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Brumm, S.*; Gabrielli, F.*; Sanchez Espinoza, V.*; Stakhanova, A.*; Groudev, P.*; Petrova, P.*; Vryashkova, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; et al.
Annals of Nuclear Energy, 211, p.110962_1 - 110962_16, 2025/02
Yamaguchi, Masatake; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito
Scripta Materialia, 255, p.116366_1 - 116366_5, 2025/01
Reduction of grain boundary cohesive energy by hydrogen has been considered as one of the candidate causes of grain boundary fracture in steels and aluminum alloys. Recently, the effects of grain boundary segregation elements have been investigated by first-principles calculations, but there are few studies that quantitatively estimate the grain boundary cohesive energy. In this study, we describe a quantitative evaluation method using first-principles calculation results and show some examples of experimental calculations.
Takahashi, Yoshio*; Yamaguchi, Akiko; Yomogida, Takumi
Treatise on Geochemistry, 3rd edition, Vol.6, 46 Pages, 2025/00
With the recent development of measurement techniques, new approaches to the environmental geochemistry of radionuclides have been applied for various research targets. In this review article, several topics within the last 10-15 years in the field of environmental geochemistry of radionuclides have been discussed. In particular, this article mainly focused on two topics, (i) studies on the migration of radionuclides emitted by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in 2011 and (ii) the development of X-ray absorption fine structure (XAFS) spectroscopy and its application to the geochemical processes of radionuclides.
Gunji, Satoshi; Araki, Shohei; Izawa, Kazuhiko; Suyama, Kenya
Annals of Nuclear Energy, 209, p.110783_1 - 110783_7, 2024/12
Since the compositions and properties of the fuel debris are uncertain, critical experiments are required to validate calculation codes and nuclear data used for the safety evaluation. For this purpose, the Japan Atomic Energy Agency (JAEA) has been modifying a critical assembly called "STACY." The first criticality of the modified STACY is scheduled for spring 2024. This paper reports the consideration results of the specifications of the basic core configurations of the modified STACY at the first criticality. We prepared two types of gird plates with different neutron moderation conditions (their intervals are 1.50 cm and 1.27 cm). However, there is a limitation on the number of available UO fuel rods. The core configurations for the first criticality satisfying these experimental constraints were designed by computational analysis. A cylindrical core configuration with a 1.50 cm grid plate close to the optimum moderation condition needs 253 fuel rods to reach criticality. As to the 1.27 cm grid plate, we considered core configurations with 2.54 cm intervals by using doubled pitches of the grid plate. It will need 213 fuel rods for the criticality. In addition, we considered the experimental core configuration with steel/concrete simulant rods to simulate fuel debris conditions. This paper shows these core configurations and their evaluated specifications.
Fukuda, Kodai
Annals of Nuclear Energy, 208(1), p.110748_1 - 110748_10, 2024/12
Miura, Taito*; Miyamoto, Shintoro*; Maruyama, Ippei*; Aili, A.*; Sato, Takumi; Nagae, Yuji; Igarashi, Go*
Case Studies in Construction Materials, 21, p.e03571_1 - e03571_14, 2024/12
Sugiyama, Hitoshi*; Kato, Kenichi*; Sekine, Naoko*; Sekine, Yurina; Watanabe, Tomoaki*; Fukazawa, Tomoko*
Chemical Physics Letters, 856, p.141655_1 - 141655_8, 2024/12
To investigate the effects of polymer hydrophilicity on structures of water in hydrogels, differential scanning calorimetry and X-ray diffraction measurements were performed. The results show that the amount of intermediate water in polyacrylamide (PAA) hydrogel is about 12% smaller than that in poly--dimethylacrylamide (PDMAA) hydrogel. Furthermore, it was found that the bound water in PAA hydrogel primarily exists around the surface of the polymer bundles, whereas that in PDMAA hydrogel acts as a crosslinker factor for dehydration and water absorption in hydrogels.
