P1 adaptation of TRIPOLI-4^® code for the use of 3D realistic core multigroup cross section generation

¹ CEA, DEN, DER/SPRC, Cadarache, F-13108 Saint-Paul-lez-Durance, France
² CEA, DEN, DANS/DM2S/SERMA, Saclay, F-91191 Gif-sur-Yvette Cedex, France

Abstract

In this paper, we discuss some improvements we recently implemented in the Monte-Carlo code TRIPOLI-4^® associated with the homogenization and collapsing of subassemblies cross sections. The improvement offered us another approach to get critical multigroup cross sections with Monte-Carlo method. The new calculation method in TRIPOLI-4^® tries to ensure the neutronic balances, the multiplicative factors and the critical flux spectra for some realistic geometries. We make it by at first improving the treatment of the energy transfer probability, the neutron excess weight and the neutron fission spectrum. This step is necessary for infinite geometries. The second step which will be enlarged in this paper is aimed at better dealing with the multigroup anisotropy distribution law for finite geometries. Usually, Monte-Carlo homogenized multi-group cross sections are validated within a core calculation by a deterministic code. Here, the validation of multigroup constants will also be carried out by Monte-Carlo core calculation code. Different subassemblies are tested with the new collapsing method, especially for the fast neutron reactors subassemblies.