Thorium-232 is a naturally occurring isotope of the element thorium, which is a silvery-white metal found in small amounts in rocks and soils. It has a long half-life of about 14 billion years, making it stable and non-radioactive in terms of immediate health risks. In nuclear science, thorium-232 is significant because it can be converted into uranium-233 through a process called neutron capture. This conversion allows thorium to be used as a fuel in nuclear reactors, offering a potential alternative to traditional nuclear fuels like uranium-235.