NUCLEAR WEAPONS COLLATERAL DAMAGE EXAGGERATIONS: IMPLICATIONS FOR CIVIL DEFENSE Nigel Cook 100 Joint Commission Report, 90 Vol. VI, Document NP-3041 Hiroshima Ashley W. Oughterson, et al. 80 Medical Effects of Atomic Bombs, Army Institute of Pathology NP-3041 (Vol, VI), 1951. 70 JOINT COMMISSION DATA FOR OVERALL bt SURVIVAL z 60 o "UNSHIELDED” SCHOOL PERSONNEL a 50 "SHIELDED" SCHOOL PERSONNEL z EXPOSED INSIDE CONCRETE BUILDINGS gq 40 POINT BUILDING NO. INDIVIDUALS > NO. DESIGNATION EXPOSED > = 30 { POST OFFICE 400* id 2 TELEGRAPH OFFICE 301 3 TELEPHONE OFFICE 474 20 4 CITY HALL 216 5 COMMUNICATIONS OFFICE 682 6 BRANCH POST OFFICE 346 10 7 PO. SAVINGS OFFICE 750 *Lower floors of Post Office were most occupied ° 0.5 1.0 15 2.0 2.5 RANGE, MILES Figure 1: Dr Ashley W. Oughterson and other members of the Joint Commission for the Investigation of the Effects of the Atomic Bomb in Japan in 1951 produced a six volume report called Medical Effects of Atomic Bombs (U. S. Office of the Air Surgeon, and U. S. Army Institute of Pathology), summarizing research done into case histories for personnel in known locations in the open and within buildings at the time of the August 1945 nuclear explosions in Hiroshima and Nagasaki. Volume VI (document NP-3041) contained the data shown above, proving the immense increase in survival due to protective actions against easily-shielded thermal and nuclear radiation. This data is vital for civil defense but is not being applied to the analysis of casualty rates from nuclear explosions for civil defense, since propaganda from America and Japan instead presents an “average” casualty curve, which covers up and obfuscates the differences in survival rates in different situations. In particular, the curves above disprove the “uniformly lethal firestorm” myth. Blast survivors were not all killed in the firestorm. The Effects of the Atomic Bomb on Hiroshima, Japan, Report No. 92 (Vols. I-III), U.S. Strategic Bombing Survey, Physical Damage Divi- sion; May, 1947. Effects of the Atomic Bomb on Nagasaki, Japan, Report No. 93 (Vols, I-III), U.S, Strategic Bombing Survey, Physical Damage Divi- sion; June, 1947, Figure 2: The U. S. Strategic Bombing Survey classified its detailed reports 92 and 93 on the nuclear explosions in Hiroshima and Nagasaki “Secret”, and instead published an obfuscating summary report which omits the evidence that the firestorm in Hiroshima was due to the overturning of charcoal cooking braziers in bamboo and paper screen filled wooden houses, not thermal radiation. This caused anti-civil defense propaganda to falsely associate the firestorm radius to the thermal radiation exposure at that radius, instead of correctly associating it to the blast effect in overturning obsolete charcoal braziers. Report 92 on Hiroshima actually states (pages 4-6, May 1947): “Six persons who had been in reinforced-concrete buildings within 3,200 feet [975 m] of air zero [i.e., (975° - 600°)'” = 770 m ground range] stated that black cotton black-out curtains were ignited by flash heat... A large proportion of over 1,000 persons questioned was, however, in agreement that a great majority of the original fires were started by debris falling on kitchen charcoal fires....” The unclassified 1957 U. S. Department of Defense book The Effects of Nuclear Weapons obfuscated this evidence, vaguely stating on pages 322-3: “Definite evidence was obtained from Japanese observers that the thermal radiation caused thin, dark cotton cloth, such as the black-out curtains that were in common use during the war, thin paper, and dry, rotted wood to catch fire at distances up to 3,500 feet (0.66 mile) from ground zero (about 35 calories per square centimetre).” Thus, black coloured curtails, thin paper and dry, rotted wood, needed 35 cal/cm’ to ignite in the coastal cities of Japan during August when there was high humidity. White curtains, which are more common now that air raid precautions no longer demand black window curtains, require much higher thermal exposures for ignition than black curtains. TOTAL MORTALITY CURVES FOR NAGASAKI SHIELDING CATEGORY UNDERGROUND SHELTER SEISMIC REINFORCED CONCRETE SEISMIC REINFORCED CONCRETE-LOWER FLOORS SEISMIC REINFORCED CONCRETE-MIDOLE FLOORS NONSEISMIC REINFORCED CONCRETE LIGHT STEEL FRAME = WOOD FRAME COMMERCIAL =e s WOOO FRAME DWELLING ses s OUTSIDE SHIELDED Ss Zs ine > sastecs is BEEEEEE SSessscecs a ESESSEEHti a Sty oO seassesss = Soascsss?, peaeaes ts BESEs~cne5 Haine SE REY SEEstins! sn itt 8 Overpressure (psi) TOTAL MORTALITY CURVES FOR HIROSHIMA SEISMIC REINFORCED CONCRETE SEISMIC REINFORCED CONCRETE-SASEMENTS SEISMIC REINFORCED CONCRETE-MIDDLE FLOORS NONSEISMIC REINFORCED CONCRETE LIGHT STEEL FRAME = VEHICLES (STREET Cans) § WOOD FRAME COMMERCIAL e WOOD FRAME DWELLING 4 OUTSIDE SHIELDED + a ar iit a atts 7 ss ° = ! 4 6 8 10 20 40 60 80 86100 Overpressure (psi) Figure 3: The Peak overpressures for casualties from all effects of nuclear explosions. Source: L. Wayne Davis, Prediction of Urban Casualties and the Medical Load from a High-Yield Nuclear Burst, Dirkwood Corporation paper DC-P-1060-1 (1968). The data assumes a yield of 22 kt for Nagasaki (close to 21 kt used in DSO2) and 12.5 kt for Hiroshima (lower than 16 kt used for DS02). Correcting the yields increases the overpressures for observed mortality, reconciling much low peak overpressure data for both cities. Small differences occur due to different neutron radiation outputs and the firestorm in Hiroshima. Peak overpressures for casualties from all effects of nuclear explosions. Source: L. Wayne Davis, Prediction of Urban Casualties and the Medical Load from a High-Yield Nuclear Burst, Dirkwood Corporation paper DC-P-1060-1 (1968) Explosion Building type 10% killed 50% killed 90% killed Nagasaki (22 kt nuclear air burst over city, Wood-frame 10 psi 15.6 psi 18 psi 1945). Below 16 psi peak overpressure, the | Qutside but in thermal flash 12.5 psi 16 psi 19 psi lower floors of buildings were subjected to shadow (no burn) the horizontal Mach stem blast wave, while Light steel frame 13 psi 17.5 psi 20 psi above 16 psi buildings were subject to CRE er | 125 psi 32 psi Re regular reflection (downward, radial incident , cea SOUNOREEC CORES: eupet pS! ee blast, then the ground-reflected blast wave). SWELEen Underground shelters 22 psi 55 psi N/A Texas City Disaster (0.67 kt non-nuclear Wood-frame 9.0 psi 22.5 psi 30 psi explosion in Texas City, 1947). Peak Light steel frame 13 psi 30.6 psi 46 psi overpressures for given casualties are higher Duden 1 flash 11 psi 26.5 psi 46 psi than at Nagasaki, because of the lack of es ane ( io e = ’ ane - pst oc Ee initial nuclear radiation; although fires were = lf d Tre AO psi 70 psi ignited by hot debris from an exploding ship. SOAR irc att a aiecenga Ss Us ES ee seismic reinforced concrete Hiroshima (16 kt nuclear air burst over city, | Wood-frame 7.0 psi 12.2 psi 13.5 psi 1945). Peak overpressures are underestimates Qutside but in thermal flash 9.0 psi 13 psi 13.5 psi based on 12.5 kt (rather than 16 kt) yield; a shadow (no burn) firestorm contributed to the fatalities shown, Light steel frame 10.5 psi 13 psi 13.5 psi because some people were trapped in fires. NAGASAKI OC peer . ’ - EEE i A Ae UL 9 Bum moray data from m Napesak TN HHH antl HHH = Data, Dirkwood Corporation report Wig Hef p? i DC-FR-1054, ‘ADE53922, April 1966 HE yord degree Fr Tae and degree & oft: (35,099 case histories; 24,044 at {HII LAL ce an a HH ft ¢ } Hiroshima and 11,055 at Nagasaki) BIE Ret TH EHR RERLH a dE ARETE EA ASEM PEMA Pe HATH TH THT ¢ H EE TEER EEE He AA GHEE Lele ie eb te a tee 5 Te ee An Le A AD fe | g He Ea EELERU TET REL enaegte fl ig PAH PAS FHI TMH EHIME UT aT Ul ! HH | L. Wayne Davis, William L. Baker, and Donald L. Summers, Analysis = of Japanese Nuclear Casualty 2 oe HERE TRUTH eet He H He qe HEE TAUPE eh i He ti i He AUUEESAL ES int A ey oe oe iui