Any discussion of the use of nuclear weapons on Hiroshima and Nagasaki tends to avoid one glaring issue. The time frame. To military commanders, the A Bomb was a tremendously powerful bomb and little more. With the development of the H Bomb it became the potential destroyer of civilization. Pictures of scientists doing research on the aftermath of the explosions in Japan, and the Pacific tests, show a pathetic lack of knowledge of the dangers of radiation.
Protection is mainly gloves and foot coverings worn over shoes.
A previous writer correctly stated the Japanese viewpoint of surrender being dishonorable. I recall a story of one Pacific island being recaptured by US Marines where the only captive taken was a legless officer who was trying to impale himself on his ceremonial sword when he was taken prisoner. An invasion of Japan by allied forces would have led to enormous loss of life on the armies involved as well as the Japanese civilian population. While the weapons were powerful, the physical damage would have been far less in European cities due to concrete, steel and brick construction, and the effects of radiation were not even a consideration at the time. A comparison between Pearl Harbor, Hiroshima, and Nagasaki is quite valid.