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Shimodaira, Masaki; Ha, Yoosung; Takamizawa, Hisashi; Katsuyama, Jinya; Onizawa, Kunio
Journal of Pressure Vessel Technology, 148(2), p.021504_1 - 021504_10, 2026/04
In the current structural integrity assessment of the reactor pressure vessel, the accurate reference temperature (T
) based on the Master Curve method is necessary. The T can be estimated by using the Mini-C(T) fracture toughness specimen in accordance with ASTM E1921 and JEAC4216, which prescribe the crack straightness criteria. A requirement in ASTM E1921 has been revised in a decade to increase the accuracy and reasonability, and the applicable crack curvature has been varied by applied codes. The crack curvature of the Mini-C(T) specimen might have an impact on the T because of the variation of the plastic constraint. In this work, the effect of the crack curvature on the fracture toughness (K
) evaluation using the Mini-C(T) specimen was quantitatively evaluated by using the finite element analysis (FEA) including the Weibull stress analysis, to discuss the difference in a requirement of the crack straightness in ASTM E1921 and JEAC4216. FEAs showed a possibility that the upper limit curvature would decrease the plastic constraint, and consequently obtain higher K in the Mini-C(T) specimen. Furthermore, if the upper limit curvature according to the ASTM E1921-21 was allowed, the T would be estimated as nonconservative based on the Weibull stress analysis. In contrast, the difference in (T) between the crack with upper limit curvature according to JEAC4216 and the ideal straight crack was not significant.
Lobzenko, I.; Mori, Hideki*; Tsuru, Tomohito
Journal of Materials Research and Technology, 40, p.3798 - 3805, 2026/01
no abstracts in English
by high-energy irradiationOtsuka, Shunya*; Sasajima, Yasushi*; Ishikawa, Norito
ECS Journal of Solid State Science and Technology, 14(12), p.124003_1 - 124003_9, 2025/12
Fukuda, Takanari; Yamashita, Susumu; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 62(12), p.1264 - 1278, 2025/12
This study compared three interface capturing schemes (ICSs) for multi-phase flow simulations based on the VOF method, focusing on bubble volume conservation. The THINC/WLIC scheme showed significant VOF diffusion and underestimated total bubble volume, while the original THINC and PLIC conserved bubble volumes. Moreover, an analysis of THINC/WLIC based on a new visualization approach revealed that VOF fragments were ripped off by shear forces around interface, making it unsuitable for accurate void fraction prediction in boiling water reactors. The original THINC may be a viable alternative to PLIC due to its simplicity.
Nakamura, Yuki*; Kojima, Yoshihiro*; Yamashita, Takuya; Shimomura, Kenta; Mizokami, Shinya
Journal of Nuclear Science and Technology, 62(12), p.1226 - 1230, 2025/12
Zr(n, 
)
Zr and 
Zr(n, )
Zr reactions at JRR-3Nakamura, Shoji; Kimura, Atsushi; Endo, Shunsuke; Rovira Leveroni, G.; Shibahara, Yuji*
Journal of Nuclear Science and Technology, 14 Pages, 2025/11
Iwamoto, Nobuyuki
Journal of Nuclear Science and Technology, 13 Pages, 2025/10
Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Journal of Nuclear Science and Technology, 12 Pages, 2025/09
Times Cited Count：0 Percentile：0.00Kondo, Ryoichi; Yamamoto, Akio*; Endo, Tomohiro*
Journal of Nuclear Science and Technology, 12 Pages, 2025/09
Times Cited Count：0 Percentile：0.00The flux distribution tallies using proper orthogonal decomposition, called POD tallies, have been developed to address issues of high-fidelity Monte Carlo simulations. The POD tallies can reduce both dimensionality and statistical error. The present study verifies the applicability of the POD tallies to sub-pin level flux distribution in the two-dimensional C5G7 benchmark. Statistical error estimation is also proposed by applying the circular block bootstrap method to the POD tallies to estimate the statistical error of the flux distribution in a single Monte Carlo calculation. In the verification, the dimensionality of the finely discretized distribution is reduced by more than 90% compared with conventional cell tallies. The statistical error is reduced by more than half as the average value of all tally regions. The proposed approach is confirmed to properly estimate the statistical error of flux distribution considering both the inter-cycle correlation and the correlation between the expansion coefficients of different POD orders.
Sato, Takuto; Nakayama, Hiromasa; Satoh, Daiki
Journal of Nuclear Science and Technology, 17 Pages, 2025/09
Times Cited Count：0 Percentile：0.00We developed a framework for rapid monitoring of radioactive plumes in the vicinity of nuclear facilities based on a quick and practical high-resolution atmospheric dispersion simulation method that combines a large-eddy simulation (LES) model pre-simulation database (pre-sim DB) of wind conditions and onsite meteorological observation results, as proposed by the previous study. However, this framework was not quantitatively demonstrated using measurement data. In this study, we evaluated the performance of the wind condition reproduction and plume dispersion analysis methods. Air dose rates observed at monitoring posts around the stack were compared with the values reproduced by the method using the pre-sim DB, and the reproducibility of both air dose rate and flow field was discussed. The pre-sim DB-based method successfully captured the temporal variation of air dose rates at the monitoring posts, though it tended to overestimate the peak values. Particularly when the vertical wind shear was pronounced, the method using the pre-sim DB could cause significant errors. This is likely because the method relies on wind conditions from a single observation point, which inherently limits its ability to represent vertical wind shear within the pre-sim DB. Despite these limitations, particularly in reproducing complex wind fields, the method utilizing the pre-sim DB offers a valuable and practical tool for rapid dose rate simulation due to its lower computational cost compared to unsteady simulations using an LES model.
