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Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki
JAEA-Technology 2022-030, 80 Pages, 2023/02
JAEA-Technology-2022-030.pdf:2.57MB
Nuclear criticality benchmark analyses were carried out for TRIGA-type reactor systems in which uranium-zirconium hydride fuel rods are loaded by using the continuous-energy Monte Carlo code MVP with the evaluated nuclear data library JENDL-5. The analyses cover two sorts of benchmark data, the IEU-COMP-THERM-003 and IEU-COMP-THERM-013 in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook, and effective neutron multiplication factors, reactivity worths for control rods etc. were calculated by JENDL-5 in comparison with those by the previous version of JENDL. As the results, it was confirmed that the effective neutron multiplication factors obtained by JENDL-5 were 0.4 to 0.6% greater than those by JENDL-4.0, and that there were no significant differences in the calculated reactivity worths by between JENDL-5 and JENDL-4.0. Those results are considered to be helpful for the confirmation of calculation accuracy in the analyses on NSRR control rod worths, which are planned in the future.
Fujimoto, Nozomu*; Tada, Kenichi; Ho, H. Q.; Hamamoto, Shimpei; Nagasumi, Satoru; Ishitsuka, Etsuo
Annals of Nuclear Energy, 158, p.108270_1 - 108270_8, 2021/08
Times Cited Count：2 Percentile：51.67(Nuclear Science & Technology)Fukushima, Masahiro; Kitamura, Yasunori; Kugo, Teruhiko; Okajima, Shigeaki
Journal of Nuclear Science and Technology, 53(3), p.406 - 424, 2016/03
Times Cited Count：9 Percentile：68.91(Nuclear Science & Technology)Okumura, Keisuke; Kawasaki, Kenji*; Mori, Takamasa
JAERI-Research 2005-018, 64 Pages, 2005/08
JAERI-Research-2005-018.pdf:3.26MB
In the KRITZ-2 critical experiments, criticality and pin power distributions were measured at room temperature and high temperature (about 245 degree C) for three different cores loading slightly enriched UO
or MOX fuels. For nuclear data testing, benchmark analysis was carried out with a continuous-energy Monte Carlo code MVP and its four nuclear data libraries based on JENDL-3.2, JENDL-3.3, JEF-2.2 and ENDF/B-VI.8. As a result, fairly good agreements with the experimental data were obtained with any libraries for the pin power distributions. However, the JENDL-3.3 and ENDF/B-VI.8 give under-prediction of criticality and too negative isothermal temperature coefficients for slightly enriched UO cores, while the older nuclear data JENDL-3.2 and JEF-2.2 give rather good agreements with the experimental data. From the detailed study with an infinite unit cell model, it was found that the differences among the libraries are mainly due to the different fission cross section of U-235 in the energy rage below 1.0 eV.
U nuclear data to improve k
biases on U enrichment and temperature for low enriched uranium fueled lattices moderated by light waterWu, H.; Okumura, Keisuke; Shibata, Keiichi
JAERI-Research 2005-013, 31 Pages, 2005/06
JAERI-Research-2005-013.pdf:3.29MB
The under prediction of k depending on U enrichment in low enriched uranium fueled systems was studied in this report. Benchmark testing was carried out with several evaluated nuclear data files, including the new uranium evaluations from preliminary ENDF/B-VII and CENDL-3.1. Another problem reviewed here was k underestimation vs. temperature increase, which was observed in the slightly enriched system with recent JENDL and ENDF/B uranium evaluations. Through the substitute analysis of nuclear data of U and 
U, we propose a new evaluation of U data to solve both of the problems. The new evaluation was tested for various uranium fueled systems including low or highly enriched metal and solution benchmarks in the ICSBEP handbook. As a result, it was found that the combination of the new evaluation of U and the U data from the preliminary ENDF/B-VII gives quite good results for most of benchmark problems.
Okuno, Hiroshi
Journal of Nuclear Science and Technology, 40(7), p.544 - 551, 2003/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A method for classifying benchmark results of criticality calculations according to similarity was proposed in this paper. After formulation of the method utilizing correlation coefficients, it was applied to burnup credit criticality benchmarks Phase III-A and II-A, which were conducted by the Expert Group on Burnup Credit Criticality Safety under auspices of the OECD/NEA. Phase III-A benchmark was a series of criticality calculations for irradiated BWR fuel assemblies, whereas Phase II-A benchmark was a suite of criticality calculations for irradiated PWR fuel pins. These benchmark problems and their results were summarized. The correlation coefficients were calculated and sets of benchmark results were classified according to the criterion that the correlation coefficients were no less than 0.15 for Phase III-A and 0.10 for Phase II-A benchmarks. When a couple of results were in a same group, one result was found predictable from the other. An example was shown for each of the Benchmarks. The evaluated nuclear data seemed the main factor of errors.
