Monte Carlo next-event point flux estimation for RCP01

Technical Report · Tue Dec 31 04:00:00 EST 1991

DOI:https://doi.org/10.2172/10193014· OSTI ID:10193014

Martz, R L; Gast, R C; Tyburski, L J

Two next event point estimators have been developed and programmed into the RCP01 Monte Carlo program for solving neutron transport problems in three-dimensional geometry with detailed energy description. These estimators use a simplified but accurate flux-at-a-point tallying technique. Anisotropic scattering in the lab system at the collision site is accounted for by determining the exit energy that corresponds to the angle between the location of the collision and the point detector. Elastic, inelastic, and thermal kernel scattering events are included in this formulation. An averaging technique is used in both estimators to eliminate the well-known problem of infinite variance due to collisions close to the point detector. In a novel approach to improve the estimator`s efficiency, a Russian roulette scheme based on anticipated flux fall off is employed where averaging is not appropriate. A second estimator successfully uses a simple rejection technique in conjunction with detailed tracking where averaging isn`t needed. Test results show good agreement with known numeric solutions. Efficiencies are examined as a function of input parameter selection and problem difficulty.

• Research Organization: Bettis Atomic Power Lab., West Mifflin, PA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC11-93PN38195
• OSTI ID: 10193014
• Report Number(s): WAPD-T--2953; CONF-910414--42; ON: DE94002521
• Country of Publication: United States
• Language: English

Related Subjects

663610
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
MONTE CARLO METHOD
NEUTRON FLUX
NEUTRON PHYSICS
NEUTRON TRANSPORT THEORY
PROBABILISTIC ESTIMATION
R CODES
SCATTERING
THEORETICAL DATA
THREE-DIMENSIONAL CALCULATIONS