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Armed Forces Special Weapons Project, Weapons Effects Division, “Radioactive Fall-out Hazards from Surface Bursts of Very High Yield Nuclear Weapons,” by D.C Borg et al., Technical Analysis Report, AFSWP No. 507, May 1954, Excised copy (under declassification review), No classification marking

- 309070 TECHNICAL ANALYSIS REPCRT - AFSWP NO 507 RADIOACTIVE FALL-OU HAZARDS FROl StJRFACE BtBSTS OF VERY HIGH YIELD NUCLEAR WEAPONS r by D C Borg L D Gates T A • Gibson Jr R • W Paine Jr · WEAP ES EFFECTS DIVISICJf Tb is Al med Forces Speciel Wee pons P roJe t Technical Analysis Report 1s a sta t 'f' i t · prepared far the Chief AFSWP on a aubJect at militer y interest The conclUG1QJUJ l e modif'ied as nev data becaii e aTid l v ble MAY 1954 Tms' ARMED FCRCES SF l CUI am WASHINGTON l 3 1 D C PR OJlx T I CLASSIFICATION r ' ' ED 0 A QI l G_rJG ii 7 _ - _it I llf f TI · BY AUTHORiTY C · 1 tt ·- °II 1 1 0 -- 4rf- L- 11 BY - -f1 - - - _I_ - - - - - - D -- IC _ - - - - - - - · oa z 1 n -v-v t J R on I ABS T - This paper presents an interim analysis of the problem of radioactive f'al 1-out from the su -f'a ce detonation of very high yield nuclear weapons The problem 1s discussed in gen ral terms and the results of a specific analysis of' the CASTLE BRAVO event are presented The contours developed by this a nal ysis have been i al ized f'or the purpose of scaling these contours to other weapon yields and to other vind conditions than actually existed at CASTLE BRAVO d the manner or perlo 'ming this scaling is described Ex- amples or scaled contours f'at 1 10 15 and 6o megaton yields are given The p sible co'I U°ses or defensive action against large scale f'al 1-out are discussed including the relative advantages afiorded by evacuation of the area · and by seeking optimu ll shelter vi thin the area A ta 1 -ed summa -y precedes the body of the report ' ··• ii · l · SUM MARY The residual radiation hazax i resulting from the fal 1-out of r6dioactive particle generated ill the surface detonation of very yield nw lear · weapons bae been demonstrated in the current ' high CASTLE test series to involve vast ai-eas extending well beyond those a ff'ected by damaging blast and thermal effects Reconstruction of fall-out pa tterne from the CASTLE BRAVO event using the prelimina 7 data_a U-able at Hqs AFSWP leads to the conclusion that i and sur ace detonation of a 15 megaton yield weapon can be expected to deposit radioactive fall-out over an area o'f the order of 5 000 square miles 0 more in such intensities as to be hazardous to human Indeed if' no passive defense measures at all are taken this life figure probably represents the m nimum area within which nearly one - hundred P°-l cent fatalities mey be expected DOE ARCHiVES ' The location of the bulk ' 9f the hazard area with respect to ' grolllld ze o is dependent p ily upon wind direction and velocity s nd mey be expe ted to cover a roughly elliptical pattern extending downwind f' -am the 'burst point Figure A is an idealized representa- tion of how the total dose contours fran a 15 megaton land-surface burst with a J 5 knot ef'f'ectfv7 wind may appear at 50 hours after b Irst tiliie It will be seex that the area representing an accumu- 4ted le dose of 500 roentgeru extends abqut J 8o mil s d d i ' ' j and is at out 4o miles across at its widest point These cc ntours ere based directly upon survey data ta ken after the CASTLE BRAVO event 1 iii - 1 •· na A 'tOUL DOSE PIIUH nJ·IE or FALL 011'1' TO 1 $0 i _ I' - •-· '• u - -- Ir -- - --- r-- ___ I I t 5ooar -- 7SOOr - 2 oor- - - - -- V _l f - _ '----- - ---- '- Pt_ --- ----- r-- V' V i__--- -ic ot -- i - - -- - - r-- r---- r--- _ r---- ------ - l------ ' -- l-----' 1-- SO' - i---- -- - - ' - ' '1S IS ' ' o ZS SO - -- - -- ---- ----- ·•- Ii---- ·- - - • ··• ·-- - - ·--·•--lSQ ___ _ 1 -- --- zso 2 MIL pOEARCHlV t __ ___ - - ___ -- - - ·· -· l • ·- - J- ·· · - - - - _ •· r ··• · - • • • • • ··· - •· J _ ·- -- - ·- 27S 00 JS -- The approximate areas involved for dosages accnmulated up to 50 hours a -f ter shot time are as follows 1 000 square miles 2 000 roentgens '_ - 1 000 roentgens · 3 400 square mil es 500 roentgens 5 500 square miles 200 roentgens • 9 4oo square miles 1 00 roentgens • 13 000 _square miles In order to obtain estimates of contaminated areas which are probably involved for other yiel ds in the megaton range it is postulated that s c based upon simpl e conservation o material will probably not introduce serious errors for yiel ds between l and 60 mega tons using -1 5 megaton input data On this ba 3is one scales linear dimensions and contour values as the cube root of yiel d and areas as the two-thirds power of yiel d Scaling in this manner one obtains the following pproximate_ contour dimensions for a cumul ative dose of 500 roentgens in the first two days assuming a 15 knot effective wind Yield Contour Length miles lMr 52 12 Ji 70 l O Ml' 1 50 34 3 900 15 MT 180 4o 5 4oo 60 34o 70 18 000 MT Contour Width miles DOE ARCHIVES Contour Area s qua re miles It must be recognized that these vast danger areas apply to per onnel in the open unshielded by buildings or • even rough terrain ' •• - # · • _ V I · l The shielding aff'orded by an ordinary frame house may effectively reduce the size of the hazard ·areas by a factor of about tvo and a basement shelter by a factor of _ten or more I ' Virt• ia lly complete protection against the lethal effects of radioactive fall-out can be obtained if personnel ve protection equal to or better than that afforded by a simple underground shelter vith at least three feet of earth cover and if they ere evacuated after a veek or ten days in such a shelter One may draw the following conclusions from this analysis Very large areas of the order of 5 0CX square miles or a more ere ·likel y to be contaminated by the detonation of a 15 megaton yield weapon on land surface in such intensities as to be hazardous to human life · b The fact that a large percentage of the radiologically hazardous area v11l lie outside the range of destructive bomb effects for normal wind conditions extending _up to s eral hundred mll s down 4 makes the radiological fall-out hazard a primary anti-personnel effect DOE ARCHIVES c Accurate pre-shot prediction of the location of the hazard- ous area vith respect to the burst point is virtually _impossible vithout extensive wind data at _al titudes up to about 100 000 feet owing to the sensitive Wind-dependence of the distribution ·mechanism d _ The fall-out contaminant can be expected 't o decay at such · rate that all but the most highl y contaminat e d areas could be occup e - by pr vio l y unexposed personnel on a calculated ris t · · vi I l itllti ill I r · · ·· - · r -· c- - •• · · · · · '_ asis vithin a fev days a fter the contaminating ev nt d-·even these _ · · - _ ·J ····· · i - - - -···· -· - - _- · __ ' - - - - _- ·- · - -·· ·· · ·- · highly contaminated areas ma y then be entered briefl y by decontam •' • •c -- • - • • • ·1nation teams e Passive ·defeD Se measures inte J-igent applie can drasti- cally reduce the lethally hazardous areas A course of action involving the seeking of optimum shelter followed by evacuation of the contaminated area after a week or ten days ·appears to off_er At the distant downvind areas as much the best chance of survival as 5 to 10 hours after detonation time may be available to take J· · ·· I •• • • shelter before fall-out commences • Universal use of a · simply constructed deep underground f shelter a sub tunnel or the sub-basement of a large buil ding could eBm1nate the lethal hazard due to external radiation fyom fall-out completely if followed by evacuation from the area when - - bient radiation intensities have decayed to levels which will permi t this to be done safely g · It is of vital importance for individuals in hazardous ' areas to seek optimum shelter at once since the dosage received in the first few hours after fall-out bas commenced will exceed that received over the rest of a week spent in the contanil Da ted area vii f · TABLE OF C ONTEN'm Abstract ii 11 Summary List of Figures X Chapter I IN'IB CDtcTI C l • • • l Chapter II FALL-00'1' CONTOT RS FCR A 15 Mr LAND-SURFACE Blm ST · • · • · • A Decay of Gamma Dose Rate with Time B Idealized Downwind Fall-out Contours for l 5 MT l 3 C Idealized Ground Zero Fall-out Contours for a 15 MT Land-Surface Burst 17 Estimation of Actua1 Dose Received in the Fall-out Pattern • l 8 APPROXIMATE SCALING OF FALL- YJl' CONTOURS wrm YIEID • • • • • • • • • • • • 21 D Chapter III DOE A CHlVES A Method of Scal ing 21 B Assumed Contour Shapes for Scaling 24 C Appl icabilit of Contour Shapes · and Scaling D Basic Numerical Parameters to be Used in Scaling Isodose-rat Contours • • Z7 E Effect of Weapon Design Upon Fall-out Scaling · 29 F Scaling of Total Dose Contours • G Examples of Scaled Fall-out Contours viii • 25 30 32 TABLE OF CONTENTS ' continued DEFENSE AGAINST THE FALL-OOT HAZARD 34 A The Effect of Shelter · • • 37 B The Effect of Decontamination 40 c The Effect of Evacuation · • • Chapter IV D•· Recommendations as to Protective Measures 44 47 Chapter V CC lCLUSICl'lS · • • • • • QO p HJV ES 50 Ap pendix A Derivation of Radiation Damage Dose Formulae 52 References 54 ix LIST CF FIGURES Fig ·A Total Dose from Fall-out to H 50 hrs • 1 5 MT Fig 1 Gamma Dose Rate Decay Fig 2 Total Gamma Dose Fram l Hour Fig 3 Contour from CASTLE B'' Fig 4 Idealized Fall-out Contours 15 Mr Dose Rate Fig 5 GZ Contours 1 5 MT Land Fig 6 Idealized Fall-out Contours 1 5 MT Dose Rate with Total· Dose Overlay Fig 7 Idealized Local Contours for Residual Radiation Fig 8 Radius and Displacement of GZ Circl e 15 MT Fig 9 Downwinc L and Crosswind Axes of Downwind Pattern l 5 MT Fig 10 Area of Dose Rate Contours 1 5 MT Fig ll Areas of Fall-out for 50-hour Total Dose l 5 MT · Fig l 2 Scaling of Representative Idealized Fall-out Contours with Yiel d DOE ARCHIVES I X RADIOACTIVE FALL-OOT HAZARDS FR M SURFACE BURSTS OF 'VmY HIGH YIELD M£LEAR WEAPONS I INmCDUC ON O the eight nuclear weapons re devices which have been deton- · ated on the surf'ace by the U s up to this time only two have been · instrumented 1n sufficient detail to permit the construction o f radiation dose rate contours with reasonable accuracy The fall-out patterns f'rOl l the low-yield JANGLE-S event in Nevada 1 2 KT in · November 1951 were ccmpletely doeumented and _e stablished that a surface burst of a nue1ea weapon or device is potenti a highly contaminating event In November 1952 ·a l O Mr device was detonated on land-surface at Eniwetok in Operation IVY from which event onl J crosswind and upwind fall -out data vere obtained The vast downwind ocean areas over which the fall-out from such a large yield weapon occurs make a good' determination of the fall -out pattern almost an ' impossible task if' the shot is to be fired safely It ·was not lllltil the BRAVO event of the current CASTLE series that sufficient land DOE ARCHIVES areas dowm -1 nd were contaminated by a very high yield surface detonation to permit a reasonably accurate del ineation o f the fall-out pattern fran su h a shot The data obtained from surveys of these _ c ontaminated i s provides an invaluabl e tie-point ·t f _radiol ogical e f'fects even bas provided Just f gh-yie1 _veap s 1 - t e-poirit for l ow he scaling even as tJ ie JANGLE-S yield a ons In order to gain an llll derstand ing of the · nature of the ·f'al 1-out· • - • - • • • • · - V O - - problem one must recall that the availabl e gamma ·activity from the 1 detonation of a nuclear device is about 300 megacuries per kil ton yiel d at a time of one hour a -Pter the burst and that for a au -f'ace burst a large amount of this activity 20 to 8o per cent can be e ted to f out rlth ul ·contours ·enclosing radiation intensities · o£ military i lterest ' nt y deposited-depend e Just where · this activity is upon a grea ·ma ny ·f ors t most important of which is weather wind direction in particular other important factors are ·the form·and ·height · of the radioactive ·· cloud end the particle size dist ibution of ·radioacti e matter within cl01 w the These factors determine in a large measure the ultimate destination and the time of arrival on the ground of a given par- tib l e Within the bomb cloud DOE ARCHI VES One can obtain a fee1 far the radiation intensities involved frcm •the fact that one megaeurie of fission products per square m11e lmifarml y distributed over a flat surface produces a radiation intensity of about four roentgens per hour measured three feet above that surface I As an illustrative example if the roughly 150 _mega curies of activity at li l hou - that is pt to fa11 out from a 1-kiloton surface burst ia distributed uniformly over a one square mi1e ea the radiation tensity three feet above tl is surface at R l hour would be about 150 x 4 or 6oo roentgens per hour For mii f'Ol l l dis ibution of thia same activity CNer larger areas the radiation µitensity w® ld be reduced proportionatel y ' We see 'im- mediatezy that burst could by -the same _ - a 10 megaton stlrf'ace reasoning cover a l 0 1 000 square _mil e area With a radiation intensity of 600 roentgens ·perhQttr ·at a ref'erence ·time of B l holll if' unif'orm-d lstribution · of··the- contmotr ant over tbat ·area and a that time could·be assimted Fortunately this not the case einee · fall-out time · ma y -require ·f'ram-··one to · twenty or ·more-·hours over same parts of this · vast area during which time the ·radioactive particles still airborne are decaying and expending their • ' · I energy harmlessly in the atmosphere Also distribution is not uniform and sane relatively small areas are very heavily contaminated while much larger areas are lightly contaminated Never- theless very large supralethal contarn1 'ated areas can be expected to result trail such a detonation and the fact that u_p to 9'1fo or even more J this supralethal area can be outside the range of blast e nd thermal effects f'ran the· expl osion makes fall-out contamination a primary rather than a bonus effect for surt'ace-burst nuclear ooE ARCl•UV E S weapons Rather extensive and sanewbat camplex changes in the mechanism a f'al 1-out may be expected 1 r the weapon is burst on deep vate'r ' rather than on a land surface or again ' 1 r the weapon is burst on sbaJ l ow water over a cJ ay mud bottcm Far the deep vater case one would expect the contaminant to be distributed as a very fine aerosol mist and t hat as a result the lower dose rate contours vould be larger and the high dose_rate contours smal l e r than for- a corresponding burs t over a land-surface Conversely tor a burst over vet I cley mud much of' the contam1 nant is l ikely to be entrained in the 3 and could be expected to fall out l ocally resul tibg in J arge l ocal high dose rate contours and smaller l ow dose rate contours than for the ·dry l and case In each case however the same amount of contaminating activity is availabl e and onl y the distribution of this activity is l ikel y to vary to a ny great extent The rate of decay of the fission product contarn1 nant follows quite cl oaely the approx1Dm te exponential relationship I ltt-1 2 DOE ARCHIVES where I is the intensity at time t and k is a c onstant and can be taken as the dose rate at H l hour This · relation is useful f'or predicting the decay of' the · contam1nant in most cases for whieh there 1s no serious dilution of' the fission product contam1ua nt by I e ron-induced activity either in b components or·in· soil ·or other materials contacted by the fireball v- In same · cases however- the contribution to the residual activity by neutron-induced · contam 24 in ants such as Na · or Np 239 may equal ' or even exceed the fission product activity f'or brief' periods This introduces perturbations into the elope of the decay curve which may cause the exponent of t to va -y for brief periods of' time between -0 8 and -2 0 1n· general however the over-all deviation from the basic fission product decay slope of -1 2 is not expected to be very great over long periods o'f time This decay r te is such that the • intensity at one hour · 1s reduced by a _factor of ten by H 7 hours and by a f factor of • ' 100' afte two t J 4 · - da ys • 4 One can see f ran the number of variabl es involved that the fall- out probl em is in practice largely a non-definitive one An unex- ' ' pected and yet very possibl e c ge in any on of a ·number of these V iables can change the f'a1l -out picture radically However it is possible to define the extent of the dange r areas involved within rather broad limits for the 15 MT yield of the BRAVO event and to indicate the manner in · which corresponding danger eas can be predicted for other yields in the megaton range and for other wind conditions Magnitudes of areas involved are not likely to be al- tered great by changes in variables other than yield specific loca ions of these areas however are more uncertain It must be emphasized that detailed analysis of this problem is still in progress so that the material presented in this paper although the best that is currently avai1ab1e to the HQ AFSWP may later be subject to mod ii ication The importance of the problem is such as to make this presentation of an interim analysis desirable at this OE ARCHl '£ 5 JJ ' time This paper is limited to coverage of the immedi te short-term problem vhich is of paramount interest in military operations No consideration is given at this time to the long-te rm effects of external radiation upon longevity nor to internal radiation health hazards following inhalation or ingestion of radioactive materials t · •- i ' 5 ' ll FALL-OUT 1 0NTOt M FOR A 15 M1 ' LAND- StlR FACE BORST 'I he only true land-Stll face bu -st f'i red by the United States whose t rta l residual radiation cO tours mve the prese tt is the JANGLE s-urfece 2hot been adequately documented to However uncerta1 nties in the postulated mechanism of' f'al l-o- it eve i f'or small yield bursts and unknown variations between fall-out mechanisms f'or small yield and very la 'ge yield devices allov little confidence to be placed in scaling of data f'rom the 1 2 KT JANGLE experience up to the megaton re nge Consequently the e pproa ch followed in this paper bas been to analyze the date w iich constitutes fragmenta -y documentation of the CASTLE 1RAVO shot in the light of postulated f'all-out mechanisms and scaling relationships derived f'rom extensive study of JANGLE DOE ARCH1VES information CASTLE ERAVO was f'ired on the surf'ace of' a coral reef and IJ ve a yiel of approximately 15 MT Al though coral is not a typical soil ms terial nor is a water-level reef surface truly comparable to dry land this particular shot provided a unique oppcrtunity to gain t least pe rt i al documentation' of f'aJ J -out radiation ef'f'ects from a large yield weapon b st under conditions at least approximating a land-surface detonation T n is is so because at least a portion of' the downwind fall-out pattern from this shot covered several atolls and isl ands thus e o abling radiological surveying and fall-out sampling to be carried out This cannot be accomplished with compar able effectiveness in the ca Be of over-water fall-out which characterized the other large yield shots of the CASTLE and IVY test series 6 - Furthermore 1 le ·other high yield detonations of the CASTLE operation were w t r-surface bursts barges whereas th IVY MIKE shot althou gi a land-surface burst lacked downYind fall-out documentation Since fall out contours depend in large measure upon the active particle eize distribution and since this distribution in turn is related' to the nature of the surface materials contacted by the fireball _CASTLE IRAVO might not be expected to behave exactly as a f typical land-surface burst on other than coral sand However the fall-out pattern f'rom a contaminating nuclear burst is essentially lmi ue _for that particular detonation depending very strongly on the particular meteorological conditions existing at the time so that-only an approximate generalization o f fall-out patterns and areas is being attempted in this paper Furthermore very preliminary data to date suggest that the magnitude and extent o f the dOWilW'ind fall-out pattern nay not be overly dependent upon the type of' surface involved For these reasons CASTLE IRA VO will be utilized as a representative -eur face shot at approximately 15 Mr for purposes o f d wnwind · fall-out scaling in this report DOE ARCHIVES i Residual radiation effects in the immediate upwind and crosswind vicinity o f ground zero appear to be more highly dependent upon the rapid fall-out of' relatively large particulate material from the turbulent mushroom cloud and upper stem Since the amount of' rela- tively large particulate _material is vastly decreased in water-sur face shots it is possible that the fall-out effects about the ground zero I 7 -- regio are more sensitive to the type of' surface involved than ·are the fall-out · effects far dmrnwind Since· the CASTIJi BRAVO shot may be_ cha racterized as a h _vbrid between a land-surface ·and a water-surface shot probably most like the former its· ground zero radiation ·data may not be very representative of' a true land-surface detonation For this ·reason the · IVY MIKE shot bas been used as · tlie primary soorce of' data for sea ling of' radiation ef'f'ects in the ground zero region IVY MIKE was detonated at approximately 10 Ml' at the tip of an island on a coral reef ' T n e downwind fall-out contours constructed for CASTLE BRAVO were based essentially' upon survey data taken on the isl ands involved in the fall-out region Re ference 2 After construction of con- tours based on this approach predictecl fall-out contours based on meteorological data from R H Maynard verbal communication were then compared and ·minor adjustments were made to maintain consistency wi both approaches Since the CASTLE BRAVO survey data consisted of a considerable number of ·di f ferent dose rate surveys taken at different times the 1 various data bad to be normalized to some reference time before do-wnwind dose rate contours could be constructed For this purpose · · consideration bad to be given to the decay characteristics· of' the residual gamma radiation A -Decay of Gamma Dose Rate with Time · In general DOE ARCHIVES gamma radiation from fission prod ucts · is said to de y - t -1 2 · This analytical representation permits easy 8 ma lipula tio i of data but it provides only a statistical fit to the best data It would not be applicable to ·the decay of dose rate gamma in a field sitnation if during fall-out there were · considerable fractionation of the various •fission p rodticts vith distance or ·if there were considerable in situ ·phyeical decay due to veatheri Dg · ef'fecte or if' · there vere considerable radiation from ·n eutron induced DOE ARCH VES radioactivity ' Preliminary collected evidence to date bas not suggested important fission product fractionation with distance at CASTLE Al so the weath r during the two weeks following BRAVO shot was dry Vi th little or no rain and fairly large islands_· probably show little change in average gamma dose rate due to the ef'fect o f ordinary trade winds ' Indu ed activities on the other hand probablyvere quite important in this shot as i sugge ted by the ked parlure from t-l- 2 decay measured for samples o f fall-out m aterial followed in the laboratory and 'also measured with f'all-out time-intensity dose-rate meters in the field The importance of induced actj vitiea is f'urther s1Jggested by preliminary radiochemical analyses and cloud samples PreJiminary