Castle Bravo
The decision to carry out the Bravo test under the prevailing winds was made by Dr. Alvin C. Graves, the Scientific Director of Operation Castle. Graves had total authority over detonating the weapon, above that of the military commander of Operation Castle. Graves appears in the widely available film of the earlier 1952 test "Ivy Mike", which examines the last-minute fallout decisions. The narrator, the western actor Reed Hadley, is filmed aboard the control ship in that film, showing the final conference. Hadley points out that 20,000 people live in the potential area of the fallout. He asks the control panel scientist if the test can be aborted and is told "yes", but it would ruin all their preparations in setting up timed measuring instruments. In Mike, the fallout correctly landed north of the inhabited area but, in the 1954 Bravo test, there was a large amount of wind shear, and the wind that was blowing north the day before the test steadily veered towards the east.
Castle Bravo
The US Navy tanker was at Enewetak Atoll in late February 1954. "Patapsco" lacked a decontamination washdown system, and was therefore ordered on 27 February, to return to Pearl Harbor at the highest possible speed. A breakdown in her engine systems, namely a cracked cylinder liner, slowed "Patapsco" to one-third of her full speed, and when the Castle Bravo detonation took place, she was still about 180 to 195 nautical miles east of Bikini. "Patapsco" was in the range of nuclear fallout, which began landing on the ship in the mid-afternoon of 2 March. By this time "Patapsco" was 565 to 586 nautical miles from ground zero. The fallout was at first thought to be harmless and there were no radiation detectors aboard, so no decontamination measures were taken. Measurements taken after "Patapsco" had returned to Pearl Harbor suggested an exposure range of 0.18 to 0.62 R/hr. Total exposure estimates range from 3.3 R to 18 R of whole-body radiation, taking into account the effects of natural washdown from rain, and variations between above- and below-deck exposure.