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Otsuka, Naohiko*; Devi, V.*; Iwamoto, Osamu
Applied Radiation and Isotopes, 225, p.111903_1 - 111903_18, 2025/11
Times Cited Count：0 Percentile：0.00(Chemistry, Inorganic & Nuclear)Iwamoto, Osamu; Koura, Hiroyuki; Endo, Shunsuke; Kimura, Atsushi; Nakayama, Shinsuke; Araki, Shohei; Nishio, Katsuhisa; Otsuka, Naohiko*; Minato, Futoshi*; Watanabe, Yukinobu*; et al.
Kaku Deta Nyusu (Internet), (142), p.18 - 30, 2025/10
no abstracts in English
Otsuka, Naohiko*; Tada, Kenichi; Cabellos, O.*; Iwamoto, Osamu
Annals of Nuclear Energy, 212, p.110977_1 - 110977_9, 2025/03
Times Cited Count：4 Percentile：66.28(Nuclear Science & Technology)The uranium-233 neutron capture cross section between 3 keV and 1 MeV was evaluated considering the recent new alpha-value measurement performed at the Los Alamos National Laboratory LANCE facility. The obtained capture cross section is systematically lower than the capture cross section in the JENDL-5 library and the reduction is close to 50% around 20 keV. The newly evaluated cross section was validated against 166 criticality experiments chosen from the ICSBEP handbook by performing Monte Carlo neutron transport calculation with the JENDL-5 library, and slight reduction of the chi-square value was achieved by adoption of the newly evaluated capture cross section.
Okuyama, Riko*; Otsuka, Naohiko*; Chiba, Go*; Iwamoto, Osamu
Journal of Nuclear Science and Technology, 61(1), p.57 - 67, 2024/01
Times Cited Count：2 Percentile：27.37(Nuclear Science & Technology)Otsuka, Naohiko*; Iwamoto, Osamu
EPJ Web of Conferences, 284, p.08011_1 - 08011_4, 2023/05
Times Cited Count：4 Percentile：91.00(Nuclear Science & Technology)Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.
Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01
Times Cited Count：375 Percentile：99.99(Nuclear Science & Technology)Otsuka, Naohiko*; Iwamoto, Osamu
JAEA-Data/Code 2022-005, 102 Pages, 2022/10
JAEA-Data-Code-2022-005.pdf:2.18MB
JAEA-Data-Code-2022-005-appendix(CD-ROM).zip:3.85MB
The neutron-induced fission cross sections were simultaneously evaluated for the JENDL-5 library for 
U and 
Pu from 10 keV to 200 MeV and for 
U and 
Pu from 100 keV to 200 MeV. Evaluation was performed by least-squares fitting of Schmittroth's roof function to the logarithms of the experimental cross sections and cross section ratios in the EXFOR library. A simultaneous evaluation code SOK was used with its extension to data in arbitrary unit. This report describes (1) construction of the experimental database, (2) selection of data points from TUD-KRI collaboration, (3) comparison with the evaluated cross sections in recent major libraries, and (4) impact of the 
U datasets published in 1970s.
Otsuka, Naohiko*; Iwamoto, Osamu
Journal of Nuclear Science and Technology, 59(8), p.1004 - 1036, 2022/08
Times Cited Count：12 Percentile：74.14(Nuclear Science & Technology)
Ga with dual monitor foils and covariance analysisPanikkath, P.*; Otsuka, Naohiko*; Iwamoto, Yosuke; Mohanakrishnan, P.*
European Physical Journal A, 55(6), p.91_1 - 91_9, 2019/06
Times Cited Count：3 Percentile：25.12(Physics, Nuclear)The thermal neutron capture cross section of Ga was evaluated to be around 4.7 b in many nuclear data libraries. On the other hand, it was evaluated to be 3.71 b in JENDL-4.0. Since these cross section data were obtained by the activation measurement with a monitor foil to determine the absolute value of cross section, data depend on the monitor foil adopted in the measurement. In this work, we measured the thermal neutron capture cross section of Ga with a few monitor foils. In the experiment, neutrons decelerated in concrete shield were irradiated with a sample with Ga foil and 
Au and 
Mn monitor foils. A covariance analysis was performed to obtain the off-diagonal weighted mean of the results determined with the two monitor reactions. As a result, the thermal neutron capture cross section of Ga was 4.05
0.27 b and is close to the value of JENDL-4.0.
