I know what fission is and what fusion is. Who needs em? I figure that most of the energy content of particles emitting from naturally radioactive materials is lost to distant locales. Am I right? If you took a sizable chunk of radioactive mineral, like uranium, whether refined or not, whether enriched or not, if that chunk were encased in a layer of lead then wouldn't it get warm after a bit? And wouldn't it stay warm for nearly forever? Please: could I use an arrangement like that to heat my cabin?