Unbiasedness and optimization of regional weight cancellation

Hunter Belanger, Davide Mancusi, and Andrea Zoia
Phys. Rev. E 106, 025302 – Published 3 August 2022

Abstract

The Monte Carlo method is often used to simulate systems which can be modeled by random walks. To calculate observables, in many implementations the “walkers” carry a statistical weight which is generally assumed to be positive. Some random walk simulations, however, may require walkers to have positive or negative weights: it has been shown that the presence of a mixture of positive and negative weights can impede the statistical convergence, and special weight-cancellation techniques must be adopted to overcome these issues. In a recent work we demonstrated the usefulness of one such method, exact regional weight cancellation, to solve eigenvalue problems in nuclear reactor physics in three spatial dimensions. The method previously exhibited had several limitations (including multigroup transport and isotropic scattering) and needed homogeneous cuboid cancellation regions. In this paper we lift the previous limitations, in view of applying exact regional cancellation to more realistic continuous-energy neutron transport problems. This extended regional cancellation framework is used to optimize the efficiency of the weight cancellation. Our findings are illustrated on a benchmark configuration for reactor physics.

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  • Received 25 May 2022
  • Accepted 18 July 2022

DOI:https://doi.org/10.1103/PhysRevE.106.025302

©2022 American Physical Society

Physics Subject Headings (PhySH)

Nuclear PhysicsEnergy Science & TechnologyStatistical Physics & Thermodynamics

Authors & Affiliations

Hunter Belanger*, Davide Mancusi, and Andrea Zoia

  • Université Paris-Saclay, CEA, Service d'Études des Réacteurs et de Mathématiques Appliquées, 91191, Gif-sur-Yvette, France

  • *hunter.belanger@cea.fr
  • davide.mancusi@cea.fr
  • andrea.zoia@cea.fr

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Issue

Vol. 106, Iss. 2 — August 2022

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