>The radioactive half life is only like 35 years, I thought. That depends on the particular radionuclides that are created during the blast. Some radionuclides will have very short half lives while others will have much longer half lives. Also, half life means how much time must past for the radioactivity to reduce by half. That means that a 35 year half life would cut the radioactivity by half in 35 years and in another 35 years it's one quarter as radioactive as its initial radioactivity. A 35 years half life radionuclide would still be radioactive for a long time and, in close proximity to your soft tissues, the amount of radioactivity will fuck you up over the years. Dose over time and proximity to the source determine what happens to your body. You can live unharmed with the very small amount of Americium-141 in your smoke detector that is on the ceiling in your home, but put that same amount of Americium-141 inside your body and you'll definitely get very sick and die very soon. These radionuclides, no matter how active they are, are inside us all and causing trouble for us. This is what makes them dangerous and the likely cause of many modern cancers. All other carcinogens only add to the problems here.