Development and verification of new nodal methods in the KIKO3DMG code

The paper reports about the development and verification of the new nodal methods to be used in the KIKO3DMG code. Two classes of the new methods are presented. The first class makes the treatment of the heterogeneities possible inside the assemblies while the extent of the crucial approximations applied on the node boundaries is more considerable in comparison to those in case of the second type. The nodal methods were validated by two VVER reference problems found in the AER benchmark book (aerbench.kfki.hu/aerbench). The AER-2 and FCM-101 benchmarks correspond to the VVER-440 and VVER-1000 geometry, respectively. It was found that the differences between the converged and the reference solutions are negligible from the practical point of view. The performance characteristics concerning the accuracy and the necessary CPU time - both depending on the mesh refinement - were also compared.