radiochemical data from cloud samples taken by AFOAT l Dr_ W D Urry - verbal co ication were used to determine ratios of various neutron induced activities to the number of' fissions occu -ring in BRAVO shot A ratio of the most important of these activities Neptunium 239 was checked with data reported orally from R • W Spence of I ASL 9 -· El Theil t knowing the characteristic decay times of the radio - 11 l'Clid es l d m d a£signi ng an appropriate gamma energy per decay ' the gamms em -ssioi1 o t e neutrcn induced activity was plot ed against time v Since this has bee n - one previously for fission fragments by Rei man Ref'ere lce 5 the relative gamma activities from induced com- ponenta ann· from f'issi n prod ucts themselves were then plotted together aga illst time and· the resu l B -were added · to give total fall-out gamma activity ·aga illst time This · is seen in ·Fig l ·where the activities are ton nalized to_ l r hr at one hour H l - DOE ARCHIVES This total ectivity c- irve may then be compared -with a total activity p ed icted by t-1 • 2 d ecay s ented by tvo curves Ol In Fig 1 t-1 2 decay is r pre- normalized to the culated total decay ' at l l hr a d the other iorma 1 ized at H 2-4-0 hr • This latter time represen s the pproxi ma ti me tha i the majority of the surveys used in e sta olishing the BRAVO fall-out patterns were ma de and this t-1 • 2 rrve - m y be te Illed the nomi la l t-1 2 decay for use vith contours resentec m this papc - It can be seen that at l east during times o- f greatest i l'ti est less hall 1000 hours the nominal and calculated ctivities are with approximately 2'71 o f each other i e tne -1 culat ed cu -ve ' pred icts activities at H l that are only SI o-r those ·predicted by extrapolation o f the omi la l curve Because of the_n n1ch greater ease with which it can be maniFW B ted the nominal C' lr l'e can probably be used with reasonable accuracy to rep'resen-c the ga mms _activity cf fall out material when' the curve is 10 1 normalized to data messured at apprm illa-taly two days or at about one to one and one-half weeks Whichevez- decay cu -ve iS U Sed it can be seen from Fig 1 ·that the gamms dose- rate is most mte ns-e in the N rst few hours and decays most ra id ly at early times Between ne hour and seven hours the intensity· fa J s aoout -te t 1 m s 0 A f'ter- tvo veeks however more than 8o days are required or another tenrold d ecrease in dose rate Actually conversion of' gamma activity curves to gamma dose rate over a wide area of f'all--out· is not exact because gamma _dose rate depends upon actual photon er ergy as veil as upon total gamma energy emitted per radioactive disintegration • Decs y schemes for many impor- tant miclides involved in 't be f'al l-out gamma · radiation are not known and even when known their ccnversion to g amma dose rate over a Yide contami Dated plane is laborious 2ee AFSWP 502A • In all probability' the calculated gamma activity veroua time presents a reasonably accur' ate p icture of the gamma dose re te in the f'all-out field against time and it rill be so used in this paper Ill Fig 2 the doae a te decay Clll ve s of' Fig l are integrated with time From th is figure total ntegrs ted dose betveen any two times after H l hr may be determined The suggested method is to subtract · the dose at the earlier t f'rcm the dose at the later time Emd then multiply by the dose ate at E l hr DOE ARC HV ES If the proble n vere to utilize the t-1 •2 decay assumption to determine the total dose bet- reen three days and seven days at a location where the dose rs t-e at H l was calculated to ' be the solution coul d be foULd by the ·suggested mE thod as folla vs ll hr From the t-l 2 de y C1lI' 7e 'J'f Fig 2 the dose at 168 hours the e cse t ' 2 - l e sves dose rs t a 1 0 34r Multiplied 3 20r less by the nominal EH c OOi- br _ tlas -would give an 5 llSlM-er of' ·68r to the problem Ir s s imilar a an icn the calculated curve of' Fig 2 might be u-tilized whe he t r la dose teat R l is known i' e 7E JI of the nomi I al dose rate a t li l as determined from ·fig 1 ··rt that i l the w-orst possible case an error of' the order of appears 35i might · C • • - - - be i ltrcduced by utilizing nominal H l dose rates vith t-1- 2 decay rather tba -utilizi lg trae B 1 dose rates with the calculated decay curve 'l e· oom l t-i 2 meth0d is theref'ore probably sui'ficiently accurate f'cr ptu s es of - his rum J ysis Because of' its greater ease _ of'_mazdpulatio it ig _reco mm c- cd ed for general application vith the isodcse-rate ·cC li ou --a presented in this paper For greater ease of'· analysis by hs ' l O t-1 2 method isodose rate contours presented in tt e figures of his repo are labeled dose rates o 8 with their nomiral H•l DOE ARCHIVES 28 time _th true' Rt-l dose rates T' le · g 2 e -al application o f Fis 1 and 2 should be noted In ·• the - onstruction of t he calcula ted decay e_ in Fig 1 Np 39 and fission prod 1 c s w--s re f ou d t p vide by f'ar the most important ccntributio ns to th total activi • therefore apply to all ases whe-e TED E suma bly Fi l _ and 2 should oa ETED f 'actiona-tion o f the fall-out sample is l - · t 3 1 08 ' 3 not severe · ED ' he actual sur rey ds -5 i' ' m CAS EF_ VO ' res assembled and correc ed to a refe -ence II e yf 3 -1 s e cording· to the nominal t-l 2 decay noted in Per- A 2s mhers were then -ulaced in their proper locations one map f' the fall-out area and con ours were drawn as shown_in Fig 3 The ta relied 1 Ipon most heavily for this pu -pose were he sury ys take f -cm s pproximately seven to eleven days folloving shot time Ref'er ce 2 - Tb rouge each a toll a gradisr t co- ild be· placed indicating increas- gradie1 ts made in this f -E li 0 1 - -those ew islands from which data were available Ou gb cc t ur lb- s ' er omil al li'f'l hr dose rates could be d i -awn It was S t n ci t e abEence o f arry data points on the ncr hern side of t s fall J' lt 'tter · that a rough symmetry existed 8 ld the o i ou - gr-aa i s there f'ore were· duplicated on the DOE ARCHIVES ·• d e-termined fr m the within data 3 t b a i migpt have been at any distance a f'ev miles to tl e 1 0rt · ·- f the islands in lved in the pattern In an ef'f'ort to be conserva tiv i drawi lg t areas of' the dose rate contours the maximum c ose te re s assumed to have been del i-vered just slightly north c f the meaeured points on the islands In this fashion the center line of tlie fall-out pattern ran very c t o e the northern · aspects of · he ic s d s and the reSllltant · fall-out con- tours were drawn as narrov try on the S the d 9 ta would permit assuming symme- n or ther i a i d scu tl er sides of the center line A later comparison of this port ion of the contours with predictions o-£ i'al l out based on metE 0rological data suggested that -the highest dose contours might h9 ve been farther north of the islands th a vas dn wn in the overlays is would bave resuited in a more northerly position of the ceter line of the f'all- ou pattern and a coi sequen1 increase in the v1a th a ud thus in the areas of the down- wind ontour zones Thus -the I € teorological data est tha the contours ai drawn from the r c L logical wrvey inf' rma tion may be 3om ewb a t Fl irthsrm --re -th fr downwind extent of the lower conservative d se contour ms poorly -icc1 m ted by ca ta avail able AB a further conservative approach_ the ntours were cl sed off in distance as short as tiJaS consistent tt e 6ne or -tlro su -Yey points available ' ilth J OE ARCHIVES for do- mvind d ista ces The resu lte tt 1 eru i S 1 11 li l do se rate contours that were drawn are inilcated ill Fig 3 overl s y several a tqlls on It -dll be noted that the contour l ines 1ou mern _s ide ot the pattern It is at these points that the cntour lines are most firmly pegged It can be seen that the fa dOW W'ind extent of the contours is d ocumented only by the re a di ga ' -om Bikar Atoll and Utirik 14 The data on fall-out re diation in ±e 1lmlled iate vicinity cf ground zero were scanty on tlie ER l VO ' hot s i the dcwmrind fsll-out contours are -not closed about ground zero The areas of the d - ' d cc nto1 1r zones a re measured by planimetry ------- ' · Do€ 1 3 OOJ TED --·---- This is f'elt t-o be reasonable figure izJ the light of f'all-out mechanisms as pr e l tly 1 m d erstocd but it also allows some what larger CO l tOU rS to b co istr 1ctsa - ri f hout dema I ding able amount of' deposited fi siGn produ c't noted the contours a s cL-a w- i B ' Ytill 'De an unre0 son- Acc-ord ingly as previously thought of as co ervative iri th e t they are probably -D15 U er th a those ba actually existed bOE ARCHIVES a t BRAVO It hould _be noted - '3 t ·si J ce in ac-tual fact f'all-out does not con mence at distances down- r'- lii -' llltil several hours have_ elapsed e nominal H l dose rate cc t ours shmm i l Fig 3 do not actually exist 15 --- as such at tbat time • would The dose rates· at the time of' actoal fall-out be lower than indicated- on the figure and could be e d from Fig 1 for each approp1iate time of fall-out along the downwind pattern The H l hr dose rate contours · d o serve as reference con- tours for dose rate and integrated -dose calculations however and thus they are presented in that form Al ougb the weather data from BRAVO indicate that viDd velocities were such as to result in a very narrow fall-out band downwind with • I less wind shear of the mushroom cloud and stem than would be expected with average weather conditions and that there was a superimposed fall-out f'rom the stem and the mushroom the contours ·may still be ·ta1ten as reasonably representative of a land-surface shot o f 15 MT The effect of a greater wind_ shear would be to broaden the area of the faJ 1-out pattern and to reduce some'Wbat the intensity of the isodose lines • However · as previously noted the contours as •drawn are somewbat conservative and narrow based on data from BRAVO and consequently they may be taken as reasonably representative for scaling purposes DOE ARCHIVES In ''order to eralize the contours from BRAVO for scaling purposes an effective vind is assumed A single hypothetical line of wind flow is assumed which gives rise to the fall-out pattern most nearly like that which in fact occurs This hypothetical wind flow is then straightened out in the major downwind direction where it can be represented by a single wind of constant velocity the 16 - so-ca 11 ed e f 'f'ective vind 11 • This is not realistic in fact but since lo meteorology is too varmble to treat analyti in a- genetal case this approach permits idealized contour shapes to be drawn If an effective wind is assumed for BRAVO the effect is to straighten out the contour liDes · of Fig 3 about a single effective wind vector 1 This results in contours as shown in Fig 4 and it is these general- ized con tours that can be conveniently used 'for scaling purposes C Idealized Ground Zero Fall-out Contours for a 15 MI' La' nd-Surf'a ce Burst ' As previously noted the best data concerning residual radiation levels in the vic ty 1 ground zero derive from IVY Here reasooably good crosswind fall-9ut data and same upwind data in the region of ground zero were collected from lagoon and island stations by USNRDL ese have been compiled and analyzed in WT-615 and from this they_have been smoothed for general sca -ing purposes by AFSWP Reference 3 In general the IVY data are consis ent with the qualitative results of Operation JANGLE and using the scaling method · to be outlined in Chapter III of this paper the quantitative comparison is also good DOE ARCI_iiVES Accordingly the scaling method of Chapter II bas b en utilized to scale the smoothed IVY MIKE ta to 15· MT I The general pattern of nominal' ' H l dose-rate cont s about ground zero can then be drawn 1 or 15 MI' This is shown in Fig 5 Fig 5 is then comparable to Fig 