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Yanagisawa, Hiroshi; Motome, Yuiko
JAEA-Research 2025-010, 197 Pages, 2025/11
JAEA-Research-2025-010.pdf:3.5MB
For understandings of nuclear criticality risks of TRIGA fuel rods and review of safety measures for handling them, nuclear criticality characteristics for infinite and finite heterogeneous lattice systems composed of the NSRR fuel rods were reevaluated with the use of a detailed computational model for the fuel rod. The MVP version 3 code was used with the JENDL libraries including the latest version, JENDL-5, for the re-evaluation. As the criticality characteristics, variations of neutron multiplication factors of the infinite and water-reflected finite systems were examined in detail with parameters of the lattice pitch and density of moderator water. From the results of the re-evaluated criticality characteristics, the minimum critical number of fuel rods for the water-reflected hexagonal shaped lattice system was obtained to be 46.8 
0.2 using the JENDL-5 library. Moreover, the attainability of criticality without the water as moderator and reflector was examined because the zirconium hydride moderator and graphite reflector are equipped with the TRIGA fuel rod. It was found that the criticality is possible to be attained by 115.7 0.6 of the number of fuel rods, which is the smaller number of fuel rods than loaded in the NSRR standard core, even though no water exists.
Yanagisawa, Hiroshi; Motome, Yuiko
JAEA-Research 2025-001, 99 Pages, 2025/06
JAEA-Research-2025-001.pdf:1.98MB
The detailed computational models for nuclear criticality analyses on the first startup cores of NSRR (Nuclear Safety Research Reactor), which is categorized as a TRIGA-ACPR (Annular Core Pulse Reactor), were created for the purposes of deeper understandings of safety inspection data on the neutron absorber rod worths of reactivity and improvement of determination technique of the reactivity worths. The uncertainties in effective neutron multiplication factor (k
) propagated from errors in the geometry, material, and operation data for the present models were evaluated in detail by using the MVP version 3 code with the latest Japanese nuclear data library, JENDL-5, and the previous versions of JENDL libraries. As a result, the overall uncertainties in k for the present models were evaluated to be in the range of 0.0027 to 0.0029 
k. It is expected that the present models will be utilized as the benchmark on k for TRIGA-ACPR. Moreover, it is confirmed that the overall uncertainties were sufficiently smaller than the values of absorber rod worths determined in NSRR. Thus, it is also considered that the present models are applicable to further analyses on the absorber rod worths in NSRR.
Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki
JAEA-Technology 2022-030, 80 Pages, 2023/02
JAEA-Technology-2022-030.pdf:2.57MBJAEA-Technology-2022-030(errata).pdf:0.11MB
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.
Takamatsu, Kuniyoshi; Shimakawa, Satoshi; Nojiri, Naoki; Fujimoto, Nozomu
JAERI-Tech 2003-081, 49 Pages, 2003/10
In the case of evaluations for the highest temperature of the fuels in the HTTR, it is very important to expect the power density distributions accurately; therefore, it is necessary to improve the analytical model with the neutron diffusion and the burn-up theory. The power density distributions are analyzed in terms of two models, the one mixing the fuels and the burnable poisons homogeneously and the other modeling them heterogeneously. Moreover these analytical power density distributions are compared wtih the ones derived from the gross 
-ray measurements and the Monte Carlo calculational code with continuous energy. As a result the homogeneous mixed model isn't enough to expect the power density distributions of the core in the axial direction; on the other hand, the heterogeneous model improves the accuracy.
Kaneko, Yoshihiko*; Nagao, Yoshiharu; Shimakawa, Satoshi
Journal of Nuclear Science and Technology, 36(11), p.988 - 995, 1999/11
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)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
Nagaya, Yasunobu; Nakagawa, Masayuki; Mori, Takamasa
Journal of Nuclear Science and Technology, 35(1), p.6 - 19, 1998/01
Times Cited Count：5 Percentile：31.90(Nuclear Science & Technology)no abstracts in English
G.D.Spriggs*; R.D.Busch*; Sakurai, Takeshi; Okajima, Shigeaki
Transactions of the American Nuclear Society, 76, p.374 - 375, 1997/06
no abstracts in English
; Naito, Yoshitaka
JAERI-M 91-164, 25 Pages, 1991/10
no abstracts in English
Kaneko, Yoshihiko; Akino, Fujiyoshi; ; Kurokawa, Ryosuke; Kitadate, Kenji;
JAERI-M 6549, 59 Pages, 1976/05
no abstracts in English
Riyana, E. S.; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Okumura, Keisuke; Kanno, Ikuo
no journal, ,
Xe, 
Kr) emitted by fuel debris for criticality estimationRiyana, E. S.; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Okumura, Keisuke; Kanno, Ikuo
no journal, ,
