Lattice physics calculations using the embedded self-shielding method in Polaris, Part I: Methods and implementation

Matthew A. Jessee; William A. Wieselquist; Ugur Mertyurek; Kang Seog Kim; Thomas M. Evans; Steven P. Hamilton; Cole Gentry

doi:10.1016/j.anucene.2020.107830

Lattice physics calculations using the embedded self-shielding method in Polaris, Part I: Methods and implementation

Matthew A. Jessee, William A. Wieselquist, Ugur Mertyurek, Kang Seog Kim, Thomas M. Evans, Steven P. Hamilton, Cole Gentry

Research output: Contribution to journal › Article › peer-review

19 Scopus citations

Abstract

Polaris is a 2-dimensional multigroup lattice physics capability in the SCALE code system for the analysis of light water reactor fuel designs. The goal of light water reactor lattice physics codes is to generate few-group homogenized cross sections for downstream full-core nodal diffusion calculations. Lattice physics calculations contain three primary components: the cross section processing calculation, the 2D transport calculation, and the depletion calculation. This paper summarizes the calculational methods and their implementation into Polaris, with an emphasis on implementation of the embedded self-shielding method. The accuracy of the embedded self-shielding method depends on the procedure used to generate self-shielding factors on the multigroup library. Numerical benchmarks calculations reveal that the accuracy of Polaris eigenvalue predictions is enhanced by (1) using heterogeneous unit cell models to generate the self-shielding factors on the library and (2) using self-shielding factors for within-group scattering cross section.

Original language	English
Article number	107830
Journal	Annals of Nuclear Energy
Volume	150
DOIs	https://doi.org/10.1016/j.anucene.2020.107830
State	Published - Jan 2021

Funding

This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. DOE will provide access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The authors would like to thank the US Nuclear Regulatory Office of Nuclear Regulatory Research, specifically Don Algama and Richard Lee for funding the development of Polaris. The authors would like to acknowledge Mark L. Williams (ORNL) and Stephen M. Bowman (ORNL) who both passed away in 2018. Mark made significant contributions to the self-shielding methodology, cross section libraries, and self-shielding tables used in Polaris. Steve was the ORNL project manager for the NRC Polaris project since its inception in 2012.

Keywords

Lattice physics
Self-shielding methods

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10.1016/j.anucene.2020.107830

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abstract = "Polaris is a 2-dimensional multigroup lattice physics capability in the SCALE code system for the analysis of light water reactor fuel designs. The goal of light water reactor lattice physics codes is to generate few-group homogenized cross sections for downstream full-core nodal diffusion calculations. Lattice physics calculations contain three primary components: the cross section processing calculation, the 2D transport calculation, and the depletion calculation. This paper summarizes the calculational methods and their implementation into Polaris, with an emphasis on implementation of the embedded self-shielding method. The accuracy of the embedded self-shielding method depends on the procedure used to generate self-shielding factors on the multigroup library. Numerical benchmarks calculations reveal that the accuracy of Polaris eigenvalue predictions is enhanced by (1) using heterogeneous unit cell models to generate the self-shielding factors on the library and (2) using self-shielding factors for within-group scattering cross section.",

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AU - Hamilton, Steven P.

AU - Gentry, Cole

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AB - Polaris is a 2-dimensional multigroup lattice physics capability in the SCALE code system for the analysis of light water reactor fuel designs. The goal of light water reactor lattice physics codes is to generate few-group homogenized cross sections for downstream full-core nodal diffusion calculations. Lattice physics calculations contain three primary components: the cross section processing calculation, the 2D transport calculation, and the depletion calculation. This paper summarizes the calculational methods and their implementation into Polaris, with an emphasis on implementation of the embedded self-shielding method. The accuracy of the embedded self-shielding method depends on the procedure used to generate self-shielding factors on the multigroup library. Numerical benchmarks calculations reveal that the accuracy of Polaris eigenvalue predictions is enhanced by (1) using heterogeneous unit cell models to generate the self-shielding factors on the library and (2) using self-shielding factors for within-group scattering cross section.

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Lattice physics calculations using the embedded self-shielding method in Polaris, Part I: Methods and implementation

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