or deposition of these radioactive products of the explosion (which may be mingled with the dust, pulverised debris and earth etc., sucked up with the ascending fireball is termed fall-out.

    'If the explosion takes place close to the ground there is also likely to be a good deal of neutron-induced activity because of the very close contact between the neutrons produced in the explosion and materials on the ground. This induced radioactivity, which is limited to the area of the crater, tends to decay very rapidly and, except immediately after the explosion, is unimportant compared with the radioactivity from fall-out. ...

    'Heavy clothing and thick boots and socks provide fairly complete protection against beta rays [even a single thickness of thin cotton summer clothing prevented beta burns to the Marshallese Islanders contaminated by fallout from a 15 megaton bomb test near Rongelap Atoll on 1 March 1954]. The skin itself acts as a barrier to most beta rays, but beta particles on the skin produce - in extreme cases - a burning effect similar to sunburn [but with the burn onset delayed for a long period of about 14-18 days after exposure, not just 5-8 hours as is the case for sunburn]. If, however, the gamma ray exposure is controlled within permissible limits, the beta hazard should not be serious. Nevertheless it would be a wise precaution to wear gloves when handling debris which may have been contaminated, so as to keep beta particles from direct contact with the skin, and it would be advisable to wash all exposed skin as soon as possible after leaving a contaminated area.

    'Because the range of gamma rays in air is much greater than that of beta rays, an appreciable part of the dose received at any one spot is made up of gamma rays coming from quite long distances; [on rough ground] half of it comes in fact from within, and the other half from beyond, a distance of about 25 feet [the radius is greater on smooth ground because there is then less shielding by irregularities in the ground surface of direct gamma rays travelling from very large distances almost parallel to the ground, i.e., along very small angles of elevation].

    Radioactive decay

    'Radioactivity cannot be destroyed or interfered with chemically, and its decay can neither be accelerated nor slowed down. The average decay rate of all the various products of a nuclear explosion is such that as the time [measured from the time of the detonation] is doubled, its activity is somewhat more than halved. More precisely, the activity is reduced by a factor of 10 when the time [after detonation] is multiplied by a factor of 7. ... This assumes of course that the radioactive material stays where it is originally deposited. If some of it is buried e.g. by the continual turning over of debris, or is physically removed by rain or wind or by active measures of decontamination such as hosing down paved areas, then the dose rates will be much less ...

    Radioactive poisoning

    'This term is used to describe the results that may follow the introduction of radioactive materials into the body. Such materials may be taken into the body in various ways, for example:

    • by breathing in contaminated dust;

    • by eating contaminated food, or drinking contaminated [milk or] water;

    • by taking in contaminated dust into the blood stream through wounds or abrasions.

    'For civil defence personnel working in contaminated areas, the chance of this happening to such an extent that a dangerous dose of any one of the radioactive explosion products can be accumulated in the body in any reasonable time is not very high [the fallout particles in local fallout where the activity concentration is significant, are simply too large to be inhaled, being similar to sand particles]. For those which are absorbed to any extent in the various organs of the body, there are recognised permissible levels just as there are for external gamma radiation.

    'It has been found that this internal risk is small compared with the external risk due to the gamma radiation from the surrounding contaminated area which is producing the dust, and if exposure to the external gamma radiation is controlled within permissible limits, the risk of radioactive poisoning alone is comparatively small. It is, however, important to avoid taking radioactive material into the body and various precautions to deal with this matter are given later.

    'The hazard may be much more serious in the case of fall-out from a ground burst hydrogen bomb which might cover a large area of country not affected by blast. In this case radioactive material would almost certainly be deposited on crops, grazing land, and open reservoirs, and might eventually find its way into the body without any corresponding external radiation hazard to act as a control. ...

    The residual radiation hazard from a nominal [20 kt] bomb

    'The nominal [20 kt] bomb produces its maximum area of blast damage if it is exploded in the air, the optimum height depending on various factors such as the nature of the target, type of buildings etc. For most British cities about 1,000 ft. is usually considered the optimum height. For heights of burst 1,000 ft. and above, radioactive ground contamination is only serious in a small area round ground zero which is within the area of general destruction by blast. ...

    Contamination in the devastated area

    'With a 10 megaton ground burst bomb the crater itself might be a mile in diameter [this is the crater size for saturated porous coral produced in the 10.4 megaton Mike test which erased Elugelab Island of Eniwetok Atoll on 1 November 1952; craters in silicate soil or rock are much smaller and don't obey the same scaling laws as saturated porous coral which is simply pulverised to sand by the shock wave]. The crater and the surrounding debris would be made strongly radioactive by neutron bombardment and by intimate admixture with the products of the explosion in the fireball. Work in the open in the central area of devastation and in the immediate area downwind would be quite impossible for some days [under peacetime radiation exposure constraints, it was 27 days before people could safely visit the crater lip of the 100 kt Sedan cratering test at Nevada in July 1962], so that in these areas rescue and fire fighting would have to be abandoned or severely restricted. From the upwind side, approach to the devastated area would have to be under strict radiological control.

    'It is likely that two main working areas would have to be established; an outer area where the surveyed activity did not exceed a certain figure and where a man could work on a shift basis for several days; and an inner area where special tasks might have to be undertaken but where it might be necessary to let a man take the whole of his permissible dose in one shift. Both areas would contract towards ground zero as time went on because of the decay of radioactivity, so that fresh operational areas would continuously be opened up.

    Contamination in the undamaged area

    'American tests have shown that the fall-out from a hydrogen bomb burst on the ground can be very extensive. Most of the heavy material sucked up by the rising fireball spills out of the mushroom stem fairly close to the crater. Lighter material is carried higher and deposited further downwind, perhaps clear of the actual devastated area. Finer material still, is swept up into the upper atmosphere and carried along by the prevailing winds for great distances before falling out over areas quite unaffected by blast and fire.

    'This very fine material may have been sucked into the rising fireball from the ground or from the atmosphere, or may have been formed by recondensation of matter which was actually vapourised in the fireball. As the cloud drifts downwind its radioactivity decays and by the time the finest particles reach the ground they are widely dispersed and present a negligible hazard.

    'The U.S. Atomic Energy Commission, in a report issued on 15th February, 1955, stated that the "thermonuclear device" (estimated at equivalent to 14 megatons of T.N.T.) exploded at ground level on an island in the Pacific [Bravo was exploded on an artificial island consisting of a pile of coral sand, dredged up from the Bikini lagoon and deposited on to a remote part of the coral reef] on 1st March, 1954, contaminated a cigar-shaped area ... At a range of 190 miles it was estimated that the dose received over 36 hours in the open would have been about 300r (5 to 10 per cent. lethal dose), at 160 miles the 36 hour dose would have been 500r (50 per cent. lethal dose) and at 140 miles it would have been lethal to everyone expose in the open for 36 hours [800r shown on illustration]. People, however, do not usually spend 36 consecutive hours in the open, and it is now necessary to consider to what extent the lives and health of the people in the whole of the contaminated area could be saved by taking the appropriate protective measures.

    Protection against fall-out

    'Because the risk is mainly from the gamma rays from the contamination on the ground and roofs of buildings, a considerable degree of protection can be obtained by remaining under cover. There are two factors involved in this protection:

    • the distance between the person and the nearest contamination, and

    • the shielding effect of the material between him and the contamination.


    It was pointed out that half the total effect from a [rough but] uniformly contaminated area comes from the fallout within a distance of 25 ft. - actually one third comes from that within a range of 12.5 ft. Thus in a house whose walls are - on the average - about 12.5 ft. from the centre, one is automatically protected from almost one third of the outside dose because the contamination which would have fallen on this area is now up on the roof. In a bungalow this would not be much of an advantage because of the low roof, but in a building with two or more storeys the contribution from the contamination on the roof would be comparatively small.


    'The intensity of the radiation coming from outside the house, i.e. from beyond 12.5 ft., is reduced by the walls to an extent depending on their thickness. Windows of course provide no protection against gamma rays, so that it would be necessary to block them up with - for example - sandbags to the equivalent thickness of the walls.

    Practical protection

    'Large buildings with a number of storeys, especially if they are of heavy construction, provide much better protection than small single-storey structures. Houses in terraces likewise provide much better protection than isolated houses because of the shielding effect of neighbouring houses. ... In choosing a refuge room in a house one would select a room with a minimum of outside walls and make every effort to improve the protection of such outside walls as there were. In particular the windows would have to be blocked up, e.g. with sandbags. Where possible, boxes of earth could be placed round an outside wall to provide additional protection, and heavy furniture (pianos, bookcases etc.) along the inside of the wall would also help. A cellar would be ideal. ...