ee EYEE SEGUE ERATE ETT EAT TRE EES TRE aT oo Hert {HBR He LHR PL HMa RMR 1A Cn te an A HHT ik 1H 20 30 HEEB EN if EDU TRA ET AE a HEE FREES EE =aeSo= ras Soesi lbeceant: Figure 4; The Dirkwood Corporation report Analysis of Japanese Casualty Data, DC-FR-1054, AD653922 (1966), gives the basic survival data for 35,099 case histories of personnel exposed to nuclear explosions over cities in Japan, August 1945 (24,044 at Hiroshima and 11,055 at Nagasaki). This graph shows the effects mortality to outdoor personnel in terms of the percentage of body area (easily derived from the “rule of nines”) subjected to thermal blistering (2"" degree) and surface charring (3™ degree) burns. Contrary to popular propaganda, the mortality depended on the body area burned, since shadows from clothing, buildings, trees, fences, vehicles, people, and terrain provided substantial protection against thermal radiation. In Hiroshima, the Dirkwood data (DC-FR-1054, Fig. 34) shows that the distance from ground zero for 50% survival ranged from 140 metres for the lower floors of earthquake-standard concrete buildings to 730 metres for vehicles (street cars/trolley buses/trams) and 880 metres for wood-frame dwellings. Outdoors, casualty rates depended essentially on thermal radiation exposure in combination with initial nuclear radiation (which suppressed the white blood cell count during burn healing, allowing fatal infections in many cases), and its shadowing by clothing, trees, buildings, fences, terrain, vehicles, etc., rather than blast. People outdoors in thermal shadows were not burned and survived high peak overpressures like those in buildings, as shown. Most people outdoors moved out of shadows into a clear radial line of sight to watch the B-29 aircraft and saw the bomb fall, unaware of the danger, and were flash-burned in silence before the blast wave arrived and knocked them down. Mortality for people outdoors without thermal shielding was 10% for 12 cal/em’, 50% for 16 cal/em*, and 90% for 18 cal/em? (these figures apply to the light summer clothing worn in August and include enhancements due to synergism of burns with initial nuclear radiation). At 3.05 km ground range in Nagasaki, 43% had o” degree burns (blistering) and 5% had ei degree burns (charring), although even light clothing offered complete protection here, so the body area burned was small and recovery was possible in all cases. There was no significant nuclear radiation at that distance to accompany the thermal flash burns and delay or prevent recovery from the burns. At 1.86 km ground range in Nagasaki, there was 10% mortality to persons outdoors without thermal shadowing, due to the 53% of cases having 3™ degree burns and 36% having 2" degree burns, an average total body burned area of 20% (DC-FR-1054, Figs. 28 and 29). A rate of 50% mortality for unshielded persons outside in Nagasaki occurred at 1.37 km from ground zero, where 72% of cases had 3" degree and 18% had 2™ degree burns, with an average total body burned area of 38%. The reason for the increase in area from 20% average area burned at 1.86 km (10% killed) to 38% average area burned at 1.37 km (50% killed) in Nagasaki was simply that the burns were more likely to occur under light summer clothing as the thermal radiation increased. At low thermal exposures, a low protection factor by clothing is sufficient to stop any burns under clothing. 100 4------ NO EXERCISE ARC CASUALTIES FROM GROUND BURST Pe ee ree ope eee + (ALL IN HOUSES) KILLED 1.2 TONS OF TNT BLAST 60 -ba-+=s d 2.4 TONS OF TNT TOTAL 40 UNTRAPPED— SERIOUSLY INJURED 20 4------+-----4-----4-X\ --4 -- - --X\- 6-9 2-4 n qe enon nn ne ponent nnn PERCENTAGE CASUALTIES DISTANCE FROM G.Z. (METRES) World War | World War Il lessons for civil defence in Britain (no Civil Defence) THE RISK OF BECOMING A CASUALTY June and July 1917 World War | London bombings = 121 casualties per ton of bombs World War Il = 2 casualties per ton of bombs, 60 times fewer than the rate in World War | STANDING IN THE OPEN OR IN A STREET (Duck and Cover) World War Il ee Civil — IN TRENCHES, GOOD SURFACE SHELTERS, OR STRUTTED BASEMENTS LYING DOWN IN THE OPEN OR IN A STREET LYING BEHIND LOW COVER OR IN A DOORWAY ] cyeLTER IN A BRICK HOUSE AWAY FROM N WINDOWS IN SHELTER Figure 5; The value of duck and cover as protection against hurricane force blast winds and flying debris was proved in Britain during the Blitz bombing. The blast casualty rates to unprotected personnel in cities during bombing in World War I was reduced by simple countermeasures during World War II. Sources: U. K. Home Office publications, “Exercise Arc” (1959), “History of the Second World War: Civil Defence” (Terrence O’ Brien for H. M. Stationery Office, 1955), and “Basic Methods of Protection Against High Explosive Missiles” (1949). (1.2 tons of TNT = 2.4 tons nuclear yield for 50% blast.) COMrIENTIAE FIGURE 5-2 DEPARTMENT OF THE ARMY TECHNICAL MANUAL TM 23-200 DEPARTMENT OF THE NAVY OPNAV INSTRUCTION 03400.18 Thermal effects: Oe aie DEPARTMENT OF THE AUR FORCE AFL 136-1 Second degree bare skin burn.. 4 61 91 MARINE CORPS PUBLICATIONS NAVMC 1104 REV Army khaki summer uniform CAPABILITIES OF ATOMIC WEAPONS (U) Prepared by Armed Forces Special Weapons Project DEPARTMENTS OF THE ARMY, THE NAVY AND THE AIR FORCE REVISED EDITION NOVEMBER 1957 ‘CONFIBENTIAE SONFIBENTHE— Table 6-1. Estimated Casualty Production in Structures for Various Degrees of Structural Damage Killed tg ners ur: outright] (hospi- | (No bos- taliza- | pitaliza- tion) tion) 1-2 story brick homes (high ex- plosive data): Severe damage...--.-.------- Moderate damage........---- <5 10 5 Light damage_..-...---------]------ <5 <5 Reinforced-concrete buildings (Jap- anese data, nuclear): | Severe damage........--.---- 100 [scsccelescsce Moderate damage.......----- 10 15 20 Light damage......---------- | <5! <5 15 Note. These percentages do not include the casualties which may result from fires, asphyxiation, and other causes from failure to extricate trapped personnel. The numbers represent the estimated percentage of casualties expected at the maximurn range where the specified structural damage occurs. 6.2 Thermal Injury a. Introduction. Before attempting to predict the number of thermal casualties which occur in a given situation, it is necessary to recognize the factors which influence the number and distribu- tion of casualties to be expected. These factors include—the distribution or deployment of per- sonnel within the target area, whether proceeding along a road, in foxholes, standing or prone, in the open or under natural cover; orientation with respect to the bomb; clothing, including number of layers, color, weight, and whether the uniform includes helmets, gloves, or other devices which might protect the bare skin, such as flash creams; and natural shielding. WAFER. 6-3 5-12 AGNE BERTI, 6.1c¢ (3) SOuROR NTE destruction. -..-..--------- 18 31 56 Navy white uniform destruc- WONsscasscssccsesiecscsess 34 60 109 Blast effects (in the Mach region): Severe damage to overpressure sensitive structures: Blast-resistant designed (PSI overpressure) buildings ........-....- 50 40 35 Reinforced concrete build- INGS occ cccececc ces ses 105 9<.5 9 Monumental wall bearing buildings -.--.-.-.----- 20 15 15 Wood frame housing... ---- 3 3 3 Window pane breakage.... 0.5 0.5 0. 5 Severe damage to dynamic pres- sure sensitive structures: Light steel frame single (PSI dynamic pressure) story buildings--...---- 45 2 0.9 Heavy steel frame single story buildings.....---. 6 3 1.5 Steel frame multistory buildings. ..-..-------- 75 2.5 0.9 150’-250’ span _ truss bridgesi.