4 for _the ·downwind fall-out pattern except that the scale is diff erent 17 - - - •- I d _ · ' --- Some uncertainty rema ins ill the use of ·Fig 5 -to - e _e nt the idealized gronnd· zero contours because the fragmentary data taken near ground zero on BRAVO do not imilcate s s extensive a fall-out pattern about the detonation site as -was seen with IVY MIKE Although the earth surface compositio was not identical in the two cases p 8 the· dif f'ere nce' ma y not have been su t' t'icient to account for the variation in the ground zero contours It 1s possible that varia tions 9 t' this order in the groUild zero pattern will be encountered • cbaracteristical1y with land-surface detonatiollf3 DOE ARCHIVES D • Estima tiori of' Actual Dose Received in the Fal 1 -out Pattern 'As noted in Part B of this chapter the nominal H•l i sodose-rate contours are very desirable for basic reference purposes but they lack physical meani lg In order to estimate actual radiation dose received during some interval after burst time the time ot actual fall-out must be taken into account For CASTLE BRAVO an ef'fective - wind of about 15 knots TiaY be shown to give a reasonable f'it Yi th the estimated or measured time o f' fa ll--out at various distances downwind This is based on the assumption that the time of' t'al 1-out can be taken roughly as downw i ld distance divided by f'ective vi d · velocity Since the rapid lateral spread of the mushroom cloud at early times re ts •in a fall-out particle source of' f'inite v0lum e perhaps 6o-70 miles in diameter or a 15 MT lal rl -sur t'ace burst some fall-out will begin at earlier times than predicted by the above approach but by the same token f'al 1-out will continue over an appreciable time 18 so - the ei' 'ectiv time of f'all out for purposee of i ltegratillg dose may _be essc sb 7 represented in this ·simple vay Wh this a pprqach is t Omparec ilitb best estimated t s 'Jf fall-out for EF AvO where actual rl d s ears did eXist- d no effective Vind si mplif' icaticn V3 S usad hS l the fcllowir g c- ompa riscn c i l be· ma cie Table T Time of Fall-out Arrival fer BRAVO Distance downwi d mi 15 46 74 10 148 210 27 0 310 30 Estimated el l- ' Ut tillls hr l 4 6 7 f- 13 15 18¼ 20 Distance effective 15 knot vino l 3 4 6 9 12 15 18 19 These times a re der Yed 'rom ac ua l observ-a ticn the eference times f'or which ' are net well standardized In order tc estimate dose it is only iecesea ry o ·s pply the method of Part A isi Dg Figs 2 plus 3 4 or 5 · Dose may be estimated from f'all-out or from some e rbitre - oy -time of entry to i finity or to 3ome other time of' i i erest To do this one goes to Fig 2 to determine the dose received over -the period of' interest which ' IlB Y begin with f'all-out as found i i Table I at a position where the nn6mi I al H-tl dose rate is 1 b r Then Fig 3 h or 5 Ill9 Y be used to determine the actual iominal dose ' te at l l and t 1e fi nB l tnswer is found as in DOE ARCHIVES the example on pages ll B lld 12 An example of hew this method IIBY 'be used to c nstruct actual total dose contours at an e rbitrary reference time bas been worked out using 19 I F g 3 and Table I H 50 hrs -was selected as a reference time of some ertinence because by that time all parts of' the dowmrind fall-out pattern have •had sufficient time to accumulate sigz if_ica lt io ages · and yet the poorly evaluated · eff'ects of biological rec very fr Il re d ia ticn damage have not yet become important in alteri lg the criteria of radiation response from the acute dose situatio vhere they are knm -n vith greatest confidence see _Chapter IV Further more although infinite residence vithin a fall-out pattern is not a realistic assumption neither is evacuation in a few hours a valid 'c onsideration to apply to large population within a vs at contaminated are end 50 hours although an arbitrar figure is of' real interest in this regard For illustrative purposes however the fall-out-to-B t50 hr dose contours vill serve to demoilStrate that because fa l l- Ut occura at later· times downwind than it does near ground zero the effect on the shape o the total dose contours is to make them shorter than iscdoserate contours wider at the head end and narrower a t the downwind end Th is is because fall-out-to-reference time is a longer inte -- ral close-in than it is far-out resulting i l 10 1 ger mtegr l ticns cf d se rate vith time -at the near portion of any given -is6dose-rate c ntour than at the downwind portion An ex ample of the rela tiv shapes· cf isodose az fi isodose-rate contours f'rom fall-o t is seen in Fig A 8 ld alao · in Fig 6 where isodose contours frOl Il fall-out to ni50 hrs are superimposed on the isodose-rate contours of' Fig 4 DOE ARCHIVES - It can readily be seen tbat isodose contours for any time interval commencing after all fall-out is completed will_be of the same shape as the isodose-rate contours 20 III APPROX MATE S C OF FALL-CUT CCNJ lRS WITH 7 EL It has been pointed out that fall-out cntou -s -f rr co r tam- inating burst are highly dependent t 'J on 9 Jllb e lt o idi -o c ha re c t erizing the detonation At the same ti ne the ase' tllpt on of 8 l effective vi d permits generalization _of fall-out conto J c 'that i l all probabilitJ will not d if' 'er 'Widely f'ram he set ntBllU na tion pattern in any given case and the icealized'' p-a i te i ilovs re9 Sonable expectations er£ area and extent of residual r13 ilat on · eti ect to be made far plann1ng purposes It is dgh l ·iesi 'e ble to generalize one step further ii' possible ao that vai les of fall -out contour parameters derived fran an experien e at a f xed yield and associated with a given ef e tive Yind - r a y e ca led to other yields and possibl r to other ·eff'ecti• -e -rlr ds i a llcwa at least a ua J itative adjustment 1n the genera l zed· 3 l J -o t patte -n s to be made for actual variations in ambient rinds A POE·ARCHlVf S Method cr£ Scaling Perhaps the most promising methca or sce li g ge ertlized contamination patterns presently availB b e s that de1•e cped b ' · U3NRDL Reference ·4 This method is based esse tial y on f 1ve prilllary assumptions· · all of which s re consonan rlth -ia i l gathered · f' am actual experience l The total ·a mount of f'all-out -ad ioactiv ity· 9 eeent m the cloud is dependent on yield or more icule r on total fission yield 21 2 The height and linear dimensi ns of the cloud both s - s l e in the same way with yield 3 For s given soil the relative size i ztrib t on c'f - -adioactive particles is independent of yield · 4 The relative spatial distribut on o'£ a ct e pe rt cles of rmy given size 1s independent of yieid 5 The rate of fall-out of active particles d epen e cmJ y on particle size The al titude 1 rcm which fall-out commences may also be important for large particles which f'all according to aerod ynamic I • princ ples i e particles with diameter greater than 250 microns From these sumptions certain general scs ling laws may be ·derived 1 For a constant effective wino linear pa smeter- e o isodose-rate contours scal e as yiel d to a n exponential 0Il3tant i e w8° and the dose-rate hi tensity of a given contom- silllultan eoua1y seal es in the same fashion lf w29- seen to scal e as Fram this contour ares a can be Tb is scaling preee rves contour ata pes ·nth changes in yield DOE ARCHIVES 2 · At cons ant yield experience with m aes faJ 1-o J t fran high explosive tests show total · area within a given_ ontcur o be q'Uite in sensitive to changes n e f' fective wind Thus if the downrtnd extent of a given contour seal es as wind velocity to an expc stial constant 1 e tr' then the crosswind extent of the a me contour -b s al es inversely 1 e U • This results n l ongei- and narrower contours with higher e f'f'ective winds 22 · Since a basic aim of the NRDL scaling method s to pree e · ' mate rial balance and thus -to retain eqttivalent f'ractions of'·tota fission product yie-1d within a ·given all-out contou - at ail n el ds • J the exponential constant a in the above acaling eqilB tions I a aet at 1 3 Analyses of bc mb cl cuds B ld -e d a tion tall-out con tours at JMULE the cloud and radiation contours ne9 ' grol md zero from IVY MIKE and ma e fal 1-out contours f'rom HE tests iuggest that the exponential constant b also JD8'1 be taken as -1 3 Th J s resul ts in the scaling laws for fal 1-out radiation contOUl s that will be 'tlSed in DOEARCHlV this paper namely • 1 At constant ef'fective wind velocity linear pa ramets s at isodose-rate contours scale as the cube root of yield actually as the cube root of fission yiel d ' and areas scaie as - be tvo-t h1-ds power of yiel d At the same time the isod ose-rate ntensitie o the respective contours scale _al so as the cube root of y1e1d 2 At constant yiel d areas within isodose-rate c ontou -s probably remain constant but dowmd nd extent varies as the 'Ube root of vind vel ocity and crossWind extent va - j es nve eely 8 the cube root of wind velocity For winds less about i ive I ota dimensions became dependent upon 111aX i mum cloud growth but e 'fect ve rlnds lees than five knots will not be seen -eal ieti 'With high yield devices whose clouds ascend to great al tituc e The scaling described in 2 ·above depe of coure e on variations n ef'fective wind only 23 The effect of actual · wind shea s will be reflected somewhat in the effective wind but considerable shearing probably will increase · areas or low iscd ose-ra te contours and decrease areas at high isodose-rate contours n a _m anner th at cannot be · easily · represented · As a n example of the use at these scaling laws suppose that a I given iscdcse rate contol U from an 8 efi ective wil d reads 100 extent is 116 miles r M ' sl U fs ce burst with a 15 knot normalized to R 1 and· ta dowmrtnd Find the downwind extent of the scaled contour and its ·scaled intensity for a 1 MT burst with a 30 knot effective wind 1 3 The downwind extent at the 1 MT contour is - ft 1 mi with a 15 x ll 6 58 knot wind 2 ·The ace J ed intensity at the 1 MT contol U ie 1 ft 3 x ioo · 50 r br at R l 3 The dmmwind extent at the l Ml' contol U with a 30 knot 1 e ective wind 1s ij 3 ·x 58 73 mi Thus the scaled contour bas an intensity of 50 r hr at 11 1 and eJCi ends 73 miles downwind B Assumed Contour ShapeQ far Scaling 'DOE A RCHlVE S Fram bot JANGLE end high explosive experience NRDL generalized a conto't l shape for fall -out patterns based upori the ttective rf d con ept About ground zero is a so-called '' grOlmd zero cir le •· GZ circle formed soon after the detonation · f'l om rapid fill-out of relatively ls rge particl es It can be defined by its ra di s and by the downwind displacement of its center from GZ as - an be seen in Fig 7 The downvind pattern of fall-out proper can be defined · 24 I by · ta iO'WJl'Wind extent major axis and its crosswi id extent minor axis althm' gi '1 the downwind ext t must prope '1 y be· i crrected for • vind she n s rr 1 actaal case Ae noted n Part C af Chapter II j and n Fig 5 he IVY MIKE falJ -ou 5 ata an be seen to be generally consistent in the _reg on near GZ 1o -it l the contour shapes predi-cted by the NRDL ''GZ _circler C onsequ entl y 1 t a wee rs varranted to utilize the NRDL · ''GZ ci ' le '' to acterize the generalized faJ l-out contours f'l-o m very large yiel d surface bu -sts Aa seen in Figs • 3 and 4 the CASTLE ERAVO d ownwi ld iaodo se- ra te Cn'tours · are not trul elliptical in shape as they a re dra -n Rmrever f' ram Part A · of Chapter II it can be seen that the exact s pes ot the iownwind portions of the contours a re aomevha t · arbitrary f' Jrther it must be re alJ ed that the conto s awn have been idealized about an effective wind AJ so ' if the dcwn- wi ld extent of_the patterns as drawn is ' aken as the major axis of an ellip 9e d the crosswind extent i 3 taken 9 S he mil or -axis he the 'l l ea