    'Streets and other public places: In addition to the natural decay of radioactivity and the physical removal of contamination by rain, hosing down can make an effective contribution to the decontamination of such places. If carried out with powerful jets, as for example from fire pumps, the contamination can be reduced by factors of between 5 and 10 according to circumstances. If the water thus used can be removed by the ordinary drainage system it is not likely to constitute a hazard elsewhere.

    'Food: Gamma rays have no harmful effects upon foodstuffs and the only significant hazard is the deposition of contaminated dist which may eventually find its way into the human system. In the area beyond that of general destruction, where buildings are still standing though damaged, stocks of food, especially those in containers or under cover, are unlikely to be affected. Deposition of contamination on growing crops will, however, be a hazard [although nearly all of it can be removed by washing crops, milling wheat and discarding husks, or by simply discarding the outer leaves of leafy crops]. Only food within the area of complete destruction could be affected by neutron irradiation and become radioactive.

    'Water: Broadly the same principles apply as with food. Gamma rays have no effect upon water, but certainly in the case of hydrogen bomb explosions the deposition of contaminated dust on catchment areas and open reservoirs would constitute a serious hazard. A special version of the contamination meter has been designed for testing water, and water undertakings are well aware of the problems which face them from this type of hazard should it arise. It is worth noting that an ordinary domestic water softener in good condition completely removes the dangerous elements (strontium and barium) from contaminated water [since fallout from surface bursts on silicate based soil is insoluble glassy spheroids, it doesn't dissolve in water and the soluble activity hazards are trivial unless the detonation occurs on coral, limestone or chalk].

    Pages 45-52: BLAST

    Nature of nuclear blast

    'As explained in Chapter I, the expansion of the hot gases in the fireball starts a pressure wave which travels outwards through the surrounding air ... the rear part of the wave, as it moves outwards, moves through a region which has already been compressed and heated by the leading part of the wave. This enables it to move more quickly and [merge with] the leading part of the wave ... The "wave front" therefore grows progressively steeper and in a short distance becomes almost abrupt ... The wave front continues to move outwards unchanged in form, but with gradually decreasing intensity, behaving like a moving wall of highly compressed air. This is often referred to as the "shock front".

    'The abrupt rise in pressure at the wave front is followed by gradually decreasing pressure, and then by a suction phase of intensity less than the pressure phase but lasting for a longer time. Associated with the rise of pressure is an intense wind which persists with diminishing velocity throughout the pressure phase, blowing in the direction in which the blast wave is travelling. The wind reverses its direction at the start of the suction phase, blowing with a lower velocity in the opposite direction, but for a longer time. The effect of these winds in the case of blast waves of long duration is to produce forces on structures for a relatively long time after the shock front itself has struct them and passed on.

    'The duration of any particular feature of a blast wave varies approximately with the cube root of the power [power in common sense of energy release, not power in the physics definition of the rate of energy release] of the explosion. ... The familiar 500 lb. [230 kg] H.E. [high explosive] bomb of the last war contained about 1/15th of a ton of T.N.T. A nominal [20 kt] atomic bomb contains the equivalent explosive energy of 20,000 tons of T.N.T. The ratio of equivalent weights is therefore 300,000 to 1, and the ratio of the cube roots of these weights is about 70 to 1. The duration of the blast pressure from a 500 lb. bomb is about 1/100th second, so with a nominal atomic bomb it should be 0.7 seconds (actually the duration of the wave increases also with its distance from the source and at distances of 2 miles is about 1 second). Applying the same scaling law, the blast pressure from a [10 megaton] 500 x nominal bomb will last 5 seconds or more.

    'These large differences in duration of the positive pressure phase for different sizes of explosion result in the mechanism of damage from an atomic or hydrogen bomb being quite different from that for an H.E. bomb. ... The ability of a suddenly applied blow to cause damage is determined both by the pressure and by its duration. In fact, it is the product of these two (known as the "impulse") which measures the damaging ability of the blast from an H.E. bomb.

    'This point can easily be demonstrated on an ordinary door. If the door is unlatched it can be pushed open by a force of only a few ounces applied somewhat slowly by one's little finger. However, if the unlatched door is struck quite a hard blow with the fist it will not move very far, even though the instantaneous force between the fist and the door (corresponding to the blast pressure) may have been many pounds. If the door is hit hard enough it is quite likely to be torn off its hinges, and this of course is just what H.E. blast does. It gives things a hard sharp blow rather than a gentle push, and many of the so-called freaks of blast in the last war can quite easily be explained once this point is fully appreciated. ... the suction in the negative phase is only about one third of the pressure in the positive phase, but the duration is about twice as long. Thus the impulses in the two phases are of roughly the same order and their potential abilities to cause damage are also approximately equal. However, since the suction phase occurs last, there is a tendency for its effects to be noticed more - for example the wall of a building may have been badly cracked in the pressure phase and then collapse outwards in the suction phase, and it is the latter effect which is of course noticed.

    'With nuclear weapons, sheer blast pressure rather than impulse tends to be the criterion of damage. If the effective blast pressure exceeds the static strength of the structure, failure must be expected. If it is less, no failure can occur however long the duration of the blast. In fact nuclear bomb blast is more like a strong wind than the sudden blow of H.E. blast, and many of the failures observed at Hiroshima and Nagasaki and in subsequent tests resemble closely the kind of damage that might be done to buildings by a hurricane.

    'The scarcity of suction damage from the nominal [20 kt] bombs in Japan was due to high blast pressures produced and to the fact that these were three or four times as great as the blast suction. With all such large explosions, if a building does not fail from blast pressure it is unlikely to fail under the lower stresses in the suction phase.

    Scaling laws

    'As already seen, the various time factors connected with the blast from a powerful explosion can be estimated from the known time values of a much less powerful explosion by applying the cube root scaling law. The distance at which a given pressure is experienced also scaled accoding to the cube root law providing the height of burst is adjusted in the same way ... the ranges of blast damage from a 10 megaton (500 x nominal) air burst bomb are those of a nominal bomb multiplied by a factor of 8 (the approximate cube root ot 8). ...

    Effect of blast on structures

    'When the front of the blast wave strikes the [rigid] front wall it is reflected back, and the pressure in the wave front builds up to more than double the original pressure. However, this build-up only lasts for a very short time and is mainly important for large flat surfaces such as walls of big buildings. As the blast wave passes over the building, the sides, roof, and finally the rear wall are subjected to what is known as the "side-on" pressure in the wave, but since they are side-on and not face-on there is no extra pressure due to reflection. At this stage the front, roof, sides and back of the building are all subjected to more or less the full blast pressure, and the principal tendency then is for the building as a whole to be crushed.

    'But the pressure at and behind the blast front is accompanied by the blast wind which, while it exerts additional pressure on the front, exerts a suction [not to be confused with the suction in the negative phase of the blast wave] on the back (since it is sucking air away from the back wall and to some extent also from the sides and roof) which tends to cancel out the pressure on the front of the building, and most of the direct blast damage is produced there with comparatively little elsewhere. The building as a whole tends to be pushed over away from the explosion.

    'However, this related only to a building with blank walls. If the blast gets inside through openings in the front wall, the pressure inside, acting upwards on the roof, is the full side-on blast pressure, whereas the pressure outside is the blast pressure less the wind suction. The net result is therefore that the roof tends to be forced violently upwards, a feature which was noted in Japan and has been observed in published photographs of American nuclear weapon trials, where houses have appeared to "explode" when struck by the blast wave [stills from movie film of the two storey brick house exposed to 5 psi peak overpressure blast at the Apple-2 nuclear test, Nevada, 1955].

    'The ability of a building to withstand the shock of the blast wave depends upon its strength, its shape, and the number of openings into the building which serve to relieve the pressure on the outside walls. The strongest structures are heavily framed steel ad reinforced concrete buildings, while the weakest are probably certain shed type industrial structures having light frames and long roof spans. The resistance to blast of brick structures is rather poor, partly because of their low resilience and partly due to their weakness against pressure from inside, since a comparatively small outward movement of the walls causes the floors to collapse.

    'The effect of shape on blast damage is not very marked in most conventional structures, where streamlining is usually absent. It is, however, most pronounced with such objects as large smoke-stacks and factory chimneys which, because of their relatively low wind drag, are surprisingly resistant to blast. Such chimneys often remain erect when other structures near to them are levelled to the ground in explosions of this kind. On the other hand, flat surfaces such as windows in an extensive wall surface, have a high probability of failure even at comparatively low blast pressures.

    'Bridges, which are built to stand high wind pressures, stand up to blast fairly well, though if they are close to the ground zero of a ground or near-ground bomb they may be shifted bodily sideways off their abutments.

