Review of Monte Carlo methods for particle transport in continuously-varying media
DES-Service d’études des réacteurs et de mathématiques appliquées (SERMA), CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
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Accepted: 28 August 2020
Published online: 2 November 2020
Monte Carlo techniques for solving the Boltzmann neutron transport equation have become increasingly popular in recent years, due to their exact nature and to the increase in computational power. Monte Carlo makes it possible to solve transport problems without discretizing the geometry or energy domain. Current mainstream methods, however, do not allow for media with continuous properties, such as spatially varying cross sections due to density and temperature variations. Being able to perform simulations under such conditions is a desirable feature for a complete Monte Carlo implementation in the contexts of multi-physics and depletion simulations. Several methods can currently be used to conduct transport in materials having non-uniform cross sections. This paper aims to compare some of these methods (substepping, direct sampling, delta tracking, and several delta tracking variants) in a simplified one-dimensional system with spatially varying cross sections, to examine their respective properties. Performance (as measured by the Figure of Merit), robustness, and ease of implementation are considered in evaluating the methods. Such results will help determine which transport methods would be most suitable for implementation in a general-purpose Monte Carlo code.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2020