Dr Carl F. Miller's reports on Fallout and Radiological Countermeasures

Dr Carl F. Miller, “A Theory of Decontamination of Fallout from Nuclear Detonations. Part II. Methods for Estimating the Composition of Contaminated Systems”, U. S. Naval Radiological Defense Laboratory, report USNRDL-466, 29 September 1961.

Dr Terry Triffet and Philip D. LaRiviere, “Operation Redwing. Project 2.63. Characterization of Fallout”, Nuclear Weapon test report WT-1317, 15 March 1961.

Above: visible appearance of a typical deposit of dangerous fallout; this is a secret photo from WT-1317 of a fallout tray automatically exposed for just 15 minutes at 1 hour after detonation of the 3.53 megaton, 15% fission surface burst Redwing-Zuni at Bikini in 1956. The fallout illustrated occurred on barge YFNB 13, located 20 km North-North-West of ground zero (downwind). The circular tray’s inner diameter is 8.1 cm. This 15 minute sample is only 22% of the total deposit of 21.9 g/m² which occurred at that location. The barge’s radiation meter recorded a peak gamma intensity of 6 R/hr at 1.25 hours after the explosion.

Because fallout sinks in the ocean (which shields the fallout quite effectively, giving only a small dose rate) and the barge deck is much smaller than a land area, the barge radiation meters record only about 25% of those on land which are contaminated to the same extent. So on land the peak gamma ray intensity for this fallout would have been 4 x 6 = 24 R/hr at 1.25 hours. Correcting from 15% fission yield to 100% fission yield would increase this to 160 R/hr. The infinite time fallout dose is 5 times the peak intensity times the time of that intensity as measured from the time of explosion. Hence the infinite dose outdoors on land for pure fission would be 5 x 160 x 1.25 = 1000 R which is lethal. Any house would provide enough protection to save your life, however. (The dose law of 5 times intensity times arrival time is based on the t^-1.2 decay law. Obviously it is well known that the fallout intensity drops below that law within 200 days, and a better law is 4 times intensity times arrival time. On the other hand, some radiation is received before the peak dose rate occurs, so it is sensible to use the factor of 5 multiplication as a rough approximation.)







Above: Dr Carl F. Miller's correlation of measurements of the decay rates of fallout from different tests during Operation Castle, 1954. (Dr Miller's own U.S. Naval Radiological Defense Laboratory report on these decay rate correlations has never been declassified, and even in one of his major fallout reports which is now declassified, some of the statistics are blanked out because they are still secret. Part of the trouble is that the neutron capture to fission ratio in the uranium-238 component of a hydrogen bomb produces substantial quantities of nuclides like Np-239, U-237, etc., which affect the decay rate of the subsequent fallout. Therefore there is a link between the highly classified thermonuclear design physics and the radioactive hazards.)



Above: Cresson Kearny explains how to shield against fallout by making a 'core shelter' inside a building: put cardboard boxes on top of, and around, a strong table that you can shelter under: then put two large waterproof plastic waste bags inside one another in each box, and simply fill them up with water. This saves you messing around with dirt for shielding. Just 5 inches of water halves the intensity of 1 MeV gamma radiation penetrating it. Actually, dirty bombs with U-238 jackets produce a great deal of softer gamma rays from Np-239 (which has a half life of 56 hours and thus contributes a peak percentage to fallout radiation at a time of 1.73 X 56 = 4 days after burst) and U/Np-240, as well as U-237 which has a longer half life and contributes substantially during the two week sheltering period. So protection is even more efficient than Kearny quotes, due to the lower-energy of fallout from dirty hydrogen bombs with neutron capture in U-238. American experiments on fallout shielding by buildings used cobalt-60 gamma rays, which have a mean energy of 1.25 MeV (see page 120, 'Transmission Factors' in the PDF file of the U.S. Army Field Manual 3-3-1, Nuclear Contamination Avoidance, linked here) whereas dirty (high fission yield) thermonuclear weapons which contaminate large areas all expose U-238 to neutrons which always results in large amounts of non-fission neutron captures in U-238, creating large amounts of very low-energy gamma emitting Np-239, U-240, and U-237. The time that any neutron induced species contributes a peak percentage of the radiation from fallout is equal to 1.73 times its half-life (the 1.73 factor is simply the ratio 1.2/ln2, where 1.2 is the decay exponent of time for the overall mixture of nuclides in fallout, while ln2 is the factor which converts the average life of a particular nuclide into its half-life, which is always a factor 1.44 smaller than its average life). Thus, for Np-239 which has a half life of 56 hours, the peak percentage contribution it gives to fallout radiation occurs 4 days after detonation. U-237 has a half-life of 6.8 days, so contributes a peak percentage to fallout radiation 12 days after detonation.

Fractionation of fission products (the loss of slowly-condensing gaseous fission product decay chains from fast-falling large particles of fallout which exit the fireball before the slowly condensing nuclides have solidified, and are thus depleted in many fission product species) also affects the spectrum of gamma ray energy in a predictable way, softening the spectrum to lower mean energies in the close-in (depleted) fallout. Dr Terry Triffet first made this effect public in the 22-26 June 1959 U.S. Congressional Hearings on The Biological and Environmental Effects of Nuclear War, pages 61-111. Triffet in that testimony, with more details in in his declassified weapon test report WT-1317, 1961 (see also Dr Miller's 1961 report USNRDL-466 for REDWING fallout station distances from ground zero, nuclide measured fractionation ratios and neutron induced activity data), showed that at 1 week after burst, the mean gamma ray energy of fractionated fallout 8 statute miles downwind on Bikini Lagoon barge YFNB29 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 LST611 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 those June 1959 hearings, Triffet explained:

'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.'



Above: Home-Made Self-Calibrating Kearny fallout meter (see Kearny's Oak Ridge National Laboratory book Nuclear War Survival Skills for instructions on building it, PDF version linked here; the self-calibrating radiation measurement accuracy data can be found in the original report ORNL-5040 linked here) being tested with a dental X-ray machine. The charged foil plates discharge and visibly fall together as soon as the X-ray machine is turned on. This is just a simple electroscope dosimeter, using the same principle as the pocket quartz fibre dosimeter, although it is in some respects better since you can clearly see the effects of radiation on discharging the plates.

You make it by taking two pieces of aluminium foil and folding them repeatedly until you have two 8-ply (8-layer) pieces of square shape and 2 inch long sides (this ensures the calibration). You hang each square in contact with the other by electrically non-conducting threads or thin non-conducting fishing line (any thin thread which has not been given anti-static treatment will do!) inside a can or jar. To get it to work you do need to have dry air inside the can (in high humidity air, you can't charge it since the water molecules almost immediately discharge the comb before it can even charge up the foil plates, so you need to put the whole thing inside a "dry bucket" with a transparent cover, adding some heated hydroscopic gypsum from plaster or re-heated silica gel to the bottom of the can, which comes in little paper packets in the packaging of all kinds of items these days, preventing moisture damage).

The top of the can is just covered by kitchen clear plastic wrap, with a little millimetre-calibrated scale on it to measure the distance between the aluminium plates when charged. A piece of wire like a straightened paperclip poked through the plastic wrap is used to charge the foil leaves; you simply bring a hair-charged plastic comb (or some other source of static electricity like a plastic ruler rubbed in a rolled up newspaper) to the charging wire, and the plates are charged. Because similar electric charges repel, the plates then move apart from one another! As air is ionized by radiation, charged air ions move between the plates, discharging them. The speed with which the plates are discharged therefore tells you the radiation level. Simple!

