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

作者：Stimpson Shane^*; Liu Yuxuan; Collins Benjamin; Clarno Kevin

来源：Nuclear Engineering and Technology, 2017, 49(6): 1240-1249.

DOI：10.1016/j.net.2017.07.006

• CASL
• Lumped Parameter
• M& C 2017
• MOC
• MPACT
• Subgroup Self-Shielding

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 x. 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 3-4x, 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 2x. In total, the improvements yield roughly a 7-8x speedup. Given these performance benefits, these approaches have been adopted as the default in MPACT.

• 出版日期2017-9