Generational Variance Reduction in Monte Carlo Criticality Simulations as a Way of Mitigating Unwanted Correlations

نویسندگان

چکیده

Monte Carlo criticality simulations are widely used in nuclear safety demonstrations, as they offer an arbitrarily precise estimation of global and local tallies while making very few assumptions. However, since the inception such numerical approaches, it is well known that bias might affect both errors on these themselves. In particular, stochastic modeling approaches developed past decade have shed light prominent role played by spatial correlations through a phenomenon called neutron clustering. This effect particularly great significance when simulating loosely coupled systems (i.e., with high dominance ratio). order to tackle this problem, paper proposes recast power iteration technique codes into variance reduction Adaptative Multilevel Splitting. The central idea iterating over generations can be seen pushing subpopulation neutrons toward generational detector (instead techniques usually do). While allow for population control, former blindly removes or splits neutrons. contrast, latter optimizes spatial, generational, spectral attributes removed split adjoint flux estimation, hence tempering correlations. illustrated present simple case bare slab reactor one-speed theory which Adaptive Splitting was applied compared variations method transport. Besides looking at resulting efficiency methods, work also aims highlight main mechanisms calculations.

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ژورنال

عنوان ژورنال: Nuclear Science and Engineering

سال: 2023

ISSN: ['0029-5639', '1943-748X']

DOI: https://doi.org/10.1080/00295639.2023.2193089