<02- 00.5505 50 8 5.5 6.2b SCONFIDERTIAL- b. Primary Radiant Energy Burns. Damage to bare skin through the production of burns may be directly related to the radiant exposure and the rate of delivery of the thermal radiation, both of which are yield dependent. For a given total ex- posure, as the weapon yield increases, the thermal radiation is delivered over a longer period of time and thus at a lower rate. This allows energy loss from the skin surface by conduction to the deeper layers of the skin and by convection to the air. c. Burns Under Clothing. Clothing reflects and absorbs much of the thermal radiation incident upon it and thereby protects the wearer against flashburn. In some cases, the protection is com- plete, but in many cases it is partial in that cloth- ing merely reduces the severity of injury rather than preventing it. At large radiant exposures, there is the additional possibility that the glowing or ignition of the clothing could deliver additional energy to the skin, thereby causing a more severe injury than bare skin would have suffered. Table 6-2. Critical Radiant Exposures for Burns Under Clothing (Expressed in cal/cm? incident on outer surface of cloth) Clothing Burn Summer Uniform........-. 1° 8 11 14 (2 layers)...------------ 2° 20 25 35 Winter Uniform._._.-_-..-- ye 60 80 100 (4 layers) 22s cicccecsces 2° 70 90 120 Note. These values are sensitively dependent upon many variables which sre not easily defined (see text), and are probably correct within a factor of two. 6-4 CONTIDENTINE— Figure 6: WWII blast and thermal casualty data was classified Confidential in TM 23-200, Capabilities of Atomic Weapons. The Effects of Atomic Weapons PREPARED FOR AND IN COOPERATION WITH THE U. S. DEPARTMENT OF DEFENSE AND THE U. S. ATOMIC ENERGY COMMISSION Under the direction of the LOS ALAMOS SCIENTIFIC LABORATORY Los Atamos, New Mexico Revised September 1950 BOARD OF EDITORS J. O. Hirscure.per, Chairman Davin B. Parker Arnotp KramisH Raupn Cariis.e SMITH Samue. Guasstone, Executive Editor For sale by the Superintendent of Documents, U. §. Government Printing Office Washington 25, D.C. - Price $1.25 (paper bound) RADIOACTIVE CONTAMINATION FROM UNDERWATER BURST 279 8.91 From measurements made at the time of the Bikini “Baker” test, it has been possible to draw some general conclusions with regard to the integrated or total radiation dosage received at various dis- tances from surface zero. WIND 5 mph (miles) Figure 8.9la. Contours for various integrated radiation dosages due to base surge from underwater burst. CHAPTER I~ PRINCIPLES OF AN ATOMIC EXPLOSION A. INTRODUCTION CHARACTERISTICS OF AN Atomic ExPLosion 1.1. The atomic bomb is a new weapon of great destructive power. It resembles bombs of the more conventional type in so far as its explosive effect is the result of the very rapid liberation of a large quantity of energy in a relatively small space. But it differs from other bombs in three important respects: first, the amount of energy released by an atomic bomb is a thousand or more times as great as that produced by the most powerful TNT bombs; second, the explo- sion of the bomb is accompanied by highly-penctrating, and deleteri- ous, invisible rays, in addition to intense heat and light; and third, the substances which remain after the explosion are radioactive, emitting radiations capable of producing harmful consequences in living organisms. It is on account of these differences that the effects of the atomic bomb require special consideration. 1.2 A knowledge and understanding of the mechanical and radia- tion phenomena associated with an atomic explosion are of vital im- portance. The information may be utilized, on the one hand, by architects and engineers in the design of structures; while on the other hand, those responsible for civil defense, including treatment of the injured, can make preparations to deal with the emergencies that may arise from an atomic explosion. 1.3 During World War II many large cities in England, Germany, and Japan were subjected to terrific attacks by high-explosive and incendiary bombs. Yet, when proper steps had been taken for the protection of the civilian population and for the restoration of services after the bombing, there was little, if any, evidence of panic. It is the purpose of this book to state the facts concerning the atomic bomb, and to make an objective, scientific analysis of these facts. It is hoped that as a result, although it may not be feasible completely to allay fear, it will at least be possible to avoid panic. 1 Material contributed by G. Gamow, 8. Glasstone, J. O. Hirschfelder. 280 RESIDUAL NUCLEAR RADIATIONS AND CONTAMINATION WIND 5 mph (miles) Figure 8.91b. Contours for various integrated radiation dosages due to con- tamination from underwater burst. Figure 7: During Operation Crossroads on 25 July 1946 an underwater nuclear explosion occurred, Baker (23.5 kt at 90 feet depth in 180 feet of water within Bikini Lagoon, Pacific). The mushroom cloud consisted of small sea-water droplets. After about 12 seconds the “column” or stem of the mushroom rapidly collapsed to form a radioactive wind-carried surface “base surge” mist, and rapidly spread out, enveloping and irradiating ships nearby. Then the water droplets in the mushroom cloud head fell back in a “rainout” which reached the surface about one minute after detonation, contaminating the ships. The wind affected both the base surge and the cloud rainout. In 1950 the dose patterns from each phenomenon were published (above). GAMMA RAYS oor The Effects of Nuclear Weapons SaMUEL GLASSTONE Editor Prepared by the UNITED STATES DEPARTMENT OF DEFENSE Published by the UNITED STATES ATOMIC ENERGY COMMISSION June 1957 For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D.C. - Price $2.00 (paper bound) ATTENUATION OF RESIDUAL NUCLEAR RADIATION 403 ATTENUATION FACTOR 70 100 ———] 0.4 0.7 1.0 7 2 THICKNESS (INCHES) 0 FM. GaumAS Figure 9.36. Attenuation of fission product radiation. ® ALLO wT) 100,000 70,000 40,000 20,000 10,000 7,000 4,000 a | 2 000 + iz = : | s E ye j 3 BI A le E all & Sf S| jE] 8 1,000] £ = BL StS § i=} = 700 g = a a Py 5 3 gs) =) 5 3 5 a] & & 400 & s | g 2 =| S| & a = z z & B Ss) . sau 3 = & a & a E 100 70 40 20 10 |__| 7 4 2 1 1 2 4 7 10 20 40 70 100 200 400 700 1,000 THICKNESS (INCHES) Figure 8.47. Attenuation of initial gamma radiation. 524 PROTECTIVE MEASURES 12.60 In the event of a surprise attack, when there is no oppor- tunity to take shelter, immediate action could mean the difference be- tween life and death. The first indication of an unexpected nuclear explosion would be a sudden increase of the general illumination. It would then be imperative to avoid the instinctive tendency to look at the source of light, but rather to do everything possible to cover all exposed parts of the body. A person inside a building should imme- diately fall prone and crawl behind or beneath a table or desk. This will provide a partial shield against splintered glass and other flying missiles. No attempt should be made to get up until the blast wave has passed, as indicated possibly by the breaking of glass, cracking of plaster, and other signs of destruction. The sound of the explosion also signifies the arrival of the blast wave. 12.61 A person caught in the open by the sudden brightness due to a nuclear explosion, should drop to the ground while curling up to shade the bare arms, hands, neck, and face with the clothed body. Although this action may have little effect against gamma rays and neutrons, it might possibly help in reducing flash burns due to thermal radiation. The degree of protection provided will vary with the energy yield of the explosion. As stated in § 7.53, it is only with high-yield weapons that evasive action against thermal radiation is likely to be feasible. Nevertheless, there is nothing to be lost, and perhaps much to be gained, by taking such action. The curled-up po- sition should be held until the blast wave has passed. 