    Height of burst in relation to bomb damage

    'When a bomb is burst in the air the pressure wave is reflected from the ground, and since the reflected wave travells through air which has been compressed and heated by the direct wave, it tends to travel faster than, and to catch up with, the direct wave. When the reflected wave catches up with the direct wave the two join together to form what is called a Mach wave, and this accounts for a pronounced increase in range of damage.

    'On the other hand when a bomb is burst on or near the ground much of the blast energy is expended in forming a crater, and in causing much heavier destruction of buildings immediately around ground zero. There is also considerable shielding of one building by another [blast cannot cause destruction without doing mechanical work, which irreversibly expends blast energy, so it is impossible for the blast not to be depleted in energy as a result of causing destruction], and by topographical features (e.g. ridges and hills), which tend to reduce the range of damage.

    'The radius of blast damage from air burst bombs therefore tends to be greater than from bombs burst on or near the ground. However, if the bomb is burst too high in the air the advantage of the Mach reflection is counterbalanced by the greater distance between the explosion and the ground, so that for all powers of bombs there are optimum heights of burst which give the greatest area of blast damage.

    'The optimum height also depends on the type of target being attacked. If the target area contains a high proportion of strongly constructed buildings then the bomb must be burst nearer to the ground in order to do the required damage in the central area around ground zero and so cause the maximum number of casualties. For more easily damaged types of property the maximum area of destruction can be obtained by bursting the bomb higher in the air. In Japan the height of burst of 2,000 ft. caused destruction over a very wide area to flimsy traditional Japanese buildings, but produced very little blast effect on the few earthquake-resisting buildings which were even as close as 0.25 mile to ground zero. For the average British city the height of burst which would produce the most serious blast situation from a nominal bomb is usually considered to be about 1,000 ft. ...

    Effects of an air burst bomb on public utility services

    'The effects of an air burst bomb, whether nominal or larger than nominal, on public utility services would be largely confined to damage above ground. Underground gas and water mains would be undamaged, except possibly where they were carried on bridges, or where they were fairly close to the surface and liable to damage by a collapse of neighbouring heavy masonry. Sewers too should be undamaged. Overground installations and services, such as gas holders, water pumping stations, electricity generating stations and sub-stations, overhead electricity, telephont and telegraph cables, buses and motor cars would be damaged more or less severely up to 1 mile or so from ground zero for a nominal [20 kt] bomb, and up to 8 miles for a 10 megaton bomb. Railway and tramway [street car] tracks would probably remain intact but might be affected by debris, overturned rolling-stock, adjacent fires, etc.

    Cratering and ground shock from a ground or near-ground burst 10 megaton bomb

    'A 10 megaton bomb bursting at ground level is expected to produce [according to data from the 10 megaton 1952 Mike test on water saturated porous coral, which results in a far bigger crater than a burst of similar size on earth] a saucer-shaped crater about a mile in diameter. The debris from the crater would be scattered around in a ring about 2 miles in diameter and the remains of any structures in this area might consequently be buried. Severe earth movements might be caused at greater ranges and underground structures might be affected up to a few miles. Some underground services should survive at ranges considerably less than that of general destruction on the surface. ...

    Effect of blast on people

    'In Japan the direct effect of blast from atomic bombs on people was found to be less than might have been expected. Where people were safe from the secondary effects of the blast there was little evidence that they had suffered from any internal injury due to the blast itself.

    'Most of the blast casualties in this country would be caused by the indirect or secondary effects of the blast, such as falling masony, flying debris and glass. Such injuries would occur up to 1.25 to 2 miles from an air burst nominal bomb [20 kt], with casualties from glass fragments predominating at the greater distances. People would also be trapped by the collapse of buildings and might become casualties for this reason or even be suffocated without receiving other physical injuries.

    The debris problem

    'In Japan debris was not a very serious handicap because most of the material of the Japanese houses, being combustible, was destroyed by fire leaving a fairly uniformly flattened area covered with a comparatively thin layer of semi-burned or unburned material, e.g. tiles. Moreover, because the bombs were burst at 2,000 ft. the few strong buildings near to ground zero were not destroyed and therefore produced very little debris.

    'The situation would be quite different in a modern city, where a large proportion of the material of almost every building is incombustible. Even if every building was affected by fire there would still remain a large amount of incombustible material to contribute to the rubble and debris which could collapse into the streets. ... At the shorter ranges, road blockage might be caused by fallen trees, etc. It will be seen at once that debris is going to be one of the outstanding problems. ... Roads with houses having front gardens or wide footpaths will obviously not be so seriously affected by debris as narrow streets, and many wide roads exist through which a way, at any rate for single line traffic, and certainly for pedestrians, could always be opened with a small amount of effort. By means of surveys in major cities suitable traffic routes can be earmarked for use should the emergency arise and ground zero occur at a variety of possible locations. Parks, open spaces, railway embankments, wide roads, rivers and canals etc., might all provide entry and exit routes because of their comparative freedom from debris.'

    Above: Fission Fragments, the restricted-classified journal of the Home Office Scientific Advisory Branch. W. F. Greenhalgh was the editor of early issues in the 1960s, P. R. Bentley and later M. J. Thompson were editors in the 1970s. Here is a spoof metaphoric letter attacking 'ambulances' (civil defence) published in the originally 'Restricted' classified U.K. Home Office Scientific Adviser's Branch journal Fission Fragments, W. F. Greenhalgh, Editor, London, Issue Number 3, August 1962, pages 14-15 (these declassified magazines are now in the UK National Archives category HO229; if you are at the UK National Archives please also see HO338 and DEFE16 in the printed catalogues, which have useful lists of related file locations on the first page):

    'Ambulance Service in Road Accidents


    'It has been brought to our attention that certain elements among the driving public, no doubt inspired by the motor car manufacturers and an irresponsible clique of hospital surgeons interested in narrow sectional interests, favour the use of ambulances to take the victims of road accidents to hospital. These elements have used the excuse that such action would save lives and suffering in the event of an accident. Although we share their concern, we remain unalterably opposed to any consideration of this course of action, for the following reasons:

    '1. The cost would be prohibitive. If it were borne by the state, an economic and social re-orientation would be needed; our country would be taking a step towards totalitarianism and the militarisation of society.

    '2. These proposals will distract the government's attention from more important things e.g. the complete prevention of accidents by road-widening schemes. Increasing the penalty for dangerous driving is no answer. The only answer, befitting the dignity of human beings, is to ban the car.

    '3. This programme would lull all road users into a false sense of security and reduce public initiative to seek means of reducing the accident rate.

    '4. It would cause undue alarm and reduce the joys of motoring.

    '5. It demonstrates lack of faith in the rational behaviour and self-restraint of our drivers.

    '6. The road-accident hysteria is being whipped up by demagogic career politicians. Where do road-accident figures come from anyway?

    '7. Motor car manufacturers will make cars which are unsafe. Big business is obviously hoping to profit from a demand for ambulances.

    '8. Why should attention be directed to only one type of accident? Just because something can be done about road accidents, but not about accidents in the home, for example.

    '9. All ambulance drivers will have to be medically qualified: this at a time when our hospitals are understaffed!

    '10. If you had an accident, a traffic jam would ensue, and the ambulance would not be able to reach you.

    '11. If the ambulance reached you, you would still be in danger from shock. Even if you do not die from shock your resistance to disease will be lowered. If you escape these horrors, you may well fall into a decline in the unfamiliar environment of hospital.

    '12. If you survive your period under the strict regime of the hospital, you will have lost your belief in the freedom of the individual.

    '13. If the hospital saves you and not the other occupants of the car, you will spend a life of remorse mourning your lost loved ones.

    '14. Most car drivers carry in their minds a load of guilt and frustration about their affluence. It is this which subconsciously forces them to desperate deeds in difficult traffic. Even if a driver is not responsible for the accident he will either spend a life of remorse or become homicidal. If he is in fact responsible for the accident, it is clear that he ought not to survive. Better dead than discomforted.

    '15. The panic engendered by a road accident would destroy all vestiges of civilised human behaviour. We shudder at the vision of one man struggling with another to get into the ambulance.

    '16. Since the first motor car accident in 1850, the speed of cars has increased tenfold and, moreover, the number of cars on the roads has increased a millionfold at least. Road accidents have, in fact, become unthinkable.

    'It is apparent that all measures to reduce the horror of road accidents are futile and, worse than that, they are morally wrong and contemptible since they increase the probability that an accident will occur. Anyone who does contemplate road accidents obviously advocates them.

    '- Committee for a Rational Accident Policy.'

