What is the radiation danger from nuclear submarines that are sunk?
As long as the core is intact and surrounded by water, almost none. There are a wide range of variables, like what happened when the boat went down. Did it implode? Crash into the bottom at speed? Usually, even if implosion and a crash occur, the danger isn’t great. Far and away the greatest radiation hazard is from damaged and leaking fuel elements. They’ll put nasty stuff into the water, but they’re pretty safe welded into a core assembly and stuck inside the pressure vessel.
