Decay Spectra of Fission Products from Uranium-235 Thermal Fission: Comparison of Calculations with Experiments

Delayed fission product beta and gamma decay spectra following short and long ²³⁵ U thermal-neutron irradiations and cooling times were calculated and compared with corresponding experimental results that have recently become available. These decay-heat source terms are of importance to nuclear reactor safety, particularly to loss-of-coolant accident analyses. The comparisons between calculations and experiments have shown that the state-of-the-art computational methods and the ENDF/B-IV-based nuclear data bases are generally adequate for ²³⁵U thermal fission product spectral source term calculations. These comparisons have also revealed some shortcomings in the data base for short-lived nuclides whose influence on the aggregate fission product spectra is mostly noticeable at very short cooling times.