    The same magazine: originally 'Restricted' classified U.K. Home Office Scientific Adviser's Branch journal Fission Fragments, W. F. Greenhalgh, Editor, London, Issue Number 3, August 1962, pages 22-26:

    'The fire hazard from nuclear weapons

    'by G. R. Stanbury, BSc, ARCS, F.Inst.P.

    'We have often been accused of underestimating the fire situation from nuclear attack. We hope to show that there is good scientific justification for the assessments we have made, and we are unrepentant in spite of the television utterances of renowned academic scientists who know little about fire. ...

    'Firstly ... the collapse of buildings would snuff out any incipient fires. Air cannot get into a pile of rubble, 80% of which is incombustible anyway. This is not just guess work; it is the result of a very complete study of some 1,600 flying bomb [V1 cruise missile] incidents in London supported by a wealth of experience gained generally in the last war.

    'Secondly, there is a considerable degree of shielding of one building by another in general.

    'Thirdly, even when the windows of a building can "see" the fireball, and something inside is ignited, it by no means follows that a continuing and destructive fire will develop.

    'The effect of shielding in a built-up area was strikingly demonstrated by the firemen of Birmingham about 10 years ago with a 144:1 scale model of a sector of their city which they built themselves; when they put a powerful lamp in the appropriate position for an air burst they found that over 50% of the buildings were completely shielded. More recently a similar study was made in Liverpool over a much larger area, not with a model, but using the very detailed information provided by fire insurance maps. The result was similar.

    'It is not so easy to assess the chance of a continuing fire. A window of two square metres would let in about 10^5 calories at the 5 cal/(cm)^2 range. The heat liberated by one magnesium incendiary bomb is 30 times this and even with the incendiary bomb the chance of a continuing fire developing in a small room is only 1 in 5; in a large room it is very much less.

    'Thus even if thermal radiation does fall on easily inflammable material which ignites, the chance of a continuing fire developing is still quite small. In the Birmingham and Liverpool studies, where the most generous values of fire-starting chances were used, the fraction of buildings set on fire was rarely higher than 1 in 20.

    'And this is the basis of the assertion [in Nuclear Weapons] that we do not think that fire storms are likely to be started in British cities by nuclear explosions, because in each of the five raids in which fire storms occurred (four on Germany - Hamburg, Darmstadt, Kassel, Wuppertal and a "possible" in Dresden, plus Hiroshima in Japan - it may be significant that all these towns had a period of hot dry weather before the raid) the initial fire density was much nearer 1 in 2. Take Hamburg for example:

    'On the night of 27/28th July 1943, by some extraordinary chance, 190 tons of bombs were dropped into one square mile of Hamburg. This square mile contained 6,000 buildings, many of which were [multistorey wooden] medieval.

    'A density of greater than 70 tons/sq. mile had not been achieved before even in some of the major fire raids, and was only exceeded on a few occasions subsequently. The effect of these bombs is best shown in the following diagram, each step of which is based on sound trials and operational experience of the weapons concerned.

    '102 tons of high explosive bombs dropped -> 100 fires

    '88 tons of incendiary bombs dropped, of which:

    '48 tons of 4 pound magnesium bombs = 27,000 bombs -> 8,000 hit buildings -> 1,600 fires

    '40 tons of 30 pound gel bombs = 3,000 bombs -> 900 hit buildings -> 800 fires

    'Total = 2,500 fires

    'Thus almost every other building [1 in 2 buildings] was set on fire during the raid itself, and when this happens it seems that nothing can prevent the fires from joining together, engulfing the whole area and producing a fire storm (over Hamburg the column of smoke, observed from aircraft, was 1.5 miles in diameter at its base and 13,000 feet high; eyewitnesses on the ground reported that trees were uprooted by the inrushing air).

    'When the density was 70 tons/square mile or less the proportion of buildings fired during the raid was about 1 in 8 or less and under these circumstances, although extensive areas were burned out, the situation was controlled, escape routes were kept open and there was no fire storm.'

    Further in the article, Stanbury gives metereological data for the U.K. which indicate a mean cloud cover of 70% of the sky at any time, and on page 24, he gives U.K. research on thermal radiation transmission: 'Lane, Stone and Edwards of the Chemical Defence Experimental Establishment at Porton have done work in this field and have shown for example that at 20 [statute] miles [32 km], the diffuse transmission of luminous flux at ground level is only 0.2 for a visibility of 16 miles; 0.1 for a visibility of 8 miles; 0.035 for a visibility of 4 miles.'

    I will point out that these experimental figures are surprisingly close to the values of 0.29, 0.082 and 0.0067 you get using transmission T = e^{-R/V} where R is range and V is visibility (in same units as R, of course!). This formula is based on my analysis of all Nevada and Pacific nuclear test data, where the average visibility was 10 miles in the Pacific (Bikini and Eniwetok) and about 50 miles in Nevada due to the generally drier air over the arid desert than that in the hot, humid mid Pacific Ocean. (The raw source of this nuclear test data can now be found online in a chart and reference in:

    The American manuals make a mess of thermal transmission. Glasstone and Dolan inaccurately claim that scattered radiation prevents a simple exponential law being valid, but they are thinking of a 'build-up' factor, i.e., a contribution from scattered radiation, which does not contribute significantly to thermal injury in most cases. Filtering actually offsets the 'build-up' factor. The American book Glasstone and Dolan relies on M. G. Gibbons' August 1966 report Transmissivity of the Atmosphere for Thermal Radiation from Nuclear Weapons (U.S. Naval Radiological Defense Laboratory, USNRDL-TR-1060) which is based on measurements using monochromatic green light. The problem is that the true fireball radiation output covers a wide range, and some components like ultra violet and infrared tend to get filtered out more quickly than visible light, so this 'filtering' effect increases the mean penetrating powerof the remaining (filtered) thermal radiation as you get further from the bomb (at long distances, only visible light survives). The 'build-up' effect, i.e., the increased contribution of less-penetrating scattered radiation with greater distance from bomb, tends to decrease the mean penetrating power of the radiation as you get further from the bomb. So the 'filtering' effect is offset in practice by the 'build up' effect. Hence the exponential law holds good in nuclear test data!

    For a variety of different American estimates (Brode 1964, Glasstone and Dolan 1977, and the 1974 NATO edition of Philip J. Dolan's Capabilities of Nuclear Weapons, EM-1) of thermal transmission (some of which are nonsense) see page 11 of Dr Harold L. Brode and Richard D. Small, Fire Damage and Strategic Targeting, Pacific-Sierra Research Corporation, Los Angeles, California, Defense Nuclear Agency report DNA-TR-84-272 (1 June 1984), accession number ADA159280.

    But a later paper of Brode's, A Review of the Physics of Large Urban Fires, co-authored with Dr Richard D. Small, quotes the substantially greater attenuation of thermal radiation suggested by the empirical green light transmission formula, T = (1 + 1.9R/V)e^{-2.9R/V}, from M. G. Gibbons' August 1966 report Transmissivity of the Atmosphere for Thermal Radiation from Nuclear Weapons (U.S. Naval Radiological Defense Laboratory, USNRDL-TR-1060).

    I will just mention that Dr Harold L. Brode and Dr Richard D. Small, in their report Fire Damage and Strategic Targeting (Pacific-Sierra Research Corporation, Los Angeles, California, DNA-TR-84-272, June 1984) assume that 50% of houses are ignited by a thermal exposure of 16 calories per square centimetre from a 50 kt weapon or 22 cal/(cm)^2 for a 1 Mt weapon. They don't provide precise reasons for these specific numbers. It is not clear that the realistic ignition energy for curtains, armchairs, carpets, beds, and so on are in that range. Brode and Small seem to be assuming folded newspapers are everywhere. However, you need to actually work out what fraction of buildings have rooms in line of sight to the fireball and then you need to estimate the probability that something inflammable is actually in the line of sight. If only 50% or fewer of buildings will have a single room in line-of-sight of a fireball (as the British studies referred to by Stanbury above indicate to be the case), then any figure for an 'average ignition energy' produced out of the hat by Brode and Small will be wrong, misleading, and deceptive. Many modern fabrics used in furnishings are fire-resistant by law and hard to ignite properly. It is true that the blast wave could throw smouldering curtains into a room, starting fires, but only if the curtains have been exposed to the thermal flash, which depends on whether a line of sight of the fireball exists from the window in question.

    In reality, in a surface burst or low air burst, the nearest buildings the the explosion will 'shadow' all the more distant buildings, and this will continue - as shown in nuclear test films - even after the blast blows to pieces the nearby buildings (the dust cloud produced by the mechanical destruction from the blast stops the thermal radiation).