In reality, of course, hazardous fallout has always proved to be extremely visible, once the political pseudoscientific fallout quackery, hype and spin (claiming that natural cancer deaths are due to radiation exposure, and other lunacy) is rejected. A land surface burst (water surface bursts produce even more!) as proved by all the American tests ALWAYS creates roughly 200 tons of sand like fallout contaminant per kiloton of total yield, so if the 1-hour exposure rate conversion factor is taken to be typically 2000 (R/hr)/(kt/sq. mile) then the 2000 R/hr at 1 hour after bursts corresponds to 200 tons of fallout mass per square mile or 77 grams per square metre. Try sprinkling 77 grams of sand or flour per square metre. It's visible. Even when the particles themselves (like tiny flour grains) are too small to be seen, the bulk of material is visible. Similarly, atoms aren't visible to the eye, but if you have enough atoms, the bulk of material becomes visible! That's the whole reason why we can see matter in bulk, despite the individual fundamental particles of matter being individually too small to see! Rainout from air bursts is visible as rain, and runs down the drain or soaks deep into the ground (which attenuates the radiation) in the same way as rain. Ocean surface burst fallout arrives as tiny non-depositing wind-carried dry salt crystals if the humidity is very low, or as wet salt-slurry droplets in a high humidity atmosphere; the depositing droplets are visible. Anti-civil defense propaganda covers up the nuclear test data on fallout particle deposits and covers up the difference between radiation and fallout to make people confused about the danger and make it seem mysterious and fearful. Actually, you can wash fallout away, you can brush dry fallout away, it can be swept up and buried under the soil while it decays. There are numerous ways to successfully decontaminate and shield the danger. (On military ships, turning on the fire sprinklers on decks during fallout deposition was found to decontaminate the ships clean while fallout landed; it went straight down the drains, and the dose rate from surrounding contaminated water was 535 times lower than on land due to the mixing and sinking of fallout in the water, which shields most of the radiation! A favourite trick is to use large sheets of plastic to collect fallout. Once fallout has deposited, you roll them up and bury them, so that the fallout is shielded underground, meaning that you don't need to take shelter!

‘A number of factors make large-scale decontamination useful in urban areas. Much of the area between buildings is paved and, thus, readily cleaned using motorized flushers and sweepers, which are usually available. If, in addition, the roofs are decontaminated by high-pressure hosing, it may be possible to make entire buildings habitable fairly soon, even if the fallout has been very heavy.’ – Dr Frederick P. Cowan and Charles B. Meinhold, Decontamination, Chapter 10, pp. 225-40 in Dr Eugene P. Wigner (editor), Survival and the Bomb, Indiana University Press, Bloomington, 1969.

For road sweeper decontamination data see D. E. Clark, Jr., and W. C. Cobbin, Removal of Simulated Fallout from Pavements by Conventional Street Flushers, report USNRDL-TR-797, 1964.

Small areas of fallout contamination, such as indoor ingressed fallout contamination, are always in practice found to make totally and utterly negligible contributions to gamma ray doses by comparison to the gamma hazard from the wide areas of fallout outdoors, because most of the gamma dose rate comes from large distances horizontally across a vast uniformly contaminated plane, and that coming vertically upwards from the small amount of fallout under your feet or nearby is trivial by comparison, so the ingress of fallout into damaged buildings makes no significant difference to gamma doses!


Above: '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.’ - British Home Office civil defence booklet, The Hydrogen Bomb (Her Majesty's Stationery Office, London, 1957, 32 pages.)



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. Kearny showed in a later Oak Ridge National Laboratory book, Nuclear War Survival Skills, 2nd ed., 1987, how to build improvised efficient, self-calibrating radiation dosimeter (a comb-charged jam-jar electroscope, calibrated accurately by the size of the aluminium foil leaves which carry the charge; the charges keeps the leaves separated against gravity until air is ionized by radiation, when the leaves lose charge and fall together, the amount of declease in separation distance in millimetres being accurately correlated with radiation dose as proved by laboratory tests!) that can be quickly made by anyone with kitchen odds and ends in an emergency, a hand-powered simple string-pulled hinged panel air cooling pump for such shelters in hot weather, and how to obtain food and water in a nuclear war.

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.

In 1964, Britain conducted experiments with Co-60 sources to validate the ‘core’ Protect and Survive shelter plan (above videos): A. D. Perryman, Experimental Determination of Protective Factors in a Semi-Detached House With or Without Core Shelters, U.K. Home Office report CD/SA117. Using Co-60, the dry fallout protective factor was 21 on the ground floor of a brick house, increasing to 39 in a core shelter, made using furniture piled near an inner wall. For real fallout with less than the 1.25 MeV mean gamma ray energy of Co-60, the protection would be far greater. See also the 75-pages long American report on these 'Protect and Survive' core shelter experiments in Britain by Joseph D. Velletri, Nancy-Ruth York and John F. Batter, Protection Factors of Emergency Shelters in a British Residence, Technical Operations Research, Burlington, Massachusetts, report AD439332, 1963.

John Newman 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 (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!

Dr Saad Z. Mikhail's paper, 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 10¹⁵ 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 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:

U.S. Congressional Hearings before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, The Nature of Radioactive Fallout and Its Effects on Man, 27 May - 3 June 1957, pages 173-216 where Dr Gordon M. Dunning testified: ‘In the case of the Marshallese who were in the fallout from the detonation at the Pacific on March 1, 1954, most of the more heavily exposed showed some degree of skin damage, as well as about half of them showing some degree of epilation [hair loss] due to beta doses. However, none of these effects were present except in those areas where the radioactive material was in contact with the skin, i.e., the scalp, neck, bend of the elbow, between and topside of the toes. No skin damage was observed where there was a covering of even a single layer of cotton clothing. ... The Marshallese were semiclothed, had moist skin, and most of them were out-of-doors during the time of fallout. Some bathed during the two-day exposure period before evacuation, but others did not; therefore, they were optimal conditions for possible beta damage. The group suffering greatest exposure [Rongelap Islanders, 175 R gamma dose from 4 hours to 2 days after burst] showed 20 percent (13 individuals) with deep lesions; 70 percent (45 individuals) superficial lesions; and 10 percent (6 individuals) no lesions. Likewise, 55 percent (35 individuals) showed some degree of epilation followed by a regrowth of hair.' On pages 944-948, Dr Eugene P. Cronkite testified: 'The fallout material consisted predominantly of flakes of calcium oxide resulting from the incineration of the coral [reef near Namu Island at Bikini Atoll]. Upon the flakes of calcium oxide fission products were deposited. At Rongelap Atoll the material was visible and described as snowlike. ... To arrive at some physical estimate of the skin dose, an attempt must be made to add up the contributions of the penetrating gamma, the less penetrating gamma, the beta bath to which the individuals were exposed from the relatively uniform deposition of fission products in the environment, and the point contact source of fallout material deposited on the skin. By all means, the largest component of skin irradiation resulted from the spotty local deposits of fallout material on deposited surfaces of the body. To put it in reverse, the individuals who remained inside had no skin burn. It was only on those on whom the material was directly deposited on the skin that received burns. ... Itching and burning of the skin occurred in 28 percent of the people on Rongelap, 20 percent of the group on Ailinginae, and 5 percent of the Americans [weather station staff exposed to fallout on Rongerik Atoll]. There were no symptoms referable to the skin in the individuals on Utirik. In addition to the itching of the skin there was burning of the eyes and lacrimation in people on Rongelap and Ailinginae. It is probable that these initial skin symptoms were due to irradiation since all individuals who experienced the initial symptoms later developed unquestioned radiation-induced skin lesions that will be described later in detail. It is possible, however, that the intensely alkaline nature of the calcium oxide [produced when the coral i.e. calcium carbonate was heated in the fireball] when dissolved in perspiration might have contributed to the initial symptoms. ... Burns were caused by direct contact of the radioactive material with the skin. The perspiration as common in the tropics, the delay in decontamination and the difficulties in decontamination certainly favored the development of the skin burns. Those individuals who remained indoors or under trees during the fallout developed less severe skin burns. The children who went wading in the ocean developed fewer lesions of the feet and most of the Americans who were more aware of the dangers of the fallout, took shelter in aluminum buildings and bathed and changed clothes. Consequently they developed only very mild beta burns. Lastly, a single layer of cotton material offered almost complete protection, as was demonstrated by the fact that skin burns developed almost entirely on the exposed parts of the body.’

