Multi-physical coupling study of neutronics/thermal-hydraulics/material corrosion based on the unified coupling framework

The implementation of supercomputers and the swift advancement of computer technology have made it possible to perform precise simulation and calculation of nuclear reactors. The trajectory of numerical simulation technology for nuclear reactors is toward fidelity and multi-physics. This paper introduces a multi-physical framework for coupled neutronic, thermal-hydraulic, and material corrosion, detailing its development and application. The entire coupling framework is constructed utilizing the internal coupling mode of the opensource computational fluid dynamics (CFD) program OpenFOAM to transmit parameters. Based on OpenFOAM, the aforementioned three modules are integrated through the utilization of the C++ programming language, and a three-dimensional high-resolution multi-physical coupling calculation platform is constructed to simulate multi-physics coupling problems in the reactor. For the neutronic module, the steady-state and transient neutron diffusion equations are solved to obtain three-dimensional high-resolution neutron flux and power distributions. The CFD approach is employed in the thermal-hydraulic module to address the solid-fluid coupling conjugate heat transfer problems in order to determine the distribution of the temperature field and other physical fields. The material corrosion module solves the corrosion growth model and the corrosion thermal resistance model of the oxidation corrosion product to acquire its oxide thickness and thermal resistance distribution. The multi-physical coupling platform is used to perform neutronics/thermal-hydraulics/material corrosion coupling calculations for the standard fuel element of the MTR research reactor. The coupling calculation results clearly show the changes in thickness distribution of corrosion products and peak cladding temperature rise distribution over time, illustrating the feasibility of the multi-physical coupling methodology. Furthermore, through the sensitivity analysis of some key parameters, the influences of different parameters on multi-physical coupling are successfully obtained.