Spent Nuclear Fuel (SNF) contains several thousand nuclides, concentration of which can be estimated using coupled neutron transport and fuel depletion calculations, based on nuclear data, operational history, geometry and material composition of fresh fuel. However, for cooling times in the range 1-1000 years, only up to 40 nuclides significantly contribute to the observables of interest for SNF: decay heat, neutron and gamma-ray emission, and reactivity. Additionally, power and burnup indicators are considered. These nuclides can be divided into 3 groups: actinides, fission products and activation products.
The list of important nuclides for a typical light water reactor will be obtained from literature. For each nuclide, its production path will be outlined, taking into account neutron induced fission, neutron capture and radioactive decay. Sensitivities of the production of each nuclide to all relevant nuclear data will be estimated, if possible, analytically. For more complex production chains, the sensitivity will be determined using random sampling codes, such as SANDY, and propagated with coupled neutron transport and fuel depletion codes, such as Serpent. For relevant nuclear data parameters, an overview of the current status of experimental and evaluated data will be given. Based on the sensitivities and current nuclear data uncertainties, a list of nuclear data requirements for improvements will be recommended.