Okuno, Hiroshi; Sakai, Tomohiro*
Nuclear Technology, 140(3), p.255 - 265, 2002/12
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In order to facilitate discussions based on quantitative analysis about the end effect, which is often talked about in connection to burnup credit in criticality safety evaluation of spent fuel, we introduced in this paper a burnup importance function. This function shows the burnup effect on the reactivity as a function of the fuel position; an explicit expression of this function was derived according to the perturbation theory. The burnup importance function was applied to the Phase IIA benchmark model that was adopted by the OECD/NEA Expert Group on Burnup Credit Criticality Safety. The function clearly displayed that burnup importance of the end regions increases (1) as burnup, (2) as cooling time, (3) in consideration of burnup profile, and (4) in consideration of fission products.
Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.
Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11
Times Cited Count：653 Percentile：96.97(Nuclear Science & Technology)Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.
Okuno, Hiroshi; Tonoike, Kotaro; Sakai, Tomohiro*
Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 8 Pages, 2002/10
As the burnup proceeds, reactivity of fuel assemblies for light water reactors decreases by depletion of fissile nuclides, especially in the axially central region. In order to describe the importance of the end regions to the reactivity change, a burnup importance function was introduced as a weighting function to a local burnup variation contributed to a reactivity decrease. The function was applied to the OECD/NEA/BUC Phase II-A model and a simplified Phase II-C model. The application to Phase II-A model clearly showed that burnup importance of the end regions increases as burnup and/or cooling time increases. Comparison of the burnup importance function for different initial enrichments was examined. The application result to the simplified Phase II-C model showed that the burnup importance function was helpful to find the most reactive fuel burnup distribution under the conditions that the average fuel burnup was kept constant and the variations in the fuel burnup were within the maximum and minimum measured values.
Okuno, Hiroshi; Naito, Yoshitaka*; Suyama, Kenya
JAERI-Research 2002-001, 181 Pages, 2002/02
JAERI-Research-2002-001.pdf:10.89MB
The report describes the final results of the Phase IIIB Benchmark conducted by the Expert Group on Burnup Credit Criticality Safety under the auspices of the OECD/NEA. The Benchmark was intended to compare the predictability of current computer code and data library combinations for the atomic number densities of an irradiated BWR fuel assembly model, which was irradiated under specific power of 25.6 MW/tHM up to 40 GWd/tHM and cooled for five years. The void fraction was assumed to be uniform and constant, at 0, 40 and 70%, during burnup. In total, 16 results were submitted from 13 institutes of 7 countries. The calculated densities of 12 actinides and 20 fission product nuclides were found mostly within a range of +- 10% relative to the average, although some results, esp. 155Eu and gadolinium isotopes, exceeded the band. Pin-wise burnup results agreed well among the participants. The results in the multiplication factor also accorded well with each other for void fractions of 0 and 40%; however some results deviated from the average noticeably for the void fraction of 70%.
Okuno, Hiroshi; Naito, Yoshitaka*; Ando, Yoshihira*
JAERI-Research 2000-041, 179 Pages, 2000/09
JAERI-Research-2000-041.pdf:6.11MB
no abstracts in English
Komuro, Yuichi
Journal of Nuclear Science and Technology, 37(6), p.548 - 554, 2000/06
no abstracts in English
; *; Suyama, Kenya; Ando, Yoshihira*
Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 2, p.566 - 575, 1999/00
no abstracts in English
Komuro, Yuichi
Nihon Genshiryoku Gakkai-Shi, 40(9), p.697 - 701, 1998/00
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Yamashita, Kiyonobu; Nojiri, Naoki; Fujimoto, Nozomu; Nakano, Masaaki*; Ando, Hiroei; Nagao, Yoshiharu; Nagaya, Yasunobu; Akino, Fujiyoshi; Takeuchi, Mitsuo; Fujisaki, Shingo; et al.
Proc. of IAEA TCM on High Temperature Gas Cooled Reactor Applications and Future Prospects, p.185 - 197, 1998/00
no abstracts in English
; Nomura, Yasushi; Suyama, Kenya
Proc. of Int. Conf. on the Phys. of Nucl. Sci. and Technol., 1, p.742 - 748, 1998/00
no abstracts in English
; Okuno, Hiroshi
JAERI-Research 96-003, 170 Pages, 1996/02
JAERI-Research-96-003.pdf:5.24MB
no abstracts in English
M.C.Brady*; ; M.D.DeHart*; Okuno, Hiroshi; A.Nouri*; E.Sartori*
PHYSOR 96: Int. Conf. on the Physics of Reactors, 4, p.L41 - L52, 1996/00
no abstracts in English
Komiyama, Kazumasa*; Okuno, Hiroshi
JAERI-Research 94-047, 39 Pages, 1994/12
JAERI-Research-94-047.pdf:0.89MB
no abstracts in English
*; Arakawa, Takuya*; Okuno, Hiroshi
JAERI-Data/Code 94-018, 36 Pages, 1994/12
JAERI-Data-Code-94-018.pdf:1.09MB
no abstracts in English
