SLIDE 1 BRAVO Cloud Dimensions. The BRAVO device was detonated on a sandspit near Namu Island, Bikini Atoll at 0645 March 1, 1954 (28/2/54 1845 GCT). It was a 17 MT thermonuclear yield. The upper limit to cloud height was 40 km (25 miles). The diameter 10 minutes after the burst was 110 km (70 miles). The fission/fusion ratio was estimated to be 0.47. It was the first in the Castle series of experiments. The second shot was 100 KT and occurred 30 days later. The next three shots were 150 KT, 9.5 MT and 10 MT respectively. The 9.5 and 10 MT shots may have contributed some fallout at Rongelap and Utirik, perhaps as mich as a 8% of the surface activity. These later shots occurred after persons were evacuated. T T T TTT T 380 hos “T UpperLimit. Cloud Height Lower Limit Cloud Top nea Sob od tt 4 / TTT 300 tg APIS ed Gadi 1,400f1. Pap oe ° Oiometer a Cloud Bottom Height | 95,30081 1 oo it é T 4 a ji | cle isp, 3 4 i Stem Ciometer 23,400 ft 4 Cloud Diameter, 10° Feat 280 — TTT T oo J NY 4000ft cpa Cloud Height (MSL) and Stem Orometer, io Feet a ZL 4 ° 4or—r Time, Minutes Cloud Dimensions: he: me we oa *. © 6 * Operation CASTLE - Shot 1 - Bravo.