Benchmarking the MCNP Monte Carlo code with a photon skyshine experiment

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Nuclear Science and Engineering; (United States)

OSTI ID:6172967

Olsher, R H; Hsu, Hsiao Hua; Harvey, W F ^[1]

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1. Los Alamos National Lab., Los Alamos, NM (United States)

The MCNP Monte Carlo transport code is used by the Los Alamos National Laboratory Health and Safety Division for a broad spectrum of radiation shielding calculations. One such application involves the determination of skyshine dose for a variety of photon sources. To verify the accuracy of the code, it was benchmarked with the Kansas State Univ. (KSU) photon skyshine experiment of 1977. The KSU experiment for the unshielded source geometry was simulated in great detail to include the contribution of groundshine, in-silo photon scatter, and the effect of spectral degradation in the source capsule. The standard deviation of the KSU experimental data was stated to be 7%, while the statistical uncertainty of the simulation was kept at or under 1%. The results of the simulation agreed closely with the experimental data, generally to within 6%. At distances of under 100 m from the silo, the modeling of the in-silo scatter was crucial to achieving close agreement with the experiment. Specifically, scatter off the top layer of the source cask accounted for [approximately]12% of the dose at 50 m. At distance >300m, using the [sup 60]Co line spectrum led to a dose overresponse as great as 19% at 700 m. It was necessary to use the actual source spectrum, which includes a Compton tail from photon collisions in the source capsule, to achieve close agreement with experimental data. These results highlight the importance of using Monte Carlo transport techniques to account for the nonideal features of even simple experiments''.

• OSTI ID: 6172967
• Journal Information: Nuclear Science and Engineering; (United States), Vol. 114:3; ISSN 0029-5639
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
PHOTON TRANSPORT
M CODES
ACCURACY
BENCHMARKS
COMPUTERIZED SIMULATION
LANL
MONTE CARLO METHOD
RADIATION DOSES
RADIATION SOURCES
SHIELDING
CALCULATION METHODS
COMPUTER CODES
DOSES
NATIONAL ORGANIZATIONS
NEUTRAL-PARTICLE TRANSPORT
RADIATION TRANSPORT
SIMULATION
US DOE
US ORGANIZATIONS
663620* - Physics of Radiations Other Than Neutrons- (1992-)