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Fukushima, Masahiro; Okajima, Shigeaki*; Mukaiyama, Takehiko*
Journal of Nuclear Science and Technology, 61(4), p.478 - 497, 2024/04
Times Cited Count:3 Percentile:73.09(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.
Fukushima, Masahiro; Ando, Masaki; Nagaya, Yasunobu
Nuclear Science and Engineering, 24 Pages, 2024/00
Times Cited Count:1 Percentile:75.38(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; Ando, Masaki; Nagaya, Yasunobu
Nuclear Science and Engineering, 15 Pages, 2024/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Fukushima, Masahiro; Tsujimoto, Kazufumi; Okajima, Shigeaki
Journal of Nuclear Science and Technology, 54(7), p.795 - 805, 2017/07
Times Cited Count:13 Percentile:74.66(Nuclear Science & Technology)A series of integral experiments was conducted in FCA assemblies with systematically changed neutron spectra covering from the intermediate to fast ones. The experiments provide systematic data of central fission rates for TRU nuclides containing minor actinides, Np,
Pu,
Pu,
Pu,
Am,
Am, and
Cm. Latest major nuclear data libraries, JENDL-4.0, ENDF/B-VII.1, and JEFF-3.2, were tested using benchmark models regarding the fission rate ratios relative to
Pu. For all the libraries, the benchmark tests by a Monte Carlo calculation code show obvious overestimations particularly for the fission rate ratios of
Cm to
Pu. Additionally, a large discrepancy about by 20% between the libraries is revealed for the fission rate ratio of
Pu to
Pu measured in the intermediate neutron spectrum. The cause of discrepancy is furthermore clarified by sensitivity analyses.
Fukushima, Masahiro; Kitamura, Yasunori*; Yokoyama, Kenji; Iwamoto, Osamu; Nagaya, Yasunobu; Leal, L. C.*
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.605 - 619, 2016/05
A nuclear data of U has been recently evaluated for the CIELO (Collaborative International Evaluated Library Organization) project. We tested the newly-evaluated data of
U using integral experiments of the Fast Critical Assembly (FCA) performed at JAEA. We selected two integral data of uranium-fueled FCA assemblies; one is the sodium-void reactivity worth of FCA XXVII-1 assembly and the other is the criticalities of the seven assemblies of FCA IX. The benchmark tests support the evaluation done in the resonance regions. However, the
U capture cross section above the unresolved resonance range needs further investigation.
Fukushima, Masahiro; Tsujimoto, Kazufumi; Okajima, Shigeaki
EPJ Web of Conferences, 111, p.07002_1 - 07002_5, 2016/03
Times Cited Count:2 Percentile:79.85(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.
Fukushima, Masahiro; Kitamura, Yasunori; Kugo, Teruhiko; Okajima, Shigeaki
Journal of Nuclear Science and Technology, 53(3), p.406 - 424, 2016/03
Times Cited Count:12 Percentile:71.76(Nuclear Science & Technology)Ando, Masaki; Kawasaki, Kenji*; Okajima, Shigeaki; Fukushima, Masahiro; Matsuura, Yutaka*; Kaneko, Yuji*
JAERI-Research 2005-026, 39 Pages, 2005/09
U Doppler effect measurements in moderated neutron spectra (uranium fuel and MOX simulated fuel) were carried out using FCA for the purpose of contributing to the improvement in prediction accuracy for Doppler coefficient in LWR. In the mockup cores for MOX fuel, the measurements were performed in different neutron spectra, where the voidage of moderator material was varied systematically. The experimental data were obtained using cylindrical uranium samples with different outer diameter up to 800
C. Analyses were performed using a standard code system designed to analyze fast reactor mock-up experiments at FCA with the use of the JENDL-3.2 library. The results of the analyses showed that the calculation accuracy did not depend on the types of the core fuel or the Doppler samples. The calculated values agreed with the experimental ones within the experimental error. Any dependency of the prediction accuracy on the neutron spectra was not observed in the MOX simulated fuel cores.
Kugo, Teruhiko; Kojima, Kensuke; Ando, Masaki; Okajima, Shigeaki; Mori, Takamasa; Takeda, Toshikazu*; Kitada, Takanori*; Matsuoka, Shogo*
Proceedings of 2005 International Congress on Advances in Nuclear Power Plants (ICAPP '05) (CD-ROM), 10 Pages, 2005/05
We have preliminarily evaluated the reduction of prediction errors of the core characteristics of the breeding light water reactor core based on the bias factor method by utilizing the FCA critical experiments carried out for MOX fueled tight lattice light water reactor cores. The prediction uncertainty of k is reduced from 0.62% to 0.39% by utilizing the FCA-XV-2 (65V) result. As for the reaction rate ratio of
U capture and
Pu fission, it is found that the FCA XXII-1 (95V) and XV (95V) results are suitable for the upper core and the upper blanket of the real core and the FCA XXII-1 (65V) and XV-2 (65V) results are suitable for the lower core and the internal blanket.
