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Fukushima, Masahiro; Ando, Masaki; Nagaya, Yasunobu
Nuclear Science and Engineering, 199(6), p.1029 - 1043, 2025/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Fukushima, Masahiro; Ando, Masaki; Nagaya, Yasunobu
Nuclear Science and Engineering, 199(1), p.18 - 41, 2025/01
Times Cited Count：1 Percentile：57.00(Nuclear Science & Technology)A series of integral experiments were conducted at FCA of JAEA, simulating LWR cores with a tight lattice cell of highly enriched MOX fuel containing more than 15% fissile plutonium. The three experimental configurations were constructed using foamed polystyrene with different void fractions to clarify the prediction accuracy of neutronic calculation codes and nuclear data among various neutron spectra. The nuclear characteristics measured in the experiments were criticality, moderator void reactivity worths, and sample reactivity worths. The preliminary analyses on experiments were conducted using a deterministic calculation code conventionally used for fast reactors with JENDL-4.0. Most reactivity worth calculations correlated well with the experimental values. Specifically for the softer neutron spectra configurations, the treatment of ultrafine energy groups obviously improved the prediction accuracy of the deterministic calculations. Furthermore, reference calculations were performed with MVP3 code by modeling the experimental setup in detail, confirming the validity of the deterministic calculations.
Fukushima, Masahiro; Okajima, Shigeaki*; Mukaiyama, Takehiko*
Journal of Nuclear Science and Technology, 61(4), p.478 - 497, 2024/04
Times Cited Count：3 Percentile：62.75(Nuclear Science & Technology)A series of integral experiments was conducted to evaluate the fission and the capture cross- sections of transuranic (TRU) nuclides at the fast critical facility FCA of the Japan Atomic Energy Agency (JAEA). The experiments were carried out using seven uranium-fueled assemblies of the FCA. The neutron energy spectra of the core regions were adjusted so as to change from an intermediate neutron spectrum to a fast neutron spectrum on an assembly-by-assembly basis. The integral data measured with these experimental configurations provide some neutron energy characteristics: 1) fission rate ratios (FRRs) of 
Np, 
Pu, 
Pu, 
Am, 
Am, and 
Cm relative to 
Pu by using absolutely calibrated fission chambers, 2) small sample reactivity worths (SRWs) of Np, Pu, 
Pu, Am, and Am where oxide powders of around 15 to 20 grams were used, 3) criticalities, and 4) spectral indices such as fission rate ratios of U relative to 
U. In this paper, details of the SRW measurements are reported, and the latest Japanese Evaluated Nuclear Data Library JENDL-5 is tested by using the integral data obtained in systematically varied neutron energy spectra.
Yokoyama, Kenji
EPJ Web of Conferences, 281, p.00004_1 - 00004_10, 2023/03
In Japan, development of adjusted nuclear data library for fast rector application based on the cross-section adjustment method has been conducted since the early 1990s. The adjusted library is called the unified cross-section set. The first version was developed in 1991 and is called ADJ91. Recently, the integral experimental data were further expanded to improve the design prediction accuracy of the core loaded with minor actinoids and/or degraded Pu. Using the additional integral experimental data, development of ADJ2017 was started in 2017. In 2022, the latest unified cross-section set AJD2017R was developed based on JENDL-4.0 by using 619 integral experimental data. An overview of the latest version with a review of previous ones will be shown. On the other hand, JENDL-5 was released in 2021. In the development of JENDL-5, some of the integral experimental data used in ADJ2017R were explicitly utilized in the nuclear data evaluation. However, this is not reflected in the covariance data. This situation needs to be considered when developing a unified cross-section set based on JENDL-5. Preliminary adjustment calculation based on JENDL-5 is performed using C/E (calculation/experiment) values simply evaluated by a sensitivity analysis. The preliminary results will be also discussed.
