Therefore, proposed reactor designs must attempt to physically isolate the protactinium from further neutron capture before beta decay can occur.Īs for uranium-based reactors, the basic classification of thorium nuclear reactors is based upon the average energy of the neutrons, which cause the bulk of the fissions in the reactor core. 233 Pa decays (negative beta decay) to 233 U. 233 Th decays (negative beta decay) to 233 Pa (protactinium), whose half-life is 26.97 days. The half-life of 233 Th is approximately 21.8 minutes. If 232 Th is loaded in the nuclear reactor, the nuclei of 232 Th absorb a neutron and become nuclei of 233 Th. On the other hand, thorium is “only” a fertile material, and the main problem can be directly in the breeding of fissile uranium 233. Currently, these reactors provide almost 90% of the world’s nuclear electricity generating capacity.Īccording to proponents, the thorium fuel cycle offers several potential advantages over a uranium fuel cycle, including thorium’s greater abundance, better physical and nuclear properties (e.g., the lower capture-to-fission ratio for thermal neutrons), reduced plutonium and actinide production, and better resistance to nuclear weapons proliferation when used in traditional light water reactors. During the fuel burning, the content of the U-235 decreases, and the content of the plutonium increases (up to ~1% of Pu ). The most common nuclear reactors are light water reactors (LWR) that are based on the uranium fuel cycle and use an enriched uranium fuel (~4% of U-235) as a fresh fuel. The main purpose of the nuclear reactor is to initiate and control a sustained nuclear chain reaction. In general, a nuclear reactor is a key device of nuclear power plants, nuclear research facilities, or nuclear-propelled ships. Therefore, additional fissile material is necessary to initiate the fuel cycle. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as thorium 231), which are insufficient to initiate and sustain the nuclear chain reaction. During the fuel burning, thorium 232 transforms into a fissile uranium 233. Thorium reactors are based on the thorium fuel cycle and use thorium 232 as a fertile material.

Thorium builder