over inhabited atolls in the sector. Since this mission took place at about H plus 6 hours to H plus 12 hours, the readings taken during the low level passes (at approximately 200 feet), when extrapolated roughly to the ground, were sufficimtly accurate to justify early assumptions relative to the presence or absence of hazardous contamination at these atulls, For shots subsequent to BR.VO the readings obtained iniicated negative or insignificant contamination for all such low level passes. Consequently, no further action was taken for these atolls on shot day exeept to schedule a cetailed preci- sion aerial survoy for D plus 1 day (NYKOPO KWaJ.LEIN Flight aalz, Tob C, Incl 6). (No NYKOPO flights were made on shot day in order that sufficient tine could elapse for fall-out to cecur in advance of the flight and in orler that the highly sensitive instruments used would not be rendered impotent due to high aircraft background arising from flight through contaminated cir.) Use of the WB=29 for low lewel passes cover tho northorn Marshalls was not made on FR.VO. For this shot the effort 4s planned ani exccutcd used < manned ground monitor station at the weather station on RONGERIK for early alert, and NYKCPq Flight «BLE on BRiVO plus one day. Unfcrtunately, the intensitics experienced on RONCERIK exceeded the limit of the instrument supplied to the weather detachment (loo or/hr maximm). The dctachment's report of "instrument off- scale" was not viewed with alarm duc to the fact that the task force fleet, mich closer to grounl sero, was. experiencing intensities of 200 to 300 mr/hr — at about the same time, plus the fact that clouc tracking operations in the RONGERIK area did not indicate intensities considercd execssive in ccmparéson. However, on the basis of the information known at the tine, a monitor was dispatened by amphibious aircraft early the following ocrning anu the ‘YKOPC Flight ~SLE aireraft was directed to make an in-flight report upon resching TAONGI.. These actions resulted in positive information on the fall-out situa- 39 .