Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Morita, Koji*; Nakamura, Kinya*; Fukai, Hirofumi*; et al.
Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-13) (Internet), 12 Pages, 2022/09
This paper describes the project overview and progress of experimental and analytical studies conducted until 2020. Specific results in this paper are the measurement of the eutectic reaction rates and the validation of physical model describing the eutectic reaction in the analysis code through the numerical analysis of the BC-SS eutectic reaction rate experiments in which a BC pellet was placed in a SS crucible.
Yamamoto, Naoki*; Nakanishi, Masahiro*; Rajan, R.*; Nakagawa, Hiroshi
Biophysics and Physicobiology (Internet), 18, p.284 - 288, 2021/12
Water is an indispensable solvent for living things. 60% of our body is composed of water, the lack of which causes lots of fatal problems. It has also been known that protein function is performed only when it accompanies water molecules around the surface, i.e. hydration water molecules. Therefore, it is essential to understand how water and biological component interact with each other in the view point of structure and dynamics. Freezing is a fundamental and simple phenomenon of water, and thus can be used as a probe for the purpose. Furthermore, preservation of cells and proteins under low temperature is crucial for numerous applications, which in turn triggers a myriad of undesirable consequences because of the freezing.
Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.
Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08
To clarify the existence of cation vacancies in Ce-doped GdAlGaO (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:YAlO, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.
Shiina, Hidenori; Ono, Katsuto; Nishi, Masahiro; Uno, Kiryu; Kanazawa, Hiroyuki; Oi, Ryuichi; Nihei, Yasuo
Dekomisshoningu Giho, (61), p.29 - 38, 2020/03
The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) was constructed in 1961, as the first one in Japan, to perform the examinations of irradiated fuels and materials. RHL consists of 10 heavy concrete cells and 38 lead cells. RHL contributed to research and development program in or out of JAEA for the investigation of irradiation behavior for fuels and nuclear materials. However, RHL is the one of target as the rationalization program for decrepit facilities in former Tokai institute. Therefore the decommissioning works of RHL started on April 2003. The dismantling of 12 lead cells has been progressing since 2010. The dismantling procedure of lead cells was performed in the following order. The peripheral equipment in lead cells were removed and contamination survey of the inner surface of the cells. Then, the backside shield doors were extracted. The lifting frame for the isolation tent was set on the cells. After that, the ceiling plates, isolation walls and lead blocks were removed. The strippable paint was used to remove permeable contamination on the inner surface of structural steel of the cells. The dismantling work will be continued to mention the efficiency of decommissioning works and reduction of radioactive waste with ensuring safety.
Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09
Eutectic reactions between boron carbide (BC) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on BC-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified BC-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.
Ishizaki, Azusa; Nakanishi, Chika*; Takubo, Kazuya*; Munakata, Masahiro
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05
Ishizaki, Azusa; Futemma, Akira; Takubo, Kazuya*; Nakanishi, Chika*; Munakata, Masahiro
JAEA-Data/Code 2018-022, 20 Pages, 2019/03
If a nuclear disaster occurs, we may evacuate indoor escape facilities and buildings such as houses as avoid extra exposure doses. In order to evaluate exposure doses, it is necessary to estimate shielding capabilities of the building materials constituting the sheltering facility. Therefore, photon irradiation tests with three kinds of photon energy were carried out for Japanese familiar building materials in Japan, and photon transmittance of each building material is acquired and summarized. As a result, it was found that the shielding capabilities of composite walls and roofs which are widely used in a tree structure and a steel structure were relatively low. And, difference of materials used for composite walls and roofs resulted in a difference in shielding capabilities. For example, in the case of composite walls, compared with the photon transmittance of wall with ceramic-based siding materials, those of wall with lightweight concrete were lower. Furthermore, photon transmittance was also measured for building materials with relatively low shielding performance added shielding materials as additional measures to enhance shielding capabilities.
Sato, Yuji*; Tsukamoto, Masahiro*; Shobu, Takahisa; Yamashita, Yoshihiro*; Yamagata, Shuto*; Nishi, Takaya*; Higashino, Ritsuko*; Okubo, Tomomasa*; Nakano, Hitoshi*; Abe, Nobuyuki*
Applied Physics A, 124(4), p.288_1 - 288_6, 2018/04
The dynamics of titanium (Ti) melted by laser irradiation was investigated in a synchrotron radiation experiment. As an indicator of wettability, the contact angle between a selective laser melting (SLM) baseplate and the molten Ti was measured by synchrotron X-rays at 30 keV during laser irradiation. As the baseplate temperature increased, the contact angle decreased, down to 28 degrees at a baseplate temperature of 500C. Based on this result, the influence of wettability of a Ti plate fabricated by SLM in a vacuum was investigated. It was revealed that the improvement of wettability by preheating suppressed sputtering generation, and a surface having a small surface roughness was fabricated by SLM in a vacuum.
