John, Peterborough asked:
Nuclear power plants - how much energy remains in there once you've taken the rods out?
Steve - Nuclear power plants arenít doing fusion, theyíre doing fission which is splitting big nuclei up: uranium. In a nuclear power plant you only use a very small fraction of the uranium so thereís something like 50 times more energy left in there that weíre unable to tap except through whatís called fast breeder reactors which we donít currently do.
Chris - How do they work?
Steve - This is a long question. They work by using the fast neutrons from nuclear reactions, from uranium, to attach to the inert part of uranium (uranium 238) to make plutonium. Plutonium can fission like uranium 235. Thatís a complicated answer.