Hybrid finite-element-based numerical solution of the SP3 equations – SP3 solution of two- and three-dimensional VVER reactor problems

Abstract

As a follow-up to the paper previously published by the authors detailing the hybrid finite element (HYBFEM) solution of the SP3 equations, in this paper, besides a semi-analytical solver verification with an analysis on the applied source fitting polynomial order, three-dimensional VVER-440, and VVER-1000 benchmarks are reproduced with the continuous Galerkin (CGFEM) and HYBFEM SP3 modules of the SPNDYN code. The effect of the applied axial nodalisation and radial element order on the calculation results is discussed. The HYBFEM solver extended with a discontinuity factor (DCF) calculation module based on Serpent 2 output parameters is verified on a two-dimensional VVER-1000 benchmark. The SPNDYN CGFEM and HYBFEM results show very good agreement. We also verify that by introducing DCFs in SP3 calculations, the reference transport solution can be reproduced with high accuracy. We highlight the effect of using scalar flux weighted linearly anisotropic scattering matrices in higher-order transport calculations.