Applying Advanced Neutron Transport Calculation for Improving Fuel Performance Codes

We present refinements of the Helium production model implemented in the TRANSURANUS fuel performance code. Helium is produced in oxide fuels by three main paths: (i) alpha decay of the actinides; (ii) (n,a) reactions; and (iii) ternary fission. In this work, the contributions due to ternary fission and the 16O(n,a)13C reaction as well as some refinements in the 241Am burn-up chain have been included in TRANSURANUS. The 16O(n,a)13C cross section has been evaluated in PWR conditions by means of the MCNP Monte Carlo code for different fuel compositions. The Monte Carlo depletion code VESTA has been used for the validation of the Helium production model. For specific PWR conditions the comparison of TRANSURANUS predictions with those of VESTA is satisfactory, and the applied cross section library is the main source of uncertainty