Reevaluation of the 154Eu thermal capture cross-section based on spent fuel benchmarking studies

Steven E. Skutnik; Nathan T. Shoman

Reevaluation of the ¹⁵⁴Eu thermal capture cross-section based on spent fuel benchmarking studies

Steven E. Skutnik
, Nathan T. Shoman

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

1 Scopus citations

Abstract

The ¹⁵⁴Eu(n,γ)¹⁵⁵ Eu radiative capture reaction is an important reaction to understanding both reactor dynamics (given the large capture cross-sections of both ¹⁵⁴Eu and ¹⁵⁵Eu) as well as for the characteristics of used nuclear fuel, where ¹⁵⁴Eu is both a strong gamma emitter and a key burnup indicator nuclide. In the most recent Evaluated Nuclear Data File (ENDF) releases (ENDF-B/VII.0, and subsequently ENDF-B/VII.1), the ¹⁵⁴Eu(n,γ)¹⁵⁵ Eu thermal capture cross-section (σ_th, reported for E = 0.0253 eV and extrapolated to lower energies via the ^l/v relationship) was updated based on evaluations compiled by Mughabghab, indicating an evaluated cross-section of 1348.5 barns, 36.6% lower than the prior reported evaluation of 1840 barns in ENDF/VI.8. Recent computational benchmarking studies based on the highly thermalized spectra of CANDU fuel assemblies suggest that this newer evaluation may in fact underestimate the true thermal capture cross-section, producing significant over-estimations of ¹⁵⁴Eu for highly thermalized systems (like CANDU reactors), while likewise producing a systematic (but more moderate) bias for light water reactor systems. In this paper, we will present the results of a series of used fuel depletion studies, evaluating the effect of employing the ENDF/VII thermal capture cross-section by calculating the effective onegroup capture cross-section for ¹⁵⁴Eu for both CANDU PHWR assemblies using ENDF/VI.8 and ENDF/VII.0 and comparing the results to destructive radiochemical assay on well-characterized assemblies. Our evaluations indicate a superior agreement for ¹⁵⁴Eu in highly thermalized systems, wherein the difference in ¹⁵⁴Eu inventories is up to 10% between the two evaluations.

Original language	English
Title of host publication	Physics of Reactors 2016, PHYSOR 2016
Subtitle of host publication	Unifying Theory and Experiments in the 21st Century
Publisher	American Nuclear Society
Pages	633-644
Number of pages	12
ISBN (Electronic)	9781510825734
State	Published - 2016
Externally published	Yes
Event	Physics of Reactors 2016: Unifying Theory and Experiments in the 21st Century, PHYSOR 2016 - Sun Valley, United States Duration: May 1 2016 → May 5 2016

Publication series

Name	Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century
Volume	1

Conference

Conference	Physics of Reactors 2016: Unifying Theory and Experiments in the 21st Century, PHYSOR 2016
Country/Territory	United States
City	Sun Valley
Period	05/1/16 → 05/5/16

Funding

This work was supported by an Nuclear Energy University Programs (NEUP) grant sponsored by the U.S. Department of Energy, Office of Nuclear Energy, award number DE-NE0000737. The authors also wish to express their sincere appreciation to Shane Hart, Doro Wiarda, and Mark Williams of Oak Ridge National Laboratory for their invaluable assistance in preparing modified AMPX master libraries for testing the 154Eu thermal capture cross-sections.

Keywords

CANDU
Cross-sections
ENDF
Eu-154
Eu-155
Neutron capture

Cite this

Skutnik, S. E., & Shoman, N. T. (2016). Reevaluation of the ¹⁵⁴Eu thermal capture cross-section based on spent fuel benchmarking studies. In Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century (pp. 633-644). (Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century; Vol. 1). American Nuclear Society.

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title = "Reevaluation of the 154Eu thermal capture cross-section based on spent fuel benchmarking studies",

abstract = "The 154Eu(n,γ)155 Eu radiative capture reaction is an important reaction to understanding both reactor dynamics (given the large capture cross-sections of both 154Eu and 155Eu) as well as for the characteristics of used nuclear fuel, where 154Eu is both a strong gamma emitter and a key burnup indicator nuclide. In the most recent Evaluated Nuclear Data File (ENDF) releases (ENDF-B/VII.0, and subsequently ENDF-B/VII.1), the 154Eu(n,γ)155 Eu thermal capture cross-section (σth, reported for E = 0.0253 eV and extrapolated to lower energies via the l/v relationship) was updated based on evaluations compiled by Mughabghab, indicating an evaluated cross-section of 1348.5 barns, 36.6\% lower than the prior reported evaluation of 1840 barns in ENDF/VI.8. Recent computational benchmarking studies based on the highly thermalized spectra of CANDU fuel assemblies suggest that this newer evaluation may in fact underestimate the true thermal capture cross-section, producing significant over-estimations of 154Eu for highly thermalized systems (like CANDU reactors), while likewise producing a systematic (but more moderate) bias for light water reactor systems. In this paper, we will present the results of a series of used fuel depletion studies, evaluating the effect of employing the ENDF/VII thermal capture cross-section by calculating the effective onegroup capture cross-section for 154Eu for both CANDU PHWR assemblies using ENDF/VI.8 and ENDF/VII.0 and comparing the results to destructive radiochemical assay on well-characterized assemblies. Our evaluations indicate a superior agreement for 154Eu in highly thermalized systems, wherein the difference in 154Eu inventories is up to 10\% between the two evaluations.",

