Coupled neutronics-fuel behavior calculations in steady state using the Serpent 2 Monte Carlo code

The two-level multi-physics coupling scheme in Serpent 2 is demonstrated by obtaining a coupled solution for the neutronics-fuel behavior problem using first the internally coupled FINIX fuel behavior module and then the externally coupled ENIGMA fuel performance code in a 3D assembly geometry. Parameters such as maximum pellet centerline temperatures can be evaluated from the coupled solution. The temperature fields obtained from the coupled solution are also used to estimate the effect of the detailed radial representation of the fuel temperature distribution compared to various radially averaged effective fuel temperature representations. The convergence of the coupled solution is investigated alongside the possibility to speed up the convergence by using the Uniform Fission Sites method.