of the comparable ellipse ge e ally i3 ess tDS l l5j greater than th e area of the actual sodoae-rate contcur3 as d own-w-• nd el ip-tical ap p rorllila tion ta gene s l z ed · -epr·e sentatio i o d ovnY i d fall-out even for large yield -ietons ticns • c Ap pllca bi lity of Contour Shapes and Scal ng bOE t CHlVE S ·-· --- --· It is ll Ip tant to bear 1n mind tbf -t the - onto U shapes and scaling discussed n •this paper apply only to sttr face bursts and 25 primarily to la nd-surf'ace bursts As discussed earlier w ter- surf'ace bursts may scale s0111ewha t ditteren and in particular the ''GZ circle'' portion of the idealized general scaling contour may be much smaller and may be displaced farther downwind than is the case With land surfaces At present no definitive data is available regarding thi effe t Underground bursts mey scale in a fashion sim11 a r to landsurface shots but the parameters of the basic contours will be different True underground bursts of very large yield weapons are not apt to be encountered operationally however hence no f'm-ther discussion of that situation will be attempted here DOE ARCHIVES True air b'l ll'sts where the fireball radius does not intersect the ea rth 1 s surface rtµ not _produce significant local fall-out areas of high intensity However where air bursts are detonated at such alt tudes that the e is considerable intersection of the f'u-eball with the ground the a situation intermediate between a ''true'' air burst and the land-sur f'ace burst discussed in this · pa per will obtain As a rough rule of thumb it may be estilDa ted that the fraction of total fission products that will fall out Vi thin the local radiation contamination contours will be· about equal to the f'raction of fireball subtended by the surface In the case of bursts exact · at the earth's surface this would be about 5 of the fission prod ts whi ch is in agreement with the rough calculation obtained f'ram the CASTLE IRA VO contours in Part A Chapter II In res lity the fireball diameter o -- -7ea-oon s Yith yields i the - megaton ra ge ia so great that even b a tired at several l mnr -ed eat y i e Hs • sn probabl y be thought · of' as a' lti'ace ours to -om the il c 9 tionE hat because of diminution of blast pressure£ at the er i Illbi t pressures associated 'With even moderate acs 1 e heights · o-f bm-a-c ta super weapons even 1 ov blast overpressures mAY be max i mi zed b y aurface bursts in the case of ·re y la ge yie da Con- sequent sur f e bursts of -weapons o r megaton yields · i ay be the noot iestte b Le ·situation in many o peratiomu s ses and n such ins a nce5 the idealized fal L-out contom-s presented in th • a paper ' vo il be di -e t appl cable D DOE _A RCiiiV E5 Bssic N'Uiller cal Parameters · to be Uaed in Sctli lg Isc ioae-rate Con tour 3 • Pa t 3 crf - his chapter is roba bl y the most valid -ei e en e on-t our u scaling· in the megaton yield -ange t tlll be ecal ed that tia atte ---n utilizes CASTLE BRAVO data fo - i a down ind fo ' l Se e 11 ee and IVY MIKE data -ror its GZ c ' le radi' S The ic- mw'_nd disp1 ement o s e GZ circle a mi no pars r -eter is scaled xp J AJ 'tJLE •·s •· by· - he nethod c f Part A of this hapter It ig ftom sea led Oa J 1ED · ------- because thia particular parameter appears dependent primarily upon cloud heights and dimensions · rather than upon total am01 m c --- ------ ---- f' sion which is the most critical variable for the scaling of the other contour parameters Basic JANGLE data is generally disregarded in deten cinir g - he n'UZ le -ic al values of parameters for contours in the Yf r'Y high yield -ange Very lov dose-rate contours from JANGLE are avail 9 ble with J ess confidence in their accuracy than for the higher dose-rate ' • I contours since they are based on air survey da yet they are important in scaling to moderate dose-rate contours at high yields Furthermore the mechanisms of falJ -out at low yiel ds JANGLE 1 2 K r and at high yields ma be sufficiently different so that scaling idealized JANGLE data aver a yield range of gre a ter than 1 000 times may be unsatisfactory JANGLE In fact the actual sc9 ling of da ca results in high D 3 ' dose-rate contours that are too short and as much as 10 times too small in area when compared with the results shown in Fig 3 or 4 and only at H l hour is ose-rate contours belov about 2 'JJ r hr do the two predictions agree closely 'DOE ARCHIV ES For the abQVe reasons basic numerical paramete -s d e ived am mare detailed contour charts of the same types as Figs 3 4- snd 5 have been utilized far refe ence numbers in this 8 and 9 these pape In Figs line parameters are presented graphically Thes e figures may be used to scale idealized iscxlose-rate contours ' _ normalized to H l hour of the type of Fig 7 for yields in tp e meg ton range and abave 28 In Fig 1 0 the areas vi thin the downwind on tours cOl ' esponding to the llne U parameters 'l isted 1n Figs· 8 and 9 are pres ed The onto u-s but a s discussed in Part B of this chspter hey ere 1n most eses less than 15'1 amallerthan the areas predi ted by assuming the dovzr ud d C oaswind extent of the O ltotr s to be equ valent to t e 118 jO ' and minor axes respectiYely of 9 l ellii se This is a ' small err vhen compared with the over-all ac Ul acy of the idealized contour ecal ng method • Jt should be noted that the isodose- -ate ntensit es indicated in Fige 8 9 10 and ll a re ''nominaJ ' H l hour intensities as dis ' Esed n part A ··n ' - ' 11 lU - -1 2 _ of Chapter II They ' DB Y be itilized vith the de av curv s di scuesed 1n 1 -· par accurs te ca lctla tions of dosages p a ' 1 reas onab J Y Greate - acc a cy u a y be achieved by c9 lcnl a tr g ''tr- e' H l 101 tr intensities ·as i oted 7 o' act rtty u -ve s o f Figs l and 2 E ••---u-- Ef 'ect or Weapo Jl Design Upon Fall -out Scaliz g UOE ARCHIVES It is mpa -tant to reillze that although i'ig- r-ee in thi s paper are scaled e ccordil g to total weapon energy release yi ld · on1 y fission e' e' 'gy release ·v as used for actual calculation of data -- DS ETED DOEARCHIY F Scaling of Total Dose Contours In Part D of Chapter II a method of constructing total dosE contours was discussed and Fig 6 and Fig A vere given as examples However scaling of totaJ dose patterns vith yield cannot be 30_ _ __ I accomplished accurately with the ease ·with which one·may · scale isodose-rate contOllrS· Part ·B of Chapter-·III This · is •so ·because ' total dose contours are calculated on a ·basis that includes time of tall-out at various distances downwind Figs A and 6 were con- structed in this f'ashion and from a similar but _more detailed f'igure the data of Fig ll were derived To scale the data of Fig ll directly to oth_er yields by the USNRDL scaling method Part B of' Chapter III would the ref'ore imply scaling of effective wind as well as of' yield It winds remain constant · scaled dose areas tor yj el ds greater than tba applying to Fig ll would be too -large Also the downwind extent of the c ntours would be too great be ause Fig ll implies integration of dose beginning at times earlier than f'all-out arrival time at scaled distances downWind 15 Similarly scaling to yields less_ than Mr vith constant effective wind would result in scaled areas and DOE ARCHIVES downwind distances that are too small Accurate construction of total isodose contours would require re-application of the method of Part D ot Chapter II in each case employing the scaled parameters based on Figs 8 and 9 in place of Figs 3 4- and 5 as _used in that Part_ This technique is laborious however and usetul approxima ions probab Ly can b_e calculated using Figs ll and A or similarly calculated figures based an 15 MT and the scaling method of Part B of this chapter Examples of scaling from a figure s1m1Jar to Fig A and from Fig ll are given in Table II and tor the 6o MT case the proper ly calculated do wind extent 31 -• and contour area using the method of Part D Chapter II are given for comparison The - simplified approximation· based · on Figs • A and 1 J is seen to be about ·as · good ·as · the · best · expected · accuracy from the ideal ized scaling meth presented in this paper Tabl e II Total Isodose Contour 500r from Fali-out to H 50 Hours Mr · 15 1 10 6o Downwind extent mi 180 52 l 52 34o Cros s vind axis mi 4o 12 34 70 Yield GZ circie radius mi Area of true 2 ellipse mi G 3 85 9 7 3 5 1 2 3 6o 307 21 GZ circl e displ acement mi 2 Area mi ll 5 5 75 54-0o 470 3880 17 900 5650 491 4o55 J 8 700 16 250 Using Part D Chapter II DOE ARCHIVES Exampl es of Scal ed Fall-out Contours Fig 12 demonstr1 3 tes on a singl e scal e exampl es of ideal ized ·fal 1- out contours for weapons of several 'yiel ds al l for l 5 knot effective wind ' The data from Figs 7 - ll and the scaling method of Part B of this chapter were utilized to scal e the parameters The •scal ed parameters used are l isted in Tabl e II isodose contours and Tabl e III isodose- rate contours Table III Nominal Isodose-rate Contours l'ield Mr ' 15 500r hr at H l l 10 6o 49 152 384 32 64 Downw-' nd extent mi 188 Crosswind axis mi 37 2 10 7 7 9 1 9 6 55 15 1 1 22 o 41 1 04 2 1 GZ circle radius mi GZ circle displ a cement mi 2 Area mi Area or true elli pse mi 2 4900 34 3360 17 f 20 5500 412 3820 19 300 DOE M CH lV 33 --- - --- --- ·- - - IT DEFENSE AGAINST THE FALL-OUT HAZAR1 lf- To evaluate the problem of passive defense against the external radiation hazard cause by the gamma radiation from the bomb fall-out i t is necessary to consider a variety of factors which affect the problem Among these factors are the effect of shielding cf decon- tamination of' radioactive decay of eva-cuation and of' the biological recovery f'rom and repair of acute radiation damage The mathematical treatment employed in the preparation of' the tables found in this Chapter is set forth in detail in Appendix A However a qualitative description of' hov th various factors enter into the problem and play their part will be given here f'or the con- venience of' the reader o does not care to work through the 'ma thematics of' the problem in detail If' the reader will keep in mind two parameters it will assist in understanding bow the situation is influenced These parameters are the swif't radioactive decay of the dose rate f'ield and the _biological repair by and recovery of the human body with respect to external gamma radiation damage That the human body does repair radiation damage cannot be denied For example the peacetime tolerance level f'or external X- and gamma l radiation currently employed in the United States limits a worker ·to 0 3 roentgens per week If' we consider that such workers may work DOE ARCHIVES oughout the discussion in this chapter the assumption is made that the area making a defense against the fall out hazard bas not been directly hit by the bomb or is outside the damage area due to blast and thermal effects 50 veeks each year tor a period of 20 years ve see that they could receive a total dosage ·· of -3oo ·roentgens··over··t u s period of 20 years This dosage of 300 roentgens if delivered over ·a time period of a minute or tvo would result 1n acute radiation effects 1n a consid erabl e percen age of any·•gi·ven popttla tion However 300 roent delivered · over a period· of 20 years is considered·· to be sufficiently safe so that oar-peacetime- to1erance · levels have ·been established accordingly The rate of bj o1ogica1 recovery-used in this paper is the same as that used by wsm in Reference 1 It is to be noted that the n1JD1eric values of the parameters employed in this pa per to represent acute radiation damage and the rate of biologica1 recovery fran radiation injury are near the upper limits As a result of this the -tables of this chapter evaluating the effectiveness of protective measures are conservative from an offensive point of viev and optimistic