tamination was found in regions which confirced the forecast cloud tre- jectories, the requirement for 8/2, through E448 hour tracking coverage was cancelled, As a result of the report from Rongerik, the advisory to CIUSPAsFL? at 2000 hours B Day included mention of fall-out at Rongerik plus einor fall-out at Rongelap and other northern Marshall Islamis. The fall-out was attributed to an 8/12 hour change in the forecast air particle tree jectory for the twenty thousand foot level. This trajectory, foraerly moving toward the ENE, was reforecast to move toward SE in a circuler clockwise path through south to west. The CINCPACFLT advisory included no health hazard problem for surface and air routes, but that fall-out on Bikini-Atoll, as well as danage to structures, would delay reentry ser eral days. During the trip back to Eniwetok on the night of B Day, the fleet en- countered a wide area of finely divided (arparently less than 5 aicron) particles which caused top-side intensities as high as 350 ar/kr. Appropriate measures were instituted by the Navy Task Group Commander to the affect that all personnel not essential to open deck duties would remin indoors. Ship's weather doors were closed and the washiown systeas ope rated intermittently to bold down the levels. Based on the advisory from the weather detachment that their instru- ment was off-scale, the Air Task Group, on the morning of B/l day, sent a monitor by amphibian aircraft to check the Rongerik situation. This monitor upon arriving over Rongerik, reported the atoll contaminated and requested permission to start evacuation of personnel. At about 1300 the monitor reported readings on Rongerik of 240 mr/hr at 250 feet and 3.2 r/br one inch off the ground. The Rongerik evacuation was completed in two segments, the first group (8 people) coming out by B30 hours and the second group (20 people) by 535 hours. The special AEC/NYOO Kwajalein Flight ABLE, requested the previcas night, had been instructed to make an in-flight report upon reaching Teongi. (4 preliminary Flight ABLE report indicated 1350 m/mr on the ground at Rongelep, 445 mr/br on the ground at Ailinginae ani zero for Wotho.) Aco cordingly, it was decided to start a destroyer on the way to Rongelap iatediately and to set up a Sh-16 amphibian with monitors to check the sure face conditions eat Renzelap before dark. The destroyer was directed to be off Ronzelappeady to start evacuation at dawn the following day, 4 Trust Territery:¥epresentative with interpreter was requested to move by PEM from Ewajalgkm to arrive et Rongelap at the same tine. The Si-lS was set up, two ressémsible monitors were especially triefed to make readings at waist heickt, use several meters of the same type for comparison and to use 4ifferent types for cross-check. An average reaiing of 1.4 r/i made in ths living area of Rongelap Islend by these monitors was used in the decision the same night to order the destroyer to commense evacuation operations at dawn. Evacuation operations began about 0730, 3 Merch ani