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：83 Percentile：97.63(Physics, Nuclear)The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - U, U, 
Pu, 
Fe, 
O and 
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.
Otsuka, Yasunori*; Ishikawa, Takanori*; Tajima, Katsuhiro*; Wada, Tetsu*; Aydan, 
mer*; Tokashiki, Naohiko*; Sato, Toshinori; Aoyagi, Kazuhei
Journal of Nepal Geological Society, 55(Special Issue), p.1 - 6, 2018/00
Ultrasonic wave reflection intensity of the wall of borehole drilled from bottom of the East Access Shaft in the Horonobe Underground Research Laboratory, Hokkaido, Japan, was obtained using an ultrasonic scanner (USS). In this paper, we compared results of USS observation with core logging data including core observation, optical digital scanner (ODS) observation, and result of Needle Penetration Index (NPI) tests. The results indicated that ultrasonic wave reflection intensity had a good correlation with other observation results. USS observation and NPI tests are useful techniques for determination of detailed rock mass classification.
Dupont, E.*; Otsuka, Naohiko*; Harada, Hideo; Kimura, Atsushi; n_TOF Collaboration*; 224 of others*
EPJ Web of Conferences, 146, p.07002_1 - 07002_4, 2017/09
Times Cited Count：5 Percentile：90.53(Nuclear Science & Technology)The n_TOF neutron time-of-flight facility at CERN is used for high quality nuclear data measurements from thermal energy up to hundreds of MeV. In line with the CERN open data policy, the n_TOF Collaboration takes actions to preserve its unique data, facilitate access to them in standardised format, and allow their re-use by a wide community in the fields of nuclear physics, nuclear astrophysics and various nuclear technologies. The present contribution briefly describes the n_TOF outcomes, as well as the status of dissemination and preservation of n_TOF final data in the international EXFOR library.
Harada, Hideo; Shibata, Keiichi; Nishio, Katsuhisa; Igashira, Masayuki*; Plompen, A.*; Hambsch, F.-J.*; Schillebeeckx, P.*; Gunsing, F.*; Ledoux, X.*; Palmiotti, G.*; et al.
NEA/NSC/WPEC/DOC(2014)446, 111 Pages, 2014/02
Takemoto, Noriyuki; Sugaya, Naoto; Otsuka, Kaoru; Hanakawa, Hiroki; Onuma, Yuichi; Hosokawa, Jinsaku; Hori, Naohiko; Kaminaga, Masanori; Tamura, Kazuo*; Hotta, Koji*; et al.
JAEA-Technology 2013-013, 44 Pages, 2013/06
JAEA-Technology-2013-013.pdf:4.42MB
A real-time simulator for operating both a reactor and irradiation facilities of a materials testing reactor, Simulator of Materials Testing Reactors, was developed for understanding reactor behavior and upskilling in order to utilize for a nuclear human resource development and to promote partnership with developing countries which have a plan to introduce nuclear power plant. The simulator is designed based on the JMTR (Japan Materials Testing Reactor) and it simulates operation, irradiation tests and various kinds of anticipated operational transients and accident conditions caused by the reactor and irradiation facilities. The development of the simulator was sponsored by the Japanese government as one of the specialized projects of advanced research infrastructure in order to promote basic as well as applied researches. This report summarizes the simulation model, hardware specification and operation procedure of the simulator.
Schillebeeckx, P.*; Becker, B.*; Danon, Y.*; Guber, K.*; Harada, Hideo; Heyse, J.*; Junghans, A. R.*; Kopecky, S.*; Massimi, C.*; Moxon, M. C.*; et al.