Dr Carl F. Miller's major fallout reports are now becoming available online thankfully: see the report linked here for Dr Miller's description of fallout and its chemical formation and fission product fractionation analysis, the report linked here for his fallout distribution analysis, the report here for Philip D. LaRiviere and Hong Lee's detailed and complete application of the Miller fallout model to civil defence problems, and finally here for the U.S. Department of Defense 1973 Attack Environment Manual for civil defense planners, which exclusively uses Dr Miller's nuclear test data-derived fallout model. Dr Miller was able to elaborate further on his work at the Naval Radiological Defense Laboratory in his speech accepting an award for decontamination research at the U.S. National Council on Radiological Protection (NCRP) symposium on 27-29 April 1981 in Virginia, published in The Control of Exposure of the Public to Ionising Radiation in the Event of Accident or Attack, pp. 99-100:

‘Someone talked a little about risks. ... In 1954 ... we were about 20 miles away when a 10-megaton shot was detonated ... The ship [YAG 39] sailed on a pathway that led to an area directly underneath the expanding cloud, so as to be exposed to a maximum amount of fallout ... Fallout arrived about 20 minutes after detonation, at which time I collected the first few drops of "hot" washdown water ... In 1957, at the Nevada Test Site, personnel from the Naval Radiological Defense Laboratory and the Atomic Energy Commission sat in an underground shelter a mile away when shot Diablo was detonated. Some of us collected fallout particles ... after about a half-hour or so, one could hardly get a reading [from a single fallout particle] ... because of the rapid decay rate. ... With most of the local fallout that we're talking about, a lot of the larger particles are fused or melted to form little glassy marbles. The tower shots had iron in them so they were magnetic and we could separate hot fallout particles from tower shots with magnetism. The radioactive atoms that could be absorbed into, or by, body organs were the few that are plated out on the surface of the fallout particles during the later stages of condensation in the fireball. That's why the elements iodine, strontium, ruthenium and a few other isotopes of that nature have been found in organs of animals and humans.’

Dr Miller tragically died from leukemia in August 1981, four months after giving that speech, and leukemia is the form of cancer which correlates most strongly with external whole body gamma radiation exposure (thyroid tumours correlate to internal intake of radioactive iodine, which concentrates in the thyroid and irradiates it with beta particles). With most cancers, the risk of per individual without radiation is not much different from the slightly enhanced risk with significant radiation exposures, but since leukemia is both a rare cancer and so strongly dependent upon radiation dose, a person who does get leukemia after a significant dose may be more likely to have the leukemia as a result of the radiation, than for it to be coincidental. Dr Miller measured his own gamma dose to total 60 rads (cGy in tissue) received at relatively high dose rates soon after nuclear tests; this more than doubled the natural 0.5% risk of death from leukemia to over 1%. The fact that he contracted leukemia therefore implies that it was over 50% certain to be due to his gamma radiation exposure at the nuclear tests where he measured the gamma spectrum of fallout and analysed the physical nature of fallout and the decontamination effectiveness against fallout hazards. He took a calculated risk to get the vital Cold War fallout protection data, and he was unlucky. It is important not to minimise the immense human costs to such scientists and their families of acquiring the valuable direct scientific information on this important subject, which has direct relevance to the problem of weapons of mass destruction in today's world of increasing nuclear proliferation and radiological warfare threats.



Above: the need for people to understand observed facts about fallout and its decontamination in an accident or disaster. These photographs are of children accidentally exposed to fallout from the Bravo nuclear test in 1954, before the scientific aspects of fallout prediction and radiological safety had been investigated. The photographs on the left were taken about one month after exposure; those on the right show the recovery about six months later. The beta burns to neck and feet only began to appear on 14 March, two weeks after exposure (all of the beta burns and hair loss had appeared within four weeks of exposure). Because the U.S. Atomic Energy Commission had ignorantly and prematurely announced on 11 March 1954 that the 236 contaminated Marshallese had no beta radiation burns, the word fallout gained a new political meaning as an unpleasant after effect subsequently.


Above: the table of fallout areas for measured dose rate contours in PLUMBBOB-SMOKY, 31 August 1957, Nevada, is taken from page 808 of the Hearings before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, Congress of the United States, 86th Congress, The Biological and Environmental Effects of Nuclear War, June 22, 23, 24, 25, and 26, 1959, Part 1, U.S. Covernment Printing Office, Washington, 1959, 966 pages.






Dr Miller's work was cited in the final chapter in the 1962/4 editions of The Effects of Nuclear Weapons, dealing with civil defence. The British Home Office Scientific Advisory Branch in 1963 dedicated an entire scientific report (U.K. National Archives file HO 227/74) to reviewing Volume 1 of Dr Carl F. Miller's Stanford Research Institute (not SRI international) report Fallout and Radiological Countermeasures.

This is the first detailed model of the thermodynamics of fallout, which - as the previous post on this blog mentions - found that the fraction of the total fireball (thermal plus blast) energy which in a surface burst on Nevada sand is used to melt fallout varies from about 7.5% for a 1 kt total yield to 9.2% for 100 Mt. This agreed with an empirical observation of 3% at the Redwing-Inca 15 kt tower burst in 1956; such a tower burst would produce less than half the melted fallout that a surface burst produces (due to the decreased interaction of the fireball with the ground).

Chapter 1 of Dr Miller's Fallout and Radiological Countermeasures begins with the experimental data, showing photographs of the fallout from every type of nuclear explosion, and describing the physical, chemical and radiological processes. Since the appearance and physical, chemical and radiological nature of actual fallout is so confusing to many people - particularly in the media and politics (who naively confuse particles of radiation with particles of fallout, and end up with complete science fiction and nonsense, a problem extending even to author Richard Rhodes who in his historical book on the tests incorrectly asserted that fallout from hydrogen bombs is consists of metallic calcium), a revised adaptation of Dr Miller's approach will follow. This is mainly because of the declassification of other reports by Dr Miller and his colleagues ( U.S. Department of Defence reports USNRDL-374, -408, -440, -TR-208, and WT-1317), which show which nuclear tests each photograph arises from, and some additional data.



Above: yellow-brown fused-silicate sand from the Nevada Sugar ground burst, 1951

In this and each of the following photographs, the photograph on the left hand side is a picture of a 30 micron thick slice through the particle (produced by gluing the particle into plastic resin and then shaving off a thin slice). The image on the right hand side is an radioautograph, i.e., an x-ray like photo in which the source of the image is the action of beta particles from the fallout particle striking a light proofed packet of photographic film. The radioautograph shows, therefore, precisely where the fission products are distributed within each fallout particle.



Above: yellow/green silicate glass spheres from the Nevada Sugar ground burst, 1951.

Pure silicate (quartz) sand particles ejected from the crater remain liquid at temperatures below 2,950 °C, and re-solidify into insoluble glass spheres when the fireball temperature falls below 1,607 °C. Before this time, condensing fission products diffuse inside molten glass droplets, creating insoluble radioactive particles, but at later times fission products are deposited on the outside of solidified glass, giving soluble (biologically available) radioactivity. I-131 on the outer surfaces of fallout particles is in the soluble –1 oxidation state (U.S. test report WT-917). Water-soluble activity is located in an outer 0.35-micron deposit on the glass, while the soluble fraction for stomach acid (0.1 N HCl, pH4) is equivalent to a deposit 10 microns thick. The insoluble fraction of the volume equals the volume of the inner insoluble glass sphere divided into the effective total volume including the soluble outer deposit:

(4/3){Pi}*r³/[(4/3){Pi}(r + X)³] = (1 + X/r)^-3,

where X is the thickness of the soluble deposit (0.35 and 10 microns respectively for water and acid) and r is the insoluble glass radius, measured in the same units. The soluble activity is:

100[1 - (1 + X/r)^-3] %.

This is validated by fallout studies in 1956-7 at Australian-British nuclear tests over silicate soil. Antler gave 1.8% and 0.4% water solubility for particles of average radius 75 and 200 microns, respectively. At Mosiac, activity in particles of 1-mm radius was 0.1% water soluble, and at the Buffalo-1 tower burst, debris of 1-cm radius had 0.01% water solubility. Silicate sand (SiO₂) has a density of 1.54 grams per cubic centimetre, and comprises 80% of soil above CaCO₃ rock at the Australian-British Maralinga test site. Silicate minerals are the most common in the Earth’s crust, forming the most rock and sand. (These fallout solubility data on Australian-British nuclear tests Antler, Mosiac and Buffalo-1 come from Porton Technical Reports in the U.K. National Archives. The British chemical warfare laboratory at Porton Down conducted fallout decontamination and solubility research at Maralinga and Monte Bello under contract to the Home Office Scientific Advisory Branch for civil defence, and the War Office for military research.)



Above: calcium oxide, -hydroxide, and -carbonate from Tewa coral reef burst, 1956. Coral sand (like chalk and limestone) is calcium carbonate, CaCO₃, which dissociates into CO₂ and CaO when heated to a temperature of 850 °C in the fireball. CaO melts at 2,570 °C, which must be reached for the core of the particle to be uniformly contaminated with fission products. The outside of the CaO core reacts with atmospheric moisture to form a calcium hydroxide layer during fallout: CaO + H₂O -> Ca(OH)₂.



