Operation Castle, Programs 1-9 Task Unit 13

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and the effectivenessof shipboard protective measures a@Mt radioactive contamination. Other effect6te-, such an long range detection studies, blast effect6 on a tree stand, generation of water voves, loading of a simple structure, etc., were included. No projects in support of a Prcpam 8 (Thermal Effect#)were included in the military effects program because meaaurements of interest to the Depprtment of Defeme were included in Program 18 under sponsorshlp of the Lor Alamos Scientific laboratory. !n general, the princtpPl objectives of the effects prcgrama were realized. ?he numerous ~ h M g e iin the shot schedule, together wlth the repeated delays due to unfavorable weather, forced m y changes and lpst &ut# fmprovfeationa in the eJp3rimental p h . In some projacts, notably those concerned wlth documenting the fall-out, much information was lost, wbile in other projects ouch aa those Involving the effect6 on aircraft, the repeated delays allowed completim of necessary batwean shot maintenance resulting in almost 100 per cant pprticipation by botb the B-36 and B-47. fir blast pressure measurement., on preliminary review, M u t e that air preasures obtabs4 in the reglono above 10 psi were approxlmrtsly 15 per cent lower tban would have been predicted from theoretical nod prior experimental work. In the low pressure reeons there was no evidence of pressure reduction, an m-ed on the ground, from atmospheric Inhomogeneties of the normal atmosphere. Hawsper, It wan observed that rain lowered peak presnves and slowed shock wave propkgation. The dynamic pre6mue ~berpnti~tl.(am made by ~ 8 sof pitot tube) Indicated that a voter nvface in not necesnarfly an "ideal" surface for a surface burst beeowe d pcmsible entrapment of voter droplets in the stock front. "ha underwater pre.c.sure meaourements obtained were of approldmntely the aalw i o t m ~ l t yM the measured W pressums for the mame -8. ~ h l r~ e o t s sthat there wan either little direct paes~ure--mittad to tho water layer or that such pressure wan highly attenuated, me vote? waves gcnanted by the detoMtloJu were found to conform to an emplrierl q ~ t i o nrelating charge si-, dewity of medium rudar the charge, and the degree of venting (In case of land shots) to the

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The fall-out studlea conducted in the CASTLE test# entnblinhed for tbe firstt h e the sigrdficant cntcmt of howQus dc a clive faU-outr edung from the muface detonmtion of high yield devices. Arean of the order of several thousnnd a w e mlles r l t b raaidud radiation intensities hpzardous to human life can be expected from the detfmation of a 15 megaton yield weapon on the ground wfnce. Because of the dependence of the distribution mechanism on meteorologicaI caditionn, accurate preabot prediction af fallsld ueaa rill Oot be pmsible for most operatloslpl situatlone. The limited rpnge d neutron and Inltlal -ma radialion effects for weapona of megaton yield renders these effects of minor significance ralrtiva ta b h t and thermal effects. For high yield surface detonntionn it wan observed that the effects of neutron and initial gpmma radiation are ma6ked by the high residual cmtamimtion rpdiotirm levels near the burst point. The mo drone Uberty ships were mccessful in ObtDinide information which lbarld lead to a complete and detailed analysis of the effectiveness of a wanhaom system designrd as a countermeasure for rodiologlcal cantaminrrtioo resulting from fall-out. Pre- estimates of the effeclivenesg of the rpcbdom sy6tam iustzdhd on one d the drone ships. as determined from the results d the firat two shots, plua the shielding amilable in tbe instrumant room below deck, reaulted in a declsion that the ship could be manned d e l y for Shots 4 and 5. Wing these two shots the sup penetmted heavy fall-out arean with no algnlficaut e!spomre of tbe personnel aboard. Decontamlmtlon of the unprotectedship and the Chemicpl Corpa reprmentative structural m a l a , which were carried on the .hip for sxposure to fall-out, proved to l e very difficult due to the nature of the contam5nant. The misadventure of done live contaminntion of inkabited atolls by fall-out fromthe first shot of the test series IOB lessened to -me degree by the opporbmity prasented for tboroogh clinical doenmentation of the response of the inbpbltanta to tbe radioactive fpU-out. Thi.documentation mu incident to accommodation of the atoll inhabitants at Kwajalein for obaemtion with a view to treatment if indicated. A totnl of aS8 Mar8hallese and 34 Americana were in tbe group that were exposed to significantammmts d radiation (up to an estimated 1 O O - N ) o r a n t - gens for one subgroup). Ihe individuals of this group hmd been, to different degrees, subjected to tom body lodgement of fall-cmt particles on their bodiee. and internal radiation from ingented or inbpled particles. No permanent effects were observed but epilation, akin lesions, and hematologic changes were observed and M e d in detail. Arrangemeats for conUnued observation have been made to determlne any poesible adverse effect6 arb- fromdeposition in the body of ingested or inbpled plutlclee. Inanmuch as these are tbe only lmom d.tn cmceming the effecte of iall-out on humans arid since it in unlikely that mch additional data will be W e d &r otber tbon war time circurmtnnces, it in believed that tt& -entation in oi catstanding imThe Air Force projects to determine effects on aircraft in flight were rery mCCeMful, but detailed data reduction and analysis in nscessPrg before exbting cpppbflity criteria w i l l ba effected.Preliminary data indicate tha! on both the B-SO and B-47. predictions d the thermal respotme of critical akin arean were conwmtive. Gust loading and reqxnme prsdlctlons seemed to be fairly consistent with results obtnined Sqerficinl overpressure damage N received by the B-SU on several shots. The reduction In the critical thermpl eawlope predicUom after lBot 1resulted In more smpltatic consideratioru d the mt lopding and response of the B-36 horimntal stabilirar for ttie larger megaton field.. Because weapm delivery and emcorthg &craft muat avoid entrapment in tbs cloud uiclhg from nuclear detonntionn, considerable pbotcgznphic effort was devoted to obtahbg data cm rate of riae and growth of the clmde formed by the rvioru .bots. Pbtogrammetric interpretation of the photcgmpby obtained in believed to have provided a basis for predicting c l d parameters which will meet operational requirements. radiation from the gross M-out pattern, 1- Irradiation from