12.62 Ifshelter of some kind, no matter how minor, e. g., in a door- way, behind a tree, or in a ditch, or trench can be reached within a second, it might be possible to avoid a significant part of the initial nuclear radiation, as well as the thermal radiation. But shielding from nuclear radiation requires a considerable thickness of material and this may not be available in the open. By dropping to the ground, some advantage may be secured from the shielding provided by the terrain and surrounding objects. However,.since the nuclear radia- tion continues to reach the earth from the atomic cloud as it rises, the protection will be only partial. Further, as a result of scattering, the radiations will come from all directions. Figure 8; Data on gamma radiation shielding and civil defence against fires was published in The Effects of Nuclear Weapons. The Effects of Nuclear Weapons SAMUEL GLASSTONE Editor Revised Edition Reprinted February 1964 Prepared by the UNITED STATES DEPARTMENT OF DEFENSE Published by the UNITED STATES ATOMIC ENERGY COMMISSION April 1962 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. - Price $3.00 (paper bound) 445 IDEALIZED FALLOUT PATTERNS 200 190 12 180 10R 170 160 10 150 140 EFFECTIVE WIND 15 MPH 130 fo) nan 3 ao TIME OF ARRIVAL (HOURS) 120 a 10R as o a Ss 8 8 > DISTANCE FROM GROUND ZERO (MILES) wo o i S So E i<) 30 \ 3000 10R 20 100 | 1000 3000 B 10 SS a eed 20 10 0 10 20 20 10 O 10 20 20 10 0 10 20 DISTANCE FROM GROUND ZERO (MILES) 1 HOUR 6 HOURS 18 HOURS Figure 9.67b. Total-dose contours from.early fallout at 1, 6, and 18 hours after surface burst. with 1-megaton fission yield (15 mph effective wind speed). Foreword This book is a revision of ‘‘The Effects of Nuclear Weapons” which was issued in 1957. It was prepared by the Defense Atomic Support Agency of the Department of Defense in coordination with other cognizant govern- mental agencies and was published by the U.S. Atomic Energy Commission. Although the complex nature of nuclear weapons effects does not always allow exact evaluation, the conclusions reached herein represent the combined judgment of a number of the most competent scientists working on the problem. There is a need for widespread public understanding of the best information available on the effects of nuclear The purpose of this book is to present as accurately as possible, within the limits of national security, a comprehensive summary of this information. MALE W) thon Secretary of Defense kw, SKcabres Chairman weapons. Atomic Energy Commission SUMMARY 661 12.78 In the event that shelters are not available, certain evasive actions may prove helpful at distances where the immediate effects are least severe. By instantly falling prone and covering exposed portions of the body or getting behind opaque objects, much of the thermal radiation may be avoided, especially in the case of large-yield weapons. Under no circumstances should an individual look in the direction of the fireball. Staying behind thick walls or lying in a deep ditch may help to avoid initial nuclear radiation. All of the above actions will also help to decrease the possible danger from the blast wave. Moreover, persons should avoid areas which have frangible materials, such as window glass, plaster, etc., which may become flying debris by the action of the blast. 12.79. After the immediate effects of the nuclear explosion are over, certain acts are required to minimize the hazards of the early fallout and from the fires which may result from thermal radiation and second- ary blast. effects. First, if small fires can be quickly extinguished, extensive conflagrations.may be ~prevented. This must be accom- plished before the arrival of the fallout-or in areas of low radioactivity levels. Some protection from the fallout may be secured in the base- ments of buildings or in a quickly constructed shelter, such as is described in §12.55. It is important to keep from coming into physi- cal contact with the fallout particles, and to prevent contamination of food and water sources. Monitoring equipment should be used to determine areas which have safe radiation levels and decontamination efforts can. proceed. to recover necessary equipment, buildings, and areas. ConcLUSION 12.80 Much of the discussion presented in earlier sections of this chapter have been based, for simplicity, on the effects of a single weapon. It must not be overlooked that in a nuclear attack some areas may be subjected to several bursts. The basic principles of protection would remain unchanged, but protective action against all the effects of a nuclear explosion—blast, thermal radiation, initial nuclear radiation, and fallout—would become even more important. Figure 7.33a. Thermal effects on wood-frame house 1 second after explosion (about 25 cal/sq em). Figure 7.33b. Thermal effects on wood-frame house about % second later. 342 THERMAL RADIATION AND ITS EFFECTS Figure 7.57. Wooden test houses before exposure to a nuclear explosion, Nevada Test Site. Figure 7.58. Wooden test houses after exposure to a nuclear explosion. NUMBER OF TRANSIENT EXTERIOR USE CLASS IGNITION POINTS PER ACRE WHOLESALE DISTRIBUTION SLUM RESIDENTIAL NEIGHBORHOOD RETAIL POOR RESIDENTIAL SMALL MANUFACTURING DOWNTOWN RETAIL GOOD RESIDENTIAL LARGE MANUFACTURING Figure 7.55. Frequency of exterior ignition points for various areas in a city the formation of a significant fire, capable of spreading, will require appreciable quantities of combustible material close by, and this may not always be available. 7.57 The fact that accumulations of ignitable trash close to a wooden structure represent a real fire hazard was demonstrated at the nuclear tests carried out in Nevada in 1953. In these tests, three miniature wooden houses, each having a yard enclosed with a wooden fence, were exposed to 12 calories per square centimeter of thermal radiation. One house, at the left of Fig. 7.57, had weathered siding showing considerable decay, but the yard was free from trash. The next house also had a clean yard and in addition, the exterior siding was well maintained and painted. In the third house, at the right of the photograph, the siding, which was poorly maintained, was weathered, and the yard was littered with trash. 7.58 The state of the three houses after the explosion is seen in Fig. 7.58. The third house, at the right, soon burst into flame and was burned to the ground. The first house, on the left, did ignite but it did not burst into flame for 15 minutes. The well maintained house in the center with the clean yard suffered scorching only. It is of interest to recall that the wood of a newly erected white-painted INCENDIARY EFFECTS 343 house exposed to about 25 calories per square centimeter was badly charred but did not ignite (see Fig. 7.33b). 7.59 The value of fire-resistive furnishing in decreasing the num- ber of ignition points was also demonstrated in the tests. Two identical, sturdily constructed houses, each having a window 4 feet by 6 feet facing the point of burst, were erected where the thermal radiation exposure was 17 calories per square centimeter. One of the houses contained rayon drapery, cotton rugs, and clothing, and, as was expected, it burst into flame immediately after the explosion and burned completely. In the other house, the draperies were of vinyl plastic, and rugs and clothing were made of wool. Although much ignition occurred, the recovery party, entering an hour after the explosion, was able to extinguish the fires. : 7.60 There is another point in connection with the initiation of fires by thermal radiation that needs consideration. This is the possibility that the flame resulting from the ignition of a combustible material may be subsequently extinguished by the blast wind. It was thought that there was evidence for such an effect from an obser- vation made in Japan (§ 7.67), but this may have been an exceptional case. The matter has been studied, both in connection with the effects in Japan and at various nuclear tests, and the general con- clusion is