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Journal Articles

IAEA Photonuclear Data Library 2019

Kawano, Toshihiko*; Cho, Y. S.*; Dimitriou, P.*; Filipescu, D.*; Iwamoto, Nobuyuki; Plujko, V.*; Tao, X.*; Utsunomiya, Hiroaki*; Varlamov, V.*; Xu, R.*; et al.

Nuclear Data Sheets, 163, p.109 - 162, 2020/01

 Times Cited Count:39 Percentile:99.01(Physics, Nuclear)

Journal Articles

Reference database for photon strength functions

Goriely, S.*; Dimitriou, P.*; Wiedeking, M.*; Belgya, T.*; Firestone, R.*; Kopecky, J.*; Krti$v{c}$ka, M.*; Plujko, V.*; Schwengner, R.*; Siem, S.*; et al.

European Physical Journal A, 55(10), p.172_1 - 172_52, 2019/10

 Times Cited Count:43 Percentile:91.23(Physics, Nuclear)

Journal Articles

Effects of the nuclear structure of fission fragments on the high-energy prompt fission $$gamma$$-ray spectrum in $$^{235}$$U($$n_{rm th},f$$)

Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, R.; L$'e$guillon, R.; Ogawa, Tatsuhiko; Soldner, T.*; K$"o$ster, U.*; Pollitt, A.*; Hambsch, F.-J.*; et al.

Physical Review C, 100(4), p.044610_1 - 044610_7, 2019/10

 Times Cited Count:10 Percentile:78.41(Physics, Nuclear)

Journal Articles

3rd RCM on Updating the Photonuclear Data Library and Generating a Reference Database for Photon Strength Functions

Utsunomiya, Hiroaki*; Iwamoto, Nobuyuki; Kawano, Toshihiko*

Kaku Deta Nyusu (Internet), (122), p.26 - 32, 2019/02

no abstracts in English

Journal Articles

Developing reliable reaction gamma-ray data

Dimitriou, P.*; Belgya, T.*; Cho, Y.-S.*; Filipescu, D.*; Firestone, R.*; Goriely, S.*; Iwamoto, Nobuyuki; Kawano, Toshihiko*; Kopecky, J.*; Krticka, M.*; et al.

EPJ Web of Conferences, 178, p.06005_1 - 06005_3, 2018/05

 Times Cited Count:2 Percentile:77.42

no abstracts in English

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:60 Percentile:98.57(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

Inter-comparison of Hauser-Feshbach model codes toward better actinide evaluations

Capote, R.*; Hilaire, S.*; Iwamoto, Osamu; Kawano, Toshihiko*; Sin, M.*

EPJ Web of Conferences, 146, p.12034_1 - 12034_4, 2017/09

 Times Cited Count:5 Percentile:94.97

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, 146, p.02001_1 - 02001_9, 2017/09

 Times Cited Count:6 Percentile:96.5

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, 146, p.02025_1 - 02025_4, 2017/09

 Times Cited Count:4 Percentile:92.82

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:5 Percentile:32.98(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:10 Percentile:56.42(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:104 Percentile:98.67(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

Measurement and model analysis of $$(n,xalpha)$$ cross sections for Cr, Fe, $$^{59}$$Co, and $$^{58,60}$$Ni from threshold energy to 150 MeV

Kunieda, Satoshi; Haight, R. C.*; Kawano, Toshihiko*; Chadwick, M. B.*; Sterbenz, S. M.*; Bateman, F. B.*; Wasson, O. A.*; Grimes, S. M.*; Maier-Komor. P.*; Vonach, H.*; et al.

Physical Review C, 85(5), p.054602_1 - 054602_10, 2012/05

 Times Cited Count:20 Percentile:72.69(Physics, Nuclear)

Neutron reactions that produce alpha-particles have been investigated for energies from threshold to 150 MeV on elemental chromium, iron, $$^{59}$$Co and $$^{58,60}$$Ni. The cross sections were measured at the Los Alamos Neutron Science Center by direct observation of alpha-particles. The model calculations are made for statistical and pre-equilibrium processes. This study particularly focuses on the pre-equilibrium cluster emission, which is described by the clustering exciton model of Iwamoto and Harada. We calculate the alpha-particle formation factors numerically without any approximations that appeared in the original model. The calculated alpha-particle production cross sections agree well with the measured data, except for the Cr case. With a simple sensitivity study for the level density parameters, it is reported that relatively small changes in the level density parameters improve reproduction of experimental data significantly.