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The Armed Forces Special Weaporu Project (AFSWP) was informed in Aprfl, 1DS1,' of plans of the Atomic Energy Commission (AEC)to conduct a developmental weapons teat of high yield weapons at the Pacific Proving Grounds in the fall of 1953 (subsequently deferred to spring of 1954) under the code name CABTLE. Inasmuch aa the Ivy operation (the f i r s t test involving high yleld weapons) at ulis time was still in the prepamtion phase for conduct ln the fall of 1953,no lmmedlate steps were taken by the AFSWP to plnn for Operation CABTLE. In August, 1952'. the AFSWP requested the Chief6 of the Services to submit project propo~almfor a military weapons effects program in CASTLE. On the bpsls of the proposals submitted by the Services, the AFSWP presented to the Committee on Atomic Energy of the Research and Development Board on 17 December 1952 an outline for a mllitary effectstests program. After further hear- on the Low Range Detection program (Program 7) and the Shtpboard AW Countermeasures prolect (Pmject 8 4 ,the Reseuch and lR?velopment Board approvd tbe program and initiated release to the AFSWP of Research and Development 0)fun& an PROGRAM TITLE R&D FUNDB Blast and Shock Measurements Nuclear Radhtion Studies Structures, Equlpment and MateriPl Service Equipment and Technique8 Long Range Dewtion Thermal Radiation Measurements The military affects teat program aa submitted to and approved by the Research and Development Board VUI of necessity conched in very general term because only prelimdata from the lVY operation had been obtrined Md because a firm schedule of planned detonaUOM and dates had not yet beon promulgated by the AEC. Bmwsr, a tenhelve project list wnm framed in accordauce with the folloalng precept.:

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a. Each project must be justified on the -is of a mllitpry requirement. b. h c h project must be such that: (1) Its objectives cannot be attained except by a full bcale test. (1)Ita objectives cannot be attained at the Nevada Proving Grounds. (3) Its objectives CM be attained at the Pacific Proving Grounds without unreasonable C. Each project must conform to the shot schedule (yields, hatiom, burnt heights) established for the developmental program of the AEC. In early March, 1953, representatives of the APBWP met at Los ALnmoa r i t h staffmembers of the J-mvision, Los Alomon Scientific LDborotory (LAEL) to review the compatibility of the desired Deputment of Defense @OD) program with me AEC developmental program. Except for non-inclunion of an air burst in the AEC developmental program the programs were generally compatible. As an outgrowth of this meeting plans for a thermal program (Program 8 ) under MID mponnorship were dropped by reason of agreement of W L to expand ita Program 18 to include thermal measurements of particular interest to the MID. Also 98 an outgrowth of thls meettng a blomedicd project involving the exponure of mice to neutron flux was dropped. During the deMed planning and preparation phase for the operation, many revisions of project plana were nscennitated by revisions to shot schedules, detailed analysis of IVY data, and support considerations. However, there was no general revision of project wjectives. h e exception 1ps that the objective of Project S.2 Crater Yeasuremmts) was reduced from obtaining true, as well an apparent, crater data because the probability of successfully obtnining meaningful data did not justify the support effortrsqulred. hother exceptton was the nddition of Project S.4, Minefield Clearance,under Navy sponsorship. Also during the detaIled planning phase the possibility of expanding the objective of Project 1.4 to include underwater pressure vs time measurements from a nurface burst over deep water was explored. Although LABL would accept, with certain restrictions, relocation of one of the barge shots to a position outside of the lagoon, at the time construction urnsiderations