Above: calcium oxide, -hydroxide, and -carbonate from the 10.4 megatons Mike coral island surface burst, 1952.

Reaction of the outer surface of this calcium hydroxide layer, Ca(OH)₂ with atmospheric CO₂ at temperatures below 30 °C creates an outer shell of CaCO₃ + H₂O. About 38.5% by mass of particles in the 1956 Zuni coral surface burst test had surface contamination only, but 98.7% of the radioactivity was contained in uniformly contaminated particles. The fallout density for coral bursts ranged from 2.36 grams per cubic centimetre for Bravo to 2.46 for Zuni. The solubility in water for Bravo and Zuni fallout was 20%. Nearly complete solubility occurred in weak acid. These fallout particles disintegrated rapidly upon contact with water and formed colloidal suspensions, almost entirely trapped above the ocean thermocline.


Above: dicalcium ferrite and calcium hydroxide; Inca steel tower shot over coral, 1956.



Above: black magnetic fallout particle (magnetite) from Inca steel tower burst, 1956. The Redwing-Inca test was a 15.2 kt-bomb was fired on top of a 61-m steel tower (containing 165 tons of iron) over coral sand at Eniwetok Atoll. Magnetite (Fe₃O₄) particles formed, and the mixed coral and steel formed marbles of contaminated black dicalcium ferrite (2CaO.Fe₂O₃) with veins of uncontaminated calcium hydroxide. By measuring the ratio of calcium to iron in the fallout, the mass of coral converted into fallout was found to be 264 tons. Only the top 2 mm of the sand around ground zero was thus swept up by the afterwinds:

‘The fact that only a thin layer of sand was actually either vaporized or melted, even though in contact with the fireball... indicates that the thermal effects penetrate only superficially into solid material during the short duration of the very high temperatures. By computing the energy required to heat, decarbonate, and melt 264 tons of coral sand and to heat, melt and vaporize 165 tons of iron ... 8.5% of the available radiant energy [i.e., 3% of bomb yield, because the radiant energy was 35% of the total energy of the explosion] was utilised for heating the tower and soil material.’ - Charles E. Adams and J.D. O’Connor, U.S. Naval Radiological Defense Laboratory, report USNRDL-TR-208, 1957, p. 13.



Above: typical glossy magnetic fallout particle, Upshot Knothole tower burst, 1953

The density of Upshot Knothole fallout from a detonation on a 91-m tall steel tower was 2.15 grams per cubic centimetre, a mixture of black magnetic iron oxide (magnetite, Fe₃O₄) from the steel tower and silicate glass from melted grains of Nevada sand. The particle core contains air bubbles and is a sand grain, melted into glass. The outer region contains the magnetite and the radioactive fission products. Studies at the 1957 tests Diablo and Shasta showed that steel tower shot fallout is 5% magnetite by mass and can be picked up with a magnet (U.S. Naval Radiological Defense Laboratory report USNRDL-466, 1961).



Above: salt slurry droplet 0.2 mm diameter with 1 mm long paper soak-in, Redwing, 1956

The salt slurry droplet from a Redwing seawater surface burst (detonation on a steel barge in Bikini Lagoon) was deposited in 80% humidity air. Its density is 1.4 grams per cubic centimetre and it contains salt crystals precipitated in supersaturated salty water. Obviously, in drier air the particles are smaller and denser because the water content of the particles falls due to evaporation. In 80% humidity air an equilibrium water content occurs because the salty droplets are hydroscopic (they form surfaces for condensation of airborne moisture, which at some diameter offsets the evaporation effect). The radioactivity solubility is 35% as ions or cations (ions with positive charge in solution), while 65% of the activity is trapped insoluble in fused tiny particles of dicalcium ferrite created from the steel barge and the coral sand ballast in the barge.

Decontamination of fallout

If the fallout is in soluble form (as for a detonation involving proximity to sea water), then the problems are at their worse because many of the fission products are present in the ionic solution and become chemically bound to surfaces. If the detonation occurs over a typical land surface which is about 50% or more silicate (e.g., typical sand), then the decontamination is easier because most of the activity is insoluble (trapped in the solidified spheres of glass). Dry fallout can be decontaminated by a range of activities from flushing it down storm drains with water hosing, to using normal mechanical street sweepers. Inclined roofs do not retain large fallout particles efficiently, simplifying decontamination of buildings. The efficiency of decontamination depends strongly upon the total quantity of fallout taken up into the mushroom cloud and stem, which is typically about 1% of the mass of material ejected from the crater in a surface burst, typically 100-300 tons of fallout per kiloton of yield.



Above: Dr Carl F. Miller did vital 1950s fallout decontamination research at nuclear tests for the U.S. Naval Radiological Defense Laboratory.

For example, when decontaminating land surface burst fallout from portland cement concrete by fire-hosing, the fallout protection factor afforded by this decontamination is 25 for a fallout deposit of 100 g/m², 50 for 330 g/m², and 125 for 1,000 grams/m². These deposits of 100, 330, and 1,000 g/m² typically correspond to 1 hour reference gamma exposure rates of 300, 1,000 and 3,000 R/hr respectively. Hence the best efficiency for decontamination occurs where the danger is most severe. Where the fallout is very light, decontamination is less efficient because the smaller number of smaller sized fallout particles involved tend to quickly get caught or trapped in small crevices, cracks or surface irregularities, where water flushing is less effective. (These data are from Radiological Recovery of Fixed Military Installations, U.S. Army Chemical Corps Technical Manual TM-3-225 (1958). This fire-hosing method uses 4-cm diameter hoses, each crewed by 2-4 people, with 100 gallons/minute of water at 5 atmospheres pressure to decontaminate 700 m²/hour; fallout is flushed into underground drains to decay, so the radiation is safely absorbed below ground level.)

Nevada nuclear weapon test experience: dry fallout on paved areas 0.6-1.6 km from nuclear tests Sugar and Uncle in 1951 was successfully removed: ‘High-pressure water hosing was found to be the most rapid and effective ... None of the tested procedures [including dry sweeping and vacuum cleaning] resulted in significant contamination of the operator’s protective clothing.’ – J. C. Maloney, Decontamination of Paved Areas (U.S. test report WT-400, 1952, Ch. 5). The contamination per unit area of vertical walls was only 0.3-10% of that on horizontal ground and roofs (Jangle Project 6.2, WT-400, 1952).

F. T. Underwood of the U.K. Home Office reported fallout adherence: over 90% of fallout particles exceeding 1 mm in diameter rolled or bounced off roofs with a 45-degree slope. But 95% of fallout particles less than 0.2 mm in diameter adhered to a 45-degree ceramic tiled roof. For a 45-degree roof slope, 90% of the retained fallout on 0.13 cm thick PVC (glued to the roof) was removed by just 1 litre/m² (0.1 cm of rain). Without PVC, fallout grains roll into, and lodge in, small pits and crevices (reports CD/SA-103 and CD/SA-125, 1961-5).

Experience of fallout in unprotected civilian areas of America was obtained after four 1953 Nevada shots on 91-m high towers: Annie, Badger, Simon, and Harry. The 1957 U.S. Congressional Hearings, The Nature of Radioactive Fallout and Its Effects on Man, pp. 231-2, show that Nevada staff washed vehicles on highways where the infinite time dose exceeded 5 R (using the t^-1.2 formula, D_infinity = 5RT, where R is dose rate at start time T after burst).

The highest public fallout is listed as being 97 km downwind from the Harry test, where the peak outside dose rate was 1 R/hr on Highway 93 at 2 hours after burst: ‘The ratio of dose rate readings on the outside of the car to inside varied from unity to about 4/1 ... One bus read 250 mR/hr outside and an average of 100 mR/hr inside with a high inside reading over the rear seat of 140 mR/hr at H + 8.75 hours.’ At St George, Utah (210 km downwind), the Harry fallout reached 0.42 R/hr at 3.75 hours with a measured peak air concentration at the same time of 154,000 Bq/m³.. The 4,500 inhabitants were requested by radio to stay indoors for two hours to avert skin contact.

