In view of the small amount of experience with water surface shots, cautious actions were imperative. Subsequent movements and events on shot day were delayed for approximately one to two hours, a factor of considerably less importance than taking an unnecessary risk with the embarked task force. At H+4, the radiological survey helicopters were launched from Bairoko. he Based on this survey, reentry to the lagoon was set at 1500. The survey covered the eastern and northern islands of the atoll a f was conclusive enough to limit scientific recovery to Eneu, Bikini, and] Aero- koj on the first day. The survey on D+l indicated that recontaminafion was limited to the Iroij-Aomen and the Bikini-Eneu sequence of islafds. t | No significant secondary fallout was encountered at Bikini as a res lt of this detonation. i E D-day readings of 4.2 R/hr were obtained at an altitude of 500 feet (about 150 meters) over ground zero. This contamination moved to the west and southwest, allowing small-boat operations in the area of ground zerd - tLa- goon water movement toward the Southwest Passage increased radiation levels in the vicinity of Oroken, Bokaetoktok, and Bokdrolul. diation intensity on the various islands. Table 44 sh Figure 84 gives the radi s tfa- ion RRNpeneer mee Lagoon water was substantially contaminated with radioactive sed iment. contours at H+l. directed to make a low-altitude (300 to 600 feet; 92 to 183 meters) at various atolls southeast of ground zero. urvey Table 45 lists the resu its of this survey. During the shot day and throughout the night, secondary fallout encountered by some of the ships as indicated in Table 46 as epee nee AS Oe At 1400, Wilson 3 (and later Wilson 4, flying from H+l2 to H+26) was (Reference 17, Tab N). Enewetak Atoll reported a maximum reading of 0.004 R/hr. Weather connaissance flights on D+l to the west, south, and northeast encoun re- red 292 7) wy