Modal methods for rehomogenization of nodal cross sections in nuclear reactor core analysis

This thesis develops novel first-principle methods to correct homogenization errors in nodal cross sections and discontinuity factors. Its aim is to improve the accuracy of nodal diffusion simulations of heterogeneous core configurations. This research builds upon previous work conducted at Framatome (Paris, France). It is based on a modal...

A neutron-leakage spectrum model for on-the-fly rehomogenization of nodal cross sections

Modeling spectral effects due to core heterogeneity is one of the major challenges for current nodal analysis tools, whose accuracy is often deteriorated by cross-section homogenization errors. AREVA NP recently developed a spectral rehomogenization method that estimates the variation of the assembly-averaged neutron flux spectrum between...

Rehomogenization of nodal cross sections via modal synthesis of neutron spectrum changes

Nodal diffusion is currently the preferred neutronics model for industrial reactor core calculations, which use few-group cross-section libraries generated via standard assembly homogenization. The infinite-medium flux-weighted cross sections fail to capture the spectral effects triggered in the core environment by nonreflective boundary...

Investigation of rehomogenization in the framework of nodal cross section corrections

Few-group cross sections used in nodal calculations derive from standard energy collapsing and spatial homogenization performed during preliminary lattice transport calculations, that implicitly assume an infinite array of identical fuel-assemblies. The infinite-medium neutron flux used for cross section weighting does not account for...