from a defensive point of viev How- ever he general nature of the conclusions that can be drawn from the material presented 1n this chapter vould n t be altered if one picked ditterent numerica1 values for the above mentioned parameters A genera1 un rstanding of the effect or the various factors under discussion on the final result namely the e dose can be obtained by examination of the following qualitative sketch DOE ARCIUVE S l3IOLOGICAL REPAIR tOO¾ TOTAL 20% Time oos --- ----- rUnear · SCtS e This sketch discloses that radioactive decay reduces the dose rate o f gamma ' radiation field as time increases The total dose received by a person in such a field approaches a · finite value at greater and greater times The damage dose 11 does not continue to increase wi h time but rather reaches a maximum and then dies away · with time and is taken in this paper to approach 201 ·of the total dose delivered at greater and greater times Obviously the criterion pertinent to this problem is tl e maximum damage dose exp_e rienced by vidual in a gamma dose rate field and this occurs_at some •finite time a fter he enters the radiation field In the numerous tables which follow this criterion has b en applied is the criterion tabulated and called damage dose One additional factor should be kept in mind when ead i 1 g the rema bder of this chapter The areas tabulated 5 ld referred ·to are those areas which are covered by the dovnw tail out patte These areas are found in Figs 10 and U the fall- o f In general they extem well outside the area damaged by the blast 9 1 d thermal weapon ef'fects A - DOE ARCHIVES The Effect of Shelter · To arrive at an appreciation of -the dsma ge to huma c s which roul d be caused by the heavy and extensive fall-out it is instructive to e x s mi l e three cases persons in the ope n in rural · areas person in the open in a ·city and persons in the best s vera ge existing available shelter within a city Ex cludu g d eep u 1der- ground shel-ters of special construction the best available existing shelters in a city to protect one against the fall out gamma radiation are fcund in the basements of large buildings ntz i i l he5 vy inasonry construction buildings and on the middle floors of mul tistory build iz gs Considering only the dosage delivered vithi l two ' days afte d e tonation and using the physiologic a 1 ef fect3 i lf'Or' 1115 - tion and the average shielding factor information from Refereuce l the follcwi lg et effects over the are as ind ica ed C8 Il --'----- bs computed Tabie IV · Areas far Various Effects from Dosage Accumulated up to H 2 Days A f'ter 15 MT Surface Detonation · AREA IN SQUARE MILES FCR SITUATION INDICATED In Open In Open In City In Rural rural dose reArea duced· to 7 In Best Aver Shelter • In City rural dose · reduced to 13 Minimum Damage Dose Within Area Acute Eff'ect 205 r SD 10 8 8oo 7 500 2 100 275 r SD 50 7 600 6 200 1 500 370 r ID 10 6 800 5 200 960 550 r w 50 5 100 3 9oo DOEARCHlV 630 r w 90 4 600 3 500 Note 1 2 320 Damage dose is taken as 0 9 ot total dose delivered far this case SD lo means sickness dose in 1 11 of personnel ID 10 means lethal dose in la of personnel Table IV serves to point up the val ue of seeking and occ' lpying the l • best available shelter should one be caught in the fall-out area It is seen from columns 3 to 5 of the Table that the area within which persons would receive ·at le t a sickness dose is decreased by a factor of four in this example chosen for illustration It ie also readily apparent from examination of the areas given in Table IV that ' -1 the radiation hazard from fall-out is effective over a significant area even when the population takes the best cover which may be currently available to them It is seen that even after staying in the best currently available radiation protection shelters in a 38 -- city t during the time f'ran the beg- nnjng of f P -out 'J ltil e 2 · ia ys that more than half of a city population can be -expected · to die ran radiation effects over e n area at four or t e undred sq are miles -and nearly a ll would be expected to e Within en area o'f about th 'ee hundred square miles • An appreciation cf hov the exees listed in Table IV compare vi th the areas of sane typical U s and USSR cities • an be gained by inspection of Table IV in oajunction vi th Table V below Table V · Areas and Populations · of Cities Areas in Sq Milee Po pula ticm Roetov USSR 24 3 500 000 Tulo USSR · 23 6 289 000 G rkiy USSR 62 0 900 000 Moscow- USSR 68 2 Denver Colorado USA Detroit Michigan USA J 4 2 4-16 000 DO£ ARCHIYE 51 850 000 69 2 ao2 ooo 365 4 7 892 000 District of Co1umbia USA New York N Y USA 4 700 ll7 The best cun-en'tl y available ahel ter 'l -otecti-ou f c1 or in a e ty used in Table IV lro S ta ken _tram Enclosure ''A of t te WSID Report cited Ref 1 It was derived 3pecifica1 ly tor he city of Rcstcv U'3SR but is thought to apply equally veil fer othe ties i l Weste D Europe • Far u s cities variations from this actor are to be expected For example the inhabitants of Manhattan Island ould protect themselves by a factor a f sev e al tQ QUS d- by staying on the - nid dle floors of the slcy-scraper buildings which exist there Qi the other hand ill a city such as Los Angeles the populat -o i could probabl v not p rotect itseli on the average by a f'actar as f'evar9 b1 e S S 13 n the new existing sheltered locations 39 --- - - It should be borne in mind that the time up to H 2 days has been chosen n Tabl e IV as a specific e%SJDPle solely far the purpose of illustration Even though the rsd ation fi'om the bomb debris dies avay apidly because of re dioactive decay vast a ea s are still contaminated to a dangerous level at H 2 days Table VI beJ ow il l ust -ates· this • The in f'crmation 1n Furthermore all but small part of the areas under discussion Tabl e VI · lie well outside of those areas which suffer damage f'ram the bl ast and therma'l effects of the weapon Tabl e VI Dose Rate Level s and Areas at Various Timee far l 5 MT Surface Detonation Time Af'te r Detonation in Days Mare than 10 r 2 2 700 mi 4 700 mi 6 B AREA IN SQ MILES ·Fffi RURAL AREA DCSE-RA'IE LEVEL INDICATED Lbr More than 1 r 2 13 000 mi 2 8 4oo mi J 00 to 200 mi 2 6 000 mi Lhr 2 2 2 10 w it in d unage area 3 800 m 2 14 within- damage area 2 4oo mi 23 within damage area 1 2q0 mi 2 42 rlthin a amage area 100 to 200 mi 71 vith n damage area witbiD damage area· The Effect of Decontamination 2 2 POE ARCBiVES The probl ems involved n the decontamination of the city of Rostov U3SR have been studied in considerable detail 4o by the wsm Reference J The wsm s t regards the results of the d eccntBlll- ' ina tion effort · and the time·· and man hoqrs invo1ved · a s being applicabl e to macy of he other· cities at rTeste -n Europe Since the populg tion · density · of Rost-ov is rel atively high 21 000 persons per square mile while the highest urban population density in the United States in' l 950 vas that o f' New Yor t City -25 000 personB per square m i e and · s Iice a high population density favara - decontamination it can be assumed for the purposes of this paper tliat · decontamination efl'ort _in _a United States city vould probabJ y not improve upon the eaults ch have bee J estimated to be Vi thin the capacity of the population POE ARCHIVE ' of Rostov far their city e liEID group concl uded that no city could be decontaminated I 'Wi h gre r than • • • 75' o reduction in d Se -e te and that in n t poten- tia L target cities this applies to cities in Weate ' l Europe ic more than The 5 JI reduction in dose rate could be achieved wsm group also assumed that any by d econta nina t on decontamination etf'ort wo'Jl d be directe toward the total c ty area exclusive o-£ any lsrge trg ts ' such as pa -ks which do not hav to be inha oited or t ave-sed ' Ln or 3 er - o indicate vba t va riabl e in duration O'f e f'f'ort might easo lably be expected · two calculatiODS were na de by the wsm • gro1 -p calculation ras based cm a set of assumptions which gave m e the popul a- tion every possibl e advantage including 3ome which borc e -ed on the ineorn h sabl _e because of physical impractica1ity tami nation in this csse was 2 2 days 41 The 'time for deeon- A Becond calculation - m 3 - b ed on somewhat mare realistic assumptions but · it still greatly favored the capability of the population to cope With the radioactive contamination in the city In the wsm report the decontamination effort was ccnsidered ·to have · reduced the dose rates to 251 of those which would have prevailed without · decontamination Since Rostov is a city of relatively high population density it ·was oncluded by the WSEJ group that the duration of the decontamination effort in · Rostov may be taken as the minimum duration necessary in -the other cities of Western Europe included in the target system considered by WSEG DOE ARC tih'i Table VII below was canpiled far the purpose of this study by taking into consideration the results of the _ R ostov exampl e the fall-out areas invoJ ved and the radioactive decay of the radiation field ·The Rostov ·exampl e assumes that the decontamination effort would reduce the radiation field to 25' of vhat it would have been had no decontamination been attempted The starting times chosen 'far the example illustrated in Table VII vere piclted because at these starting times radioactive decay vill not reduce the dose rate greater than down to 251 of what it vas vhen decontamination started In other words it appears reasonable to stay 1n shelter if such is va ila ble at these early t es until the radioactive decay has al owed dO' m to this point It should be appreciated that a reduc- tion in dose rate brought about by decontamination· is over and above t he reduction c used bf radioa ctive decay Table VII Minimum Dosages Within Areas For City Decontamination 15 MT Surface Burst Case When Decontamination Takes 2 2 Days and Starts at H Days 1000 mi2 3000 m12 5000 mi2 8oOO m12 160 r 65 r 4o r 23 r Damage dose during decont ruuinetion effort received by 6fl1 o f population which 120 r is engaged H 2 days to Hi-4 2 days 50 r 30 r 17 r Total Damage dose received up to H 4 2 days 28o r 115 r 70 r 4o r Acute biological effect LD 1 None None · None AREA Damage dose after stayillg in best average shelter fall-out time · to H 2 days SD 55 Case When Decontamination Takes AREA Is lllS ge dose before de ontamination begins -when in best average shelter fall-out time• to H -6 days Damage dose duriDg de ontarnination effort received by of population which is engaged H 6 Days to Hf-19 days 13 Days ' and Starts at H 6 Days 1000 m 12 3000 m 12 5000 m 12 24o r llO r 6or 8000 · 3or DOE ARC Hi 'r £ Bo additional damage dose riceived · due to biological recovery Total damage dose received up to H l9 days 24o r Acute biological effect ' sn 25 4 3 nor I None 30 r None None mi 2 i Examination of Table VII discloses that even· if de ontamination were successful my tbie during·_the period of' approximate-J y 20 days f'ollowing the detonation the ·persons ·residing- in large areas down- Yind f'ram ·groand· zerovow d receive extremely bazardpns dosages of radiation It can thus be argued that decont t on proced es will probably not provide adequate protection to a population sub- jee ed to such extensive ·f'a ll -out This does not mean that decontamination · would prove to be of little value in all situations Rather it means that f'or early times days to several -weeks fol 1owing bomb detonation a population can receive mare protection trom the residual radiation by staying in suitable shelters than it can by attempting decontamination On the other hand if suitable shelter does·not ·exist decontamination wo- tl d be o£ value even during the'se · early times C DOE ARCHIVES _ The Ettect of Evacuation As seen in Figs A and 3 of · this paper · the fa