Neutron Capture Energies for Flux Normalization and Approximate Model for GammaSmeared Power
Abstract
The Consortium for Advanced Simulation of Light Water Reactors (CASL) Virtual Environment for Reactor Applications (VERA) neutronics simulator MPACT has used a single recoverable fission energy for each fissionable nuclide assuming that all recoverable energies come only from fission reaction, for which capture energy is merged with fission energy. This approach includes approximations and requires improvement by separating capture energy from the merged effective recoverable energy. This report documents the procedure to generate recoverable neutron capture energies and the development of a program called CapKappa to generate capture energies. Recoverable neutron capture energies have been generated by using CapKappa with the evaluated nuclear data file (ENDF)/B7.0 and 7.1 cross section and decay libraries. The new capture kappas were compared to the current SCALE6.2 and the CASMO5 capture kappas. These new capture kappas have been incorporated into the Simplified AMPX 51 and 252group libraries, and they can be used for the AMPX multigroup (MG) libraries and the SCALE code package. The CASL VERA neutronics simulator MPACT does not include a gamma transport capability, which limits it to explicitly estimating local energy deposition from fission, neutron, and gamma slowing down and capture. Since the mean free path of gamma rays is typicallymore »
 Authors:

 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Univ. of Michigan, Ann Arbor, MI (United States)
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1437916
 Report Number(s):
 ORNL/SPR2017/471
CASLU20171377000; TRN: US1900039
 DOE Contract Number:
 AC0500OR22725
 Resource Type:
 Technical Report
 Country of Publication:
 United States
 Language:
 English
 Subject:
 22 GENERAL STUDIES OF NUCLEAR REACTORS; FISSION NEUTRONS; NEUTRON REACTIONS; ENERGY ABSORPTION; FISSION; WATER MODERATED REACTORS; GAMMA RADIATION; WATER COOLED REACTORS
Citation Formats
Kim, Kang Seog, Clarno, Kevin T., Liu, Yuxuan, Wang, Xinyan, Martin, William R., and Collins, Benjamin S. Neutron Capture Energies for Flux Normalization and Approximate Model for GammaSmeared Power. United States: N. p., 2018.
Web. doi:10.2172/1437916.
Kim, Kang Seog, Clarno, Kevin T., Liu, Yuxuan, Wang, Xinyan, Martin, William R., & Collins, Benjamin S. Neutron Capture Energies for Flux Normalization and Approximate Model for GammaSmeared Power. United States. doi:10.2172/1437916.
Kim, Kang Seog, Clarno, Kevin T., Liu, Yuxuan, Wang, Xinyan, Martin, William R., and Collins, Benjamin S. Fri .
"Neutron Capture Energies for Flux Normalization and Approximate Model for GammaSmeared Power". United States. doi:10.2172/1437916. https://www.osti.gov/servlets/purl/1437916.
@article{osti_1437916,
title = {Neutron Capture Energies for Flux Normalization and Approximate Model for GammaSmeared Power},
author = {Kim, Kang Seog and Clarno, Kevin T. and Liu, Yuxuan and Wang, Xinyan and Martin, William R. and Collins, Benjamin S.},
abstractNote = {The Consortium for Advanced Simulation of Light Water Reactors (CASL) Virtual Environment for Reactor Applications (VERA) neutronics simulator MPACT has used a single recoverable fission energy for each fissionable nuclide assuming that all recoverable energies come only from fission reaction, for which capture energy is merged with fission energy. This approach includes approximations and requires improvement by separating capture energy from the merged effective recoverable energy. This report documents the procedure to generate recoverable neutron capture energies and the development of a program called CapKappa to generate capture energies. Recoverable neutron capture energies have been generated by using CapKappa with the evaluated nuclear data file (ENDF)/B7.0 and 7.1 cross section and decay libraries. The new capture kappas were compared to the current SCALE6.2 and the CASMO5 capture kappas. These new capture kappas have been incorporated into the Simplified AMPX 51 and 252group libraries, and they can be used for the AMPX multigroup (MG) libraries and the SCALE code package. The CASL VERA neutronics simulator MPACT does not include a gamma transport capability, which limits it to explicitly estimating local energy deposition from fission, neutron, and gamma slowing down and capture. Since the mean free path of gamma rays is typically much longer than that for the neutron, and the total gamma energy is about 10% to the total energy, the gammasmeared power distribution is different from the fission power distribution. Explicit local energy deposition through neutron and gamma transport calculation is significantly important in multiphysics whole core simulation with thermalhydraulic feedback. Therefore, the gamma transport capability should be incorporated into the CASL neutronics simulator MPACT. However, this task will be timeconsuming in developing the neutron induced gamma production and gamma cross section libraries. This study is to investigate an approximate model to estimate gammasmeared power distribution without performing any gamma transport calculation. A simple approximate gamma smearing model has been investigated based on the facts that pinwise gamma energy depositions are almost flat over a fuel assembly, and assemblywise gamma energy deposition is proportional to kappafission energy deposition. The approximate gamma smearing model works well for single assembly cases, and can partly improve the gamma smeared power distribution for the whole core model. Although the power distributions can be improved by the approximate gamma smearing model, still there is an issue to explicitly obtain local energy deposition. A new simple approach or gamma transport/diffusion capability may need to be incorporated into MPACT to estimate local energy deposition for more robust multiphysics simulation.},
doi = {10.2172/1437916},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {9}
}