    Brode and Small do usefully quote a study of secondary fires caused by blast in Hiroshima and Nagasaki; J. McAuliffe and K. Moll, Secondary Ignitions in Nuclear Attack, SRI International, Menlo Park, California, SRI Project 5106, July 1965. This study found that for every 1000 square feet of modern-type damaged buildings, there was 0.006 'secondary' fire created by the blast effect on electrical or gas equipment. This estimate does not include the many thousands of wood-frame houses which were ignited by overturned charcoal cooking braziers in Hiroshima and Nagasaki. (Brode and Small however ignored that hard experimental data and preferred to use a completely non-validated assumption that 100% of buildings with heavy damage - which is caused by a peak overpressure of 4 psi for American wood-frame residences - will be ignited by blast damage.)

    A few more details about the Fission Fragments magazine No. 3, August 1962: inside the front cover there is the warning 'Restricted: The information given in this document is not to be communicated, either directly or indirectly, to the Press or to any person not authorised to receive it.' (It is now long since declassified, since it is openly viewable at the National Archives in Kew, London.) Below that warning, there is published a quotation from American strategist H. A. Kissinger:

    'As weapons grow more destructive, and forces-in-being more invulnerable to surprise attack and to defense systems, the real contest in an all-out war will be between the vulnerabilities and the degrees of resilience of the opposing societies.'

    To give a taste for the wide range of problems covered (ranging from fire, fallout, electromagnetic disruption due to high altitude tests, and detecting nerve gas in chemical warfare), it is telling to quote a couple of sentences from page 37, dealing with the use of early electronic computers to assess fallout decay rates and radiation doses:

    'A danger with the use of computers is that things tend to become stereotyped. Thus people get used to a narrow range of circumstances and will be flummoxed "on the day" when - and nothing is more certain - something different will happen. It is hoped that this rigidity has been avoided to some extent here by such things as having irregular plume shapes ... and by introducing clean bombs and neutron-induced isotopes into the decay laws.'

    Page 38 quotes the following extract from the May 1959 issue of Wireless World magazine:

    'Man-made blackouts

    'One gathers that there has been considerable uneasiness in the U.S.A. owing to the discovery that wireless and radar signals can be blocked by bursting a nuclear bomb at a great height above the earth's surface. Before any announcement on the subject was made officially in America, Russian scientists had attributed the unexpected density of the inner radiation zone (which at the magnetic equator is 1,500-4,000 miles above the earth) to the effects of nuclear explosions. Later, an official statement was made in the U.S.A. that, as part of the I.G.Y. [International Geophysical Year] programme, three such tests had taken place last year at heights of about 300 miles [actually these Argus test burst heights were 200, 240 and 540 km]. In each case the flash of the explosion was followed at once by a faint luminosity extending along the magnetic line of force through the burst point. This line of force returns to our atmosphere in the northern hemisphere near the Azores. Aircraft stationed in the region for observation purposes noted a short auroral glow. The work was then taken up by the satellite Explorer IV which, travelling day after day "through the man-made 'shell' of trapped radiation", sent back to earth measurements which enabled its intensity and shape to be worked out. It has been suggested that anyone mad enough or wicked enough to start a nuclear war could put the other side's distant early warning radar system almost, if not entirely, out of action by leading off with a number of bursts in the right places.'

    The same page (38) then gives this:

    'Extract from Estimated effects of nuclear explosions of various megaton yields, United States Atomic Energy Commission news release 31st October, 1961.

    'Electromagnetic Effects on World Communications

    'Communication blackouts due to low-altitude, high-yield explosions are probably too localised to be of interest. If the cloud stabilizes at an altitude of about 25 miles, however, the possibility exists of producing observable effects on radio waves over distances of about 100 miles from air zero.

    'As a result of a 50-megaton detonation at an altitude of about 50 miles, large-scale high-frequency communications blackouts could be expected within a region of 2,500 miles radius and for a time span of the order of a day. At 30 miles altitude the radius of effect would be about 1,000 miles.'

    The last page of the magazine contains a notice to the reader by the Editor, W. F. Greenhalgh which states 'Fission Fragments is in the Restricted security class. ... Views expressed in Fission Fragments are not necessarily endorsed by the Scientific Adviser's Branch of the Home Office. ... Si vis pacem, para bellum. [If you wish for peace, prepare for war.]'

    Some other particularly valuable articles in Fission Fragments are:

    (1) A. Preston (Ministry of Agriculture, Fisheries and Food, Fisheries Radiobiological Laboratory, Lowestoft), 'The Effect of Fallout on Fisheries', Fission Fragments, Issue No. 14, February 1970, pages 32-41, 48.

    This relates the gamma dose rate at a standard time after burst to the deposited activity of those fission product nuclides which become significantly concentrated in the aquatic food chain (in order of decreasing fission product activity in fish flesh soon within days of a nuclear explosion): iodine-131, cerium-141, cerium-144, zirconium-95, strontium-89, ruthenium-103, caesium-137, strontium-90, ruthenium-106.

    Account was taken of fission product fractionation in fallout (the relative depletion from local fallout in surface bursts of those nuclides which will not have condensed or decayed into solids at the time that the large fallout particles drop out of the fireball), but neutron-induced activity in the weapon casing was ignored.

    This gives the amount of nuclide deposited per square metre of surface on the water. To get the concentration of the nuclides in a cubic metre of water, the water solubility of the radioactive material in the fallout is used (this is where a knowledge of the chemistry and physical properties of fallout particles is vital):

    'Using these depositions and solubilities, the activity was assumed to mix uniformly to 100 m, the average depth of the surface mixed layer of the oceans, or to the bottom in shallower water, within 48 hours. This assumption has been borne out by weapon test data in the Pacific. The resulting water activities were then used to assess the specific activities in fish flesh by the use of suitable concentration factors selected for each radionuclide.'

    The doses from ingested fish were then computed. The largest fish ingestion threat within 2 weeks of a nuclear explosion thyroid irradiation from I-131 in fish. Since I-131 has a half life of only 8 days, it is not a long-term problem. The article shows that in an area where the fallout gamma dose rate at 48 hours after burst is 1 R/hour on land, assuming 10% fallout solubility in water, the total thyroid I-131 radiation dose from eating 1 kg of fresh fish caught 48 hours after the explosion would be 0.205 R, compared to a dose to the bones of only 0.117 R. The relative importance of Sr-89 and Sr-90 in fish depends crucially on the concentration factor, which depends on the salts normally present in the water. In the ocean, there is plenty of dissolved calcium present as ions which, being chemically similar to strontium, 'dilute' the radioactive Sr-89 and Sr-90 problem, crowding it out and reducing the concentration factor in biological uptake. In rivers of 'soft' water with little dissolved calcium, however, strontium uptake is concentrated in the fish to levels far above those per kilogram of the water.

    (2) Fission Fragments, Issue No. 21, April 1977, pages 18-25.

    This issue has not been released to the U.K. National Archives, which lists it as a 'Closed Or Retained Document, Open Description... This document was closed under the Public Records Act or is exempt under the Freedom of Information Act 2000.' However, the information in it is vitally important for understanding the real EMP problems of nuclear attack, and it includes a report on the experimental research by the Home Office into EMP on portable radios. The reason for the continued secrecy seems to be articles by Dr J. McAulay (author of the article, 'Science in civil defence' published in Contemporary Physics, Volume 2, Issue 4 April 1961 , pages 245 - 252) and others dealing with EMP effects using classified American data from the U.S. Defense Nuclear Agency's Capabilities of Nuclear Weapons. On page 18, Dr McAulay's article EMP in Proper Perspective states:

    'In 1974 the US Defense Nuclear Agency (DNA) issued a new 1600 page, 2 volume new edition of their classified (Restricted) document, "The Capabilities of Nuclear Weapons".

    'Vol. I "Phenomenology" has 8 chapters of which chapter 4 deals with X-ray radiation phenomena, Chapter 6 with transient radiation effects in electronics phenomena, and chapter 8 with phenomena affecting electromagnetic wave propagation.

    'Vol. II "Damage Criteria" has Chapters 9 to 17 of which Chapter 7 deals with radio frequency signal degradation relevant to communications and radar systems.'