that the blast wind has no significant effect in extinguishing fires (§ 7.68). Spreap or Fires 7.61 The spread of fires in a city, including the development of a “fire storm’ to which reference is made in § 7.75, depends upon a variety of conditions, e.g., weather, terrain, and closeness and com- bustibility of the buildings. Information concerning the growth and spread of fires from a large number of ignition points, such as might follow a nuclear explosion, and their coalescence into large fires (or conflagrations) is limited to the experience of World War IT incendiary raids and the two atomic bomb attacks. There is consequently some uncertainty concerning the validity of extrapolating from these limited experiences to the behavior to be expected in other cities. It appears, however, that if other circumstances are more-or-less the same, an important criterion of the probability of fire spread is the distance between buildings. It is evident, from general considerations, that the lower the building density or “built-upness” of an area, the less will be the probability that fire will spread from one structure to another. Furthermore, the larger the spaces between buildings the greater the chances that the fire can be extinguished. HIROSHIMA —--- 9.011 (approrl Scattered be points ranging from 0.025 to -_- - Results of the Naval Medical Research Institute (NMRI) survey performed in Hiroshima November 1-2, 1945, showing residual radiation levels of 0.069 he vicinity of ground zero” and 0.011 mR/hr at the outermost c The NMRI survey report (Measurement of the Residual Radiation Bomb Sites, NMRI-160A) documents a resi residual exposure rate of 0.081 measurements of 0 and 9 mR/hr among the “scattered points” to the Tepresented on the map in DNA 5512F. Suilt-up area of eity Tomei ererer tt eam Severe blast and fire damage to structures within ontour. Source: DNA 5512F. milliroentgen per hour (mR/hr) in the Intensity at the Hiroshima and Nagasaki Atomic mR/hr at the hypocenter, as well as spot ‘west of the city center. These values are not Figure 9: Residual radioactivity due to fallout and neutron induced activity in Hiroshima was collected in detailed surveys during 1945 that were kept secret. Hiroshima and Nagasaki have been continuously occupied! The two 16-21 kt air bursts at about 600 metres over the cities produced no significant local fallout. DNA EM-1 PART | =| = DEFENSE NUCLEAR AGENCY EFFECTS MANUAL NUMBER 1 Mm CAPABILITIES 2| OF NUCLEAR WEAPONS = 1 JULY 1972 = HEADQUARTERS Defense Nuclear Agency Washington, D.C. 20305 Contours for Bursts in the Transition Zone Figure 5-43 may be used to determine whe or not a burst is in the transition zone, i.e, below a height of burst of 100W°->5 feet. Burst heights below the curve in Figure S-43'are in the transition zone. Burst heights above the curve are air bursts. In some situations, it may tz dzdratis te consider bursts below 180W?-* feet to be in the transition zone for conservative estimates. The means for doing this are discussed below. Wher a burst occurs in the transition zone, an approximation of the resulting fallout contamination pattems may be obtained by multiplying the dose rate contour values for a contact surface burst weapon of the same yield the assumption that the ratio of the dose rate values from a burst in the transition zone to the dose rate values for the same contour from 2 surface burst are proportional to the ratio of the volume of a segment of a sphere intercepted by the ground surface to the volume of the hemi- sphere, where the radius of the spheze is 1000-35 feet, ie., (oa rT where h is the actual height of burst in feet, and W is the total weapen yield in kilotons. In view of the lack of data from bursts in the transition zone over a land surface, a more conservative estimate may be desired. In this case, the height of burst for the upper limit of the transition zone is taken to be 180W”-‘ feet. The adjustment factor to be applied to dose rate values for the same contours from a surface burst of the same yield can be calculated from: Adinerment Fartor = (e-sal omc) 117x107 iven: A hypothetical weapon with 2 totel yield of 600 kt, of which 200 Ft resulte from fission, is burst 560 feet over a land surface with 10 knot effective wind conditions. Find: The contour parameters for a dose rate of 15 rads/hr at H + 1 hour reference time over smooth terrain. Solution: From Figure 5-43, a 600 kt weapon burst below about 940 feet would be in the transition zone. A height of burst of 560 feet is less than three quarters of the limiting altitude of the transition, so fallout is the only residual radiation to be considered. The 15 rads/ hr contour for a fission yield to total yield ratio of 200/600 = 1/3 corresponds to the contour for 15 + 1/3 = 45 rads/hr for a weapon of 600 kt fission yield. The dose rate over reasonably level terrain is about 70 percent of that over an ideal smooth plane. Thus, the ideal smooth plane con- tour parameters for this weapon burst on the surface would correspond to 45 - PS 7” 64 radsjar. From Figure 5-44 (or from the normal adjust- ment factor equation given above) the height of burst adjustment factor for a 600 kt weapon burst at 560 feet is 0.21. Therefore, the desired contour can be obtained by entering Figures 5-28, 5-31, 5-34, and 5-37 with a yield of 60C kt and reading the parameter values cor- Tesponding to an H + 1 hour dose rate of Adjustment Factor = OL 021 300 rads/hr. Figure 10: By the time cloud stem debris is carried into the fireballs of air bursts, the fission products and weapon residue have long since condensed into solid particles within a toroidal shaped vortex. Incoming dust enters the hole in the ring and up over the top, cascading back without mixing with the condensed fission products, so no significant local fallout is formed. COMPARISON of FALLOUT CONTOURS 5MT BURST 1KT BURST Figure 11: Pacific 5 Mt 87% fission surface burst Redwing-Tewa (1956) and Nevada 1.2 kt 100% fission surface burst Jangle- Sugar (1951), from Dr Terry Triffet’s testimony to the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, U. S. Congress, Biological and Environmental Effects of Nuclear War, hearings on 22-26 June 1959. Failures in fallout predictions at both Nevada and Pacific tests were due to the fact that the shots had to occur under unstable wind conditions, since the prevailing winds in both cases blew towards the east (towards inhabited St George and Rongelap Atoll). A FaAtiout Forecasting TECHNIQUE WITH yes RESULTS OBTAINED AT THE ENIWETOK PROVING 0.25 == ae Comparteow: of Taleur Jorcouss sith: Fost ronates Grounp, USNRDL-TR-189, E. A. Schuert, ra _ United States Naval Radiological Defense 77 MEASURED, \ Laboratory / HOT LINE ‘ “-—_——_ Updated from WT-1317 (1961) Fa , ~ \ FORECAST AREA ° 20 40 60 ‘ os =k NOUN oc-r~ u ee ed \ XN N ra SA NAUTICAL MILES \ N I : = (Scale corrected) \ ‘\ = “HOT ‘ va H ! 4 | oman ao” aa MEASURED ISODOSE % RATE CONTOURS 4 (LAND R/HR, aN ( 48 HRS) ‘\ \ / PARTICLE SIZE LINES. 