Ll- O t areas ex- tend in a long wide band downwind' tran ground zero If considerable wind shear exiats then these contours may be much broader and corThe effective time of' onset of' this fa ll -out -espondingly_shorter depends upon the winds and the distance downwind tram the detonation point If' we take as •an example a point in the middle of the pattern and about 150 miles downwind referring to Fig 4 -we find that the f'a ll -out occurs here at about H 8 hours and that the width of band is about 65 miles the If' persons 1n· the center of the fall-out ··-· _44 __ 65 and 130 zone at this point remain they would ·receive· between roentgens during the time·· from ·H 8 h - to H 2 days even- tl' t ey vere in the average best shielded positions available in a · c ty reference Fig A On the other ' hand if they were able to ascer- · tain beforehand that they · wer to be · in such a dangerous position and could furthermore predict the shortest evacuation route vhich ' 'W'ould take them out of the area to be con aminated they could escape the fall-out hazard by moving about 35 mil es This line of reasoning presupposes that these actions could be taken between I-hour and H 8 hours which is the time interval before appreciable ounts of fall-out reach the position Less time for evacuation before fall-out commences would be avail able closer to ground zero and conversely considerably more time would be avsilable at position a greater distance from ground zero DOE ARCHiVE5 Even though evacuation before fall-out begins is theoretically ossibl e many practical considerations weigh against it The _success _o f the evacuation operation W uld require a very aci m-ate prediction ot where the fall-out would reach the earth and tlu s would certainly prove to be difficult in practice othe - f'actars vhich militate against this procedure are the danger of the population being caught in the fall-out in less shielded sit-uations than they had not moved and the physical difficulty of mov-4-ng vast numbers of people such distances in a short time with so little advance notice In addi tion the downwind fal 1-out areas are so vast that if the country bad been subjected to severai detonations 45 - of the yield tm der discussion it is conceivable that a person might find· himself · moving· into- the radiation field of a second bomb • l while attempting to move out of • the rad 1 ation field of a first_bomb • The J data presented in Table· VIII below was calcul ated 'by con- sidering the situation wich would prevail if' a population waited tm til the arrival of fall-out before attempting evacuation and by assuming that the fall-out pattern is known and that people can be directed along the shortest route out of the contaminated area Tabl e VIII Dosages Received if' Evacuation at Time DOE ARCHlVE 3 ___ _-··· of· On-set of Fall-out is Attempted -15 MT Surface Burst Evacuee takes -shortest route out at rate of 1 0 - · mph in automobile - shiel ding of the automobile reduces the rad 1 ation by a factor of o 5 Distance Downwind f'rom I Ground Zero Distance Traveled Shortest route out of contaminated_area 50 mi 32 mi H 4 to i1 7 2 hrs 21 0r SD 10 100 mi 42mi H 7 to H ll 2 120r probably_ none Taken Dosage Acute BioTime Interval Rec'd l ogical for Evacuation _ During Ef'f'ect Evacuation to be the damage dose in assessing biological effect Every advantage was granted the population being evacuated in the two examples of Table VIII hence in an actual case one would expect the dosages indicated to be a minimum One must conclude therefore that e uation beginning at the time f'all -out ree cµies a position cannot be considered as an attractive defense measure 46 • -- -- - ' · Evacuation -becames mare feasible at later times because radioactive decay reduces · the dose rates · of the fall -out contamination For ex ample at R 2 days evacuation achieved under the assumptions at Table VIII would ·resu1t in approx tely 1 20th of ·the dosages during evacuation indicated in Table VIII Furth rmore evacuation at R 4 hys under the same conditions would result in dosages during· evacuation of approximately l 4oth of those indicated in Table VIII An added advantage of waiting for several days in shelter before I attempting evacuation is that by this time -the fall -out areas vould probably be fairly well known and thus the best route out of the co taminated areas could probably be chosen correctly D Recommendations as to Protective Measures DOE ARCHIVES · Fram the previous discuss ons an decontamination and vacuation the possibillty ' of avoiding excessive doses of radiation by remain1ng in suitable shelter for several days becomes more attractive In order to arrive at a quantitative estimate of the results of such pro' tective measures the 1 nf'ormation presented in Table IX be 1-ow was calculated Far the purpose of this Table it vas assumed that all 'all -out occurred at R 6 hours This assumption does not detract f'rom the general impart of the inf'ormation disclosed by the table Howeve t° this assumption does make the dosages given in the Table for the 1 000 square mil e area problem somewhat lower than they should be and conversely the assumption makes the dosages given in the 8 000 aquare mil e column of the Table somewhat higher than they should be 47 Table IX Mi nimuru Dosages Within Various Areas t Sb elte r s 11 11ations In lio ted 15 MT Land - aur- f ace Burst Cvnd f ti 1 n ill pt r ioas ·o 1 1t 1 V uhelte r f rom Rt6 hmt1 • -- t akcn oa tim fti-11 -1' 'fllt 'iieg tno -- Ul'lt 1 1 · H 4 d a t ay then l€ f1 V1 shel t er d 1•el ei re on the average o ne - ha 1 f' of the open rural area dose rtt te for all time thereafter AREA Ap proximatc Damage Dose and Acute Biological Ef'tect 000 mi 51000 mi a Fr stay in basem 't of typical Eaa·tern U s home protection f'a tur 05 to 1 4 3r to 86r 20r to 4or lOr to 2O r 6r to 12r 80r 45r 24r 55r to 65r 30r to 36r None None 2 After leaving basement ' · Total ·180r 220r to Z Or w 1 lOOr to 120r SDI 20 to SD 50 _ Acute biological effect b Fr stay in wood-frame single story home protection factor 3 to 6 · After leaving home ' I • Total Acute biological effect c From stay in commercial building mul ti-story ·reinforced concrete _ protection factor 013 to 07 _ · r 1 ' ·I ·' After leaving milding Total Acute biological ef'tect d ·Fr stay in special shelter below ground with at least 3 ft of earth co-ver protection factor 0002 After leaving shel er Total Acute biological effect None 2 8L000 mi 2 · 14or to 280r 550r to llOOr 250r to 500r 75r to 150r 1 No add 1 da mage dose rec'd due to biological recovery 550r to llOOr m rp to ID loo 250r o 500r sn 25 to ID 35 l to 280r 75r to 150r SD 1 to sn 55 None to sD 1 Q LI AR CH l V £S llr to 60r 5r to Z7r 180r 80r 190r to 24or 85r to llOr SD 7 to SD 25 Less than lr 180r 180r SD 5 None Less than lr 80r 80r None 3r to 14r 45r 50r to 60r · None Less than lr 45r 45r None 2r to Sr 24r 25r to 30r None Lese than l r 24r 24r None e additioni i assumption tbat individuals outside of their shelters would receive ne-balf' of the open rural area dose rate averaged ov r the c e of a typical day is based upon the · general results of numerous RW tudies and applies to city and urban area dwellers An examination of the various damage doses and their biological effects presented · in ·Table IX demonstrates the value of an especially constructed simple underground shelter to protect against r - out gamma radiation OOE ARCHIVES In practice the best passive defense measures ·would in all probability invol ve the occupation of shelters for time periods which would depend upon the dose rate level of the residual radiation field in the particular l ocality For some areas a time of ' stay in the shelters of four days would be sufficient In other more highly contaminated areas the time of stay in the shelters should be l onger F other still more 1 rl ghly contBlJ inat_e d a eas - it can be expected tbat the_best passive defense would be to stay in the shel ter for a week or more and then to evacuate the area ____49 -- V CONCLUSIONS The following conclusions may be drawn regarding radio logical hazards from the surf'ace detonation o f very large yield nuclear weapons a DOE RCH1V£ S The detonation o f a 15 megaton yield weapon on land sur- face can be expected to deposit radiological fall-out over eas o f about 5000 square miles or more in such intensities as to be Comparable danger areas may be involved ba zardous · to human li fe in the case o f deep water surf'ace bursts and harbor surf'ace bursts with some differences in distribution likely b A large percentage o f the radiologically hazardous area can be expected to lie outside the range o f destructive bomb e f fects extending up to several hundred miles downwind thus the · radiological hazard becomes a primary anti-personnel effect c The sensitive·· wind-dependence o f the distribution of the con aroinant ma kes accurate pre-shot prediction o f the location of the hazardous area with respect to burst point virtually impossible without extensive wind data at altitudes up to maximum cloud ·height about lOCY 000 feet d ' The rate of decay _o r the contaminant is such that all but the most highly contaminated areas a few hundred sq e miles can probably be occupied by previously unexposed personnel on_a ·calculated risk basis within a few days after the con aininating 50 event and even - hese highly contaminated areas may then be entered briefly by- decom amination teams e The two nmdaroental passive defense measures that are likely to be most · ef fective are the seeking ·of optimum available shelter and evacuation o f the danger ·area These two courses of action taken in succession with the optimum time and direction o f evacuation being determined and· controlled· by competent- authority can be exp cted in effect to reduce lethally hazardous areas by a factor of ten or more f DOE ARCHIVES Universal use of a simple erground shelter with · about three feet of earth cover could reduce areas made hazardous by fall-_ out diation by a factor of a thousand or more This means that the lethal fall-out hazard can probably be completely overcome by remaining in such a shelter for a period of a week or ten days a fter -which the area should be evacuated g Seeking optimum s elter at once is of vital importance since without shelter the dosage received in the first few hours will exceed that received over the rest of a week spent in the conta minat ed area and the dosage received ill a week Will exceed that ' accumulated in the rest of a li fetime spent in the area 51 APPENDIX A Derivation of Radiation Damage Dose Formulae In a· recent study Refer nce 6 it bas been conjectured that damage due to radiation can be · divided into · a permanently retained portion which is 2 Jf of the total received and · a remainder vhich is repaired at a rate represented by an ·exponential decay law if D0 is an acute dose received at time t o ·time t is given by D t 0 2 Thus the damage dose at • D0 0 8 De -'3t 0 where f3 is · the decay constant J Qg CHlV J Experimental evidence indicates that the decay constant has a val ue o£ about O 29 In this report it bas been ass'UIDed as was done in Reference J that the dose continuously _recei ed f'rcrn a decay radioactive f'ield can be· treated in the same manner If the dose rate is given by R t kt-J 2 2 where k is the rate at time t l then the damage dose at e ny time T assum l ng the individual entered the field at time T • l T D t l 0 2 0 is I o Be -ll f-t l Ilet-1 2dt 3 0 The integrand in the above expression can be plotted and the definite integral A T · T J · 1 2 e t- • at 4 0 25 52 - Using eqUB tion 4 evaluated far various values of T by planimeter D T ° is given by 0 2 D T k To- • -ir-0 2 o 8ke- e T -A To • 5 Equation 5 was used in this paper to calculate the maximum dose for 'simple cases by