You are repeating the standard mantra. However, all the experience of nearly 80 years and the understanding of radiation biology that confirms it, shows that the effect of a nuclear bomb are indeed "somewhat contained", as you put it. Sakharov, and Einstein and other serious scientists of his day, were wrong. They did not have the evidence we now have. It is a biological matter that low and medium exposure to nuclear radiation is harmless and its effects do not accumulate. They could not possibly know then what we know now. I am not in favour of nuclear weapons, but they should no longer be a source of extreme irrational panic and horror as Sakharov and others thought decades ago.
Wade Allison is Emeritus Professor of Physics and Fellow of Keble College at the University of Oxford, and the author, most recently, of Nuclear is for Life. He is also Honorary Secretary of SONE (Supporters of Nuclear Energy).