Plutonium-239 is not waste. It is fuel. Use it. The longer the half-life, the less we care. Bismuth and tungsten are radioactive, with half-lives longer than t

Plutonium-239 is not waste. It is fuel. Use it. The longer the half-life, the less we care. Bismuth and tungsten are radioactive, with half-lives longer than the age of the universe, but they aren't going to hurt anybody.