Dear Prof Steve
Other than Uranium and Thorium heavy elements, which other Actinides can be considered for generating nuclear power in a nuclear power plant ?.
Thanks & Regards,
Prashant S Akerkar
Wow, you asked me a relevant nuclear physics question, for a change! Excellent, but the question is a little generalized, so I will clarify a bit.
Uranium has two fissile heavy elements which can be used for generating nuclear power. In fact, 233U (92 protons and 141 neutrons) is made from 232Th in a reactor. So, by itself, Thorium is actually not useful. Once nuclear reactions are started, however, the 232Th (91 protons and 141 neutrons) starts absorbing neutrons and becomind 233Th (91 protons and 142 neutrons). That decays into 233U, which is actually what fissions and creates power. So 232Th is a breeder isotope, which can be used for fuel by making 233U on the fly. This concept is critical for traveling wave reactors, which are fascinating reactor ideas that should definitely be explored. 235U is also fissile, and occurs naturally in small amounts, which is where we started this whole mess of making fissile material. Of course, 239Pu works, we downblend it from old weapon stock all the time to destroy it as reactor fuel.
Basically, a lot of the isotopes (different types of chemical elements) up in that mass range with an odd neutron number are fissile...but not so many of them have a half life long enough to be actually manufactured into fuel and used for power. There's an excellent list of the half lives here: http://en.wikipedia.org/wiki/Fissile_material#Fissile_nuclides
I'd say that anything with a half life under 100,000 years is useless, the fuel would be too hot to manufacture reasonably. That leaves a few isotopes of Th, U, Np, Pu, and Cm as usable...but really only Th, U, and Pu are ever used for practical reasons.