: ai . he ~ . . wreh - 5ares as oolnils ant oie eee thal tas tinction * a ee ee soe - * _ ete,a ee dee we ree Bt ee er ne So i SEar ees eee ABSTRACT This report is an addendim to tha final Wport of Project U.1, Operation CASTLE, and Its purpos3 is to consider the physical factors dosinetry of the fall ae on the Marshall Yslands fras the first ahot of Operation CASTLE Data was summarize: = hoe. fron field fiadiological Safety surveys, fallout radiochemical stidtes, and fallout gamma spectral measurce aentg, The influence of these and other facturs on an ovaluation of gurvey meter response and total dose estinates waa considered, Estimates of fallout duration tines and enercy distritution of the dose fron a plane source were made and the effect of diffuse source=goonetry, . on the depth-dose to air~-dosa relationship was considered, doses fram Since which data atruct ths soft parma and beta radiation were also the fallout incident created an initial collection was of secondary importance, avont have been uncertain, choof the rather than exact. Superficial,- considered, emergency dusting attempta to meco? cata was indicati However, a fairly consistent estimate of external gamma dosage was possible, ai thou gh the question of beta exposure remains mostly unanswered, It has been assumed that no significant neutron or alpha particle exposure occurred, Internal doses from in- haled or ingested material and the bio-medical aspects of the incident have been discussed in other CASTLE Project 4.1 reports, It was concluded that: (1) the AN/POR-394 requires a correction factor of about plus 20 percent in dose-rate readings mada under the conditions described ; (2) dacay cf the 70.835 (3)th of the fallout is believed expressible. by the factor of T (3) the external gamma dose was delivered primarthy by radiation energies of 100, 700, and 1500 kev; (4) the beta dose was delivered by beta radiation of maxinum energies of 0,3 and 1.5 Mev, mostly from fallout deposited on the skin itself; (S) the exposures occurred betwesn 4 and 73 hours after the detonation = the fallouts were probably of 12-hmrs duration; (6) diffusa source fpeometry increased the midline dose by about 50 percent caonpared to the midline dose which would have resulted from a hilatarel narrow beam exposure of the same air-dose; (7) error in the estinates 4s believed to be less than 50 percent; and (3) total air ganna doses were estimated as follows; 8l r; and Utirik, 13 r,. Rongerik, 86 r; Rongelap, 182 r; Ailinginae, : j