Which fissionable fuel is used in all US nuclear reactors?

Uranium is the primary fissionable fuel used in all US nuclear reactors, specifically uranium-235 isotope, which constitutes a small fraction of natural uranium. This choice is supported by the fact that when uranium-235 nuclei absorb a neutron, they become unstable and undergo fission, releasing a significant amount of energy, as well as additional neutrons that can propagate a chain reaction.

Most nuclear reactors in the United States are designed to utilize this isotope due to its availability and the relatively well-known technology for handling uranium as reactor fuel. The enrichment process increases the proportion of uranium-235 to enhance its fissionable properties and meet the specific fuel requirements of light water reactors, the most common type in use today.

While other materials like plutonium, thorium, and tritium are relevant in various contexts, including advanced reactors or research applications, they do not serve as the primary fuel source across all operational nuclear power plants in the US. Uranium remains the cornerstone of the nuclear energy industry due to its proven efficiency and substantial infrastructure developed over decades.