    On pages 20-24 there is an article by C. H. Lewis, MSc, The Effects of EMP, in Particular on Home Defence Communications which states:

    'For a near ground-burst the downward component [of the outward Compton electron current in the air, produced by initial gamma radiation] is largely suppressed leaving the upward component to form what is virtually a conventional dipole aerial with a tremendously high current. ... Field strengths for a 5 Mt weapon may be about 20 kV/m at 3 miles, 5 kV/m at 5 miles and 1 kV/m at 8 miles, where blast pressure will be down to 2 psi. ... Consider first the possible effects on the power system. Fortunately the super-grid (which is designed to work at 400 kV) is not thought to be particularly vulnerable, but perhaps 1/4 of the pulse energy picked up by the supergrid may be passed on by the distribution transformers with consequent current surges in the lower voltage systems of perhaps 20,000 amps. Thus although the supergrid may survive, the current surges in the distribution system may result in major system instability with consequent serious breakdown ... It will be remembered that system instability in 1965 resulted in a total black-out of the north-east US for several days. ... Turning to communications ... transmitters appear to be vulnerable to EMP, which can generate peak currents in the aerials of medium wave transmitters (which may be of the order of 100 m long) of several kiloamperes. As a result there is a considerable risk of breakdown in the high voltage capacitors of the transmitters. Additionally, the continuity of broadcasting depends on power supplies, communication with the studio and the studio equipment. Ironically the ordinary domestic transistor receiver with ferrite rod aerials is likely to survive, but VHF receivers with stick aerials are vulnerable when the aerial is extended. ... At this stage the vulnerability of various devices may be considered. A 300 ft length of conductor may pick up between 0.1 and 40 Joules (1 Joule = 1 watt-second). According to US sources, a motor or transformer can survive about 10,000 J, electronic valves about 0.01 J. Small bipolar transistors are sensitive to about 10^{-7} J and microwave diodes, field effect transistors, etc., are sensitive to about 10^{-9} J. ... With a rise time of 10^{-8} secs, 10^{-8} J equates to 1 watt - well beyond the capacity of small transistors. Clearly, motors and transformers are likely to survive, thermionic valves are reasonably good, but transistors in general are vulnerable, whilst equipment using field effect transistors or microwave diodes is especially vulnerable.'

    The remainder of that article discussed the effects of EMP on the British wired telephone system: 'The effect of any EMP pick-up in the system will be to cause flashover at one or more of a number of points - terminal boards, relay contacts, relay coil terminations, capacitors, etc. ... There are likely to be many domestic telephones connected in part by overhead lines, and these lines can pick up EMP currents, passing them into the exchange equipment. Because most telephone lines are underground, it is no longer Post Office policy to provide lightning protectors at the exchange or on subscribers premises. Within the exchange, all incoming cables are terminated at the Main Distribution Frame, and from this point the internal wiring to the exchange equipment is unshielded. In view of the tremendous amount and complexity of this internal wiring it appears that the major source of EMP pick-up may lie within the exchange. ... The limit of satisfactory direct speech transmission is about 25 miles and since this must include the subscribers lines to and from the exchange it is customary to provide "repeaters" (amplifiers [including inductance coils to prevent frequency-dependent distortion]) at intervals of 15 miles between exchanges.'

    The next very interesting article in Fission Fragments, Issue No. 21, April 1977, is at page 25: A. D. Perryman (Scientific Advisory Branch, Home Office), EMP and the Portable Transistor Radio. Perryman states: 'In an attempt to answer some of these questions [about EMP effects on communications] the Scientific Advisory Branch carried out a limited programme of tests in which four popular brands of transistor radio were exposed in an EMP simulator to threat-level pulses of electric field gradient about 50 kV/m.

    'The receivers were purchased from the current stock of a typical retailer. They comprised:

    '1. a low-price pocket set of the type popular with teenagers.

    '2. a Japanese set in the middle-price range.

    '3. a domestic type portable in the upper-price range.

    '4. an expensive and sophisticated portable receiver.

    'All these sets worked on dry cells and had internal ferrite aerials for medium and long wave reception. In addition, sets 2, 3 and 4 had extendable whip aerials for VHF/FM reception. Set 3 also had one short wave band and set 4 two short wave bands... .

    'During the tests the receivers were first tuned to a well-known long-wave station and then subjected to a sequence of pulses in the EMP simulator. This test was repeated on the medium wave and VHF bands. Set 1 had no VHF facility and was therefore operated only on long and medium waves.

    'The results of this experimentation showed that transistor radios of the type tested, when operated on long or medium waves, suffer little loss of performance. This could be attributed to the properties of the ferrite aerial and its associated circuitry (e.g. the relatively low coupling efficiency). Set 1, in fact, survived all the several pulses applied to it, whereas sets 2, 3 and 4 all failed soon after their whip aerials were extended for VHF reception. The cause of failure was identified as burnout of the transistors in the VHF RF [radio frequency] amplifier stage. Examination of these transistors under an electron microscope revealed deformation of their internal structure due to the passage of excessive current transients (estimated at up to 100 amps).

    'Components other than transistors (e.g. capacitors, inductors, etc.) appeared to be unaffected by the number of EM pulses applied in these tests.

    'From this very limited test programme, transistor radios would appear to have a high probability of survival in a nuclear crisis when operated on long and medium bands using the internal ferrite aerial. If VHF ranges have to be used, then probably the safest mode of operation is with the whip aerial extended to the minimum length necessary to give just audible reception with the volume control fully up.

    'Hardening of personal transistor radios is theoretically possible and implies good design practice (e.g. shielding, bonding, earthing, filtering etc.) incorporated at the time of manufacture. Such receivers are not currently available on the popular market.'

    The slide rule above is the Nuclear Weapon Effects Computer No. 3, issued by the Home Office in 1988 based on brand new computer model of blast casualties developed in 1986 by Home Office scientists Dr S. Hadjipavlou and Dr G. Carr-Hill, a brief description of which is published in the article, 'A Revised Set of Blast Casualty Rates for Civil Defence Use: An Overview' by S. Hadjipavlou and G. Carr-Hill, Journal of the Royal Statistical Society, Series A (Statistics in Society), Vol. 152, No. 2 (1989), pp. 139-156.
    (The previous version, Nuclear Weapon Effects Computer No. 2, had been issued in April 1965 to replace the first version of the computer, which contained inaccurate data on the injured, killed and trapped survivors in U.K. houses as a function of peak overpressure, based on the Home Office 1959 "Operation Arc" World War II bombing data where the damage and injury statistics had been correlated to overpressures causing similar damage from nuclear weapons. The 1963 No. 1 version at 30 psi peak static overpressure predicted 85% killed, 25% trapped, and 3% untrapped but seriously injured, totalling 113%!)

    The original 1986 Home Office report, A review of the blast casualty rules applicable to U.K. houses, U.K. Home Office Scientific Research and Development Branch, Publication 34/86, is about an inch thick and printed on both sides of each sheet of paper. The report is based largely on American detailed scientific nuclear test data collected during Operations Teapot and Plumbbob in Nevada, 1955 and 1957. At these tests, the effects of window glass fragments and debris from blast broken walls was analysed in detail, together with filmed displacement data showing the 'translation' of mechanically realistic dummy human beings by blast waves. In the case of glass fragments and debris from broken walls, the distributions of fragments by size and by velocity due to blast wind pressure acceleration were deduced, and were related to the physical measurements of the blast wave.

    In this way, a physically reliable mathematical model was developed which would predict how many fragments and how much debris would hit someone in a house exposed to a blast wave, and what their velocities would be. Studies of the effects of fragments striking simulated human tissue allowed prediction of biomedical effects. In the case of human translation, the acceleration coefficient for a human and the cross-sectional area exposed in a variety of orientations allowed the acceleration and velocity to be deduced for any given blast wave, and separate studies showed the deceleration effects of striking rigid objects (walls for example), and effects of being slowed down by rolling along the ground.

    Effects of building collapse were available from nuclear data collected in Japan and in conventionally bombed houses in World War II. The result is that casualty rate for people prone in British brick houses with 9 inch thick outer walls was calculated to be 1% killed by 20 kPa (2.9 psi) peak overpressure 7 km from a 1 Mt surface burst and 19% killed by 40 kPa (5.8 psi) peak overpressure at 4 km from a 1 Mt surface burst. Because the blast winds last longer in a bigger bomb explosion, 50% mortality in brick houses occurs at 50 kPa (7.2 psi) for a 10 Mt bomb, but requires 67 kPa (9.7 psi) for a 100 kt bomb. Hence the range for 50% mortality in brick houses from a surface burst would be 1.45 km for 100 kt and 7.3 km for 10 Mt. There would be a lot of survivors in a nuclear attack. The effects for physical reasons do not scale up in direct proportion from the Hiroshima and Nagasaki data.

