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Title: A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT

An essential component of the neutron transport solver is the resonance self-shielding calculation used to determine equivalence cross sections. The neutron transport code, MPACT, is currently using the subgroup self-shielding method, in which the method of characteristics (MOC) is used to solve purely absorbing fixed-source problems. Recent efforts incorporating multigroup kernels to the MOC solvers in MPACT have reduced runtime by roughly 2×. Applying the same concepts for self-shielding and developing a novel lumped parameter approach to MOC, substantial improvements have also been made to the self-shielding computational efficiency without sacrificing any accuracy. These new multigroup and lumped parameter capabilities have been demonstrated on two test cases: (1) a single lattice with quarter symmetry known as VERA (Virtual Environment for Reactor Applications) Progression Problem 2a and (2) a two-dimensional quarter-core slice known as Problem 5a-2D. From these cases, self-shielding computational time was reduced by roughly 3–4×, with a corresponding 15–20% increase in overall memory burden. An azimuthal angle sensitivity study also shows that only half as many angles are needed, yielding an additional speedup of 2×. In total, the improvements yield roughly a 7–8× speedup. Furthermore given these performance benefits, these approaches have been adopted as the default in MPACT.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Published Article
Journal Name:
Nuclear Engineering and Technology
Additional Journal Information:
Journal Volume: 49; Journal Issue: 6; Journal ID: ISSN 1738-5733
Publisher:
Korean Nuclear Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; CASL; Lumped Parameter; M&C 2017; MOC; MPACT; Subgroup Self-Shielding
OSTI Identifier:
1373334
Alternate Identifier(s):
OSTI ID: 1407807

Stimpson, Shane G., Liu, Yuxuan, Collins, Benjamin S., and Clarno, Kevin T.. A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT. United States: N. p., Web. doi:10.1016/j.net.2017.07.006.
Stimpson, Shane G., Liu, Yuxuan, Collins, Benjamin S., & Clarno, Kevin T.. A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT. United States. doi:10.1016/j.net.2017.07.006.
Stimpson, Shane G., Liu, Yuxuan, Collins, Benjamin S., and Clarno, Kevin T.. 2017. "A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT". United States. doi:10.1016/j.net.2017.07.006.
@article{osti_1373334,
title = {A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT},
author = {Stimpson, Shane G. and Liu, Yuxuan and Collins, Benjamin S. and Clarno, Kevin T.},
abstractNote = {An essential component of the neutron transport solver is the resonance self-shielding calculation used to determine equivalence cross sections. The neutron transport code, MPACT, is currently using the subgroup self-shielding method, in which the method of characteristics (MOC) is used to solve purely absorbing fixed-source problems. Recent efforts incorporating multigroup kernels to the MOC solvers in MPACT have reduced runtime by roughly 2×. Applying the same concepts for self-shielding and developing a novel lumped parameter approach to MOC, substantial improvements have also been made to the self-shielding computational efficiency without sacrificing any accuracy. These new multigroup and lumped parameter capabilities have been demonstrated on two test cases: (1) a single lattice with quarter symmetry known as VERA (Virtual Environment for Reactor Applications) Progression Problem 2a and (2) a two-dimensional quarter-core slice known as Problem 5a-2D. From these cases, self-shielding computational time was reduced by roughly 3–4×, with a corresponding 15–20% increase in overall memory burden. An azimuthal angle sensitivity study also shows that only half as many angles are needed, yielding an additional speedup of 2×. In total, the improvements yield roughly a 7–8× speedup. Furthermore given these performance benefits, these approaches have been adopted as the default in MPACT.},
doi = {10.1016/j.net.2017.07.006},
journal = {Nuclear Engineering and Technology},
number = 6,
volume = 49,
place = {United States},
year = {2017},
month = {7}
}