10-10-2021-0119 - Thorium Fuel Cycle (nuclear fuel cycles, closed fuel cycle; etc.)

 The thorium fuel cycle is a nuclear fuel cycle that uses an isotope of thorium, 232

Th
, as the fertile material. In the reactor, 232
Th
 is transmuted into the fissile artificial uranium isotope 233
U
 which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as 231
Th
), which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source is necessary to initiate the fuel cycle. In a thorium-fuelled reactor, 232
Th
 absorbs neutrons to produce 233
U
. This parallels the process in uranium breeder reactorswhereby fertile 238
U
 absorbs neutrons to form fissile 239
Pu
. Depending on the design of the reactor and fuel cycle, the generated 233
U
 either fissions in situ or is chemically separated from the used nuclear fuel and formed into new nuclear fuel.

The thorium fuel cycle has several potential advantages over a uranium fuel cycle, including thorium's greater abundance, superior physical and nuclear properties, reduced plutonium and actinide production,^[1] and better resistance to nuclear weapons proliferation when used in a traditional light water reactor^[1][2] though not in a molten salt reactor.^[3][4]

https://en.wikipedia.org/wiki/Thorium_fuel_cycle