Nuclear Data Sheets, 113(12), p.3054 - 3100, 2012/12
Times Cited Count：128 Percentile：97.51(Physics, Nuclear)Iwamoto, Osamu; Nakagawa, Tsuneo; Chiba, Satoshi; Otsuka, Naohiko*
Journal of the Korean Physical Society, 59(2), p.1224 - 1229, 2011/08
Times Cited Count：18 Percentile：67.36(Physics, Multidisciplinary)Covariances of nuclear data in JENDL-4 have been evaluated. The covariance evaluations are basically based on available experimental data. The fission cross sections for 6 major actinides of 
U and 
Pu were evaluated simultaneously using experimental data of both cross sections and their ratios. The deduced covariance has correlations between the data of different nuclei. For minor actinide, covariances of the fission cross sections were obtained from evaluation using GMA code. For other many reaction cross sections, theoretical calculations with CCONE code were performed for cross section evaluations. The covariances were estimated using KALMAN code with sensitivities against model parameters. For resonance parameters and average number of fission neutrons, covariances were also evaluated.
Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Katakura, Junichi; Otsuka, Naohiko*
Journal of the Korean Physical Society, 59(2), p.1046 - 1051, 2011/08
Times Cited Count：22 Percentile：70.50(Physics, Multidisciplinary)In JENDL-4, much emphasis is placed on the improvements of FP and MA data. For achieving this, new nuclear model codes POD and CCONE were developed, since experimental data are very scarce for those nuclei. The global coupled-channel optical model parameters, which were obtained in the wide mass region, were used for the evaluation of cross sections. Thermal cross sections of actinides were determined by carefully examining available experimental data. Special care was taken for the resonance region of U in order to reproduce measured criticalities and Na-void reactivities for U fueled fast-neutron cores. As for FP, resolved resonance parameters were updated for more than 100 nuclei. The cross sections of above the resonance region were evaluated by using the POD and CCONE codes. Fission product yield data were obtained from the ENDF/B-VII.0 data with some modifications. The new library, which contains neutron data for 406 nuclei, will be made available in 2010.
Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; et al.
Journal of Nuclear Science and Technology, 48(1), p.1 - 30, 2011/01
Times Cited Count：1840 Percentile：99.99(Nuclear Science & Technology)The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.
Iwamoto, Osamu; Nakagawa, Tsuneo; Otsuka, Naohiko*; Chiba, Satoshi; Okumura, Keisuke; Chiba, Go; Osawa, Takaaki*; Furutaka, Kazuyoshi
Journal of Nuclear Science and Technology, 46(5), p.510 - 528, 2009/05
JENDL Actinoid File 2008 (JENDL/AC-2008) was released in March 2008. It includes nuclear data for neutron-induced reactions for 79 nuclides from Ac (
) to Fm (
). The neutron energy range is 
eV to 20 MeV. Almost all data for 61 actinoids in JENDL-3.3 were revised. New evaluations were performed for 17 nuclides which have half lives longer than 1 day. New comprehensive theoretical model code CCONE was widely used for the evaluation of cross sections and neutron emission spectra. Thermal cross sections for many nuclides were revised based on experimental data. Resonance parameters were readjusted to reproduce them. Simultaneous evaluations of fission cross sections were performed for six important nuclei. The least-squares fitting code GMA was used for evaluation of fission cross sections for minor actinoid. In this paper, we present the evaluation methods and results of the JENDL/AC-2008.
Zukeran, Atsushi*; Chiba, Go; Otsuka, Naohiko*; Ishikawa, Makoto; Takano, Hideki*
JAEA-Research 2008-091, 162 Pages, 2009/02
JAEA-Research-2008-091-01.pdf:5.8MBJAEA-Research-2008-091-02.pdf:45.78MB
Uncertainty of Doppler reactivity is theoretically formulated and then uncertainties of self-shielding factor and its temperature gradient due to errors of resonance parameters were evaluated from NJOY output. Sensitivity analysis was made for U, U, Pu and Pu of JENDL-3.3 based on JFS-3 70 group structure. Resultant sensitivity coefficients are provided for the uncertainty evaluation of Doppler reactivity.
