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Title: SuPer-Homogenization (SPH) Corrected Cross Section Generation for High Temperature Reactor

Abstract

The deterministic full core simulators require homogenized group constants covering the operating and transient conditions over the entire lifetime. Traditionally, the homogenized group constants are generated using lattice physics code over an assembly or block in the case of prismatic high temperature reactors (HTR). For the case of strong absorbers that causes strong local depressions on the flux profile require special techniques during homogenization over a large volume. Fuel blocks with burnable poisons or control rod blocks are example of such cases. Over past several decades, there have been a tremendous number of studies performed for improving the accuracy of full-core calculations through the homogenization procedure. However, those studies were mostly performed for light water reactor (LWR) analyses, thus, may not be directly applicable to advanced thermal reactors such as HTRs. This report presents the application of SuPer-Homogenization correction method to a hypothetical HTR core.

Authors:
 [1];  [1];  [1]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1369365
Report Number(s):
INL/EXT-17-41516
TRN: US1701963
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; GROUP CONSTANTS; TEMPERATURE RANGE 0400-1000 K; BURNABLE POISONS; CONTROL ELEMENTS; THERMAL REACTORS; FUELS; Advanced Reactor Technologies; DRAGONv5; High Temperature Gas Cooled Reactors; High Temperature Reactor; SuPer-Homogenization; supercell

Citation Formats

Sen, Ramazan Sonat, Hummel, Andrew John, and Hiruta, Hikaru. SuPer-Homogenization (SPH) Corrected Cross Section Generation for High Temperature Reactor. United States: N. p., 2017. Web. doi:10.2172/1369365.
Sen, Ramazan Sonat, Hummel, Andrew John, & Hiruta, Hikaru. SuPer-Homogenization (SPH) Corrected Cross Section Generation for High Temperature Reactor. United States. doi:10.2172/1369365.
Sen, Ramazan Sonat, Hummel, Andrew John, and Hiruta, Hikaru. Wed . "SuPer-Homogenization (SPH) Corrected Cross Section Generation for High Temperature Reactor". United States. doi:10.2172/1369365. https://www.osti.gov/servlets/purl/1369365.
@article{osti_1369365,
title = {SuPer-Homogenization (SPH) Corrected Cross Section Generation for High Temperature Reactor},
author = {Sen, Ramazan Sonat and Hummel, Andrew John and Hiruta, Hikaru},
abstractNote = {The deterministic full core simulators require homogenized group constants covering the operating and transient conditions over the entire lifetime. Traditionally, the homogenized group constants are generated using lattice physics code over an assembly or block in the case of prismatic high temperature reactors (HTR). For the case of strong absorbers that causes strong local depressions on the flux profile require special techniques during homogenization over a large volume. Fuel blocks with burnable poisons or control rod blocks are example of such cases. Over past several decades, there have been a tremendous number of studies performed for improving the accuracy of full-core calculations through the homogenization procedure. However, those studies were mostly performed for light water reactor (LWR) analyses, thus, may not be directly applicable to advanced thermal reactors such as HTRs. This report presents the application of SuPer-Homogenization correction method to a hypothetical HTR core.},
doi = {10.2172/1369365},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

Technical Report:

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  • This document replaces the earlier versions (CRRP-680 and CRRP-787) and now employs the σ (E) information contained in Supplement 1 (1960) of the 2nd edition of BNL-325 and other data privately collected to a cut-off date of April 1, 1960. The compilation is also enlarged to include higher temperatures (thus superseding CRRP-862) and for the first time also includes s-factors calculated using the epithermal cut-off functions exhibiting a maximum at just above the cut-off energy, which have recently been indicated by Swedish and U.K. measurements, as well as by analysis of some calculated spectra. As in the earlier compilation, themore » notation of the author's Geneva Conference (1958) paper is used, the effective cross section σ being given in terms of the 2200 m/sec. value σo by the relation σ σo (g + rs), where g and s are the factors listed in this compilation and r is a measure of the proportion of epithermal neutrons in the reactor spectrum. (author)« less
  • The deep-burn prismatic high temperature reactor is made up of an annular core loaded with transuranic isotopes and surrounded in the center and in the periphery by reflector blocks in graphite. This disposition creates challenges for the neutronics compared to usual light water reactor calculation schemes. The longer mean free path of neutrons in graphite affects the neutron spectrum deep inside the blocks located next to the reflector. The neutron thermalisation in the graphite leads to two characteristic fission peaks at the inner and outer interfaces as a result of the increased thermal flux seen in those assemblies. Spectral changesmore » are seen at least on half of the fuel blocks adjacent to the reflector. This spectral effect of the reflector may prevent us from successfully using the two step scheme -lattice then core calculation- typically used for light water reactors. We have been studying the core without control mechanisms to provide input for the development of a complete calculation scheme. To correct the spectrum at the lattice level, we have tried to generate cross-sections from supercell calculations at the lattice level, thus taking into account part of the graphite surrounding the blocks of interest for generating the homogenised cross-sections for the full-core calculation. This one has been done with 2 to 295 groups to assess if increasing the number of groups leads to more accurate results. A comparison with a classical single block model has been done. Both paths were compared to a reference calculation done with MCNP. It is concluded that the agreement with MCNP is better with supercells, but that the single block model remains quite close if enough groups are kept for the core calculation. 26 groups seems to be a good compromise between time and accu- racy. However, some trials with depletion have shown huge variations of the isotopic composition across a block next to the reflector. It may imply that at least an in- core depletion for the number density calculation may be necessary in the complete calculation scheme.« less
  • The MC 2-3 code is a Multigroup Cross section generation Code for fast reactor analysis, developed by improving the resonance self-shielding and spectrum calculation methods of MC 2-2 and integrating the one-dimensional cell calculation capabilities of SDX. The code solves the consistent P1 multigroup transport equation using basic neutron data from ENDF/B data files to determine the fundamental mode spectra for use in generating multigroup neutron cross sections. A homogeneous medium or a heterogeneous slab or cylindrical unit cell problem is solved in ultrafine (~2000) or hyperfine (~400,000) group levels. In the resolved resonance range, pointwise cross sections are reconstructedmore » with Doppler broadening at specified isotopic temperatures. The pointwise cross sections are directly used in the hyperfine group calculation whereas for the ultrafine group calculation, self-shielded cross sections are prepared by numerical integration of the pointwise cross sections based upon the narrow resonance approximation. For both the hyperfine and ultrafine group calculations, unresolved resonances are self-shielded using the analytic resonance integral method. The ultrafine group calculation can also be performed for two-dimensional whole-core problems to generate region-dependent broad-group cross sections. Multigroup cross sections are written in the ISOTXS format for a user-specified group structure. The code is executable on UNIX, Linux, and PC Windows systems, and its library includes all isotopes of the ENDF/BVII. 0 data.« less