70,000 —_70 7s Ome 78000 PARAMETER ASSUMPTIONS USED 1, CLOUD TOP: 90,000 FT 2 CLOUD BASE: 50,000 FT 3 CLOUO DIAMETER: 60N MILES 4. HOT LINE FALLOUT: FROM 50-60,000 FT METEOROLOGICAL PARAMETERS 1. TIME VARIATION OF THE WIND FIELO SURFACE ZERO Figure 12: The accurate Redwing-Tewa (1956) fallout prediction of the hotline and high-intensity areas were made using a hand fallout forecasting technique by Edward A. Schuert aboard ship under simulated combat conditions. Schuert explained why fallout prediction was hard in his report A Fallout Forecasting Technique with Results Obtained at the Eniwetok Proving Ground (USNRDL-TR-139, 1957): “proper firing conditions, which required winds that would deposit the fallout north of the proving ground, occurred only during an unstable synoptic situation of rather short duration.” R/hr at 1 hour We? 7 yo vl "40 Réhrat 4 hour fh / Vi ] | H 10 / J I} / jf 4 / 1 ory / / : / | PP / 1 | | J } / | / I » } /\ i|/ | A | | | i / y pS) ; i AH / y | Fy MH Aa NAT fi Wey VY /} \ | If] 4 // WW! / AN { Wt \ N oy ) ——a Wea = — ies oa. & & » 2 3 \ tA \Vi THOUSANDS OF FT THOUSANDS OF FT _ WAS —- w : SZ y ; 1_ig pti 4 1.2 kt ‘Sugar’ surface burst ;: 1.2 kt ‘Uncle’ burst at 5.2 m depth Figure 13: Dr Albert D. Anderson’s U. S. Naval Radiological Defense Laboratory computerized “Dynamic Fallout Model” in 1959 reproduced the Jangle-Sugar (1951) fallout pattern with sufficient accuracy for civil defense using only shot-time winds (The NRDL Dynamic Model for Fallout from Land-Surface Nuclear Bursts, USNRDL-TR-410). At the June 1959 U. S. Special Subcommittee on Radiation hearings, Biological and Environmental Effects of Nuclear War, the fallout research project officer for Redwing, Dr Terry Triffet, testified (p. 110) that wind shear and instability (variations over short intervals of time) were characteristic of the Pacific testing area: “... the winds over the Eniwetok Proving Grounds have a tendency to vary more than the winds over the United States ...” Charles K. Shafer later testified (p. 208): “... Dr Triffet showed yesterday ... a multimegaton detonation [Redwing-Tewa] in the Pacific in which there was a tremendous fanning out of the fallout ... We do not have that type of wind behavior in the United States except possibly in the Gulf States in the summertime ...”. This Dynamic fallout model was the precursor to DELFIC, the U. S. Department of Defense’s Land Fallout Interpretative Code, and it included some of the key features. The “Dynamic” in its name is due to its analysis of fallout from the time of creation, through the sweep-up process in the mushroom stem updraft, to deposition: “Large particles reach their maximum altitude and are falling while smaller particles are still rising.” In the Jangle-Sugar test fallout pattern there was little wind shear at the cloud altitude, and the mean vector wind velocity from thr ground to the cloud top was 40 km/hour. The maximum dose rate from fallout (outside of crater) was 540 R/hr at | hour, which occurred 900 feet downwind. Dose rates of 500, 300, and 100 R/hr occurred 2,200, 4,900, and 12,500 feet downwind at 1 hour after detonation. The Jangle-Uncle test was a similar 1.2 kt device detonated 5.2 metres underground in Nevada soil, where the mean vector wind velocity was 20 km/hour. The surface wind was only 3.2 km/hour, which allowed the ground level “base surge” to carry radioactivity a considerable distance upwind (a factor which Anderson did not include in his fallout prediction, which assumed it to be a surface burst). The maximum dose rate from fallout (outside the crater) was 3,400 R/hr, which occurred 930 feet downwind. Dose rates of 1,000, 500, 200 and 100 R/hr occurred 1,250, 3,500, 10,000, and 17,200 feet downwind at | hour after detonation. Anderson’s Dynamic model predicts that a 1 megaton fission Nevada soil surface burst under 10 knot mean winds will produce a maximum downwind | hour dose rate hotspot of 6,126 R/hr at 6.9 km downwind. Doubling the windspeed reduces this hotspot dose rate by factor of 1.64 (by dispersing the same fallout over a larger area), but increases the downwind distance of the peak dose rate by factor of 1.49. Doubling the weapon yield only increases the maximum dose rate by a factor of 1.18, but increases its downwind distance by a factor of 1.34. Weather Bureau Testimony of Dr W. W. Kellogg (RAND Corp.) to U.S. Congress fallout distribution The Nature of Radioactive Fallout and Its Effects on Man, predicted at H-2 hours 1957, part 1, pp. 113-4. Cd Eureka ra ¢ Imr/hrat H+i2hrs Observed fallout / distribution / --7™ (dashed lines) -occ- rae i“mr/hre at H+12 hrs 7 / / / Pe fe) ; 7 observed fallout a ! distribution / ; (dashed lines) / jf Weather Bureau / hand computation f with time and space variation of winds “3 "Nevada test site (0) 30 60 Nevada test site @ ground zero ener MEN @ ground zero May 5, 1955 Statute miles May 5, 1955 Figure 14: Teapot-Apple 2 fallout predictions and result, 5 May 1955: Nevada Test Site, burst on the top of a 500 foot high steel tower burst, 29 kt total yield (100% fission yield). Solid lines show fallout predictions by Kenneth Nagler of the U.S. Weather Bureau, for winds forecast 2 hours before detonation (left), and for wind variations in space and time (right). Meteorologist Dr William W. Kellogg of the RAND Corporation presented the fallout patterns in his testimony to the U.S. Congressional Hearings before the 1957 Special Subcommittee on Radiation, The Nature of Radioactive Fallout and Its Effects on Man, pp. 104-41, where he states that Kenneth Nagler and Dr Lester Machta of the U. S. Weather Bureau found that (for 12-18 kt tests), the local fallout percentage (activity deposited within 200 miles of ground zero) was 10.8 % for the average of five 300-foot steel tower bursts, 5.4 % for a 500 foot steel tower burst (14 kt Teapot-Apple 1) and 1.0 % for an air burst at 524 feet (the 15 kt Grable test in 1953), compared to 87 % for the 1.2 kt Jangle-Sugar Nevada surface burst in 1951, 85 % for the 1956 Redwing coral surface bursts (Zuni and Tewa), and 65-70% for Redwing ocean surface bursts (Flathead and Navajo). 3.53 Mt coral surface burst REDWING-ZUNI: close-in fallout fractionation factors 0.5 (Precursors in Parenthesis) AVERAGE LAGOON AREA COMPOSITION Te-132 (1.9 min Sb) 0.1 c = Sr-89 5 (192 sec Kr) () 5 | SOURCE: |-131 Cs-137 = WT-1317, (21 min Sb) (234 sec Xe) a Fig. 3.32. 0.01 A 1 10 100 HALF-LIFE OF PRECURSOR (SECONDS) Figure 15: close-in fallout from surface bursts is fractionated, with greatly reduced abundances of the soluble volatile fission product like iodine-131, which can only plate the outer surfaces of fallout particles in the later stages of fireball condensation. This graph is from Terry Triffet and Philip D. LaRiviere’s report Operation Redwing, Characterization of Fallout, WT-1317, 1961. It shows that there is a correlation between fractionation and the half-life of the volatile precursor in each decay chain. PARTICLE FORMATION “SMALL PARTICLES => Dia FISSION PRODUCTS \ Se y B a Ob on aan +s t:] CONDENSED PARTICLES KZ Smee 209 MELTED ENVIRONMENTAL Cis YF MELTED ENVIRONMENTAL MATERIALS . ‘ A INSOLUBLE SOLIDS - ee INITIAL 7 Melted, insoluble solid containing oo ENVIRONMENTAL = Salt slurry translucent air bubbles and mineral grains MATERIALS white soluble droplet Figure 16: lethal fallout is not an invisible gas that can only be detected by special instruments. It must be carried down from high altitudes rapidly on large particles in order to produce high doses before the radioactivity decays. Only the Marshallese who saw visible fallout deposited from the 1954 Castle-Bravo 14.8 megaton coral reef surface burst 115 miles away received beta burns to bare skin, and they were burned only on moist areas of skin and coconut oil dressed hair that retained fallout for many hours. Because ordinary clothing did not retain the dry fallout particles, clothed areas were protected from beta radiation exposure. However, waterproof clothing is required for protection against wet sticky fallout particles from water surface bursts in humid air. (Illustration adapted from Dr Triffet’s testimony before the Special Subcommittee on Radiation, June 1959.) A HEAVY COLLECTION FAR OUT 1S MINUTE EXPOSURE TRAY NO 411 YAG 40, B-7 ZUNI A HEAVY COLLECTION CLOSE IN 15 MINUTE EXPOSURE TRAY NO. 1204 YFNB 13, E-57 ZUNI Figure 17: surface bursts loft hundreds of tons of soil/kt as fallout, so the specific activity per unit mass of fallout is relatively low, and the carrier soil makes the fallout clearly visible where there is a lethal hazard. You do not need radiation meters to determine that a lethal fallout hazard exists. These 8.1 cm-diameter trays were exposed for just 15 minutes (report WT-1317). EFFECTIVE ARRIVAL TIME (HOURS) 