reeentry for YANKEE, personnel were re-grouped, following which, all ships put to sea (some te EXIWETOK, others scheduled for BIKINI roll-up, to remia overnight at sea due to water readings at the NAN Anchorage of appeacimately 20 mr/he). Relative te the apparent laek of up-welling of radioactive material, some work was done early in the operation by Dr. J. Isaacs of Project 1.6 (Water Wave Studies) whieh disclosed a deep stratum of radjoactive water which sgoved aocrthwest toward GEORGE’ and HOW, just prier to KOON, This layer was quite concentrated Vertical sections were run at several stations using 4 dunked survey mater, The distribution was as expested with the astonishing addition of a stratum of clean water at about 110 feet overlying the radicactive water at 130 feet. Since no major storm wasexperienced during the operation, there remains for conjecture the effegtof4 violent disturbance of the lagoon. Whether or not this low-lying layer of radioactivity would be brought up and distributed mére or less uniformly iadepth by sueh a dise turbance is net mown. 7. Split Atoll Operations: ‘The onesingle feature of the CASTLE Opere- tion which nade Radsafe somewhat difficult was the fact that coverage was required at ‘bothBIKING|and ENTHETOR Atolls. These two sites are separated by 180 miles; persone)_krensportation, betugsn, thety,sites way prinarily oy Cmu7? -airoraft. _ swe wed Astheoperetion progressed@ point wisreached at which 4 capability of firing & shot et erch atoll was simultaneously maintained to take advantage of faverable winds occurring at one site and not the other, The principle adverse effect of this situation was the requirement to split the basic 1 7.1 Radsale Unit personnel and equipment in order to be ready to Operate regardless of which atoll became favorsble for a shot. During the planning stage this unit was designed to sove from one atoll to the otner %< 50