Energy-dependent fission yields in advanced reactors

Fission product yields vary over incident neutron energies and between the different fissionable nuclides. An improved representation of this energy dependence could affect the assessment of advanced reactor designs which utilise a fast neutron spectrum. The present work involves the implementation of energy-weighted averaging of fission yields in various reactor unit cell models to determine its effect on neutronics, spent fuel decay power and radiotoxicity. The energy dependence is captured through the GEF code, which has enabled the estimation of fission product yields at any incident energy point. Yield
values from 77 energy groups were condensed to a single value by preserving overall isotope production rate from fission. Unit cell investigations were performed with a modified version of the SERPENT Monte Carlo particle transport code. The results indicate that the neutronics and radiotoxicity implications of yield energy dependence is likely to be negligible in most reactor designs.