Journal Articles

Clustering pre-equilibrium model analysis for nucleon-induced alpha-particle spectra up to 200 MeV

Kunieda, Satoshi; Kawano, Toshihiko*; Chadwick, M. B.*; Fukahori, Tokio; Watanabe, Yukinobu*

EPJ Web of Conferences, 21, p.09003_1 - 09003_8, 2012/02

 Times Cited Count:2 Percentile:63.08

The clustering exciton model of Iwamoto and Harada is applied to the analysis of pre-equilibrium $$(N,xalpha)$$ energy spectra for medium-to-heavy nuclei up to 200 MeV. In this work, we calculate alpha-particle formation factors without any approximations that appear in the original model. The clustering process is also considered in both the primary and second pre-equilibrium emissions. We optimize the exciton and the clustering model parameters simultaneously by looking at the experimental $$(N,xN)$$ and $$(N,xalpha)$$ energy spectra. The experimental alpha-particle spectra are well reproduced with a unique set of clustering model parameters, which is independent of incident neutrons/protons. The present analysis also implies that the clustering model parameter is not so different between the medium and heavy nuclei. Our calculations reproduce experimental data generally well up to the incident energy of $$sim$$150 MeV, but underestimations are seen above this energy.

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:1869 Percentile:100(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.

Journal Articles

Direct and semi-direct capture in low-energy ($$n$$,$$gamma$$) reactions of neutron-rich tin isotopes and its implications for $$r$$-process nucleosynthesis

Chiba, Satoshi; Koura, Hiroyuki; Hayakawa, Takehito; Maruyama, Toshiki; Kawano, Toshihiko*; Kajino, Toshitaka*

Physical Review C, 77(1), p.015809_1 - 015809_7, 2008/01

 Times Cited Count:23 Percentile:78.15(Physics, Nuclear)

We calculate the direct and semi-direct (DSD) components of the neutron capture cross sections for a series of tin isotopes and compare them with the Hauser-Feshbach (HF) contribution in the energy region of astrophysical interests. It was found that the HF component, which is known to be dominant for isotopes in the vicinity of the stability line, drops off rapidly for isotope $$^{132}$$Sn and toward more neutron-rich ones, while the DSD component decreases only smoothly. As a consequence, the direct portion of the DSD component comes to give the largest contribution to the total ($$n$$,$$gamma$$) cross section below a few MeV. Therefore, the direct capture process modifies the astrophysical ($$n$$,$$gamma$$) reaction rates for these neutron-rich isotopes to a great extent. The reason of the difference in the isotopic dependence between the HF and DSD components is discussed, and its implication for the $$r$$-process nucleosynthesis is given.

Journal Articles

Nucleon direct-semidirect radiative capture with Skyrme-Hartree-Fock-BCS bound states

Bonearu, L.*; Kawano, Toshihiko*; Watanabe, Takehito*; Chiba, Satoshi

Physical Review C, 75(5), p.054618_1 - 054618_10, 2007/05

 Times Cited Count:20 Percentile:77(Physics, Nuclear)

The nucleon direct-semidirect (DSD) capture cross sections are obtained by calculating a transition amplitude to the Hartree-Fock-BCS bound states. The radial matrix elements in the DSD amplitudes are calculated from the radial part of the single-particle wave functions. For deformed nuclei the single-particle states are expanded in the cylindrical harmonic-oscillator basis and then projected on the spherical harmonic-oscillator basis. The pairing correlations are treated in the BCS approach and the calculated spectroscopic factors are in fairly good agreement with experimental data in the even tin isotopes from $$^{116}$$Sn to $$^{124}$$Sn. The resulting DSD cross sections for the neutron capture by $$^{208}$$Pb and $$^{238}$$U are found to be in good agreement with the available experimental data. The calculations are also performed for the neutron capture on $$^{122}$$Sn and $$^{132}$$Sn isotopes that are important for ther-process in astrophysics.

JAEA Reports

Report of investigation on malfunction of reserved shutdown system in HTTR

Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.

JAEA-Technology 2006-030, 58 Pages, 2006/03


During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B$$_{4}$$C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of B$$_{4}$$C/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.

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