calculating D T for various values of ff until a rela' tive maximum was obtained DOE ARCHIVES If an individual is 1n a radiation shelter tram time T 0 to time T and then emerges e l uation 3 must be al ered to- ake into account 1 the fact that from time T the constant k bas one value ' and f'ram time T1 to T a dif f'erent val ue In this case then O Ti D T to T 1 2 o ae-t3 T-t k it-J 2dt 0 T 0 T1 T 6 This form can be sillq lified to give Equation 7 was used t9 find a second relative maximum damage dose if a ny which occurs af'ter an individual leaves shelter This can be compared with the first relative maximum occurring before he leaves - the shelter The largest of these is o-r course the maximum damage dose during the time interval considered 53 J REFERENCES 1 WSEG Report Bo 9 - An Evaluat±on of' U S _Capabilities in 1956 and 1960 f'or Employment· of' Radiological •W arfare Weapons Systems in Air and 'Ground Operations 0ctober _1953 TOP SECRET Restricted - I a ta 2 Headquarters JTF-7 letter subject Radiological Surveys of' Several Marshall Island Atolls dated 18_ March 1954 with enclosures SECRET Restricted Data DOE ARCHlVES 3 AFSWP 351- B Super Ef'f'ects Handbook Second Revision December 1953 SECRET Restricted Data 4 USNRDL Draft Paper 006705 Scaling of' Cont arnination Patterns Surface and Underground Detonationslf Ksanda Minvielle and Moskin 1953 Restricted Data 5 USNRDL-387 Contribution of Different Chemical Elements ·to the Rate of Gamma Radiation at Various Times Af'ter an Underwater Atomic Burst W J Heiman November 1952 SECRET Restricted Data - 6 E H Smith Company 1953 Unclassified Informal study for _the Chief' AFSWP ' · t M-' - - - - c f1 ·· ' r - J t± - 1 t- -t-· - -H lr- --t--t---1---1-t-t---tr·t--t-tt ---t-- -t-1 -t-t1·1-·-t--t- t-H--t---t--lr _ --- s • • •• - ·-· - - '- 1 qr -r ' ' - t' ttt1i •• ·· ' ' · · ·- · · - -tt ·--·· • ·l i · •· ··•·ii r -·· •- _- _ · · - I _______ j · 1 l 1 N·'v- i --l--- - -H-- t-HH--H-i - ' -t---t--t- --t--t- H- -- --ir- -t- -t- - • I • '- - • -• - • • •••' • •·••• •• • • -i-- -t- -•t • 1 •i i • • • ·- · I· · - - ···-· ·- ·•- -c · I ' ' T I •· i- -- - ·- t-- _ 1 r i liHHtf 101 t t t t tt - t • t t t ttt • t t 4 t4'· · - - - - ·-·I- 1 I L- -1 1i ll LI · 1 1-- --4-4h-i -i f 44' i R- -i-- P F -li a 4'f-· · Hl- i t-'±- t -t -t t-t -- -it-- '-t-'H --IH r-f' tt-- - -- -- · -·i···l 1- -t -- - --- -- 4 i i I 1 ·· ' I I Ll l-- - c- f 1 --JH H'-'f l1T - - ' r - t l -f ' -f tl H-t-- --t- -t- - -H r-H-ttt-- --1r-t- --t- -r - -rtir-- - ·- - i' ·h' ••• • - -1 1 i i -11 -·•• • i-- ' ' -- · -· -- -- - - - · - • _ _ _ _ 1- • •• • I1 · - ·H- -t fr - i-- •-· 1- 1'2 1 _ -1-- j ·• Da ET - ------- - - -t-l · · t · '- - I l ' - ED · - T_ · - - · - · ·· _ - - 1-- --l--l-l-1--1--i-4 -H -t- - H a ' fl t 'f 't4-'- -·· - '' ' 'i-'l' 'j'i- - -H -IHH ·t-t -- -f -t--t----t-1-1-MH-t- -- '-·----- • I1'p •t' f' ' I • 1-- -l -H -H H- - -t t t •- • a - rl -ii -- • 't' bHl-t·t--t -t-t-tir - - - - t t-t- 'i '1-f'- t-t-t tiTt---r-i- ·- · - - - -I- c ir M 1 1 - ' ' • f' r- r · -t-t·-1'-r - - ' _ j µ - •- - --- - ·I H -- · ·-1-- - 1-•l--l-l• ·- --iL ' -- f i j - · -·J - - ·4 t- - -r - i ·H -IH -H ' ' i1-' '· •H - f' •1-·• ' t· - -1 f - 1 1 '·1 _· f f-t- '- ' i' • 'd' -t -t-t-1' t- ·t·-1-t•-t-- -- -1--'- 1 · ''l ' I ' • i ' i -HI-- -- • ·-·- - r · • ···· I I ' •J t x ·· · i • f · · · __ p 1 rT I I' _ ·f-- ---t-i-t---t--t _ 1 · · T · i i - E _ · T · 1 - I ·r Jr _ ••• ••••-t--i•••• - •· f• • •r -••• _' ·• • -r•-•1 ••r••• 1 - ••· • • --t- r ·ttr- · J - ·· T·r - i'- I - _ - · - t -f - - -H - -- -·--·r· - '-t - I' - t 1-1--1-l-l-l--1-- - -I _ ' j-- - ··I ·s- - I· I r ' 1 l · · ······· •j·-· 1 li i f · i 1o' L- L J_LL l J J l l LLIO- _ _J_ J J I J J J L LI L10- -1- 1 _ J J -1 -1 -1 -Ll l -o''_ J _·_ 1- - - - - - o •1 - - - -··--- --- o 1 2 1 8 • _•• I •• • ' ••• • t • • • Doae r- 'i • • ' - • 1'6 ' if 168' r· 110• 1 I IJJ · · t 1 I NAUTl IIL IWl• c· J - ·· I Plr • CONTOURS oose RATE •r•·•· 1 hr at CASTLE 11 811 H 1 I YAl1 l'4 S '£ llt • ' tl'f #lA SlltG l ' ANHVAU'r I I z• t JT lil u1r Tfl•• r r iJSN I AIKUIIA _ l IO • I · · FIG 4 IDEALIZED ·FALL OUT CONTOURS 75 - - -- - - - -- - r - - -- - - - - - - -- - - - - - -- - - - - ---- ---- - - -- - '° I 50 r---- ----- -·- - - - - - - - - - - - - - - - - - - - t - - t- -·· 75 I _____ _______ ___ ___--------L--______ __ L - ------1 _______J _ _ 0 50 100 150 __ _____ ___ - I 200 DOEARCHlVE s SCALES IN STATUTE MILES · r 1 r hr ·at • H 1 250 · oOO 50 - ·-· - '• 15 MT LAND ' FIG 5 G CONTOURS - • L • • - • • • • ------------------------· ------------------ ------------ ------------------- - ---- 40 0 r WINDl 1J M 600r 'Tf • c ra __ _ _ j - c • IOOOr J 1500 r 2000r • r • 1r hr at H l -_ • 5 Ml - - ·FIG 6 IDEALIZED FALL ·our CONTOURS 75 - - - - - - ·--· · ' ' I I so 2480-r -··-· ·1600r ·· IOOOt · 25 0 25 SCALES · IN STATUTE MI LES - - - - -·- -·-· 1 Jt••· --· ··-· - ·------··------------------ IDEALIZED LOCAL CONTOURS • FOR RESIDUAL RADIATION DOWNWIND DISPLACEMENT OF CENTER OF G Z CIRCLE GROUND ZERO CENTER OF G Z CIRCLE DIAMETER OF G Z CIRCLE I i ' I '' '' I '' ✓ I CROSSWIND DISTANCE - - - - - - - -- DOWNWIND DISTANCE UPWIND DISTANCE ' - - - ----- l Fig 8 i 5 MT RADIIB AND DISPLACEMENT CF GZ CIRCLE at H l reference time 15 knot effective vind Displacement miles 2 4 6 8 · ID 12 1 4 1 6 1 8 2 0 2 2 2 4 2 6 f'F Scale is ' nc m1na l ll l pattern adjusted to allov t - • 2 decay to be used far intermediate tiJDes ' ' rue H l pattern is arrived at by multi ing dose rate by 0 78 ' I ' -i 103 al a I ' C 'a '0 Q Radius· of GZ Circl --- ·---- -· -·- -·- i I HuJ ius mUl i Doe An Cfil V Es 2 8 • Fig 9 DU -l f IND PJID CRCSSilillD AXES OF DOWNWIND P Tl'ERN 15 n' at Crosswind Diameter miles •0 10 H l refere ce time 15 k ot effective vind 5 10 15 20 J ± -' • - '- ·- - -- - i ·- _'-----i '' _ - _-_- 25 30 ¢ c ·-c c i_'-_ -_- 1-- --sc- t- ' - ·' _ s _ ' ••f- _ - • 'i· • 1-1- - ' - t ' ' ' -·· 35 40 45 50 • 1-- _-t i • ' · ·- I I ' 1- · - · ·- __- --_- __-·· ·- · - _ -- 70 60 -- j -- - • - - - -- --- -- ----- - - ---·· ·- -- - · 6 --- · -- - -·- - _ -· - I I· · - -- · Scale is far rnaninal Htl patternr adjusted to all ow t -1 2 decay to be used far intermediate times True H l pattern is arrived at by multi- - plying dQSe rate by 0 76 I -- d I _ I I ' I I I I I I I I I -- ' ' I I I I I I G Gl a G 0 A t t t j j ti t t t t t t t t --·-_-· - · 1 I I I I I' I I I I I '- I I I I I '- ' c --- · ·- C··· •· - ---- ---· ___ - c - ---- Major Downvind Axis I i t-- -- - - -- ------ -' -- ·· ----- -·- -__ _ · -· I - -- - - ·- · f _- __ -_- -_-_-_ 1-_-_-_-_-_-_-_ If _- - -_-- - -- -_t- _- --- --- - ·- -- ·- - ·- - - - - - - ·- --r - --i--i-f ' --1- --- --·- -·-- - -1- '- '- • _ - _- _ - - -_ - -- -- - - --- --r- - ·- • _ __ ±- - ___ _ -1-- -·-·__- - - -_ - - •- - - - - _ · • ' t t c _ --1 _- - _- _- _- _-_' - ' - - -_-__-_ ---· - · ----·· -· - -- --· - -- r -----· ---· ·· -- - - - -• · •- ······ -- -------- -- · - -- ·-- - -- - - - ----- ---·-·- ·-·--· - ·- - - - _ - - - - ___- _ _- - ·-- - - · - _ - - ' - ·•- - - - _- - ·•- - - •-- •·• • 1 __ __ ___ ___ __ _ • •- • •-• - __ __--- - _ __ • · - - _ I I I · ·-· - - _- - ----1_ '_ -- _- _ _ 120 140 160 180 200 l _ ' t j _ N_ _ _- _ ' - _ i _ 1 ' '----''-'-'c _-'--·- __ _ ___ 100 - ' · · 220 240 260 _ ___ _ ___ _ _ _ __ 280 300 D1 · mvind Axis Mil DOE ARCHIVEs 320 340 __ 360 --- - ----------------------- Fig 10 AREA OF DCSE RATE CONTOURS 15 MT At H l reference time IO i---- - - -t_ - t- _ r t -t 1--- - _ l -• ·-t- -1 ·1· • t- - - 1- me - -t _- t e t- t- - - i- -- - - - - - --t ' ' ' i il ill ii u n'l j1 j j ilil 1 · fi l rn ' '' ' ' - · • ·· ' ' l- Scale is for_ ''nominal H l pattern'' adjusted ··•· ii li i · l to allow t- 1 · 2 decay to be used for inter ' 1 t I i '' I _ mediate times True H l pattern is arrived ' I i i I • • ••• •• It • I ' 1 at by multiplying dose ra e by· 0 78 i · · I i i1 1 - ii 1 n I ' I • I II Ii 'I' l' 1•1 1 •••• •iii 111· ••I ' Io•' 1 •• • i •• • 1 · ti 't • i • • I -1 t I I I i i i ···• ··· · ''· 1· r•f I ' d · -- ' I f i· · - _# I 1 ·111·1' llll i · 1'· · ' • f i Ii ·· Iiij_µic i t t i i I 1 I ' ii · · I 1'1 1 · '1· 1 '• • · 1 il A - 1 liH i I 1i'1 ' _ • f lii il1 il l •if I' • • 11 I • • • • • • • •• •• · 0 • l • I ' I I' I' l ' 1 1 · I I j ' I • ' I · ·j • • • • • I • ·• ' · t 1 • ·•·· • I • J ' fl 1· i • · · 1 II 1 ii 1 · I I _ ' • ·1 ' I II ·i · I 1 I 1 1' ' I I I I I 1 1' i I ii j 11 I i · ' I II iI I •• I •· I I i 11 lj I I I 1•I 1 1 1 ·· I · 'i in1 q I I I' · I ·1 1 j I i I _ ·· • · ··· · I ' II I il l 11 I j ii l i ' i I j i j II I j1 I I i I Ii I i ·1• I I li I Ii p I ' 1 I I · •· I • - II ' I • ' ' I I i t i I ' _ _ • N' I I Ii ·I' I I I ' •· • • ••• • • •• • ' • •• l • ' ' t • i ·i•· • · I • ' l ' ' i Hi 1 · o • f•• ' I t •• · i I I ·- ·· 1•1 · r'I I ' t ' i i 1•· 1 ·•1· I ' • 1 • • i ••· · i i iiI t t i ·i' i 1 1 · 1 'I ' ' I 1 ' 1 ·· i 1 ·· i iill iii i _· i •••1 Ill i H ii p11 iH 1·1 p ···1 r Pt n i t n d · l -·· · I · · I• If j • I •• ' I I 11 '• i I I I 1 ' • 'r'i 1 ·i 11il 1 i · I I r H I f1 ' • I 11 'I ' I 11 •11I l It i i ' 1 I N ii · i i i i i IN I i 'l 1 _ _ _·_ _ _ _ - _ _ 1·1 111 11 q 1 t - 111 f1'l 1 1• P 1 ·· ··· 1111•i 1 I I 1li i t1·•· - 1 1H n 111··· - · 1 1· · · 1 ·' ' 11'1· 1 il l ' N I• I 1 •' • I I I 1H t-nt 11_ i ··lI i· - 1· -· _ i j • • i i - ll1 l · 1 i •··· o r · l·li P •ii - · f-• H ·•• 1 l t i ···· · ·· - It r1 I 1 Ii 1i 1 - - l - · 1 · 11 i l l 1 •1 1 r · · ' H I t·j'I i i i 11 I •• ' t I ·J1• nJ lJ lti - t' J • 1 1j ' I 1'1 t1·I 1·• · 11 I ' HH ji i J i l - - ·· • q i' 11 1---· I I f 't I •• i 1l a ix I i i _ ··' ···· ' i i· -ll 1- tl t1· 1· •• a I 1 1 · i 'II 1 •• • I -- 1- 8 A I i - - a - t••• • t · ' ' ••·• I •••• 'I · · ' t I 1· I • • i t w i I i 1 · 1 · • · 21-____J_ _ --L · '_·_· 1---1- 1 --'---'-- _·_· ·_ _ _ _ ' '·_ ···' '·-·-1 -1 -' _· _ i_l i'- -_ _·_· _ __ _ ·- · 1' iu · _ • 1 iu' · _-1-··- ·-1·_· _ ·- · - --- 1-'i'-'-- _ _ ' _ _ _ _ _ · - _ __•_ _·_ ___ - _ _· ••__ I ' ·• •• • · · 10 02 103 104 2 Area within Contour m1les DOE AAC J4Y oa • Fig 11 AREAS OF FALL-w r TO 50-HOOR T Yl'AL DCSE 4 10 '-'-· ··- • -H 1 · - -·-- - · -ti- i t-ttr ··-o- - · 7 l _ __ _ _ - - - -- 1-8-- tt titi- - - -1-t rl- tn l- -1 - -- --- -··_ -_·--- -·- __-- ---- ---1---- --- --- - j j r-i - - ·H-f t l -HH Tl 1- i- 15 Ml' 15 knot effective Wind _ · · l f ' Fr - ' __ _ ' '· -c r_ - ·-- - • - - _ 1- - _ j - _-_i-1-1 I I ' pltm fl- - -i_ W -Hf fl - - • ·i· ·- - - _ •• I ' - - ' 1 It It I I I tI 1111 1111 11 ° 11 t II I I I ' • - h - -1- '' -· - - -- • I I t•I I I Ill I _ _ _ _ ___ _ t 1 1 • I di ·r 1 · ·•· a 1-- - ··- I i· --- - -·-_ __ I t ·I· ' ' - ··-·· c -'- Rf4J4-'I I __ i- 4J - c f '- - · ·-·-·· ·-·-- - 1 1- - ·tf I l --- - - - ·-- ' H-H-·H-- l l i- -'-1 rl ' • - -1-11 '--' L -l-4 W'- JI I tr • ·- --- _ it -_ j •- • •- - ·f¥2· W --· 1 _ ----- - ·· - _·_ _ ' ··- - Cb 0 'I 11 I I I It · I ··- 0 1 11 11 r ' 1· t _ _ j i- - ·_ ' ' _ c • • • - ·- - H- 'l-l- --'-'-l- µ-14 1-l-1-l-WIL't J I I I I' I Ufi H- -H- 1 1-- '- _ 4- eH'-r-1--1-H Ti11 il - _fu7 7T I I 111 11 i _ _ i- - - - -11111 N 11 4H I -r-n-T -r--r - - i I t I l i I ffi1 I I I II - - - --H-H µ f¼ ' '- 1- -i- ·1 - '' l i t I I •I lj • I • °7 ·- T• f ·· • • 1-- · - ·· ir 0 · c · -- zt - H- i·dT Hr 'f H· i n l t ttH iL _ __• c ri-i-i ··· I-· ··· · H-t H ½ - t-H - · H -r--H t - I I ' j1j i I• ·-•· · · - •I • ·-·· t - -i · - · r ijj i • r• • • ' U - _ _ _ 1 -· · · l I I -• · ····I - I I i • i- - · · -·-· -· - I --l- -- ·· i - · · I I 1 ·t ii I ' I i 10 2 Area Receiving Dose miles DOE ARCtllVES Fig 12 SCALING OF REPRESENTATIVE IDEALIZED FALL-OUT CONTOUR WITH YIEID Yield MT No aJ 500r hr IspdoseRate Contour at H l Approximate 500r isodose contour integrated from fall- out to H 50 l 10 60 POE ARCHIVES I 0 100 • - - 200 300 - 400 Scale Miles --- --- - DElETED 1 ¢£ h 3 · Htoourate Cqnto for 60 · Ml' Chapter III j OJ ·