Decontamination of Farms: roads, paved areas, building surfaces, vehicles, aircraft and ships can be decontaminated by water hosing. For fields, single-pass deep-ploughing to 20-25 cm depth (3,250 m²/hour using an old 125 horse-power tractor with a 3-share plough) reduced the above-ground fallout gamma radiation by an average factor of 6.7 (U.S. Army Chemical Corps technical manual TM-3-225, 1958).

If needed, fallout can be deep-ploughed to a depth below the roots of the crops to prevent root uptake, or the long-term agricultural uptake of Sr-90 and Cs-137 can simply be dramatically diluted by adding calcium and potassium salts to contaminated soil. About 2.6% of the Earth’s crust is potassium, which minimises Cs-137 uptake, but there is often a shortage of calcium so Sr-89 and Sr-90 can contaminate food. However, in chalky, limestone or coral soils there is plenty of calcium (which blocks Sr-89 and -90 uptake), but little potassium, so Cs-137 is important. Adding potassium chloride to the coral soil of Bikini Atoll (scene of 76.8 Mt of tests) in the 1990s reduced the Cs-137 in coconuts from 3,700 Bq/kg to 185 Bq/kg. Growing crops with low calcium content reduces the uptake of Sr-89, -90 (potatoes contain only 1 mg of calcium per 10 calories).

City decontamination: Britain planned decontamination by fire-hosing residential areas where the 1-hour reference gamma dose rate was 500-3,000 R/hr (Home Office report SA/PR-97, 1965, originally secret). At lower levels, there are few casualties indoors anyway (200 R producing a casualty), while higher levels expose decontamination crews to excessive doses even 5 days after detonation, so evacuation is then a better option. Decontamination is feasible at 1-5 days after detonation, when a 1-hour outdoor dose rate of 500-3,000 R/hr has decayed to 10 R/hr. Decontamination crews restricted to areas below 10 R/hr cannot get more than 10 x 8 = 80 R in an 8 hour shift.

The three key stages during radiological recovery after first aid, rescue and fire spread prevention: (1) evacuation of people with inadequate shielding from heavy fallout areas; (2) sheltering for 1-5 days in the part of the house furthest from the roof and outside walls, with as much mass around the ‘inner refuge’ as possible, and staying indoors as much as possible for a month, and (3) outdoor decontamination.

Washing skin removes 97.5% of fallout with a diameter of 0.02 mm, and removes 100% of fallout of 0.1-mm diameter or more. For clothes, 90% of the fallout on denim overalls is removed in 5 minutes by a washing machine (100 revolutions per minute, 1% detergent), for particle diameters over 0.01 mm. (Reference: E. Neale and E.H. Letts, Radiological Decontamination: Removal of Dry Fallout from Skin and Clothing, U.K. Chemical Defence Experimental Establishment, report PTP-R-16, 1958.)

Internal fallout contamination of humans: inhalation of fallout in Britain from the American and Russian tests of 1958 peaked at 3.7-Bq/day of beta emitters between January-June 1959, when the total fallout intake from food was 120-Bq/day. The maximum concentration of plutonium in the air was lower than natural radon-222. For Sr-90, the intake in Britain in 1959 was 0.33-Bq/day from food, 0.015-Bq/day inhalation, and tap water contained 0.016-Bq/litre (reference: The Hazards to Man of Nuclear and Allied radiations: Second Report to the Medical Research Council, H. M. Stationery Office, London, 1960).

The initial danger is due to eating fallout: even after years of fallout from nuclear tests, 80% of the Sr-90 in milk in Britain during 1958 was from cows eating fresh fallout deposited on the grass and soil, and only 20% was due to chemical uptake by roots and ingestion of older fallout in the soil. (J.D. Burton et al., Nature, Vol. 185, 1960, p. 498.)

Decontamination of water and milk: boiling water does not remove fallout or affect radioactivity. Filtering removes fallout particles, but it is the dissolved, soluble radioactivity that causes the major ingestion problem. Activated charcoal cartridges or ion exchange softens tap water by removing calcium carbonate ions, and also remove dissolved fission products. Distillation also makes water safe. Milk is decontaminated by filtering with on-exchange resin, but this also removes the calcium from the milk.

On 7, 11, 14 and 17 July 1962 low-yield nuclear weapons were detonated near ground level in Nevada, and the 100-kt Sedan Nevada test occurred on 6 July. Fallout on grass 560 km downwind in Salt Lake City was relatively soluble, so milk contained enough I-131 to give a total I-131 intake from milk of 1,370-Bq. Families switched to using milk powder. Out of 759 milk producers in the area, 285 switched their cows from pasture to uncontaminated dry feed, and 211 stopped selling milk but instead used it to make long-life products like cheese, which outlive I-131 (which has a half-life of only 8 days).

After Britain’s Windscale nuclear accident of October 1957, the concentration of I-131 in contaminated milk was 500 times higher than that in tap water from reservoirs in the same areas. Ion-exchange interaction of soluble nuclides with soil or rock slows down the migration of dissolved radioactivity in groundwater and surface rain run-off. It was 30 days after the Chernobyl reactor accident in 1986 when tap water, obtained from a river in the nearby city of Kiev, attained a peak activity of 370-Bq/litre, which returned to natural background within a year. The 1957 U.S. Congressional Hearings on fallout, p. 233, shows that the maximum contamination of tap water 3 days after any 1953 Nevada nuclear test was only 44-Bq/litre (at Bunkerville, Nevada, where the gamma outdoor infinity dose was 7 R), compared to 3,200-Bq/litre in an irrigation canal.

The ocean food chain: concentrates iron (Fe) and zinc (Zn) in clams, fish and fish-eating birds. But soil usually contains plenty of soluble iron and zinc that dilutes their uptake to insignificance. In oceans, natural potassium and calcium similarly dilute the uptake of cesium-137 and strontium-90, respectively. But oxygen dissolved in the ocean soon oxidises soluble ferrous (2+) iron into insoluble ferric (3+) iron, which precipitates as a solid. Soluble iron, zinc and cobalt are extremely rare in seawater and are therefore taken up in ocean food chains. A month after the 1.69 Mt Nectar shot at Eniwetok in 1954, 95% of the activity of fish was Fe-55, 3.1% was Zn-65, and the rest cobalt. The activity in sea birds at Bikini, in 1954-6, was mainly Zn-65. Fe-55 gave 73.5% of the activity of a clam kidney at Eniwetok, 74 days after the 1.85 Mt 1956 Apache shot (cobalt-57, -58, and -60 contributed 9.6, 9.2, and 1.8%; fission products gave 3.5%). Zn-65 in fish at Bikini, 2 months after 1956 Operation Redwing, gave 35-58% of the activity, Fe-55 gave 15-56%, and cobalt gave the rest (U.S. report UWFL-51, 1957).

The fallout uptake after the 10.4 Mt Mike land surface burst in 1952 were measured at and near the islands of Rigili, Bogombogo-Bogallua, Engebi, Aomon-Aaraan, and Runit, in Eniwetok Atoll (U.S. test report WT-616, 1953). The activity per gram of muscle tissue of rats was similar to that in their lung tissue, so ingestion rather than inhalation was the mechanism of internal contamination by fallout. The average ratio of beta activities collected at 7 days and measured at 30 days, to the adjacent land gamma dose rate at 1 hour, (Bq/kg)/(R/hr), was 1.8 for lagoon water, 8,800 for plankton, 15,000 for land plants, 2,800 for crab muscle, 120 for the muscle of plankton-eating fish, and 58 for rat muscle (DASA-1251, 1963, was used for gamma dose rates). Half the water is flushed out of Eniwetok lagoon (which has a mean depth of 48 m) in 15 days.

Farm and food decontamination after fallout is particularly important. In 1960-1, Kendal D. Moll of Stanford Research Institute showed in Post-Attack Farm Problems that while a 400 Mt Russian first-strike on American military bases would kill 2% of the population (assuming a fallout protection factor of 20), farm food output falls by 10%. For 19,000 Mt, he found that a population reduction by 12% occurs with a 65% fall in food output. Norman Hanunian stated in his 1966 RAND Corporation report Dimensions of Survival, p. 33: ‘the possible post-attack state of the farm sector ... constitutes the greatest threat to national viability.’

