Abstract
The Consortium for Advanced Simulation of Light Water Reactors (CASL) has developed the CASL toolset, Virtual Environment for Reactor Analysis (VERA), for pressurized water reactor (PWR) analysis. Recently the CASL VERA was improved for Magnox reactor analysis, which required the development of a new cross section library and new geometrical and thermal feedback capabilities for graphite-moderated Magnox reactors. The MPACT neutronics module of the CASL core simulator is a 3D whole core transport code, which requires a new cross section library with a different energy group structure due to the different neutronic characteristics of Magnox compared with PWR. A new 69-group structure was developed based on the MPACT 51-group structure to have more thermal energy groups and to be a subset of the SCALE 252-group structure. The ENDF/B-VII.1 MPACT 69-group library was developed for Magnox reactor analysis using the SCALE/AMPX and VERA-XSTools for which a super-homogenization method was applied, and transport cross sections were generated for graphite using a neutron leakage conservation method. Benchmark results show that new MPACT 69-group library works reasonably well for Magnox reactor analysis.
Highlights
The MPACT neutronics module [1] of the Consortium for Advanced Simulation of Light Water Reactors (CASL) [2] core simulator is a 3D whole core transport code being developed for the CASL toolset, Virtual Environment for Reactor Analysis (VERA) [3]
Since thermal reaction rates are dominant in core reactivity and local neutron spectra are significantly influenced by surrounding materials, a new energy group structure needs to be developed for Magnox reactor analysis
More energy groups are required for thermal energy ranges
Summary
The MPACT neutronics module [1] of the Consortium for Advanced Simulation of Light Water Reactors (CASL) [2] core simulator is a 3D whole core transport code being developed for the CASL toolset, Virtual Environment for Reactor Analysis (VERA) [3]. These MPACT 51-group libraries cannot be used for Magnox reactor [11] analysis because neutron spectra of Magnox are very different from and much softer than the spectra of LWRs due to the graphite moderator. A new 69-group structure was developed, special transport cross sections for graphite were generated using the NLC method, and an improved SPH procedure was applied to 238U self-shielded cross section tables to conserve reaction rates at both thermal and resonance energy groups with which the ENDF/B-VII.. A companion paper demonstrates more detailed benchmark results to verify the MPACT 69-group library [12]
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