I(n, 
) using fast neutron source in the "YAYOI" reactorNakamura, Shoji; Toh, Yosuke; Kimura, Atsushi; Hatsukawa, Yuichi*; Harada, Hideo
Journal of Nuclear Science and Technology, 59(7), p.851 - 865, 2022/07
Times Cited Count：1 Percentile：10.00(Nuclear Science & Technology)The present study performed integral experiments of I using a fast-neutron source reactor "YAYOI" of the University of Tokyo to validate evaluated nuclear data libraries. The iodine-129 sample and flux monitors were irradiated by fast neutrons in the Glory hole of the YAYOI reactor. Reaction rates of I were obtained by measurement of decay gamma-rays emitted from 
I. The validity of the fast-neutron flux spectrum in the Glory hole was confirmed by the 
ratios of the reaction rates of flux monitors. The experimental reaction rate of I was compared with that calculated with both the fast-neutron flux spectrum and evaluated nuclear data libraries. The present study revealed that the evaluated nuclear data of I cited in JENDL-4.0 should be reduced as much as 18% in neutron energies ranging from 10 keV to 3 MeV, and supported the reported data by Noguere 
below 100 keV.
Fukushima, Masahiro; Goda, J.*; Oizumi, Akito; Bounds, J.*; Cutler, T.*; Grove, T.*; Hayes, D.*; Hutchinson, J.*; McKenzie, G.*; McSpaden, A.*; et al.
Nuclear Science and Engineering, 194(2), p.138 - 153, 2020/02
Times Cited Count：7 Percentile：53.80(Nuclear Science & Technology)To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worth was conducted systematically in three fast spectra with different fuel compositions on the Comet critical assembly of the National Criticality Experiments Research Center. Previous experiments in a high-enriched uranium (HEU)/Pb and a low-enriched uranium (LEU)/Pb systems had been performed in 2016 and 2017, respectively. A follow-on experiment in a plutonium (Pu)/Pb system has been completed. The Pu/Pb system was constructed using lead plates and weapons grade plutonium plates that had been used in the Zero Power Physics Reactor (ZPPR) of Argonne National Laboratory until the 1990s. Furthermore, the HEU/Pb system was re-examined on the Comet critical assembly installed newly with a device that can guarantee the gap reproducibility with a higher accuracy and precision, and then the experimental data was re evaluated. Using the lead void reactivity worth measured in these three cores with different fuel compositions, the latest nuclear data libraries, JENDL 4.0 and ENDF/B VIII.0, were tested with the Monte Carlo calculation code MCNP version 6.1. As a result, the calculations by ENDF/B-VIII.0 were confirmed to agree with lead void reactivity worth measured in all the cores. It was furthermore found that the calculations by JENDL 4.0 overestimate by more than 20% for the Pu/Pb core while being in good agreements for the HEU/Pb and LEU/Pb cores.
Yokoyama, Kenji; Kitada, Takanori*
Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.1221 - 1230, 2018/04
no abstracts in English
Fukushima, Masahiro; Goda, J.*; Bounds, J.*; Cutler, T.*; Grove, T.*; Hutchinson, J.*; James, M.*; McKenzie, G.*; Sanchez, R.*; Oizumi, Akito; et al.
Nuclear Science and Engineering, 189, p.93 - 99, 2018/01
Times Cited Count：9 Percentile：61.01(Nuclear Science & Technology)To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worths was conducted in a high-enriched uranium (HEU)/Pb system and a low enriched uranium (LEU)/Pb system using the Comet Critical Assembly at NCERC. The critical experiments were designed to provide complementary data sets having different sensitivities to scattering cross sections of lead. The larger amount of the U present in the LEU/Pb core increases the neutron importance above 1 MeV compared with the HEU/Pb core. Since removal of lead from the core shifts the neutron spectrum to the higher energy region, positive lead void reactivity worths were observed in the LEU/Pb core while negative values were observed in the HEU/Pb core. Experimental analyses for the lead void reactivity worths were performed with the Monte Carlo calculation code MCNP6.1 together with nuclear data libraries, JENDL 4.0 and ENDF/B VII.1. The calculation values were found to overestimate the experimental ones for the HEU/Pb core while being consistent for the LEU/Pb core.
