EIR_EVENT OPERATION HARDTACK 1. FIR was detonated at Q550M, 12 May 1958, on a barge off Charlie Island (Nam Isiend, t Bikini Atoll), The cloud was reported by rader to have risen to $0,000 feet, then stabilized at 60,000 feet, Initial radar reports from the USS Boxer indicated the cloud moved on a bearing of 260 degrees at approximately 12 knots per hour within the first 12 minutes, At Ht+25 minutes, radar from Rongelap confirmed the bearing and height at 90,000 feet. Within one-half hour after the burst neither radar cculd track the cloud. A P2V reported over the USS Boxer at H+30 minutes for initial cloud tracking and radiological surveying, but owing to commnication difficulties, no immediate information vas obtainable. 2. Contact was resumed with the P2V, and at 0825M on a bearing of 240 degrees and 060 degrees from Oboe at 200 to 500 feet, .4 r/hr was reported, The PoV was directed to fly at 10,000 feet east of Nan. 30 miles he reported 340 mr/hr at 1O10M, at 2,500 feet, he reported 240 m*/hr. At At 1112M, 10 miles east of Nan In general, the use of the P2V was ineffective because of initial communication difficulties. 3. Ahslicopter survey by TU-6 at Nan indicated 36 mr/hr at George at 0909M and indicated 370 mr/hr at Charlie at 0922M, Other islands (Uncle, William, Peter, Oboe, Tare, Nan and How) indicated only normal nominal background readings, 4. ™ Ms! “4 Ss ek ek The fallout forecast was accurate, except that tha spread was more northerly than predicted. The main axis was forecast 220 degresas through 040 degrees, end substantially all of the fallout fell within a SE this area. Bra fo OAT oleaeS 2 Ty oat amr hk. wake |