It is worth summarizing some of the more reliable Nevada nuclear test empirical data for surface bursts JOHNIE BOY (0.5 kt, 1962), SUGAR (1.2 kt, 1951) and SMALL BOY (1.65 kt, 1962) which is tabulated on page 61 of Hillyer G. Norment's DELFIC report DNA 5159F-1, 1979 (his data for Pacific shots KOON and ZUNI are from error filled reports and are both obsolete). At 1 hour after burst, a measured gamma dose rate on point-source-calibrated survey meters of 100 R/hr at 1 m height over contaminated Nevada desert (corresponding to an ideal smooth plane dose rate of roughly 200 R/hr for a survey meter which isn't partially shielded by its own batteries and by the person holding it) occurred in an elliptical belt 0.25 km wide extending 2.73 km downwind from 0.5 kt JOHNIE BOY, 0.49 km wide extending 3.74 km downwind from 1.2 kt SUGAR, and 0.84 km wide extending 5.66 km downwind from 1.65 kt SMALL BOY. It should be noted that the exact depth of burst has a greater effect on the dangerous levels of fallout than the wind velocity. The wind doesn't affect the fallout dose rates very much, because if you double the wind speed, the same amount of fallout gets deposited over twice the area with therefore only half the concentration than for the lower wind speed, so the increase in downwind distance reached by any given fallout particle is largely offset by the fact that the particles are spread out over a greater tract of ground. Thus, in practice there is relatively little wind effect on fallout, apart from obviously determining the directions which the fallout plumes travel.

However, the fallout contour data show a great dependence on the exact depth or height of burst. Very shallow depths of burst greatly increase the cratering efficiency, producing more intense close-in fallout contours due to the extra activity carried by large particles contaminated at early times by the cratering ejecta mechanism. For example, the 1000 R/hr contour at 1 hour extended 1.38 km downwind and 0.26 km in width after the JOHNIE BOY 0.5 kt shot at 0.584 m depth, but such dose rates were confined to the crater in the 1.2 kt SUGAR burst detonated 1.067 m above ground!

Perhaps the best set of data comes from the 1962 SMALL BOY shot (1.65 kt Nevada burst at 3.05 m height above ground):

1000 R/hr at 1 hr reached 1.0 km downwind with a width of 0.28 km
500 R/hr at 1 hr reached 1.62 km downwind with a width of 0.41 km
200 R/hr at 1 hr reached 2.22 km downwind with a width of 0.54 km
100 R/hr at 1 hr reached 5.66 km downwind with a width of 0.84 km
50 R/hr at 1 hr reached 8.10 km downwind with a width of 1.42 km





Above: Dr Carl F. Miller's fallout model from 1963 is based on a semi-empirical analysis of the Pacific nuclear test fallout patterns from CASTLE and REDWING nuclear test operations in 1954 and 1956, in combination with a theoretical analysis of all the physics and chemistry of the fallout mechanism itself. (C. F. Miller, Fallout and Radiological Countermeasures, Stanford Research Institute, January 1963, vol 1 - AD410522, vol. 2 - AD410521.) Miller's model predicts an earliest fallout arrival time of 4W^0.2 minutes after burst, where W is the total weapon yield in kilotons. Hence, fallout under the mushroom cloud begins to arrive at 16 minutes after burst for 1 Mt, 22 minutes after burst for 5 Mt, and 30 minutes after burst for 25 Mt. (These data are from the DCPA Attack Environment Manual, Chapter 6, What the Planner Needs to Know About Fallout, U.S. Department of Defense, Defense Civil Preparedness Agency, report CPG 2-1AG, June 1973, Panel 29.)



Above: the earth penetrator warhead destroys hardened underground targets by ground shock and cratering with a low fission yield and can dramatically reduce fallout by trapping fission products deep within the crater ejecta layer. (The data for SEDAN is scaled back to 1 hour after burst using the decay rate curve, and thus exaggerates the radiation levels which occurred far downwind when the arrival time was greater than 1 hour.)



Above: Nevada nuclear test data shows the effect of burial on dose rate contours. Very shallow depths can enhance local fallout, but greater depths reduce it. Notice that the 100 R/hr contour at 1 hour after burst extends several km downwind for 1.2 kt surface or shallow detonations in dry soil, but much less than 1 km downwind for the bursts of 0.42-31 kt yields at depths of 34-110 m in hard rock.

Fallout information in previous posts on this blog can be found at:

http://glasstone.blogspot.com/2006/04/white-house-issues-new-civil-defence.html

http://glasstone.blogspot.com/2006/05/clean-nuclear-weapons-tests-worked.html

http://glasstone.blogspot.com/2006/04/fallout-prediction-and-common-sense-in.html

http://glasstone.blogspot.com/2006/03/clean-nuclear-weapon-tests-navajo-and.html

The posts here are supposed to be particularly important information. However the arrangement of the information is haphazard and I'm compiling a book on the application of science to nuclear reactions, with chapters ranging from the big bang evidence to nuclear forces, nuclear explosions, and all of the effects produced. This will be available freely as PDF page files on my domain http://quantumfieldtheory.org/ as soon as possible. It will be edited more carefully (and will of course be better organized) than this blog, and will contain far more detailed information on each topic.

Update:

Articles by Dr Miller and others in the August 1958 Journal of Colloid Science:

Heiman W. J.
Variation of gamma radiation rates for different elements following an underwater nuclear detonation.
Journal of Colloid Science, pp:329-336; vol. 13, issue 4, August 1958:

“Calculations are made of the gamma radiation rates for the 13 radioisotopes contributing the major portion of gamma radiation from a deep underwater nuclear detonation. These calculations are carried out for 14 different times after the burst ranging from 40 min to 3 years. The gamma emitters include activities induced in sea water and possible bomb components as well as fission products.”


Miller Carl F., Cole Richard, Heiman Warren J.
Decontamination reactions of synthesized fallout debris for nuclear detonations : I. Nuclear detonation in sea water.
Journal of Colloid Science, pp:337-347; vol. 13, issue 4, August 1958:

“The expected general composition of fall-out from a nuclear detonation in a homogeneous liquid medium (sea water) is discussed, Simplified contaminants each containing a single fission product element and sea water applied to a painted surface were decontaminated by water washing. Decontamination as a function of initial level or surface density of most of the FP elements used was found to follow the modified Freundlich relationship R = aI/sup n/ in which I is the initial level, R is the level remaining after decontamination, and a and n are constants for each element.”


Miller Carl F., Cole Richard, Lane W. B., Mackin J. L.
Decontamination reactions of synthesized fallout debris for nuclear detonations : II. Land-surface nuclear detonation.
Journal of Colloid Science, pp:348-357; vol. 13, issue 4, August 1958:

“The decontamination of San Francisco harbor bottom soil, Nevada test site soil, and a commercial clay from a paint surface was done with stirred and sprayed water, The surface density of soil remaining after decontamination was found to depend on the initial condition according to the equation, R/sub m/ = R/ sub M/(1-e/sup -ay/) in which R/sub M/ is a constant related to tbe mean particle size remaining, a is a constant related to the mean particle size and density of the deposited soil, and y is the surface density of the initial deposit. Estimates are made for the gamma radiation intensity over the contaminated and decontaminated surfaces for the case in which the surface area is large and the soil is fallout from a surface land atomic detonation.”

Above: The Control of Exposure of the Public to Ionizing Radiation in the Event of Accident or Attack, Proceedings of a Symposium Sponsored by the National Council on Radiation Protection and Measurements (NCRP), April 27-29, 1981, Held at the International Conference Center, Reston, Virginia. (The proceedings were published on May 15, 1982, by the U.S. National Council on Radiation Protection and Measurements, Bethesda, Md.) The NCRP was chartered by U.S. Congress in 1964 to analyze and publish information on radiation protection issues.


In several previous posts quotations are made from Dr Carl F. Miller's enlightening acceptance speech for an award (published beginning on page 99), which give a first-hand idea of the awesome task of obtaining the vital early-time data on arrival and deposit characteristics of fallout during the 1950s American atmospheric nuclear test series in the Pacific and also at the Nevada test site. Dr Miller's 60 rads gamma dose more than doubled his natural leukemia risk from 0.5% to over 1%, and he tragically died from leukemia in August 1981. A longer excerpt from the Session B Discussion text is as follows, and illuminates the whole subject very clearly:

'Mr Greene [Jack C. Greene, Moderator]: 'As all should know, much of the work that Jim Sartor described [in a summary of decontamination data] was done under the very able direction of Dr Carl Miller who is with us today and will join the panel.

