Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Harada, Masahide; Tajima, Takahiro*; Ito, Taku*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Muto, Giichi*; Suzuki, Akio*; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 45, p.011053_1 - 011053_5, 2026/06
At Materials and Life science experimental Facility (MLF) in J-PARC, a mercury target of an intense pulsed spallation neutron source is designed to be irradiated by 3 GeV and 1MW proton beams to provide high intensity neutron beams to a suit of neutron instruments. A unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a gamma-ray energy analysis with Germanium semi-conductor detectors. It is composed of three units of sampling port and radiation monitors: 1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, 2) CAM for atmosphere in the hot cell where the target loop is operated and 3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In addition, A gas monitor is equipped at CAM to detect tritium. Until now, several operation experiences could be obtained as the follwoing. 1) Xe-121 and Xe-123 gas could be detected at CAM. These radio-active gaseous radioactive nuclides are slightly leaked from cover gas of mercury target. 2) Humidity in the helium vessel could be detected at VAM, because detection of annihilation gamma-ray and N-15 were increased. 3) The detection of Ar-41 indicated the air mixing in helium atmosphere.
Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*
JPS Conference Proceedings (Internet), 45, p.011184_1 - 011184_4, 2026/06
At Materials and Life Science Facility in J-PARC, 3 GeV and 1 MW pulsed proton beam hits mercury and carbon targets and intense neutron and muon beams are provided for various measurements. As samples in the measurements are activated, estimation of radioactivity of samples is very necessary for a radiation safety of user experiments. Therefore, estimation system, SAmple Radioactivity Evaluation program (SARE), is developed. SARE can estimate radioactivity of samples at each neutron and muon beam line with neutron flux and activation cross section. The neutron flux data was applied from references and the activation cross section data was obtained from DCHAIN-SP-2001. The activation of negative-muon can be also estimated from a database. SARE has a user-friendly interface of Web servlet based on JAVA and JAVA script and can select various conditions for the estimation. In the presentation, we will introduce SARE and validation results performed at BL10 with the foil-activation method.
Sakakibara, Ryotaro*; Terasawa, Tomoo; Kawauchi, Taizo*; Fukutani, Katsuyuki; Ito, Takahiro*; Norimatsu, Wataru*
Small Methods, 10(8), p.e01889_1 - e01889_12, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Asamori, Koichi; Sueoka, Shigeru; Komatsu, Tetsuya; Ogata, Manabu; Uchida, Mao; Nishiyama, Nariaki; Tanaka, Kiriha; Kobayashi, Tomoharu; Mitsuguchi, Takehiro; Murakami, Osamu; et al.
JAEA-Review 2025-035, 29 Pages, 2025/10
JAEA-Review-2025-035.pdf:1.12MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2025. The objectives and contents of this research are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Takeuchi, Masayuki; Takata, Takeshi; Saito, Keita*; Chikazawa, Takahiro*
Progress in Nuclear Science and Technology (Internet), 7, p.135 - 141, 2025/03
Control of insoluble sludge from fuel dissolution process is one of the important issues to secure the safety in reprocessing plant operation. In order to achieve the higher sludge recovery in the clarification stage, new clarification system which is an integrated technology of centrifugal device and filter unit has been developed for spent MOX fuel reprocessing. In this study, over-all clarification performance of this integrated system was evaluated on engineering scale. As results, total sludge recovery rate of more than 99.5 % was achieved in all test conditions by this system from the engineering test and this new clarification system showed excellent clarification performance. The sludge recovery rate of centrifugal device was influenced by test conditions and was in the range from 87 to 98 %. This study showed this technology is one of the promising clarification systems to improve the performance of sludge recovery greatly.
Hosoda, Masahiro*; Omori, Yasutaka*; Orita, Makiko*; Saito, Kimiaki; Sanada, Tetsuya*; Takeda, Hikaru*; Tani, Kotaro*; Tsujiguchi, Takakiyo*; Hirao, Shigekazu*; Hokama, Tomonori; et al.
Hoken Butsuri (Internet), 59(4), p.206 - 207, 2024/12
no abstracts in English
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
Times Cited Count：3 Percentile：91.16(Physics, Atomic, Molecular & Chemical)Ito, Kengo*; Kawakami, Takahiro*; Kato, Chizu*; Fukutani, Satoshi*; Matsumura, Tatsuro; Fujii, Toshiyuki*
Journal of Radioanalytical and Nuclear Chemistry, 333(10), p.5183 - 5189, 2024/10
Times Cited Count：1 Percentile：20.46(Chemistry, Analytical)Solvent extraction behaviors of Se (VI) from nitric acid solutions were investigated with multiple extractants used for uranium, plutonium, minor actinides, and rare earthelements separation processes from high-level liquid waste. During the processes, Se remained in the residual aqueous solutions, as all extractants showed distributionratios 
1. In contrast, Se showed distribution ratios 
1 with 
-phenylenediamine in dilute nitric acid ( 2 M HNO
), octanol as the organic phase, and concentrated nitric acid (8 M HNO) for back extraction, suggesting a potential new single separation process and recovery of Se.
Tanaka, Takuro*; Fukuoka, Masafumi*; Toda, Kanako*; Nakanishi, Takahiro; Terashima, Motoki; Fujiwara, Kenso; Niwano, Yuma*; Kato, Hiroaki*; Kobayashi, Natsuko*; Tanoi, Keitaro*; et al.