Fukushima, Masahiro; Okajima, Shigeaki; Ando, Masaki; Yamane, Tsuyoshi; Kataoka, Masaharu*
JAERI-Research 2005-008, 57 Pages, 2005/03
no abstracts in English
Kojima, Kensuke; Okajima, Shigeaki; Yamane, Tsuyoshi; Ando, Masaki; Kataoka, Masaharu*; Iwanaga, Kohei
JAERI-Tech 2004-016, 38 Pages, 2004/03
To investigate the void coefficient in the Reduced-Moderation Water Reactor (RMWR), an infinite multiplication factor was measured in the FCA-XXII-1 (65V) core. Axial and radial fission rate distributions were measured by micro fission chambers with four different kinds of nuclides. The infinite multiplication factor was derived from the material buckling, which was obtained from both the axial and radial fission rate distributions, and the migration area calculated. The value of it in the test region of the FCA-XXII-1 (65V) core was 1.3440.034. It was compared with the calculation, the ratio of the calculation to the measurement was 1.008
0.026. The improvement in measurement accuracy was also considered.
Iwanaga, Kohei; Yamane, Tsuyoshi; Nishihara, Kenji; Okajima, Shigeaki; Sekimoto, Hiroshi*; Asaoka, Takumi*
Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 10 Pages, 2003/04
no abstracts in English
Nishihara, Kenji; Iwanaga, Kohei; Yamane, Tsuyoshi; Okajima, Shigeaki
JAERI-Research 2002-030, 63 Pages, 2002/12
During the experiments using the critical assembly such that reactivity is added to the stationary state and the core shifts to the other stationary state, the neutron flux transitionally changes after some change of the reactivity or source. Inverse kinetics method (IK method) can generally adopted as the technique of obtaining the reactivity and/or source by analyzing the neutron flux. However, the conventional analysis method was not able to obtain the solution with the maximum likelihood considering the error of the measured neutron flux and to estimate the error of the solution. In the present research, by adopting the maximum likelihood methodology to the problem, developed is the technique to obtain the reactivity and source intensity with maximum likelihood and the errors of them. Moreover, the technique is applied to the rod drops experiment in FCA, and the validity of a technique is checked.
Iijima, Susumu; Ando, Masaki; Oigawa, Hiroyuki
Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 9 Pages, 2002/10
no abstracts in English
Sakurai, Takeshi; Okajima, Shigeaki
Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 12 Pages, 2002/10
The cross section adjustment method was applied to total delayed neutron yields of U,
U and
Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction
at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. Furthermore, to validate these adjusted delayed neutron yields, analyses were performed for the
experiments at ZPR fast critical facility. These adjusted yields brought a reduction of uncertainty of calculated
and an improvement in agreement of
between experiment and calculation.
Yoshida, Tadashi*; Okajima, Shigeaki; Sakurai, Takeshi; Nakajima, Ken; Yamane, Tsuyoshi; Katakura, Junichi; Tahara, Yoshihisa*; Zukeran, Atsushi*; Oyamatsu, Kazuhiro*; Osawa, Takaaki*; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.136 - 139, 2002/08
no abstracts in English
Oigawa, Hiroyuki; Iijima, Susumu; Ando, Masaki
Journal of Nuclear Science and Technology, 39(7), p.729 - 735, 2002/07
Times Cited Count:2 Percentile:16.45(Nuclear Science & Technology)no abstracts in English
Oigawa, Hiroyuki; Maekawa, Fujio; Meigo, Shinichiro; Kasugai, Yoshimi; Tsujimoto, Kazufumi; Nishihara, Kenji; Sasa, Toshinobu; Konno, Chikara; Kai, Tetsuya; Ikeda, Yujiro
JAERI-Tech 2002-037, 220 Pages, 2002/03
no abstracts in English
Sakurai, Takeshi; Okajima, Shigeaki
Journal of Nuclear Science and Technology, 39(1), p.19 - 30, 2002/01
Times Cited Count:6 Percentile:38.99(Nuclear Science & Technology)The cross section adjustment method was applied to total delayed neutron yields of U,
U and
Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction
at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. After the adjustment, the yield of
U was almost uniformly decreased by about 3% below 7 MeV. The yield of
Pu was increased by 2.6% and that of
U was decreased by 0.9% at the thermal energy point, while the change of yield was less than 0.3% at the other energy points for these nuclides. By using these adjusted yields, the uncertainty of calculated
was reduced and the agreement of
between experiment and calculation was improved.
Tsunoda, Hirokazu*; Sato, Osamu*; Okajima, Shigeaki; Yamane, Tsuyoshi; Iijima, Susumu; Kobe, Mitsuru*
Proceedings of International Congress on Advanced Nuclear Power Plants (ICAPP) (CD-ROM), 6 Pages, 2002/00
no abstracts in English