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Journal Articles

CIELO collaboration summary results; International evaluations of neutron reactions on uranium, plutonium, iron, oxygen and hydrogen

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.

Nuclear Data Sheets, 148, p.189 - 213, 2018/02

 Times Cited Count:8 Percentile:4(Physics, Nuclear)

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - $$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{56}$$Fe, $$^{16}$$O and $$^{1}$$H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.

Journal Articles

The CIELO collaboration; Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Kahler, A. C.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Pigni, M.*; Dunn, M.*; Leal, L.*; et al.

EPJ Web of Conferences (Internet), 146, p.02001_1 - 02001_9, 2017/09

 Times Cited Count:4 Percentile:0.6

The CIELO collaboration has studied neutron cross sections on nuclides ($$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U and $$^{239}$$Pu) that significantly impact criticality in nuclear technologies with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

Journal Articles

A New evaluation of the neutron data standards

Carlson, A. D.*; Pronyaev, V.*; Hale, G. M.*; Zhenpeng, C.*; Capote, R.*; Dur$'a$n, I.*; Hambsch, F.-J.*; Kawano, Toshihiko*; Kunieda, Satoshi; 13 of others*

EPJ Web of Conferences (Internet), 146, p.02025_1 - 02025_4, 2017/09

 Times Cited Count:3 Percentile:1.43

Evaluations are being done for the $$^1$$H(n,n), $$^6$$Li(n,t), $$^{10}$$B(n,$$alphagamma$$), $$^{10}$$B(n,$$alpha$$), C(n,n), $$^{197}$$Au(n,$$gamma$$), $$^{235}$$U(n,f) and $$^{238}$$U(n,f) standard cross sections. Evaluations are also being done for data that are not traditional standards including: the Au(n,$$gamma$$) cross section at energies below where it is considered a standard; reference cross sections for prompt $$gamma$$-ray production in fast neutron-induced reactions; reference cross sections for very high energy fission cross sections; the $$^{235}$$U thermal neutron fission spectrum and the $$^{252}$$Cf spontaneous fission neutron spectrum and the thermal constants.

Journal Articles

Toward advancement of nuclear data research in the resonance region

Kunieda, Satoshi; Shibata, Keiichi; Fukahori, Tokio; Kawano, Toshihiko*; Paris, M.*; Hale, G.*

JAEA-Conf 2015-003, p.33 - 38, 2016/03

We present recent progress of nuclear data evaluation method in the resolved resonance range. Our multi-channel R-matrix code now includes photon-channel and computational capability of charged-particle elastic scattering. We also present the physical constraint from the theory in the analysis of experimental data. Example analysis results are shown for $$^8$$Be and $$^{17}$$O compound system. Finally, perspectives are discussed toward the advancement of nuclear data in the resonance region including those for medium-heavy nuclei.

Journal Articles

Covariance of neutron cross sections for $$^{16}$$O through R-matrix analysis

Kunieda, Satoshi; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*; Shibata, Keiichi; Fukahori, Tokio

Nuclear Data Sheets, 123, p.159 - 164, 2015/01

 Times Cited Count:3 Percentile:61.22(Physics, Nuclear)

The collision matrix in the R-matrix theory is unitary, hence theory brings strong constraints to behavior of the parameters. An unitarity-imposed R-matrix analysis is carried out for $$^{17}$$O system to evaluate $$^{16}$$O neutron cross-sections in the resolved resonance range. Covariance matrices are also estimated both for the cross-sections and angular distributions with a deterministic method. Present results mirror the nature in the theory as well as experimental information.

Journal Articles

Estimation of neutron cross-sections for $$^{16}$$O up to 5.2 MeV through R-matrix analysis

Kunieda, Satoshi; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*; Shibata, Keiichi; Fukahori, Tokio

NEA/NSC/DOC(2014)13 (Internet), p.33 - 39, 2014/07

There still remain differences among measured data, which makes the evaluated cross-sections uncertain, and which consequently affects some integral calculation. $$^{16}$$O is one of the important nuclei in the nuclear application, but such kinds of issues appears in elastic-scattering and (n,$$alpha$$) reaction cross-sections. Purpose of this study is to solve those issues as they are common concerns in the world. We present estimated cross sections and their covariance data which are "physically" constrained by the R-matrix theory. The differences between the estimated and the measured cross-sections will be also discussed.