ACS ES&T Water (Internet), 4(8), p.3579 - 3586, 2024/08
shetta lakes in the Soya Coast region and their paleoenvironmental significance with glacial isostatic adjustment in East AntarcticaInoue, Genki*; Honda, Eisuke*; Ito, Keisuke*; Kang, I.*; Seto, Koji*; Tani, Yukinori*; Watanabe, Takahiro; Kashima, Kaoru*; Otani, Shuji*; Yamanaka, Toshiro*; et al.
Quaternary Science Reviews, 338, p.108822_1 - 108822_18, 2024/08
Times Cited Count：0 Percentile：0.00(Geography, Physical)We studied Holocene paleolimnological changes inferred from biomarkers and microscopic observation of microalgae and cyanobacteria in sediment cores from Rundvshetta lakes (Maruwanminami-ike and Maruwan o-ike) in the Soya Coast of East Antarctica, along with sedimentary facies and radiocarbon dating. Coastal marine environment: Maruwanminami-ike (147-72.5 cm, 5,010-2,590 cal BP) and Maruwan-oike (226-47.2 cm, 5,700-3,190 cal BP) were characterized by low biological production with the predominance of diatoms. Transition period of stratified brackish lake environment: Maruwanminami-ike (72.5-65.6 cm, 2,590-2,500 cal BP) and Maruwan-oike (47.2-28.8 cm, 3,190-2,890 cal BP) were characterized by stratified conditions with marine water overlain by freshwater, and a chemocline developed together with an anoxic layer in the bottom of photic zone.
Nakamura, Izumi*; Takito, Kiyotaka; Shimazu, Ryuya*; Okuda, Yukihiko; Sakai, Michiya*; Otani, Akihito*; Watakabe, Tomoyoshi; Okuda, Takahiro; Shibutani, Tadahiro*; Shiratori, Masaki*
Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07
Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.
JAEA-Technology 2024-003, 17 Pages, 2024/06
JAEA-Technology-2024-003.pdf:1.91MB
In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.
-FeNi films with island structures on LaAlO(110) substrates by nitrogen insertion and topotactic extractionNishio, Takahiro*; Ito, Keita*; Kura, Hiroaki*; Takanashi, Koki; Yanagihara, Hideto*
Journal of Alloys and Compounds, 976, p.172992_1 - 172992_8, 2024/03
Times Cited Count：3 Percentile：19.88(Chemistry, Physical)Nakamura, Izumi*; Otani, Akihito*; Okuda, Yukihiko; Watakabe, Tomoyoshi; Takito, Kiyotaka; Okuda, Takahiro; Shimazu, Ryuya*; Sakai, Michiya*; Shibutani, Tadahiro*; Shiratori, Masaki*
Dai-10-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu (JCOSSAR2023) Koen Rombunshu (Internet), p.143 - 149, 2023/10
In 2019, the JSME Code Case for seismic design of nuclear power plant piping systems was published. The Code Case provides the strain-based fatigue criteria and detailed inelastic response analysis procedure as an alternative design rule to the current seismic design, which is based on the stress evaluation by elastic response analysis. In 2022, it was approved to revise the Code Case with improving the cycle counting method for fatigue evaluation to the Rain flow method. In addition, the discussion to incorporate the elastic-plastic behavior of support structures is now in progress for the next revision of the Code Case. This paper discusses the contents and background of the 2022 revision, the progress of the next revision, and future tasks.
Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito
Vacuum and Surface Science, 66(9), p.525 - 530, 2023/09
As Au (001) surfaces exhibit a quasi-one-dimensional corrugated structure, Hex-Au(001), its periodicity was predicted to change the electronic structure of graphene when graphene was grown on this surface. Furthermore, the hybridization between graphene and Au is known to introduce bandgap and spin polarization into graphene. Here, we report angle-resolved photoemission spectroscopy and density functional theory calculation of graphene on a Hex-Au(001) surface. A bandgap of 0.2 eV in the graphene Dirac cone was observed at the crossing point of the graphene Dirac cone and Au 6sp bands, indicating that the origin of the bandgap formation was the hybridization between the graphene Dirac cone and Au 6sp band. We discussed the hybridization mechanism and anticipated spin injection into the graphene Dirac cone.
Saito, Takumi*; Motokawa, Ryuhei; Okubo, Takahiro*; Miura, Daisuke*; Kumada, Takayuki
Environmental Science & Technology, 57(26), p.9802 - 9810, 2023/07
Times Cited Count：4 Percentile：22.62(Engineering, Environmental)Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.
JAEA-Technology 2022-039, 117 Pages, 2023/06
JAEA-Technology-2022-039.pdf:11.96MB
Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process.
Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.
JAEA-Technology 2023-005, 33 Pages, 2023/05
JAEA-Technology-2023-005.pdf:5.25MB
During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.
Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Natori, Hiroaki*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Tampo, Motonobu*; Kawamura, Naritoshi*; Teshima, Natsuki*; et al.
Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03
Times Cited Count：2 Percentile：92.31(Physics, Applied)
-edge for Ce in bauxites using transition-edge sensors; Implications for Ti-rich geological samplesLi, W.*; Yamada, Shinya*; Hashimoto, Tadashi; Okumura, Takuma*; Hayakawa, Ryota*; Nitta, Kiyofumi*; Sekizawa, Oki*; Suga, Hiroki*; Uruga, Tomoya*; Ichinohe, Yuto*; et al.
Analytica Chimica Acta, 1240, p.340755_1 - 340755_9, 2023/02
Times Cited Count：20 Percentile：78.35(Chemistry, Analytical)no abstracts in English