'Carl, I am very pleased to use this occasion to present to you a "certificate of appreciation" from the Planning Committee for this symposium, joined by members of the former NAS Advisory Committee on Civil Defense and others who have worked with you over the years. Here's what the certificate says:

'We hereby present a Certificate of Appreciation to Carl F. Miller. Dr Miller's many years of dedicated research have combined the best of theoretical and applied work and have resulted in an unparalleled contribution to our understanding of the physical and chemical characteristics of radioactive fallout, as well as the means for protecting against it. It is specially meaningful to those of us who have known and admired Carl over the years to have an opportunity to publicly acknowledge and honor the work of this extraordinary, versatile and innovative scientist.'

'We will start the discussion period by giving Carl five minutes to comment on anything he chooses.

'Dr Miller: Thank you very much. I appreciate this commendation and your comments. I might add here that thanks should also be given to my co-workers who helped me and did most of the hard work - this includes, of course, Pete [Peter O. Strom of Sandia National Laboratories] and Jim [James D. Sartor of Woodward-Clyde Consultants] who just completed their presentations. Sitting here and listening, I was impressed with many of the talks that were given. Starting with Lew Spencer's, I think he did a very good job in giving the outline for the hazards to be discussed. One thing that occurred to me and probably occurs to a lot of you is that the real hazards in a nuclear attack are not from radiation - the real hazards are in the blast and other initial effects. Though his paper was clearly limited to the radiation effects, he knows, and you know, that the countermeasures against the other hazards would be more difficult to achieve.

'Someone talked a little about risks. One thing that usually comes to my mind when risks are discussed goes back to World War II when I was in Burma working with the Chinese Fifth Army as an artillery-man. We (and they) used to be supplied by airplanes that would fly over and parachute-drop food and ammunition and so forth. The thing about risk was that we used to watch the behavior of the Chinese soldiers - they would make bets on who could catch a sack of peanuts dropping down and they would truly try. I don't know what the LD50 for that "exposure" was or might be, but it was exceedingly high for a good catcher. It was a high risk game in a rather high risk environment. However, in the (now) old days, some of us at the then existing U.S. Naval Radiological Defense Laboratory did about the same thing with fallout at nuclear weapons tests.

'In 1954, some civilians and Navy men were on a specially outfitted ship - a monstrosity bedecked with all kinds of sprinklers for testing the Navy washdown system [i.e., the continuous spraying of decks by fire sprinklers, to flush fallout off the deck as it landed]. On one test, we were about 20 miles away when a 10-megaton shot was detonated. At the time, one piece of data we were interested in obtaining was the early time decay; also, additional data on the characteristics of the fallout were desired. My job was to put out a series of funnels, tubes, and other things on this ship to collect some of the fallout. The ship was sailed on a pathway that led to an area directly underneath the expanding cloud so as to be exposed to a maximum amount of fallout. The ship, called the YAG-39, was highly instrumented with gamma detectors; it was accompanied by a sister ship, the YAG-40, which was operated by remote control but without the washdown system. Fallout arrived about 20 minutes after detonation, at which time I collected the first few drops of "hot" washdown water from tubing that extended from the deck to the bottom of the ship across from where the radioactive assay equipment was located.

'In 1957, at the Nevada Test Site, personnel from NRDL and the AEC sat in an underground shelter a mile away when Shot Diablo was detonated. Some of us collected fallout particles as they fell out of the sky from this event. We didn't chase after them on the outside of the shelter because we had little funnels and tubes running to the outside from inside. One could hear that stuff trickle down into containers in a deep cave from which we picked out single particles for assay. I was trying to do gamma spectrometry on particles. I picked up one little particle, and the spectrometer just about blew up, so I quickly put it back and got a smaller one. That didn't work either: it was too hot. Finally, I got a teeny one, but it was still too hot. So I took it back in and smashed it into smaller pieces, picked up a chip with tweezers and found out it didn't blank out the spectrometer. Of course, after about a half-hour or so, one could hardly get a reading on it anymore, because of the rapid decay rate. Many people received some gamma exposure on ventures such as these. I did as well. ...

'I like the way Jim Sartor brought out the character of the fallout, and Pete Strom, too. With most of the local fallout that we're talking about, a lot of the larger particles are fused or melted to form little glassy marbles. The tower shots had iron in them so they were magnetic and we could separate hot fallout particles from tower shots with magnetism. The radioactive atoms that could be absorbed into, or by, body organs were the few that plated out on the surface of the fallout particles during the later stages of condensation in the fireball. That's why the elements iodine, strontium, ruthenium and a few other isotopes of that nature have been found in organs of animals and humans.'

Above: this is a summary of the decontamination data tables presented by James Sartor which Dr Miller was commenting on. This type of empirical field information is vital for informed decision making about how best to deal with a nuclear fallout disaster of any kind, be it an accident or a weapon attack.

The volume also contains other information of background importance. Dr Clarence Lushbaugh goes through the history of the LD50, i.e., the estimated dose which kills 50% of exposed people. He reveals that even before the bombs fell on Hiroshima and Nagasaki, the Manhattan Project had determined a figure of 500 +/- 100 R as the human LD50, based on extrapolations from animal data, and shows that the commonly quoted 450 R estimate of the LD50 stems not directly from any particular analysis of evidence, but instead from an average of the guesses made by 24 consultants to the U.S. Armed Forces Special Weapons Project who met at San Francisco in 1947 under the chairmanship of Dr R. R. Newell. (This 450 R human LD50 estimate was first published in 1950 by S. Warren and J. Z. Bowers in "Acute Radiation Syndrome in Man," Ann. Int. Med., v32, pp207-16.)

Dr Lushbaugh also comments on the disagreement which occurred in 1959, when Dr Payne Harris testified before the U.S. Joint Committee on Atomic Energy that the human LD50 was 700 R +/- 25%, based on Oak Ridge and Yugoslavian accident data, while Drs Cronkite and Bond testified using Marshallese evidence plus dog and swine data that the human LD50 was 350 R. As a result of this disagreement (one estimate above the previous LD50 estimate of 450 R, and the other estimate below that figure), the 450 R estimate continued to be used as the best available consensus. Lushbaugh however notes that he and Dr Auxier, using the best available data for shielding by buildings in Japan and the best empirical estimates of the radiation doses (confirmed by measurements of neutron induced activity in Hiroshima and Nagasaki, with thermoluminescent data which allow measurement gamma ray doses in roof tiles at various distances because some radiation energy is transferred to the ceramic as energy trapped in the crystalline structure, which is released as light when the material is subsequently heated), found an LD50 estimate of 260 REM, assuming a relative biological effectiveness (RBE) factor of 2 for neutrons. (REM = exposure in roentgens multiplied by RBE.) Lushbaugh comments that this low figure of the LD50 from Hiroshima and Nagasaki data is due to the blast and burn trauma the people took from the shock wave and thermal radiation which accompanied the nuclear radiation. (C. C. Lushbaugh and J. Auxier, "Reestimation of Human LD50 Radiation Levels at Hiroshima and Nagasaki", Radiation Research, v39, p526, 1969.)

He reports another study of Hiroshima and Nagasaki effects which found that a 50% incidence of epilation (hair loss) occurred at a dose of 310 REM if the neutron RBE is 4, and 50% incidence of hemorrhage (i.e., platelet suppression in blood due to irradiation of the bone marrow where blood cells are produced; the reduction in the platelet count causes small vessels to leak, producing small but visible skin hemorrhages below the outer skin layer). Some of these data will be obsolete now because they were based on the 1965 dosimetry of Hiroshima and Nagasaki, which has been updated with improved radiation transport models (although the 'improved" estimates of the yields of the Hiroshima and Nagasaki bombs may be a step backward, because the yields depend on random chances of the time of initiation of the chair reaction after fissile assembly, and other chance factors, and so should be evaluated from the actual measured blast effects data like the crushing of petrol tins and the overturning of stone slabs of known mass, as Penney did in his 1970 report, not on computer simulations of bomb dynamics).

Lushbaugh also discusses the effects of protracted exposure, where the body can repair some of the damage if the radiation is received at a low dose rate. A man accidentally irradiated by a Co-60 radiotherapy source in Mexico in 1964 for 106 days at a gamma exposure rate of 9-16 R/day (total dose 980-1,700 R) was still alive 17 years later, but four others who suffered daily exposure rates as least twice that amount were all killed within 80 days due to suppressed blood cell counts, hemorrhages and infections accompanying the reduced white blood cell count.

