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Hybrid Monte Carlo/Deterministic Transport Methodology for the Neutronic Analysis of VHTRs |
Wei Ji, Gokhan Yesilyurt, Shikha Prasad, John C. Lee, William R. Martin
University of Michigan
Substantial progress has been made to develop a simplified Monte Carlo methodology to analyze Very High Temperature Reactor (VHTR) configurations in far less time than conventional Monte Carlo methods, accounting for temperature feedback and depletion. Progress will be reported and results presented for three related efforts: (1) the development and testing of an automated temperature feedback capability between MCNP5 and RELAP-ATHENA, using a “pseudo-temperature construct” to eliminate the need to regenerate cross sections at different temperatures; (2) the incorporation of the MCNP5 code as a “subgrid Monte Carlo method” within the CPM-3 lattice transport code, allowing CPM-3 to perform an overall VHTR keff calculation, while MCNP5 does the resonance absorption calculation in the tristructural-isotropic (TRISO) fuel; and (3) the development of a simplified Monte Carlo methodology that allows a fast and accurate analysis of VHTR configurations by chord length sampling rather than analog Monte Carlo tracking in the TRISO fuel. This chord length sampling methodology has also led to a new and more accurate formula for predicting Dancoff factors in stochastic media. The methodology we are developing will allow for routine analysis of 3D VHTR configurations, for both pebble bed and prismatic cores, with accuracy comparable to full core Monte Carlo that explicitly models the TRISO fuel particles.
Contact
William R. Martin
Department of Nuclear Engineering and Radiological Sciences
University of Michigan
2355 Bonisteel Blvd
Ann Arbor, MI 48109-2104
wrm@umich.edu