Ono, Hirokazu; Ishii, Eiichi; Takeda, Masaki
Geoenergy (Internet), 2(1), p.geoenergy2023-047_1 - geoenergy2023-047_10, 2024/12
Ozaki, Yusuke; Ishii, Eiichi
Geoenergy (Internet), 2(1), p.geoenergy2023-056_1 - geoenergy2023-056_11, 2024/12
This study estimated the effective hydraulic conductivity around the Horonobe URL from the monitoring data of inflow into shaft and change in hydraulic pressure measured in HDB-6 for over ten years. The effective hydraulic conductivity was related to the fault transmissivities and flow dimension using Landau-Lifshitz-Matheron's formula. From the comparison of the estimated effective hydraulic conductivity with the calculated fault transmissivities, the effective hydraulic conductivity was compatible with the transmissivities considering the dependency on ductility index and flow dimension.
Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.
Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12
Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.
Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12
Tsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*
Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12
Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Nakamura, Jumpei*; Shimomura, Koichiro*
Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12
Fujihara, Masayoshi; Okabe, Hirotaka*; Koda, Akihiro*
Interactions (Internet), 245(1), p.13_1 - 13_6, 2024/12
Quantum states are difficult to observe experimentally. In addition, ideal model materials have not been found for some of the lattice systems in which exotic quantum states are predicted to be realized. Numerous candidates for low-dimensional quantum magnets are hidden in copper minerals, and the number of candidates is increasing every year. We succeeded to synthesize seven copper minerals by imitating the environment where they are discovered and reported their quantum states. The properties of pulsed muons are very suitable for investigating the spin state of artificial copper minerals.
Sakuma, Kazuyuki; Kurikami, Hiroshi; Wainwright, Haruko*; Tanimori, Soichiro*; Nagao, Fumiya; Ochi, Kotaro; Sanada, Yukihisa; Saito, Kimiaki
Journal of Environmental Radioactivity, 280, p.107554_1 - 107554_11, 2024/12
In this study, we created the integrated radiation air dose rate maps in the Fukushima region during 2011-2022 using multiple types of surveys such as air-borne, car-borne and walk surveys as well as fixed-location measurements. We applied the Bayesian geostatistical method developed by Wainwright et al. (2017, 2019) to the 80 km radius of the Fukushima Dai-ichi Nuclear Power Plant and the whole of Fukushima Prefecture while considering the history of the lifting of the evacuation zone in Fukushima. The integrated maps fixed the bias to underestimate air dose rates in forest areas, and successfully created more reproducible integrated maps with a wider area and time series than the previous studies. It is highly expected that the results of this study will be used to evaluate detailed exposure doses to the general public.
Takito, Kiyotaka; Okuda, Yukihiko; Nishida, Akemi; Li, Y.
Journal of Pressure Vessel Technology, 146(6), p.061301_1 - 061301_12, 2024/12
Teshigawara, Makoto; Lee, Y.*; Tatsumoto, Hideki*; Hartl, M.*; Aso, Tomokazu; Iverson, E. B.*; Ariyoshi, Gen; Ikeda, Yujiro*; Hasegawa, Takumi*
Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12
At Japanese Spallation Neutron Source in J-PARC, the para-hydrogen fraction was measured by using Raman spectroscopy in-situ for an integrated beam power of 9.4 MWh at 1 MW operation, to evaluate the functionality of the ferric oxyhydroxide catalyst. This result showed that full functionality of the catalyst was retained up to the 1 MW operation. We attempted to study the effect of neutron scattering driven para to ortho-hydrogen back-conversion rate in the absence of the catalyst effect with a bypass line without catalyst. The measured increase of ortho-hydrogen fraction was 0.44% for an integrated beam power of 2.4 MWh at 500 kW operation, however, which was considered to be due to not only to neutron collisions in cold moderators but also to the high ortho-hydrogen fraction of initially static liquid hydrogen in the bypass line and passive exudation of quasi-static hydrogen in the catalyst vessel to the main loop.
Sato, Tatsuhiko; Hashimoto, Shintaro; Mrquez Damin, J. I.*; Niita, Koji*
Nuclear Instruments and Methods in Physics Research B, 557, p.165535_1 - 165535_8, 2024/12
Okada, Kazuho*; Shibata, Akinobu*; Kimura, Yuji*; Yamaguchi, Masatake; Ebihara, Kenichi; Tsuji, Nobuhiro*
Acta Materialia, 280, p.120288_1 - 120288_14, 2024/11
Sumita, Takehiro*; Osawa, Takahito; Chiu, I.-H.; Ikeda, Atsushi
Analytica Chimica Acta, 1329, p.343256_1 - 343256_10, 2024/11