Question

Thorium-232 is not fissionable. How then is it used within a thorium fission reactor?

Answer 1

There are two type of fuel used in nuclear reactors

1) Fissile material - These substance undergo fission directly with slow neutrons liberating large amount of energy. Example U- 233 and Pu- 239

2) Fertile material - These substance in itself is non-fissible converted into a Fissile material by reaction with neutron Example U-238 is converted into P-239 ; Th- 232 is converted into U-233.

Th-232 is a fertile material it cannot undergo fissile reaction by bombarding with neutron. Th-232 is not capable of sustaining nuclear fission chain reaction because neutron produced are having low energy than original neutron used in bombardment.

For use in nuclear fission reaction it is converted into fissible material. Thorium - 232 absorb a neutron and converted into Th-233 with half life - 21.8 minutes .Th undergo negative beta emission to Pa-233 and Pa- 233 undergo beta negative emission to Uranium -233 . It is called Uranium breeding. This is the material used in nuclear reactor.

- Uranium 233 breeding n+ 332Th→ 332 18