Nagasaki
On the day of the nuclear strike (August 9, 1945) the population in Nagasaki was estimated to be 263,000, which consisted of 240,000 Japanese residents, 10,000 Korean residents, 2,500 conscripted Korean workers, 9,000 Japanese soldiers, 600 conscripted Chinese workers, and 400 Allied POWs. That day, the Boeing B-29 Superfortress "Bockscar", commanded by Major Charles Sweeney, departed from Tinian's North Field just before dawn, this time carrying a plutonium bomb, code named "Fat Man". The primary target for the bomb was Kokura, with the secondary target being Nagasaki, if the primary target was too cloudy to make a visual sighting. When the plane reached Kokura at 9:44 a.m. (10:44 a.m. Tinian Time), the city was obscured by clouds and smoke, as the nearby city of Yawata had been firebombed on the previous day. Unable to make a bombing attack on visual due to the clouds and smoke and with limited fuel, the plane left the city at 10:30 a.m. for the secondary target. After 20 minutes, the plane arrived at 10:50 a.m. over Nagasaki, but the city was also concealed by clouds. Desperately short of fuel and after making a couple of bombing runs without obtaining any visual target, the crew was forced to use radar in order to drop the bomb. At the last minute, the opening of the clouds allowed them to make visual contact with a racetrack in Nagasaki, and they dropped the bomb on the city's Urakami Valley midway between the Mitsubishi Steel and Arms Works in the south, and the Mitsubishi-Urakami Ordnance Works in the north. 53 seconds after its release, the bomb exploded at 11:02 a.m. at an approximate altitude of 1,800 feet.
Stafford L. Warren
The detonation of the two atomic bombs in Japan "raised as many military and medicomilitary questions as they answered". A series of nuclear tests was planned, codenamed Operation Crossroads. Some 42,000 personnel were deployed to Bikini Atoll as part of Admiral William H. P. Blandy's Joint Task Force 1 to conduct the test. Their health and safety was Lyons's responsibility, but the specialised job of radiological safety was handled by the Manhattan Project. Warren, as Chief of the Radiological Safety Section (RADSAFE), planned and implemented measures to assess, limit and control the impact of radiation. Teams were given special training at Oak Ridge in the operation of instrumentation to measure radioactivity, and the interpretation of their readings. Training was also conducted aboard en route to Bikini Atoll, where it arrived on 12 June 1946. In all, some 3,500 personnel were assigned to RADSAFE. Warren was appalled by the effects of radioactive contamination on the environment. "The deadly range of radioactive products from the atomic bomb has been clearly demonstrated under controlled conditions..." he wrote, "the only defense against atomic bombs still lies outside the scope of science. It is the prevention of atomic war."