Another interesting item in the report is the table of neutron induced activities due in soils on different bedrocks (igneous, shale, sandstone, limestone and sediment) as part of Dr Peter Strom's paper on page 81. This shows that the initial beta Al-28 radioactivity induced in soil is on the order of 1,000 times as intense as that of Na-24. This is partly due to the higher typical abundance of aluminium than sodium in most soils, but is mainly due to the shorter half life of Al-28 (2.3 minutes, contrasted to 15 hours for Na-24). The faster something decays, the more intense the decay rate (decays/second, i.e., Becquerels) during its decay.

The typical igneous rock sample (at least half silicon dioxide, by mass) initially (i.e., at zero time) would give an beta activity from neutron induced Al-28 which is 550 times that from Na-24. After an hour (26 half lives of Al-28, but only 1/15th of a half life of Na-24) the ratio is only 0.0000088. Hence, despite the initial higher radiation levels from Al-28, it is always trivial within a fraction about half an hour of a nuclear explosion, as compared to other nuclides.

There are two interesting appendices in the volume. The first is by Philip J. Dolan of SRI International and is entitled Appendix A: Characteristics of the Nuclear Radiation Environment Produced by Several Types of Disasters, Summary Volume. On page 264, Dolan comments that:

'The hypothetical attack selected for use is a strategic attack on U.S. military installations, military supporting industrial and logistics facilities, other basic industries, and major population centers.

'The attack consists of 1,444 weapons with a total of 6,559 megatons, of which 5,051 weapons are surface burst. ...

'More than 67 million persons are located in areas receiving unit-time [1 hour reference time, although fallout is obviously not deposited everywhere within 1 hour of detonation so these unit-time figures are gross exaggerations if applied to distances of several hours downwind] reference dose rates in excess of 3,000 R/hr, more than 159 million in areas receiving in excess of 300 R/hr, and more than 188 million in areas in excess of 30 R/hr.

'The dose rates mentioned above would not necessarily exist since the deposition would take place over an extended time period and the fallout is decaying while deposition takes place. The four-day doses, which consider arrival time and which represent most of the lifetime accumulations, corresponding to the above-mentioned unit-time dose rates are 5,400, 360, and 24 roentgens, respectively. Shielding or relocation could reduce these accumulated doses.'

On page 265, Dolan adds:

'The four major ways to reduce adverse effects of fallout are: shelter, relocation, decontamination, and minimization of ingestion and inhalation ...

'The effectiveness of shelters usually is described in terms of a protective factor (PF), which is the ratio of the dose rate that would be measured 3 feet above an (imaginary) infinite smooth plane to the dose rate expected inside the shelter (accounting for surroundings as well as protection afforded by the shelter). About 20 percent of the urban population and 19 percent of the rural population of the U.S. could be afforded a PF of 1,000 or more (subways, mines, caves, and some basements) without evacuation, while about 75 percent of the urban population and 43 percent of the rural population could be afforded PF's of 100 or greater. ...

'The consequences of a multiweapon nuclear attack would certainly be grave, but exact numbers have large uncertainties. Estimates of 20 to 160 million short term fatalities have been made, with the majority of the survivors receiving doses from >10 to a few hundred rem. Nevertheless, recovery should be possible if plans exist and are carried out to restore social order and to mitigate the economic disruption.'

Commenting on the uranium and plutonium hazards of nuclear weapon accidents on page 272, Dolan states:

'Uranium taken internally represents a heavy-metal poison hazard in quantities less than those required to be a radiation hazard.

'Less than 10^{-4} of the plutonium eaten by man is absorbed from the intestine. Inhalation is a more probable route of deposition, but once the cloud has passed, inhalation requires that the plutonium be resuspended. This is an inefficient process.

'"Soluble" plutonium may be cleared from the lung within a year or so and will be translocated primarily to bone and liver. "Insoluble" plutonium will be retained much longer in the lung and will be translocated principally to lymph nodes. Plutonium dispersed in a weapon accident is expected to be in the form of insoluble oxides.

'Two accidents of this type are recorded. ... The first occurred near Palomares, Spain on January 17, 1966. A B-52 collided in flight with a tanker during a refueling operation, and 4 weapons were dropped. One weapon was found on the beach undamaged, and one was recovered intact from the sea at a much later date. The other 2 weapons resulted in high explosive detonations on impact with the earth. The resulting contamination covered about 650 acres with a concentration of about 5 micrograms per square metre or more.

'The second accident occurred near Thule, Greenland on January 21, 1968. A B-52 crashed on an ice floe just off the coast. Snow was falling at the time of the accident, and the precipitation increased after the accident. Most of the plutonium sank with the aircraft debris, and the rest was trapped under the snow and the ice. ... The worst consequence of such an accident is likely to be a partial denial of the use of a relatively small area.'

The second appendix is by Dr Alvin M. Weinberg, Appendix B: Civil Defense and Nuclear Energy, pages 275-7:

'The rejection of nuclear energy has been catalyzed by the articulate and influential energy radicals in the Western world. ... I continue to believe, and preach, the obvious: that defensive systems are less threatening than offensive systems: 100 million Americans can't be killed with Russian ABM's or civil defense ... Escalation of defense is not nearly as threatening as is escalation of offense. ... The ultimate issue is not how many people are going to be killed in a nuclear war: it is how can we both maintain our freedoms and avoid nuclear war. ...

'Nuclear power is an instrument of peace because it reduces pressure on oil. The energy crisis is primarily a crisis of liquid fuels. Insofar as nuclear power can replace oil, it helps stabilize the world order.

'The world today uses about 60 million barrels of oil per day; of that, about 18 million barrels per day came through the Straits of Hormuz before the Iran/Iraq war. A nuclear reactor of 1,000 megawatts electric output uses the equivalent of about 25,000 barrels of residual oil per day. If the world had 1,000 reactors operating now, the primary energy supplied by uraniu to those 1,000 reactors would exceed 18 million barrels of oil per day that go through the Straits of Hormuz. To be sure, the substitution is not direct, since what would be displaced is residual oil, not gasoline or other higher distillates. But with an expenditure of about $10-15 thousand per daily barrel of capital equipment, refineries could convert the residual oil into higher distillates [i.e., break the longer hydrocarbon molecules into smaller ones]. So to speak, residual oil, made available by conversion from oil-fired to nuclear power plants, is the best feedstock for a synthetic fuel plant. To make high distillates from coal requires an expenditure of about $100,000 per daily barrel. To make high distillates from residual oil takes only about one tenth as much. ...

'This simple-minded argument cannot be ignored: substitution of nuclear energy for oil reduces the pressure on oil and therefore reduces the political pressures that lead first to political instability, then to war, and possibly eventually to nuclear war. We forget that the immediate cause of the Japanese attack on Pearl Harbor was the decision by the United States to prevent Japan from moving into Indonesia to get oil. The Japanese entry into World War II demonstrated how oil can trigger a world conflagration. ...

'I do not know whether nuclear energy, which is now in a state of moratorium [following Three Mile Island controversy in 1979], will get started again. ... That people will eventually acquire more sensible attitudes towards low level radiation is suggested by an analogy, pointed out by William Clark, between our fear of very low levels of radiation insult and of witches. In the fifteenth and sixteenth centuries, people knew that their children were dying and their cattle were getting sick because witches were casting spells on them. During these centuries no fewer than 500,000 witches were burned at the stake. Since the witches were causing the trouble, if you burn the witches, then the trouble will disappear. Of course, one could never be really sure that the witches were causing the trouble. Indeed, though many witches were killed, the troubles remained. The answer was not to stop killing the witches - the answer was: kill more witches. ...

'I want to end on a happy note. The Inquisitor of the south of Spain, Alonzo Frias, in 1610 decided that he ought to appoint a committee to examine the connection between witches and all these bad things that were happening. The committee could find no real correlation ... So the Inquisitor decided to make illegal the use of torture to extract a confession from a witch. ...

'I don't know whether the modern witch - low level radiation and the hysteria that is exhibited about nuclear energy - will be resolved soon enough for nuclear energy to play a proper part in avoiding the oil confrontation. After all, it took 200 years for the Inquisition to run its course on witches. I only hope that our attitude towards nuclear energy will become more sensible long before 200 years have gone by. The possible alternative - nuclear war sparked by competition for dwindling oil - is far too horrible to accept, whether or not we have civil defense.'