A thorium reactor is a type of nuclear reactor that uses thorium as its primary fuel instead of the more common uranium. Thorium is more abundant and produces less long-lived radioactive waste. In these reactors, thorium-232 absorbs neutrons and transforms into uranium-233, which can then undergo fission to generate energy. These reactors are considered safer than traditional nuclear reactors because they operate at lower pressures and temperatures. Additionally, they have a built-in mechanism that can automatically shut down the reaction in case of an emergency, reducing the risk of meltdowns and other accidents associated with nuclear power generation.