keywords = "CANDU, Cross-sections, ENDF, Eu-154, Eu-155, Neutron capture",

author = "Skutnik, \{Steven E.\} and Shoman, \{Nathan T.\}",

year = "2016",

language = "English",

series = "Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century",

publisher = "American Nuclear Society",

pages = "633--644",

booktitle = "Physics of Reactors 2016, PHYSOR 2016",

note = "Physics of Reactors 2016: Unifying Theory and Experiments in the 21st Century, PHYSOR 2016 ; Conference date: 01-05-2016 Through 05-05-2016",

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Skutnik, SE & Shoman, NT 2016, Reevaluation of the ¹⁵⁴Eu thermal capture cross-section based on spent fuel benchmarking studies. in Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century. Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century, vol. 1, American Nuclear Society, pp. 633-644, Physics of Reactors 2016: Unifying Theory and Experiments in the 21st Century, PHYSOR 2016, Sun Valley, United States, 05/1/16.

Reevaluation of the ¹⁵⁴Eu thermal capture cross-section based on spent fuel benchmarking studies. / Skutnik, Steven E.; Shoman, Nathan T.
Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century. American Nuclear Society, 2016. p. 633-644 (Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century; Vol. 1).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

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AU - Shoman, Nathan T.

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N2 - The 154Eu(n,γ)155 Eu radiative capture reaction is an important reaction to understanding both reactor dynamics (given the large capture cross-sections of both 154Eu and 155Eu) as well as for the characteristics of used nuclear fuel, where 154Eu is both a strong gamma emitter and a key burnup indicator nuclide. In the most recent Evaluated Nuclear Data File (ENDF) releases (ENDF-B/VII.0, and subsequently ENDF-B/VII.1), the 154Eu(n,γ)155 Eu thermal capture cross-section (σth, reported for E = 0.0253 eV and extrapolated to lower energies via the l/v relationship) was updated based on evaluations compiled by Mughabghab, indicating an evaluated cross-section of 1348.5 barns, 36.6% lower than the prior reported evaluation of 1840 barns in ENDF/VI.8. Recent computational benchmarking studies based on the highly thermalized spectra of CANDU fuel assemblies suggest that this newer evaluation may in fact underestimate the true thermal capture cross-section, producing significant over-estimations of 154Eu for highly thermalized systems (like CANDU reactors), while likewise producing a systematic (but more moderate) bias for light water reactor systems. In this paper, we will present the results of a series of used fuel depletion studies, evaluating the effect of employing the ENDF/VII thermal capture cross-section by calculating the effective onegroup capture cross-section for 154Eu for both CANDU PHWR assemblies using ENDF/VI.8 and ENDF/VII.0 and comparing the results to destructive radiochemical assay on well-characterized assemblies. Our evaluations indicate a superior agreement for 154Eu in highly thermalized systems, wherein the difference in 154Eu inventories is up to 10% between the two evaluations.

AB - The 154Eu(n,γ)155 Eu radiative capture reaction is an important reaction to understanding both reactor dynamics (given the large capture cross-sections of both 154Eu and 155Eu) as well as for the characteristics of used nuclear fuel, where 154Eu is both a strong gamma emitter and a key burnup indicator nuclide. In the most recent Evaluated Nuclear Data File (ENDF) releases (ENDF-B/VII.0, and subsequently ENDF-B/VII.1), the 154Eu(n,γ)155 Eu thermal capture cross-section (σth, reported for E = 0.0253 eV and extrapolated to lower energies via the l/v relationship) was updated based on evaluations compiled by Mughabghab, indicating an evaluated cross-section of 1348.5 barns, 36.6% lower than the prior reported evaluation of 1840 barns in ENDF/VI.8. Recent computational benchmarking studies based on the highly thermalized spectra of CANDU fuel assemblies suggest that this newer evaluation may in fact underestimate the true thermal capture cross-section, producing significant over-estimations of 154Eu for highly thermalized systems (like CANDU reactors), while likewise producing a systematic (but more moderate) bias for light water reactor systems. In this paper, we will present the results of a series of used fuel depletion studies, evaluating the effect of employing the ENDF/VII thermal capture cross-section by calculating the effective onegroup capture cross-section for 154Eu for both CANDU PHWR assemblies using ENDF/VI.8 and ENDF/VII.0 and comparing the results to destructive radiochemical assay on well-characterized assemblies. Our evaluations indicate a superior agreement for 154Eu in highly thermalized systems, wherein the difference in 154Eu inventories is up to 10% between the two evaluations.

KW - CANDU

KW - Cross-sections

KW - ENDF

KW - Eu-154

KW - Eu-155

KW - Neutron capture

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T3 - Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century

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