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Main Authors: Biondo, Elliott, Evans, Thomas, Johnson, Seth, Hamilton, Steven
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2406.13849
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author Biondo, Elliott
Evans, Thomas
Johnson, Seth
Hamilton, Steven
author_facet Biondo, Elliott
Evans, Thomas
Johnson, Seth
Hamilton, Steven
contents Monte Carlo (MC) neutron transport provides detailed estimates of radiological quantities within fission reactors. This involves tracking individual neutrons through a computational geometry. CPU-based MC codes use multiple polymorphic tracker types with different tracking algorithms to exploit the repeated configurations of reactors, but virtual function calls have high overhead on the GPU. The Shift MC code was modified to support GPU-based tracking with three strategies: dynamic polymorphism with virtual functions, static polymorphism, and a single tracker type with tree-based acceleration. On the Frontier supercomputer these methods achieve 77.8%, 91.2%, and 83.4%, respectively, of the tracking rate obtained using a specialized tracker optimized for rectilinear-grid-based reactors. This indicates that all three methods are suitable for typical reactor problems in which tracking does not dominate runtime. The flexibility of the single tracker method is highlighted with a hexagonal-grid microreactor problem, performed without hexagonal-grid-specific tracking routines, providing a 2.19$\times$ speedup over CPU execution.
format Preprint
id arxiv_https___arxiv_org_abs_2406_13849
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Comparison of nested geometry treatments within GPU-based Monte Carlo neutron transport simulations of fission reactors
Biondo, Elliott
Evans, Thomas
Johnson, Seth
Hamilton, Steven
Distributed, Parallel, and Cluster Computing
Computational Engineering, Finance, and Science
Computational Geometry
Monte Carlo (MC) neutron transport provides detailed estimates of radiological quantities within fission reactors. This involves tracking individual neutrons through a computational geometry. CPU-based MC codes use multiple polymorphic tracker types with different tracking algorithms to exploit the repeated configurations of reactors, but virtual function calls have high overhead on the GPU. The Shift MC code was modified to support GPU-based tracking with three strategies: dynamic polymorphism with virtual functions, static polymorphism, and a single tracker type with tree-based acceleration. On the Frontier supercomputer these methods achieve 77.8%, 91.2%, and 83.4%, respectively, of the tracking rate obtained using a specialized tracker optimized for rectilinear-grid-based reactors. This indicates that all three methods are suitable for typical reactor problems in which tracking does not dominate runtime. The flexibility of the single tracker method is highlighted with a hexagonal-grid microreactor problem, performed without hexagonal-grid-specific tracking routines, providing a 2.19$\times$ speedup over CPU execution.
title Comparison of nested geometry treatments within GPU-based Monte Carlo neutron transport simulations of fission reactors
topic Distributed, Parallel, and Cluster Computing
Computational Engineering, Finance, and Science
Computational Geometry
url https://arxiv.org/abs/2406.13849