meee days, after which time water leaching became stabilized and radioactive decay became pre- dominant. Radioactive decay approxima¥ed the T~':? law in the longer periods and was de- termined from laboratory counting of an air-filter dust sample collected 40 min after shot time from a point 7'4 miles south of ground zero (Table 10.17). 10.1.3 Lagoon Contamination Lagoon-contamination surveys were conducted f10m TG 132.3 water-sampling helicopters. These helicopters could hover over water positions A, B, C, D, E, F, G, and H (Fig. 10.1) and sample water at the surface and at 30-[t depths. These samples were returned to the radiological laboratory for evaporation and counting. No attempt was made to correlate counts/ minute/milliliter and milliroentgens/hour. The purpose of this survey was to use counts/ minute/milliliter as an indication of diffusion of radioactive material throughout the lagoon and as an indication of possible ship contzmination in the Eniwetok anchorage (Table 10.26). Results of these lagoon surveys illustrate the nature of diffusion in the upper lagoon and the currents that move from east tc west on the surface and from west to east in the subsur~ face in conformance with the surface trade-wind directions, 10.2 KING SHOT Location: Reef—northeast of north end of Runit Island, Eniwetok Atoll. Height of burst: 1480 + 20 ft. Yield: 570 + 20 Kt. Timelired: 1130, Nov. 16, 1952. 10.2.1 Cloud Disposition Fall-out pattern predictions indicated strong easterly winds below 35,000 ft. Upper-level ee A tem BAG Cok RIES OR IRAeA IAC EIae weet hee ME BF eneORT NNRAREUe ARIDANEDnTi SE 2 RGwENiitreme we winds just below the tropopauee were toward the southeast quadrant after shot time. Surface radex was from 210” true to 290° true from H hour to H+ 3 hr. Air radex was concentrated in Ground Contamination The residual contamination from Mike shot obscured residual contamination from King shot in the northern islands. Runit and the southwestern islands revealed material increases in radiation readings after King shot (Fig. 10.2). Contamination of Runit Island from King shut had decayed to negligible amounts by K + 5 days (Table 10.23). 10.2.3 Lagoon Contamination Aerial sample collection was completed by H + 3 hr, and no material increase of radioactivity was noted in lagoon and anchorage stations. 10.3 POTABLE WATER SUPPLIES Samples of distant-atoll water supplies were analyzed in the radiochemical laboratory before and after each shot. No radioactivity above background was noted in any potabie water supplies. Samples were obtained from springs and cisterns of Kusaie, well-water stores from Majuro, untreated storage water at Ponape, drinking water and cistern storage at Kwajalein, drinking water at Bikini, fresh water at Ujelang, and drinking water of Parry and Eniwetok islands. 65 “t parecernears 10.2.2 74 aan Cp atad dime the west-southwest sector. The atomic cloud rapidiy dispersed owing to strong wind shear at several altitudes; therefore ro consequent heavy fall-out was observed.