Research reactor fuels

Approximately 250 research and test reactors are used for materials research, education and training, neutron scattering, isotope production, and materials research in 55 countries. This class of nuclear reactors operate over an enormous range of core power densities, ranging from near zero to more than 30 times higher than conventional pressurized water reactors. Because research and test reactors are designed to meet a wide range of needs, a broad spectrum of fuel system designs and material chemistries are used to meet reactor performance objectives; this is most apparent in the class of high-performance research reactors. High-performance research reactors are designed with the overarching goal of producing a sustained high neutron flux focused toward a specific purpose; for example, neutron scattering, material testing, or isotope production. To achieve this goal requires fuel systems designed to operate at power levels and fission densities that exceed the requirements of commercial power reactors. The complex irradiation-enhanced chemical evolution of the fuel with respect to the cladding, noble fission gases, and solid fission products determines the performance and lifetime of these fuels.