1 6 8 9 0 11 12 1 14 15 16 17 18 19 20 Estimated total-dose contours in roentgens at 96 hours BIKAR ATOLL UTIRIK ATOLL 170 ~~ 220 RONGERIK TAKA 18 104.120 agoLL ATOLL AILINGINAE ATOLL 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 DISTANCE FROM GROUND ZERO (MILES) Figure 18: surface burst Castle-Bravo on 1 March 1954 contaminated downwind inhabited atolls (Glasstone and Dolan). Note the effective arrival time of 1 hour near ground zero: the mean fallout arrival time in the lagoon was 28 minutes, but the fallout dose rate peaked at | hour and material continued arriving for 2 hours, as stated in report WT-915. The fallout forecasting error was mainly due to unexpectedly high yield, since was known at before the test that Rongelap and Rongerik were downwind. Operation Castle, Radiological Safety, Final Report, volume Il (ADA995409, 1985, pages K3-K7): “At the midnight weather briefing, the forecast offered a less favorable condition in the lower levels (10,000 to 25,000 feet). Resultant winds at about 20,000 feet were forecast in the direction of Rongelap and Rongerik; however, it was considered that the speeds and altitudes did not warrant a conclusion that significant quantities and levels of debris would be carried out so far.” The March 1957 University of Utah Master of Science thesis by meteorologist Frank Cuff, A Study of the Time Variability of Integrated Winds Near Las Vegas, Nevada, showed that mean vector wind direction from the surface to 20,000 feet (measured by tracking the direction of weather balloon while it rises at a constant rate) varied by an average of only 12 degrees over a 3 hour period and 22 degrees over a 6 hour period, while even smaller variations occurred for the mean vector wind direction between the surface and 50,000 feet: 6 degrees over 3 hours and 13 degrees over 6 hours. The smaller average variation that occurs over the larger altitude range is due to the overall cancellation of the effects of some random shifts in wind directions by opposing changes at different altitudes: this is relevant to fallout prediction where the “hotline” or axis of maximum activity is determined by fallout concentrated at the lower portion of the mushroom cloud. Schuert states in USNRDL-TR-139, 1957: “The height lines describing the fallout from the lower portion of the mushroom immediately establish the ‘hot line’.” RADIOACTIVE DECAY RATE SURFACE BURST 107 nee ) ar i) i] ' a _ i o ' e iS] TEWA cloud f: FLATHEAD IONIZATION RATE ( TEWA LAGOON" 10-2 1 10 102 103 104 TIME (HR) Figure 18: surface burst radioactivity decay rates depend on fractionation and neutron induced activities such as Np-239 and U-237 produced by neutron capture reactions with U-238 in the bomb. But Zuni (3.53 Mt 15% fission coral island surface burst), Tewa (5.01 Mt 87% fission coral reef surface burst), Flathead (365 kt 73% fission ocean surface burst) and Navajo (clean 4.5 Mt 5% fission ocean surface burst) led to a fractionated (lagoon) and unfractionated (cloud) fallout decay ~(time)'” Measured capture to fission ratios in nuclear tests* Number of neutron capture atoms per fission Test shot Weapon design Yield Fission % U-239 & Np-239 U-237 U-240 & Np-240 Jangle-Sugar U238 reflector 1.2 kt 100 0.59 Jangle-Uncle U238 reflector 1.2 kt 100 0.59 Castle-Bravo U238 pusher 14.8 Mt 68 0.56 0.10 0.14 Castle-Romeo —_U238 pusher 11 Mt 64 0.66 0.10 0.23 Castle-Koon U238 pusher 110 kt 91 0.72 0.10 Castle-Union —_U238 pusher 6.9 Mt 72 0.44 0.20 0.07 Redwing-Zuni 3.53 Mt 15 0.31 0.20 0.005 Redwing-Tewa 5.01 Mt 87 0.36 0.20 0.09 Diablo U238 in core** 18 kt 100 0.10 Shasta U238 in core** 16 kt 100 0.10 Coulomb C U238 in core** 0.6 kt 100 0.03 * Data is derived from all analyses of aircraft cloud fallout samples and deposited fallout samples in Dr Carl F. Miller, U.S. Naval Radiological Defense Laboratory, report USNRDL-466 (1961), Table 6. **In these Plumbbob weapon tests, there was no U238 reflector and the only U238 in the bomb was that contained in the fissile core as an impurity. Measured relationship between the fusion yield of the nuclear explosive and the quantity of neutron-induced activities in the fallout* Test Redwing-Navajo Redwing-Zuni Redwing-Tewa Design Lead pusher Lead pusher U-238 pusher Total yield 4.5 Mt 3.53 Mt 5.01 Mt % Fission 5 15 87 % Fusion 95 85 13 Nuclide Half life Abundance of nuclide in bomb fallout, atoms per bomb fission RI** Na-24 15 hours 0.0314 0.0109 0.00284 1284.7 Cr-51 27.2 days 0.0120 0.0017 0.00030 0.280 Mn-54 304 days 0.10 0.011 0.00053 0.614 Mn-56 2.58 hours 0.094 0.00053 2668 Fe-59 45.2 days 0.0033 0.00041 0.00017 6.19 Co-57 272 days 0.00224 0.0031 0.00018 0.113 Co-58 71 days 0.00193 0.0036 0.00029 3.11 Co-60 5.27 years 0.0087 0.00264 0.0008 1 0.299 Cu-64 12.8 hours 0.0278 0.0090 0.0023 89.5 Sb-122 2.75 days 0.219*** 38.4 Sb-124 60 days 0.073 *** 6.92 Ta-180 8.15 hours 0.038 0.0411 35.9 Ta-182 114 days 0.038 0.0326 0.01 2.67 Pb-203 52 hours 0.0993 0.050 0.000018 26.0 U-237 6.75 days 0.20 0.20 6.50 U-239 23.5 minutes 0.085 0.31 0.36 173 Np-239 56.4 hours 0.085 0.31 0.36 14.9*+% U-240 14.1 hours 0.005 0.09 0 (no gamma rays) Np-240 7.3 minutes 0.005 0.09 150 *Dr Terry Triffet and Philip D. LaRiviere, “Characterization of Fallout, Operation Redwing, Project 2.63,” U.S. Naval Radiological Defense Laboratory, 1961, report WT-1317, Table B.22. Data on U-238 capture nuclides is from USNRDL-466, Table 6, in combination with WT-1315, Table 4.1. **Triffet’s 1961 values for the gamma dose rate at | hour after burst at 3 ft above an infinite, smooth, uniformly contaminated plane, using an ideal measuring instrument with no shielding from the person holding the instrument, from 1 atom/fission of induced activity, (R/hr)/(fission kt/square stat mile). ***The Zuni bomb contained a lot of antimony (Sb), which melts at 903.7K and boils at 1650K. The abundances of Sb-122 and Sb-124 given in the table are for unfractionated cloud samples; because of the low boiling point of antimony, it was fractionated in close-in fallout, so the abundances of both Sb-122 and Sb-124 in the Zuni fallout at Bikini Lagoon were 8.7 times lower than the unfractionated cloud fallout. *+*Note that Np-239 at 1 hour after burst is still forming as the decay product of U-239. Figure 19: The low energy of gamma rays from Np-239 and U-237 in the first couple of weeks makes it easier to shield gamma from U-238 cased “dirty” weapons. The original anti-civil defense propaganda on fallout in the 1950s and 1960s originated from false claims about neutron induced activity affecting the decay rate of the fallout substantially for salted or cobalt-60 weapons, e.g. Shute’s novel On the Beach and the Kubrick film Dr Strangelove. But for each neutron used for the fission of U-238 you get 200 MeV of energy, including far more residual radioactivity energy than from capturing the neutron in cobalt-59 to produce cobalt-60. The smaller dose of gamma ray energy from the cobalt-60 gets spread over a longer period of time, producing smaller dose rates, enabling decontamination to wash the fallout away before a high dose is accumulated. FALLOUT PARTICLE Figure 20: At 1 metre height above a uniformly contaminated smooth, unobstructed surface, 90% of the gamma dose rate is from direct gamma rays and 10% is from air scatter. Some 50% of this gamma radiation dose is contributed by the fallout deposited beyond a radius of 15 metres, so the average angle of the gamma rays contributing most of the dose is almost horizontal. The air scattered gamma rays have a wide distribution of angles, and are not all coming down vertically, so some of them are also absorbed. This is why typically 90% (i.e. the direct gamma ray dose) is stopped in any below ground depression such as a narrow ditch or trench. The fallout directly under your feet contributes a negligible proportion to your dose, owing to the long range of gamma rays in air. Fallout