    More information on thermal ignition and fire storms is available in these previous posts:

    Earlier post on the EMP effects at nuclear tests:


    HO 226/19 The numbers of deaths resulting from an attack on the British Isles with 29 atomic bombs and 27,000 tons of high explosive/incendiary bombs 1953

    HO 226/16 Atomic attacks and water undertakings: the significance of the ratio of groundburst to airburst weapons 1953

    HO 226/33 The protection afforded by trenches and refuge rooms against radioactive ground contamination 1954

    HO 226/36 Refuge rooms as shelter against radioactive fallout 1955

    HO 226/45 Casualty rates for a groundburst 10 megaton bomb omitting residual radiation, all in houses 1956

    HO 226/52 The likely extent of fallout from a nominal groundburst bomb 1956

    HO 226/54 Effectiveness of gamma radiation spread, over a period of time, in producing radiation sickness 1957

    HO 226/68 The hazard due to exposure in the open in the damaged area during fallout 1957

    HO 226/70 A survey of methods used for the removal of radioactive contamination from water 1958

    HO 226/75 The contribution of U239 and Np239 to the radiation from fallout 1959

    HO 226/83 Casualties due to immediate effects of groundbursts 1963

    HO 226/93 Papers read at conference on radiological recovery, Berlin, October 1967

    HO 226/92 Notes on radiological decontamination for Scientific Intelligence Officer refresher courses 1968

    HO 226/91 Publications of interest: chemical weapons 1967

    HO 338/8 Nuclear weapons: hazards of flying glass after explosions; effects of blast winds; protection of vehicles from fall-out 1957

    HO 338/7 British Scientific and Service Mission to Japan: eye-witness account of the bombing of Nagasaki; comparison with traditional bombing effects 1947

    HO 338/6 British Scientific and Service Mission to Japan: diary and progress of mission; disposal of materials to various museums 1947

    HO 338/9 Nuclear weapons: protection provided by open trenches; personal anti-radiation protection; production and dispersal of gamma radiation 1957

    HO 338/11 Nuclear weapons: effects of thermal radiation 1957

    HO 338/25 Protection afforded by smoke screens against the effects of an atomic attack 1955

    HO 338/69 Thermal and fire aspects of nuclear blast: risk of fire-spread following an attack 1965

    HO 338/72 Radioactive decay rates: charts and papers 1966

    HO 338/73 Distribution of fall-out in and around buildings 1959

    HO 338/78 Hazards of direct exposure to fall-out 1962

    HO 338/80 Biological recovery and effective residual doses from gamma radiation 1961

    HO 338/82 Decontamination: use of water for washdown purposes 1961

    HO 338/83 Decontamination: methods of decontamination of building roofs 1965

    338/116 Communications: effects of a nuclear attack on GPO communications 1964 [NEVADA TEST EMP SUMMARY]

    HO 338/115 Communications: effects of radiation on radio transmission and equipment 1963 [NEVADA TEST EMP SUMMARY]

    HO 338/117 Fire Service Study `Torquemada', 20-22 July 1959

    HO 228/1 Notes on the occupancy of shelters during attack by V1 weapons on London, 1944 1948

    HO 228/2 USA Naval Technical Mission to Japan: extracts and notes on atomic bombs, Hiroshima and Nagasaki 1948

    HO 228/3 Crater debris 1948

    HO 228/5 Radiation hazards from atomic bombs 1948

    HO 228/6 Some thoughts on the fire problem from atomic bombs 1948

    HO 228/7 Notes on the distribution of the population of Greater London 1949

    HO 228/8 The effect of window opening on the fire risk in domestic property 1949

    HO 228/10 The resistance of concrete to explosions and projectiles 1950

    HO 228/11 Papers read at the meeting held on 12 April 1950 between the staff of the Civil Defence Staff College, the Civil Defence Schools and the Scientific Adviser's Branch: radioactive ground contamination and civil defence; shelter policy and atomic casualties; problems of civilian morale; the potentialities of nerve gas as a chemical weapon agent 1950

    HO 228/13 Papers read at the meeting held on 6-8 November 1950: deaths from the explosion of an atomic bomb more or less powerful than that used at Nagasaki; debris, its distribution and the means of negotiating it; the zoning of towns for fire susceptibility; mustard gas on cities; social and economic effects of German air raids on the UK in World War II; estimates of homeless from atomic, explosive and incendiary bomb attack; the possible economic effects of atomic attack on centres of UK population; the risk of inhaled or ingested fission products compared with the external radiation risk; a problem connected with fallout 1951

    HO 228/15 Papers read at the meeting held on 7-9 April 1952: Lessons from incendiary attacks on Hamburg; fireguards, to be or not to be; assessment of an attack on a city area with mustard gas; shadowgraphs; influence of the height of burst on the effects of an atomic bomb; some chemical warfare problems; combined operations; obstruction by debris in city streets after an atomic attack 1952

    HO 228/14 Summary of papers read at the meeting held on 16-17 May 1951: possible trend of future developments in atomic weapons; experimental developments in air raid warnings; regional scientific advisers and technical aspects of reconnaissance; decontamination; some aspects of the debris problem arising from an airburst atomic bomb assumed to burst over Trafalgar Square; respirators and protective clothing for civil defence personnel; an appreciation of radiological hazards in time of war; nerve and mustard gas; the atomic bomb as a fire raiser; memorandum on the use of radiation metering instruments in civil defence operations and training; discussion on practical monitoring and the present position regarding policy and organisation 1951

    HO 228/16 Report of a conference of the Regional Scientific Advisers for Civil Defence held at the CD Staff College Apr 1953: strategic assumptions for CD; CD aspects of the Monte Bello trial; warning systems and the general public; some factors affecting shelter design and policy; the allowable radiation dose in wartime and its implications; civilian behaviour under air attack; implications of FP (fission products) deposition 1953

    HO 228/17 Report of a conference of the Regional Scientific Advisers for Civil Defence held at the CD Staff College 1-3 June 1954: impact of hydrogen bomb on civil defence; a theoretical evacuation study; expected scale of types of attack; thermal effects of the British atomic bomb trials; gamma ray penetration at the Woomera tests; Admiralty gamma ray measurements at Monte Bello and Woomera; the work of the Scientific Advisers in the regions; training of radiac officers; radioactive training grounds; biological warfare; hazards of radioactive contamination from a water burst; agricultural problems resulting from a water burst; recent trends in radiac instrumentation 1954

    HO 228/18 Report of a conference of the Regional Scientific Advisers for Civil Defence held at the CD Staff College 23-25 May 1955: the consequences of a thermonuclear explosion; fallout from a groundburst bomb; the characteristics of residual radioactivity; the fallout and the metereological problems; the physiological effects of radiation; the contamination of water supplies; hazards to grazing animals in the period immediately following a nuclear explosion; hazards from fallout to vegetation immediately following a thermonuclear explosion; monitoring and plotting of fallout; problems in the fallout area; technical reconnaissance; leader equipment; concluding discussion 1955

    HO 228/20 Report of a conference of the Regional Scientific Advisers for Civil Defence held at the CD Staff College 4-6 June 1957: civil defence policy; fallout prediction from meteorological information; the work of the Radiobiologist Research Unit; introductory talk on fallout plotting; aerial survey and possible applications to civil defence; report on tests on structures, of atomic trials; radiological work during the Buffalo atomic trial; thermal radiation; chemical warfare-training of radiac officers 1957

    HO 228/21 Report of a course given to university physics lecturers at the Civil Defence Staff College 8-11 July 1957: nuclear weapons and their effects; blast from nuclear weapons; thermal radiation; biological effects of nuclear radiation; radiological control in the damaged area; control of civil defence forces; protection afforded by buildings against gamma radiation from fallout; meterological aspects of radioactive fallout; fallout plotting; public control in a fallout area; introductory talk on fallout plotting; problems of water contamination; effects of nuclear weapon attack on agriculture and food; radiological decontamination; trends in radiac instrumentation; radiac fallout simulator; assessment of the protection afforded by buildings against gamma radiation from fallout 1957

    HO 228/22 Report of the conference of the Regional Scientific Advisers for Civil Defence held at the Civil Defence Staff College 20-22 May 1958: the travel and deposition of radioactivity in the Windscale accident; fallout - an analysis of the most recent data; meteorology and the fallout prediction; fallout plotting and reporting up to the regional level; new plans for the control of civil defence operations; the regional scientific organisation in relation to new operational plans; the effects of ionising radiation on human beings; radiation hazards 1959

    HO 227/1 The effect of a limit on the travelling distance allowed between private house and communal buildings on the spectrum of protective factors 1960

    HO 227/2 Refuge space in communal buildings of various classes in a sample of six towns 1960

    HO 227/6 Estimated casualties from an attack with two 3 megaton bombs on each of 71 different bases, with one 3 megaton bomb on each of 16 cities 1960

