Modeling and Validation of IAEA 3D PWR Benchmark Problem Using COMSOL Multiphysics Code

A relevant challenge in nuclear reactor analysis is to achieve a broad description of nuclear systems through the coupling between neutronics and thermal-hydraulics. A multi-physics approach improves the reactor safety analysis and the design of different types of nuclear reactor phenomena where accurate modeling is essential for the integration of different physical effects at different scales of time and space. COMSOL Multiphysics software provides an advanced tool to integrate user-defined physics module to analyze reactor state at steady and transient state by mathematics module. To validate the capability of solving different nuclear reactor phenomena e.g., neutron flux distribution and effective multiplication factor in COMSOL software, it’s worth solving a benchmark problem. The neutron diffusion equation is used widely in academia and in the industry to perform core-level neutronic calculations which consist of a set of second-order partial differential equations over the spatial coordinates. A classic 3D IAEA benchmark problem is solved for validation which is defined by B. Micheelsen in 1971 and the goal of this benchmark problem is to validate software capability with the help of neutron diffusion equation by calculating the multiplication factor, neutron flux, radial, and axial power distributions in the core. The 3D model has been built up using SolidWorks software and later model is imported into COMSOL to solve neutron diffusion equations for the 3D IAEA PWR benchmark problem. An adaptive meshing algorithm has been used to omit peculiarities that often arise when solving the neutron diffusion equation using unstructured grids. Effective multiplication factor “k_eff ”, thermal and fast neutron flux profiles, and power distributions were calculated and compared to the results of another standard PARCS code. There is a good agreement between the results from COMSOL and PARCS code. The obtained neutron multiplication factor (k_eff ) 1.02799 from COMSOL is consistent with the PARCS code in the benchmark at the level of 0.11%. This paper documents the use of the commercial finite element Multiphysics software package COMSOL 5.4 on a 3D benchmark problem for LWR.