What is the difference between fissile and fertile material?
The fissile material is the one which undergoes nuclear fission (splitting of atom) upon bombardment by slow/fast neutrons. The fissile materials used are Uranium 235, Plutonium239 and Uranium233. (India is the only country in the world to use U 233 fuel, used in Purnima & Kamini Reactors. Fertile material is the one which by itself is not fissionable but will capture the neutron and will get converted to a fissile material. Examples are Uranium 238 becoming Plutonium 239. Thorium 232 becoming Uranium 233 etc.