5=3/729.3 SUBJECT: LL Dececber 1953 Radicicgical Hazards in tho Marshall Islands arca During C.STLE routes through Wake and the Marshall Islands for specified periuds cf time and that arrangomonts shuulé be sade for elosing cr adifying these cutos on shcrt actice in the event such acticn beccaes essantial. It is alsc anticipated that, for operaticnel reasons, Scth Zaiwotik and Bikini air bases will be closed for shat perdids befcre and sfter each detonaticn. appropriate advisories to CINCP..C will incluce tnforeition supporting such activa. 7. Refsrence paragraph 7, ycur letter, the commonts below refer to the numbered parsgrapha of your letter: a. Reference parrgr=ph 7a(1), inf: rmation from atcaic sn-ts in Nevada indieato that clouda which reach the trvpcpouse ¢creop cut a unique ind maj -r porti.a of the fall-out at a distance -n the order of 100 miles cr lose froa GZ. Om the assumticn (as on IVY) that the tropopause acts as a trapping barrier for all ccntaminiti a at cr abeve this levol, it is expected thit high yleld shuts should similarly react, extending perhapa to a slightly greater horisontal distance due to the fect that the Pacific tr.ppause height is higher by approxinatily 15,00) feet. On the assumption that the trapping actica of the tropee pause 4a net se acaalete as to prevent a gredual sifting of mterial from above it, the wide and distant area coverage ty NYOO of ..20 is considered essential. The weak point of the first argument lies in the fact that, due to operational difficulties, none of the high yield ehots in the Pacific have been sufficiently documented in this resp::ct. Consequently, our operational planning anticipates a romote pcssibility of adverse conditicnas cut te populated atolls. be. Reference parngraph 7a(2), 1£¢ is suggested that the aug- mented cloud tracking effort cutlined above should alleviate the iifficulties presented. @. Reference paragraph 76(1), the decisions to shoot will be reached with the understanding that no health hazarts to units and popue lated islands of the Pacific are forecast. It is not baliowed the decision can be reached with the uiderstanding that no racsafa conditions condusive to pogaible adverse criticisa will ensua. The differontiation made hore is due to linitations on weathar and radsafe forecssting tacnniques and due to the many and diverse interpretations of radsafa conditions which are adverse, a. Reference paragraph 7¢(2), CJTF SEVEN pre-shot advisorics, (based on forecasts) will act contain conalusions requiring evacuation of populated isliacs to avoid « hoalth Basard. Information will neces- earily be insluded relative to the probabilitioa of something less tran & health hazard occurring. @. Raference paragraph 70(3), Sniwetok and Ujelang ire ccn- sidered thu aost critical sitas, and sinco contamination of these sites will likely be « collateral cccurrence, all task forse shins will & Cc-/8 |