Uranium is one of the fissile material which is used for power generations. But All isotopes are not categorised as fissile. The certain minimum standards have to be met to qualify as fissile material:
- It should be able to sustain the chain reaction.
- It should have a high probability of fission when bombarded with slow/fast neutrons.
- Should release two or more neutrons on an average per collision so that it can compensate for non fission and absorptions in the moderator.
- It should have reasonably long half life.
- It shall be available in large quantities.
U-235 fits into above all criteria except the last one. Its enrichment is one of the important reason for high cost. Naturally uranium is available in the form of U-238. It is not fissile. .
The Advantage of thorium reactors are as follows:
- The first advantage is that it is four time more available than the uranium and is widely spread in the earth crust.
- Thorium has superior physical and nuclear properties.
- Smaller size of the reactor.
- There is reduced production of Plutonium and actinide. Hence low amount of radioactive waste.
- Thorium reactors offer better resistance to nuclear weapons of proliferation.
- Reduced risk of nuclear melt down.