Kamiya, Junichiro; Wada, Kaoru*; Htwe, N. T. T.*
Journal of Vacuum Science and Technology B, 43(5), p.054204_1 - 054204_13, 2025/09
Times Cited Count：0 Percentile：0.00Yano, Yasuhide; Miyazawa, Takeshi; Tanno, Takashi; Akasaka, Naoaki; Yoshitake, Tsunemitsu; Kaito, Takeji; Otsuka, Satoshi
Journal of Nuclear Science and Technology, 62(8), p.748 - 755, 2025/08
Times Cited Count：0 Percentile：76.46(Nuclear Science & Technology)The effects of strain rate on tensile properties of irradiated modified 316 stainless steel (PNC316) claddings were investigated. PNC316 claddings were irradiated at the experimental fast reactor Joyo using CRT402 control rod assembly at 400
C up to 25 dpa. Post-irradiation ring tensile tests were carried out at strain rates of 3.3
10
, 3.310
and 3.310
s
at a test temperature of 350C. The results showed no obvious dependence of all strain rates on tensile properties, although a slight decrease in total elongation was observed at the slowest strain rate of 3.310 s. In addition, only a part of fracture surface at the slowest strain rate showed intergranular type region in the inner surface area, although the grain boundary separation occurred on inner surfaces near the fracture region at all strain rates. It is suggested that presence of a high content of helium near the inner surfaces would be related to the fracture behavior.
Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*
Journal of Nuclear Science and Technology, 62(8), p.756 - 765, 2025/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
-AlO
(0001) for use as an adsorbentEntani, Shiro*; Honda, Mitsunori; Takizawa, Masaru*; Koda, Makoto*
Beilstein Journal of Nanotechnology (Internet), 16, p.1082 - 1087, 2025/07
Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 4 of others*
Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07
Times Cited Count：1 Percentile：79.97(Materials Science, Multidisciplinary)
Ho(n,)
Ho reactionsNakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 14 Pages, 2025/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
Co inventory in the core of the Fukushima Daiichi Nuclear Power Plant; Contribution of fuel deposits to the reactor core inventoryUchida, Shunsuke*; Kino, Chiaki*; Karasawa, Hidetoshi; Takahatake, Yoko; Koma, Yoshikazu
Journal of Nuclear Science and Technology, 17 Pages, 2025/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Evaluation of radioactive nuclide behavior on and after the accident is important for the estimating radioactive nuclide composition in the wastes. The reactor core inventories have been obtained from the ORIGEN2 analysis, but the inventory of activation products is determined by the amount of their parent nuclides which are impurities contained in the structural materials. The ORIGEN2 does not treat fuel deposits including the impurities. Estimation of the initial Co-60 inventory in accurate is needed on the evaluation of some kinds of radioactive nuclide amount, since it is possible Co-60 is standard in the scaling factor. In this study, contribution of fuel deposits to the reactor core inventory was estimated by comparing the amount of Co-60 and Ni-63 calculated by the amounts of deposition by the microlayer-evaporation and drying-out model (MEDO model) and the result of the ORIGEN2 analysis, and then the method of estimating the reactor core inventory was proposed.
Er(n,)
Er and 
Hf(n,)
Hf reactionsNakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 62(7), p.617 - 630, 2025/07
Times Cited Count：1 Percentile：76.46(Nuclear Science & Technology)Murakami, Masashi; Yoshida, Yukihiko; Nango, Nobuhito*; Kubota, Shogo*; Kurosawa, Takuya*; Sasaki, Toshiki
Journal of Nuclear Science and Technology, 62(7), p.650 - 661, 2025/07
Times Cited Count：1 Percentile：76.46(Nuclear Science & Technology)Hayakawa, Kosetsu*; Muraguchi, Masakazu*; Masebo, Yumeno*; Kojima, Yoichiro*; Oda, Masato*; Yabuta, Rina*; Ishii, Hiroyuki*; Honda, Mitsunori
e-Journal of Surface Science and Nanotechnology (Internet), p.2025-041_1 - 2025-041_6, 2025/07
We are developing materials using clay minerals for thermoelectric materials that can be used at high temperatures in environmental friendly applications. We have succeeded in obtaining thermoelectric properties at high temperatures, but we do not know why these properties are exhibited. In order to elucidate the structural changes of weathered biotite under high temperature conditions, we will develop an XAFS analysis method and clarify the local structure of Fe at high temperatures. The local structure analysis of Fe in samples sintered in atmospheric and vacuum environments reveals changes in the chemical bonding state of Fe.
