A 2D/1D Algorithm for Effective Cross-Section Generation in Fast Reactor Neutronic Transport Calculations

Abstract

Fast resolution of the Boltzmann transport equation over a nuclear reactor core presupposes the definition of homogenized and energy-collapsed cross sections. In modern sodium fast reactors that rely on heterogeneous core designs, anisotropy in the neutron propagation cannot be neglected, so three-dimensional (3D) models should be used to efficiently compute those effective cross sections. In this paper, the 2D/1D approximation is carried out to overcome computationally expensive 3D calculations while preserving consistent angular representations of the neutron flux. An iterative procedure is defined to solve the 2D/1D equations and produce coarse group homogenized cross sections that account for 3D transport effects. Accuracy of the algorithm is tested on a realistic model of the ASTRID core showing very good results against Monte Carlo simulations for all neutronic parameters (eigenvalue, sodium void worth, and fission map distribution).

Keywords:

• Neutronics
• transport
• 2D/1D method
• homogenization
• sodium fast reactor

Acknowledgments

The authors acknowledge the CEA of Cadarache for funding this work and FRAMATOME and EDF for their long-term support. They also thank the APOLLO3 development team for the provided support and effort in developing the code. One of the authors (B.F.) would like to address many thanks to S. Santandrea and E. Masiello for their great help while developing the methods presented in this paper. This work was supported by the Commissariat à l’Énergie Atomique et aux Énergies Alternatives.