Fukushima, Masahiro; Tsujimoto, Kazufumi; Okajima, Shigeaki
EPJ Web of Conferences, 111, p.07002_1 - 07002_5, 2016/03
Times Cited Count：2 Percentile：79.62(Nuclear Science & Technology)In the IX-th series at FCA, central fission rate ratios for TRU such as Np, Pu, Pu, Am, Am, Cm and Pu were measured in the seven uranium-fueled assemblies with systematically changed neutron spectra. The FCA-IX assemblies were constructed with simplicity both in geometry and composition. Taking their advantage, benchmark models with respect to central fission rate ratios had been recently established for the assessment of the TRU's fission cross sections. By virtue of these FCA-IX assemblies where the simple combinations of uranium fuel and diluent in their core regions were systematically varied, the neutron spectra of these benchmark models cover those of various reactor types, from fast to epithermal reactors. As an application of these benchmark models, JENDL-4.0 was utilized by a Monte Carlo calculation code. Several results show obvious discrepancies between calculation and experimental values. The benchmark models would be well suited for the assessment and improvement of the nuclear data for TRU's fission cross sections.
Verzilov, Y. M.; Sato, Satoshi; Ochiai, Kentaro; Wada, Masayuki*; Klix, A.*; Nishitani, Takeo
Fusion Engineering and Design, 82(1), p.1 - 9, 2007/01
Times Cited Count：10 Percentile：56.90(Nuclear Science & Technology)no abstracts in English
Nishitani, Takeo; Ochiai, Kentaro; Maekawa, Fujio; Shibata, Keiichi; Wada, Masayuki*; Murata, Isao*
IAEA-CN-116/FT/P1-22 (CD-ROM), 8 Pages, 2004/11
no abstracts in English
Verzilov, Y. M.; Sato, Satoshi; Nakao, Makoto*; Ochiai, Kentaro; Wada, Masayuki*; Nishitani, Takeo
JAERI-Research 2004-015, 55 Pages, 2004/10
JAERI-Research-2004-015.pdf:3.29MB
no abstracts in English
Fusion Neutron Laboratory
JAERI-Review 2004-017, 163 Pages, 2004/07
JAERI-Review-2004-017.pdf:25.47MB
no abstracts in English
Oyama, Yukio; ; Watanabe, Yukinobu*; Kawano, Toshihiko*; Numajiri, M.*; Ueki, Kotaro*; ; Yamano, Naoki*; Kosako, Kazuaki*; ; et al.
JAERI-Review 98-020, 130 Pages, 1998/11
no abstracts in English
Yamane, Tsuyoshi; Takeuchi, Mitsuo; Shimakawa, Satoshi; Kaneko, Yoshihiko*
Nihon Genshiryoku Gakkai-Shi, 40(2), p.122 - 123, 1998/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
Kukita, Yutaka; Yonomoto, Taisuke; ; Nakamura, Hideo; Kumamaru, Hiroshige; Anoda, Yoshinari; T.J.Boucher*; M.G.Ortiz*; R.A.Shaw*; R.R.Schultz*
Journal of Nuclear Science and Technology, 33(3), p.259 - 265, 1996/03
Times Cited Count：31 Percentile：89.97(Nuclear Science & Technology)no abstracts in English
Kaneko, Yoshihiko*; Yamane, Tsuyoshi; Shimakawa, Satoshi; Yamashita, Kiyonobu
Nihon Genshiryoku Gakkai-Shi, 38(11), p.907 - 911, 1996/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
Oyama, Yukio;
Purazuma, Kaku Yugo Gakkai-Shi, 72(1), p.83 - 90, 1996/00
no abstracts in English
Oyama, Yukio; ; Maekawa, Hiroshi
Fusion Technology, 26, p.1098 - 1102, 1994/11
no abstracts in English
Oyama, Yukio; Konno, Chikara; Ikeda, Yujiro; Maekawa, Fujio; Kosako, Kazuaki*; Nakamura, Tomoo; Maekawa, Hiroshi; M.Z.Youssef*; A.Kumar*; M.A.Abdou*; et al.
JAERI-M 94-015, 193 Pages, 1994/02
no abstracts in English
