Choosing Transport Events for Initiating Splitting and Rouletting
- Univ. of Michigan, Ann Arbor, MI (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
A study was performed to determine which transport events should be used to initiate a weight window lookup to achieve the best variance reduction performance. A weight window lookup potentially triggers particle splitting (in important regions of phase space) or rouletting (in unimportant regions), thereby optimizing computational effort. Potential initiating transport events include collisions (both pre- and post-collision), geometry surface crossings, traversing a mean-free path, and streaming across a weight window boundary. Permutations of these initiating events were tested on an urban model with background radiation sources and a spent fuel cask with a neutron dose mesh tally. Generally, all methods perform better with finer weight window meshes. Tracking on weight windows performs well for coarse weight window meshes, while a combination of splitting each mean-free path, geometric surface crossing, and before collisions performs well for fine weight window meshes.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation; US Nuclear Regulatory Commission
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1777699
- Journal Information:
- Journal of Nuclear Engineering, Journal Name: Journal of Nuclear Engineering Journal Issue: 2 Vol. 2; ISSN 2673-4362
- Publisher:
- MDPICopyright Statement
- Country of Publication:
- United States
- Language:
- English
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