COX-SIMU: A 3D Real Time Nodal Kinetic Code for the EDF EPR TREFLE Simulator

The goal of the EDF TREFLE® project is to provide to the EPRTM project a full-scope simulator in order to perform design studies and operator training for the EPRTM reactor under construction at Flamanville, France. This article describes the 3D real time neutronic module, COX-SIMU, developed by EDF engineers and integrated in the simulator by the CORYS T.E.S.S Company. For the calculation of the 3D power distribution, COX-SIMU solves the neutron diffusion equations with 2 energy groups (transient and steady states). A full 3D distribution is needed due to the specifications of the EPRTM reactor internal instrumentation which requires knowledge of the detailed flux distribution for the Protection System. COX-SIMU includes thermal-hydraulical and thermal conduction modules to take into account the water moderator and fuel feedback on neutronic reactions. A simple model based on exponential functions is used for the calculation of the Residual Heat. COX-SIMU is fully validated against the industrial EDF neutronic code COCCINELLE with fine mesh discretization. The modularity and flexibility of COX-SIMU allow its integration in any Pressurized Water Reactor simulators. Thus, COX-SIMU is also integrated in the EPRTM TAISHAN Simulator.