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Ithn she efforta were devoted to documeuting'the inteneity and dlstrikdion of f d - out from a~ dots of the CABTLE teat. Numenns experhentpl f.iluree and extensive equipment losses resulted fmm blast and d e r wave action, delays in shot schedules, and the mpny operational difficulties lnherent in the sampling of fall-out over extended water areas. h spite of these difficulties a considerable volume of data '1~11collected rhlcb should make poasible the d n - ation of the nature and distribvtlon of fall-cut lrom Lnnd and d e r surface damptlons of high yield weppons. Became mold d these data have not been evaluated, this sactlon W be deooted to mmmuizing the important data 8Gvces and results for each shot. The ebvncteristics of the fall-out from dace cord and wince der shotn and the prellmtnnrJ fall-& contamid m patterns for Bhots 1 arid 5 are eummui%edin ee que nt sectlone of this chPpter. Shot 1 VPB detonated on the surface of the coral reef betreen Able md Charlie lalands, BikW Atoll. The data obtpined should give, on complete analysi6, a reasonably reliable picture of the nature anddintrlhtiond fall-out from a surface land shot ol high yield. The principal sources of data which cau be applied to such &udy are M follows: a. Edensive activity distribution and time d arrival data were collected at fall-oat stations in the lagoon and on the island# of BiLLni Atoll by Projects 2.50 and 2.a. b. Rpdlologid survey of several downwld atoU8, inclndhg Ailhghm, Rongelap, Rower&, IRirIk, and BiLnr, mu conducted under the leadership d E Bcovllle of Headquarters, AFBWP. The results of this surrey are reported elsewhere.' hples taken during this swey are being analyzed by Project 2.6% and field decay rate for 24 to 48 hours were colle&ed at several talanb of BikW Atoll by Project 2.2 and are reported by thnt project.' lected by Project 2.5b are reported in Appendix A, Project 1.5h preliminary report. cation~~of all pmma dosimet- stations. Project 2.1 presents effective gamma field decay rates" computed from gunmi; dintion exposure data, fall& arrival times, and gamma field rates at the time of dosimeter recovery. f. Limited Shot 1 data, related to fringe area and aeeaulary fall-oat, u e a m l e from free iloathg dpn hwys and YAG's SD and 40 which were west of ground sem at sbot time. Mditionnl informotion ia availnble from reporb of fall-out received by ITF-7 ship, rad fall-out received by the Japanwe 5htng vessel Fnhuyu ldptll V which wan in the downwind fall-out area. ~a iuteremting report re- to the bitter tmidmt h~ h n given limited circulation." west and clear ofthe BikW Atoll aceptfor Ahle and Charlie I6lmds adjacentto the seo point. The following limited informatim m a cbt.ined: poned in M arc of 35 to 50 miles ractlu in the quadrmta0rthwe.t d t h e zero point These bxy were instrumsntsd with liquid a d dry SMple collectors plus film wetem. The umples oWned pmnlde a gma v o ~ w l n dprofile of the actbity dbWbutifm and led themKhas to aswlad study of the physical and chemical propertie#of f.U-out from a .lukce Mentificatton a s , Tbs tro of bigheat intenalty meamred SO r/hr at rscovery time (+35 hr), a b n b g an order of mapttude of higher lntenaity thrn the total collector# on the -e buoys. 6 Monitor survey data collected by Tank Unit 7, TG 1.1, augmented by cmrrey data cole. Limited, reliable ground monitor m e r data were collected by Proiect 2.1 at the loE. Analy& of weather data for 8hoi 1 VPB completed by the Weather Bection, Headquarters Bhat 2 V.LI fired on abrge near the center ofthe ,¶I& 1 crater andthm senentially a a. Snccessful reemery wsm made of 11 out of 14 free UoaMng Whop rhlehwere dis-

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SNDY OF RESPONSE OF HUMAN BEINGS ACCIDENTALLY EXPOSED TO SIGNIFICANT FALL-OUT RADIATION The .ttldg represented the first obsurrtions by Americpas on human beings expeed to excessive &ses of radlation from W-out. The groups of exposed individunlr, are srdlldently large to allow good statistles. Althcmgh no pre-expoaure clinical studies or blood counts were available, it waa poesible to obtain MarahaUese and American control gmops that &&ed the exposed popllloton closely rith regard to age, eex, and background Thus the conclusionr W h i c h may eventually be dram from group comparison should be htghly reliable. of rPdi.tLon received, and the mrnwr in which the radintion dose wps delivered differed in smral important respects from that seen in the Hiroshima and Np&pBpbl mties, the Argonne or Loa Alamas accidents, or in the bulk of animal laboratory rndiatiw Qposures. In addition to a wide .pectrum of gwnma ray energies in the h i o n product field there wan a beta componenk &me clinical, and especially loboratory findings in this s …