Extension of the fully coupled Monte Carlo/S sub N response matrix method to problems including upscatter and fission

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6218527

Baker, R S; Filippone, W F ^[1]; Alcouffe, R E ^[2]

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1. Arizona Univ., Tucson, AZ (USA). Dept. of Nuclear and Energy Engineering
2. Los Alamos National Lab., NM (USA)

The neutron transport equation is solved by a hybrid method that iteratively couples regions where deterministic (S{sub N}) and stochastic (Monte Carlo) methods are applied. Unlike previous hybrid methods, the Monte Carlo and S{sub N} regions are fully coupled in the sense that no assumption is made about geometrical separation of decoupling. The fully coupled Monte Carlo/S{sub N} technique consists of defining spatial and/or energy regions of a problem in which either a Monte Carlo calculation or an S{sub N} calculation is to be performed. The Monte Carlo and S{sub N} regions are then connected through the common angular boundary fluxes, which are determined iteratively using the response matrix technique, and group sources. The hybrid method provides a new method of solving problems involving both optically thick and optically thin regions that neither Monte Carlo nor S{sub N} is well suited for by itself. The fully coupled Monte Carlo/S{sub N} method has been implemented in the S{sub N} code TWODANT by adding special-purpose Monte Carlo subroutines to calculate the response matrices and group sources, and linkage subroutines to carry out the interface flux iterations. The common angular boundary fluxes are included in the S{sub N} code as interior boundary sources, leaving the logic for the solution of the transport flux unchanged, while, with minor modifications, the diffusion synthetic accelerator remains effective in accelerating the S{sub N} calculations. The Monte Carlo routines have been successfully vectorized, with approximately a factor of five increases in speed over the nonvectorized version. The hybrid method is capable of solving forward, inhomogeneous source problems in X-Y and R-Z geometries. This capability now includes mulitigroup problems involving upscatter and fission in non-highly multiplying systems. 8 refs., 8 figs., 1 tab.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: DOE/AD
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6218527
• Report Number(s): LA-UR-91-117; CONF-910414--11; ON: DE91007387
• Country of Publication: United States
• Language: English

Related Subjects

653003* -- Nuclear Theory-- Nuclear Reactions & Scattering
654003 -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
CROSS SECTIONS
EQUATIONS
FISSION
MONTE CARLO METHOD
NEUTRON TRANSPORT THEORY
NUCLEAR REACTIONS
REACTOR KINETICS EQUATIONS
RESPONSE MATRIX METHOD
SCATTERING
TRANSPORT THEORY