Journal Articles

R-matrix analysis for n + $$^{16}$$O cross-sections up to E$$_{rm n}$$ = 6.0 MeV with covariances

Kunieda, Satoshi; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*; Shibata, Keiichi; Fukahori, Tokio

Nuclear Data Sheets, 118, p.250 - 253, 2014/04

 Times Cited Count:7 Percentile:39.56(Physics, Nuclear)

Oxygen is one of the most important materials in nuclear applications. However, there are big discrepancies among experimental and evaluated data in $$^{16}$$O($$n,alpha$$) cross section. Also, there are increasing demands for giving uncertainties in evaluated cross section to estimate the margin of integral calculations. We analyzed experimental cross sections with R-matrix theory, and estimated cross sections with their uncertainties. In this analysis, not only the neutron but also an inverse reactions were included. The systematic uncertainties were also considered for each measurement. The resulting cross sections and uncertainties mirror both experimental and theoretical knowledges.

Journal Articles

The CIELO Collaboration; Neutron reactions on $$^1$$H, $$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U, and $$^{239}$$Pu

Chadwick, M. B.*; Dupont, E.*; Bauge, E.*; Blokhin, A.*; Bouland, O.*; Brown, D. A.*; Capote, R.*; Carlson, A. D.*; Danon, Y.*; De Saint Jean, C.*; et al.

Nuclear Data Sheets, 118, p.1 - 25, 2014/04

 Times Cited Count:75 Percentile:0.97(Physics, Nuclear)

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely $$^{1}$$H, $$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U, and $$^{239}$$Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes. The evaluated data for these materials in the existing nuclear data libraries are reviewed, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

Journal Articles

ENDF/B-VII.1 nuclear data for science and technology; Cross sections, covariances, fission product yields and decay data

Chadwick, M. B.*; Herman, M.*; Oblo$v{z}$insk$'y$, P.*; Dunn, M. E.*; Danon, Y.*; Kahler, A. C.*; Smith, D. L.*; Pritychenko, B.*; Arbanas, G.*; Arcilla, R.*; et al.

Nuclear Data Sheets, 112(12), p.2887 - 2996, 2011/12

 Times Cited Count:1155 Percentile:0.01(Physics, Nuclear)

The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. It features extension of covered nuclei, covariance data for 190 nuclei, R-matrix analyses of neutron reactions on light nuclei, updates for some medium-heavy and actinoid nuclei, etc. Criticality benchmark tests with a transport simulation code MCNP shows improved performances.

Oral presentation

Development of R-matrix code and neutron cross sections for O-16 with covariance

Kunieda, Satoshi; Shibata, Keiichi; Fukahori, Tokio; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*

no journal, , 

Light nuclei are used as the moderator, coolant and reflector in the reactors. Also, they are main constituents of human body. Therefore it is important to evaluate neutron cross sections and their covariances for those nuclei for reactor engineering and radiotherapy. In this study, we developed a multichannel R-Matrix code to estimate the cross sections and covariances in the resonance region. The code also has functions for parameter search and covariance estimation from experimental cross sections. In the presentation, we will show main features of our R-matrix code and example results for O-16.

Oral presentation

Application of R-matrix theory to cross-section evaluation for light nuclei

Kunieda, Satoshi; Shibata, Keiichi; Fukahori, Tokio; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*

no journal, , 

The collision matrix calculated from the R-matrix theory is the unitary. Hence the theory brings physical constraints to the analysis of measured cross-sections. That means it may reduce some inconsistencies in the present experimental and evaluated data. The unitarity constraint analysis was carried out for the cross-section evaluation for O-16. We confirmed that the calculated differential cross-sections were also consistent with measured values.

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