directly under your feet contributes an insignificant percentage of the dose. Even if there is fallout blown into a house through blast shattered windows, the walls will continue to shield the major portion of the radiation dose, which is from the direct gamma rays from a wide area outdoors (Kearny, ORNL-5037). Spectrum of fission product gamma rays from the thermonuclear neutron fission of U-238 (Glenn R. Crocker, Radiation Properties of Fractionated Fallout; Predictions of Activities, Exposure Rates and Gamma Spectra for Selected Situations, U.S. Naval Radiological Defense Laboratory, USNRDL-TR-68-134, 27 June 1968, 287 pp.) Gamma Fission product gamma spectrum at | hour Fission product gamma spectrum at 1 week Tay Sr-89 abundance (relative to unfractionated fallout) Sr-89 abundance (relative to unfractionated fallout) energy, 10% 50% 100% 200% 10% 50% 100% 200% MeV Rgo95 = 0.1 Rgo.95 = 0.5 Rgo.95 = lies Rgo 95 = 2 Rgo 95 = 0.1 Rg 95 = 0.5 Rgo 95 = sa R995 =2 0-0.5 0.396 0.354 0.350 0.304 0.695 0.662 0.678 0.637 0.5-1 0.385 0.379 0.363 0.357 0.262 0.270 0.245 0.265 1-1.5 0.1605 0.1863 0.1914 0.232 0.01339 0.01358 0.01218 0.01273 1.5-2 0.0327 0.0466 0.0558 0.0596 0.0287 0.0519 0.0591 0.0790 2-2.5 0.01628 0.0203 0.0279 0.0290 0.001114 0.001313 0.001268 0.001445 2.5-3 0.00429 0.00717 0.01192 0.01305 0.001372 0.00253 0.00291 0.00388 3-3.5 0.00340 0.00301 0.00267 0.00273 0.0000260 0.0000490 0.0000564 0.0000760 3.5-4 0.001425 0.001187 0.001705 0.00214 0 0 0 0 Total: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Relative gamma 0.547 0.756 1 1.25 0.563 0.768 1 1.12 activity Mean energy, 0.710 0.767 0.807 0.856 0.444 0.486 0.483 0.526 MeV EFFECTS OF FRACTIONATION AND NEUTRON INDUCED ACTIVITY ON GAMMA RAY ENERGY OF FALLOUT Sources: Dr C. S. Cook, Health Physics, v4 (1960), pp42-51 Dr T. Triffet, Testimony in the U.S. Congressional Na-24 effect Hearings, Special Subcommittee on Radiation, bd Joint Committee on Atomic Energy, June 1959, "Biological and Environmental Effects of Nuclear War" Data points are Nal (Tl) gamma spectrometry es Unfractionated U-235, thermalized neutrons *, (DrC. F. Miller, USNRDL-TR-247, 1958) aN 95 km downwind ey, , from REDWING-TEWA é MeV/PHOTON from REDWING-TEWA Np-239 + U-237 (H-bombs with U-238 fusion charge pusher) 1 2 5 10 20 50 100 200 500 1,000 2,000 5,000 10,000 TIME (hr) PENETRATION OF UNFRACTIONATED U-235 FISSION PRODUCT GAMMA DOSE RATE IN CONCRETE NN Source: L. K. Donovan and A. B. Chilton, "Dose Attenuation Factors for Concrete Slab Shields Covered . N with Fallout, as a Function of Time after Fission", U.S. Naval Civil Engineering Lab, report R-137, 1961 , . O. (Uses spectra published by A. T. Nelms and J. W. Cooper in Health Physics, v1, 1959, pp427-41.) 10° CHILTON & SAUNDERS (1.0 MeV) 1072 10°3 2.11 DAYS 23.8 HRS ATTENUATION FACTOR 10-4 208 pays” 10°? 0) 0.5 1.0 1.5 2.0 2.5 3.0 THICKNESS OF CONCRETE (feet) Figure 21: fallout radiation protection factor calculations are traditionally made assuming the 1.25 MeV mean gamma ray energy of cobalt-60, not the wider spectrum of actual gamma rays from bomb fallout. This leads to substantial underestimates of protection factors which are smaller than 100. The effect of Np-239 and U-237 (which make a maximum percentage contribution to t'* fallout decay radiation at a time of 1.2/In2 = 1.73 times their respective half-lives of 56 hours and 6.8 days, i.e. 97 hours and 12 days, respectively) further softens the gamma ray spectrum, increasing the benefits of any shielding, as explained by Operation Redwing fallout characterization project officer Dr Terry Triffet to congress in June 1959. Dr Triffet at the 22-26 June 1959 Congressional Hearings on the Biological and Environmental Effects of Nuclear War pages 61-111 showed that at 1 week after burst, the mean gamma ray energy of fractionated fallout 8 statute miles downwind of a megaton range surface burst was 0.25 MeV, while at 60 statute miles downwind it was 0.35 MeV (due to less depletion of high energy fission products at greater distances, a fractionation effect). 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: “T 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 [i.e. in high fission devices employing U-238 ablative “pushers” or fusion capsule 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.” There is extensive data on the gamma ray spectrum of fallout from the Zuni, Tewa, Flathead and Navajo surface bursts in Table B.21 of Triffet and LaRiviere’s 1961 report Characterization of Fallout (WT-1317) and in Tables | and 2 of W. E. Thompson’s report Spectrometric Analysis of Gamma Radiation from Fallout from Operation Redwing (U. S. Naval Radiological Defense Laboratory technical report USNRDL-TR-146, 1957). For example, Thompson gives the detailed spectrum of gamma radiation measured on Bikini Island (codenamed How Island, fallout collector F-61, sample GA) at 13 miles east-north-east of ground zero for the 3.53 Mt 15% fission coral surface burst Zuni. At 10 days after this detonation, the mean gamma ray energy emitted by this sample was just 0.218 MeV. Since shielding thicknesses are roughly proportional to the square root of the gamma ray energy, shielding thicknesses needed for a given protection factor at this time were 2.4 times smaller than for cobalt-60 gamma radiation (1.25 MeV mean). Zuni fallout gamma ray spectrum measured at 10 days after detonation, 13 miles downwind (sample How F-61 GA)* Gamma ray energy (MeV) % of gamma rays emitted by fallout sample 0.060 15.5 0.105 38.8 0.220 19.4 0.280 9.3 0.330 3.8 0.500 3.9 0.650 3.1 0.750 6.2 Mean energy 0.218 MeV *W.E. Thompson, Spectrometric Analysis of Gamma Radiation from Fallout from Operation Redwing, U.S. Naval Radiological Defense Laboratory technical report USNRDL-TR-146, 29 April 1957, Tables 1 and 2. Note that this is the gamma ray spectrum actually measured for a fallout sample placed near the scintillation crystal of a gamma ray spectrometer, so it does not include the further reduction in gamma ray energy that occurs from Compton scattering in the atmosphere. Ocean water surface burst fallout is unfractionated so it emits slightly higher energy gamma rays. For example, R. L. Stetson’s report Operation Castle, Project 2.5a, Distribution and Intensity of Fallout, WT-915, 1956, on page 145 states that the measured mean gamma ray energy of a fallout sample from the 13.5 Mt 52% fission Castle-Yankee ocean surface burst was 0.344 MeV at 8 days after detonation. Nevertheless, this is still substantially less than the 1.25 MeV mean energy of the cobalt-60 gamma rays assumed in most protection factor calculations, and is only about half of the 0.7 MeV figure mentioned by Glasstone. (The Castle- Yankee U-238 neutron capture nuclide abundances are similar to those for Castle-Romeo in Figure 19 above.) Further reading on the effects of nuclear weapons Bridgman, Charles J., Introduction to the Physics of Nuclear Weapons Effects, DTRA, 2001. Dolan, Philip J., Capabilities of Nuclear Weapons, DNA-EM-1, 2 volumes, 1972, change | (1978), change 2 (1981). Glasstone, Samuel, and Philip J. Dolan, Effects of Nuclear Weapons, 3" ed., 1977. Northrop, John A., Handbook of Nuclear Weapon Effects: Calculational Tools Abstracted from DSWA’s Effects Manual One (EM-1), Defense Special Weapons Agency, 1996. Military Research and Development Subcommittee, Committee on Armed Services, Electromagnetic Pulse Threats to U. S. Military and Civilian Infrastructure, Published record of Congressional Hearings held on 7 October 1999. Special Subcommittee on Radiation, Joint Committee on Atomic Energy, Biological and Environmental Effects of Nuclear War, Published record of Congressional Hearings held from 22-26 June 1959. Special Subcommittee on Radiation, Joint Committee on Atomic Energy, Nature of Radioactive Fallout and Its Effects on Man, Published record of Congressional Hearings held from May-June 1957.