    HO 227/7 The adaptation of basement garages under new office buildings for use as shelters 1960

    HO 227/11 Hamburg shelters: some notes on occupancy, prepared May 1960

    HO 227/23 Attenuation of thermal radiation by the atmosphere 1961

    HO 227/24 Science in civil defence 1961

    HO 227/27 Civil defence studies 1961

    HO 227/32 Note by Scientific Adviser's Branch on washdown installations 1960

    HO 227/31 Inter-departmental Committee on Shelter against Fallout: the effect on casualties of moving people from bungalows and pre-fabs into communal refuge 1961

    HO 227/35 The effect of high explosive bombs on the estimation of ignition ranges for megaton explosions 1961

    HO 227/40 Basic assumptions for use in the assessment of the radiological hazard to food from fallout 1962

    HO 227/60 Probability of becoming a casualty due to a 3 megaton groundburst weapon having various CEP's as a function of distance from the target 1962

    HO 227/53 Day and night populations of the administrative County of London 1962

    HO 227/51 The Soviet strategic air threat to the United Kingdom 1962

    HO 227/50 The scientific data and basic information required in preparing for protection by shelter against fallout: summary of presentation to NATO Shelter Working Party 1962

    HO 227/61 Annuli for calculation of prompt casualties from groundburst bombs 1962

    HO 227/62 Some effects of fallout on the operation of mobile fire columns 1962

    HO 227/64 Some calculations and tables on the neutron-induced activity in fallout due to soil and sea water 1962

    HO 227/65 Delayed fallout in the casualty area 1962

    HO 227/72 Glass breakage by blast 1963

    HO 227/74 Fallout and radiological counter-measures Vol 1 1963

    HO 227/75 Protection of cities against thermal flash: USA feasibility studies 1963

    HO 227/78 The implication of clean bombs for civil defence 1964

    HO 227/90 The number of fires caused by nuclear attack atmospheric attenuation 1965

    HO 227/97 The value of area decontamination in reducing casualties from radioactive fallout 1965

    HO 227/100 The protection against fallout radiation afforded by core shelters in a typical British home 1965

    HO 227/105 Summary and critical review of the basis of the new Medical Research Council concept on recovery from the effects of gamma radiation 1966

    HO 227/106 Distribution of basement fallout shelters by size 1966

    HO 227/108 The biological effects of nuclear radiation 1966

    HO 227/107 The calculation of fallout risks for a set of localities 1966

    HO 227/112 Comments on Management Research Group report: A Review of Biological Warfare 1966

    HO 227/114 Extracts from a draft report entitled Operation Antler, the Attenuation of Residual Radiation by Structures 1976

    HO 227/121 The beta radiation hazards in fallout 1967

    HO 225/1 Some aspects of shelter and dispersal policy to meet atomic attack 1948

    HO 225/4 The ‘builtupness’ of Inner London 1948

    HO 225/5 An assessment of the effects of an attack on an average area of Inner London with nerve gas 1950

    HO 225/115 Report to NATO Shelter Working Party on Fallout Shelters 1962

    HO 225/119 Civil defence aspects of radioactive contamination in agricultural produce 1964

    HO 225/120 The implications of clean bombs for civil defence 1964

    HO 225/121 Ignition and fire spread in urban areas following a nuclear attack 1964

    HO 225/125 The behaviour of simulant fallout on roof surfaces covered in polyvinyl chloride 1965

    HO 225/128 The psychology of fear 1965

    HO 225/129 Civil defence in tall buildings 1965

    HO 225/103 Retention of fallout particles on roof surfaces and their removal by washdown with water 1961

    HO 225/109 The fire ranges of nuclear explosions in the 10-100 megaton range 1962

    HO 225/112 The estimation of ignition ranges for megaton explosions outside the earth's atmosphere 1962

    HO 225/114 Chemical protection against effects of ionising radiations 1962

    HO 225/113 Report on road decontamination trials carried out at the Fire Service Training Centre, Moreton in Marsh, on 16 February 1962

    HO 225/116 Research on blast effects in tunnels with special reference to use of London tubes as shelter 1963

    HO 225/117 Experimental determination of protective factors in a semi detached house with or without core shelters 1964

    HO 225/130 The energy required for ignition with very short exposure times 1966

    HO 225/92 The deployment of civil defence forces into damaged area contaminated by fallout 1959

    HO 225/94 Upwind fallout from megaton explosions 1959

    HO 225/95 Survey of protection afforded in communal buildings and private houses against radiation from fallout 1959

    HO 225/96 The decontamination of residential areas 1959

    HO 225/97 Uptake of radioactivity in fire hoses 1959

    HO 225/99 The decay of fallout radiation: lecture given at Regional Scientific Advisers' Conference 11 May 1960

    HO 225/100 The hazards from direct exposure to fallout in a damaged area 1960

    HO 225/101 Downwind fallout area from groundburst megaton explosions 1960

    HO 225/68 Protection against gamma radiation from fallout 1956

    HO 225/69 The penetration of gamma radiation from a uniform contamination into houses: first report on some field trials 1956

    HO 225/30 Atomic warfare in relation to civil defence: lectures given to the staffs of HO Regional Scientific Advisers at AERE, Harwell, 4-6 December 1951

    HO 225/31 The standard of protection of trench shelters 1952

    HO 225/42 Estimates, for exercise purposes, of the radio-active contamination of land areas from an adjacent underwater explosion 1953

    HO 225/45 Gamma radiation dose rates at heights of 3-3000 feet above a uniformly contaminated area 1953

    HO 225/46 Basic studies on the casualties and homeless to be expected from heavy air attacks 1953

    HO 225/47 The vulnerability of flour mills to atomic attack 1954

    HO 225/51 Assumed effects of two atomic bomb explosions in shallow water off the port of Liverpool 1954

    HO 225/52 Fatal casualties likely to result from an air attack on UK cities with 20 atomic or hydrogen bombs of varying power 1954

    HO 225/58 Seriously injured casualties likely to result from an attack on UK cities with 20 atomic or hydrogen bombs of varying power 1954

    HO 225/29 The increase in the number of atomic casualties due to large public gatherings 1952

    HO 225/28 Deaths from fire in large scale air attack with special reference to the Hamburg fire storm: report by Kathleen F Earp 1953

    HO 225/27 Deaths from fire in large scale air attack with special reference to the Hamburg fire storm 1952

    HO 225/26 Some radiological hazards of atomic warfare in relation to civil defence 1951

    HO 225/23 The hazard from inhaled fission products in rescue operations after an atomic bomb explosion 1951

    HO 225/17 Comparison of day and night population distributions of Birmingham 1950

    HO 225/16 The number of atomic bombs equivalent to the last war air attacks on Great Britain and Germany 1950

    HO 225/15 Some advantages and disadvantages of a multi-standard shelter scheme 1949

    HO 225/14 The advantage of lying prone in reducing the dose of gamma rays from an airburst atomic bomb 1949

    HO 225/13 The economic and social effects of the German air attacks on certain British cities 1949

    HO 225/12 A comparison between the number of people killed per tonne of bombs during World War I and World War II 1949

    HO 225/11 A summary of information on the effect of atmospheric conditions on heat flash, gamma radiation, and blast from an airburst atomic bomb 1949

    HO 225/10 The fire risk attendant on the use of blackout curtains during an atomic bomb attack 1949

    HO 225/9 Notes on a possible method of defining ‘bulls eye’ areas 1949

    HO 225/8 The risk of fire from air attack (prepared for the Working Party on Emergency Fire Fighting) 1949

    HO 225/7 The relative advantages of open and closed windows during air attack 1949

    HO 225/6 The atomic bomb as a fire raiser: a study of the mechanism of initiation and development 1949

    HO 225/5 An assessment of the effects of an attack on an average area of Inner London with nerve gas 1950

    HO 225/61 Neptunium-239 as a residual radiation hazard 1955

    HO 225/62 The effective energy of fission product gamma radiation 1955

    HO 225/64 The protection afforded by trenches and refuge rooms against radioactive ground contamination 1954

    HO 225/70 A comparison between observed and calculated protection against fallout radiation 1956

    HO 225/71 Numbers of casualties from a groundburst megaton weapon likely to be personally contaminated by radioactive material 1956

    HO 225/72 Casualty estimates for ground burst 10 megaton bombs 1956

    HO 225/73 The hazard from inhaled fission products in rescue operations after an atomic bomb explosion 1956

    HO 225/74 Durability of coated window glass as a heat radiation shield 1956

    HO 225/87 Some recent information from USA about fallout from groundburst megaton weapons 1957