REST TiC kien rec@® ect 12'5 bt a DISCUSSION OF OFF-SITs FaLLOUT ‘ tbe 1 in, of Pallout off-site followed the pattem immediately established at and adjacent to the proving ground where the cloud in gmezal aoved east north easterly with prevailing winds. Task force ships southeast of NAN received the first fallout, being on the southern edge of the main strip of contamination. Fallout on the ships ranged from in- tensities of 1500 milliroentgens per hour on the BATROKO which was closest to the center of the fallout path to a few millircectgens per hour on vessels farther south, Fallout began at Rongerik Atoll at 1348 hours, 1 March as show by a self-recording radiation detection station placed there by the KYOO AEC and operated by personnel of the Air Weather Station. This instrument went off scale at 100 mr per hour at 1418 hre 1 Varch. Based upon query from air weather personnel a monitor was dispatched with the supply PBK on the moming of 2 March. A ground reading of 2000 or/hr was obtained at 1115 by the mnitor who evacuated 8 of the personnel on his ow initiation and recomended evacuation of the re- mainder as soon as possible based upon the high radiation levels. Thies was concurred in and the remaining 20 were evacuated by Fal! at 1445, 2Mareh. Calevlations estimating the dose received indicated that personnel evacuated at 1115 would have received 85 r apd the racainder 95 r- This was in fair agreezent with readings of film badges on per- sonnel, Maximum film badge reading was 98r representing 3 men, 52Fr for 1, 44r for 1, 40r for 9. Average dose for all personnel, 54 roeatgms. Inasmuch as the data from Rongerik is the only data showing exact time the fallout occurred at any location east of the proving ground and adjacent to populated islands affected by substantial radiation, its importance is such that calculation of dosages received by native populations are based upon it for time of fallout in those locations. 4 detailed analysis of this data is therefore appended in the medical tab. Survey of Rongelap was made by Pattem ABLE of Security Patrol Squadron (Patron 29) with NYOO Scintameters aboard on 2 March and found an estimated reading of 6750 mr/hr. (Later calibration for aerial survey equipment revised this to 1350). Based on this and its proximity to Eongerik it was decided thet it would probabiy be necessary to evacuate the atoll. Consequently, the PHILIP, DDE 498, was dispatched to reach Rongelap on the moming of 3 Marck. In the neantine a Pal was sent to ground survey the atoll and at 1830 hours, 2 Lareh, their grouna survey showed @ reading of 1400 milsiroentgens per hour. Caleriation of acsage to 3 Maren incicated about 110 roentgens so the order to evacuate was given. The destroyer PHILIP evacuatec the natives by 0935 to 1025, 3 March. Calculation of the total dose indicated that 130 roentgens were received. Detailed calculations are appenced in the medical tab. A total of 65 natives were recoved, 16 natives (the old anc sickest) by PSL and 49 by DDE, tiee=*