Evaluation of SNS Beamline Shielding Configurations using MCNPX Accelerated by ADVANTG
Abstract
Shielding analyses for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory pose significant computational challenges, including highly anisotropic highenergy sources, a combination of deep penetration shielding and an unshielded beamline, and a desire to obtain wellconverged nearly global solutions for mapping of predicted radiation fields. The majority of these analyses have been performed using MCNPX with manually generated variance reduction parameters (source biasing and cellbased splitting and Russian roulette) that were largely based on the analyst's insight into the problem specifics. Development of the variance reduction parameters required extensive analyst time, and was often tailored to specific portions of the model phase space. We previously applied a developmental version of the ADVANTG code to an SNS beamline study to perform a hybrid deterministic/Monte Carlo analysis and showed that we could obtain nearly global Monte Carlo solutions with essentially uniform relative errors for mesh tallies that cover extensive portions of the model with typical voxel spacing of a few centimeters. The use of weight window maps and consistent biased sources produced using the FWCADIS methodology in ADVANTG allowed us to obtain these solutions using substantially less computer time than the previous cellbased splitting approach. While those results were promising,more »
 Authors:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1213985
 DOE Contract Number:
 AC0500OR22725
 Resource Type:
 Conference
 Resource Relation:
 Conference: SATIF12, Bavaria, IL (United States), 2830 Apr 2014
 Country of Publication:
 United States
 Language:
 English
 Subject:
 43 PARTICLE ACCELERATORS; OAK RIDGE SPALLATION NEUTRON SOURCE; SHIELDING; MATHEMATICAL SOLUTIONS; WEIGHTING FUCTIONS; EVALUATION; MAPS; SPALLATION; ANISOTROPY; DATA COVARIANCES; M CODES; A CODES; BEAM TRANSPORT
Citation Formats
Risner, Joel M, Johnson, Seth R., Remec, Igor, and Bekar, Kursat B. Evaluation of SNS Beamline Shielding Configurations using MCNPX Accelerated by ADVANTG. United States: N. p., 2015.
Web.
Risner, Joel M, Johnson, Seth R., Remec, Igor, & Bekar, Kursat B. Evaluation of SNS Beamline Shielding Configurations using MCNPX Accelerated by ADVANTG. United States.
Risner, Joel M, Johnson, Seth R., Remec, Igor, and Bekar, Kursat B. 2015.
"Evaluation of SNS Beamline Shielding Configurations using MCNPX Accelerated by ADVANTG". United States.
doi:. https://www.osti.gov/servlets/purl/1213985.
@article{osti_1213985,
title = {Evaluation of SNS Beamline Shielding Configurations using MCNPX Accelerated by ADVANTG},
author = {Risner, Joel M and Johnson, Seth R. and Remec, Igor and Bekar, Kursat B.},
abstractNote = {Shielding analyses for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory pose significant computational challenges, including highly anisotropic highenergy sources, a combination of deep penetration shielding and an unshielded beamline, and a desire to obtain wellconverged nearly global solutions for mapping of predicted radiation fields. The majority of these analyses have been performed using MCNPX with manually generated variance reduction parameters (source biasing and cellbased splitting and Russian roulette) that were largely based on the analyst's insight into the problem specifics. Development of the variance reduction parameters required extensive analyst time, and was often tailored to specific portions of the model phase space. We previously applied a developmental version of the ADVANTG code to an SNS beamline study to perform a hybrid deterministic/Monte Carlo analysis and showed that we could obtain nearly global Monte Carlo solutions with essentially uniform relative errors for mesh tallies that cover extensive portions of the model with typical voxel spacing of a few centimeters. The use of weight window maps and consistent biased sources produced using the FWCADIS methodology in ADVANTG allowed us to obtain these solutions using substantially less computer time than the previous cellbased splitting approach. While those results were promising, the process of using the developmental version of ADVANTG was somewhat laborious, requiring userdeveloped Python scripts to drive much of the analysis sequence. In addition, limitations imposed by the size of weightwindow files in MCNPX necessitated the use of relatively coarse spatial and energy discretization for the deterministic Denovo calculations that we used to generate the variance reduction parameters. We recently applied the production version of ADVANTG to this beamline analysis, which substantially streamlined the analysis process. We also tested importance function collapsing (in space and energy) capabilities in ADVANTG. These changes, along with the support for parallel Denovo calculations using the current version of ADVANTG, give us the capability to improve the fidelity of the deterministic portion of the hybrid analysis sequence, obtain improved weightwindow maps, and reduce both the analyst and computational time required for the analysis process.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 1
}

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