Shiina, Hidenori; Ono, Katsuto; Nishi, Masahiro; Nihei, Yasuo
Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 7 Pages, 2017/00
The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) is the first facility in Japan for the post irradiation examination (PIE) on reactor fuels and structural materials, which had contributed to advancement of the fuels and materials since 1961. The building of RHL consists of two stories above ground and a basement, in which 10 heavy concrete and 38 lead cells were installed. In RHL, all operations for PIE had been completed in 2003. Then the decommissioning program has been implemented in order to promote the rationalization of research facilities in JAEA. As the first step of the program, PIE apparatuses and irradiated samples were removed from the cells, which have been managed as radioactive wastes. The dismantling of lead cells was initiated in 2005. At present 26 lead cells are successfully dismantled. This paper shows technical review of dismantling operations for the lead cells.
Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.
JAEA-Research 2016-016, 131 Pages, 2016/10
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.
Sanada, Yukihisa; Mori, Airi; Ishizaki, Azusa; Munakata, Masahiro; Nakayama, Shinichi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika; Yamada, Tsutomu; Ishida, Mutsushi; et al.
JAEA-Research 2015-006, 81 Pages, 2015/07
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report.
Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.
Sato, Takeshi; Muto, Shigeo; Akiyama, Kiyomitsu; Aoki, Kazufumi; Okamoto, Akiko; Kawakami, Takeshi; Kume, Nobuhide; Nakanishi, Chika; Koie, Masahiro; Kawamata, Hiroyuki; et al.
JAEA-Review 2014-048, 69 Pages, 2015/02
JAEA was assigned as a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national government and/or local governments in case of disaster responses or response in the event of a military attack, etc. In order to fulfill the tasks, the JAEA has established the Emergency Action Plan and the Civil Protection Action Plan. In case of a nuclear emergency, NEAT dispatches specialists of JAEA, supplies the national government and local governments with emergency equipment and materials, and gives technical advice and information. In normal time, NEAT provides various exercises and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response institutions of the national and local governments, police, fire fighters, self-defense forces, etc. in addition to the JAEA itself. The NEAT also researches nuclear disaster preparedness and response, and cooperates with international organizations. In the FY2013, the NEAT accomplished the following tasks: (1) Technical support activities as a designated public institution in cooperation with the national and local governments, etc. (2) Human resource development, exercise and training of nuclear emergency response personnel for the national and local governments, etc. (3) Researches on nuclear disaster preparedness and response, and sending useful information (4) International contributions to Asian countries on nuclear disaster preparedness and response in collaboration with the international organizations
Jarrige, I.*; Ishii, Kenji; Matsumura, Daiju; Nishihata, Yasuo; Yoshida, Masahiro*; Kishi, Hirofumi*; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*; Kasai, Hideaki*; et al.
ACS Catalysis, 5(2), p.1112 - 1118, 2015/02
Takahashi, Ryuichi*; Ishimaru, Yasuhiro*; Shimo, H.*; Bashir, K.*; Senoura, Takeshi*; Sugimoto, Kazuhiko*; Ono, Kazuko*; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; et al.
PLOS ONE (Internet), 9(6), p.e98816_1 - e98816_7, 2014/06
Sato, Takeshi; Muto, Shigeo; Okuno, Hiroshi; Katagiri, Hiromi; Akiyama, Kiyomitsu; Okamoto, Akiko; Koie, Masahiro; Ikeda, Takeshi; Nemotochi, Toshimasa; Saito, Toru; et al.
JAEA-Review 2013-046, 65 Pages, 2014/02
When a nuclear emergency occurs in Japan, the Japan Atomic Energy Agency (JAEA) has the responsibility of providing technical support to the National government, local governments, police, fire stations and nuclear operators etc., because the JAEA has been designated as the Designated Public Institution under the Basic Act on Disaster Control Measures and the Act on Response to Armed Attack Situations, etc.. The Nuclear Emergency Assistance and Training Center (NEAT) of JAEA provides a comprehensive range of technical support activities to an Off-Site Center in case of a nuclear emergency. Specifically, NEAT gives technical advice and information, dispatches specialists as required, and supplies the National Government and local governments with emergency equipments and materials. NEAT provides various exercise and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response organizations at normal times. The tasks of NEAT, with its past experiences as a designated public institution including the responses to TEPCO's Fukushima Accident, have been shifted to technical supports to the national government for strengthening its abilities to emergency responses; the NEAT therefore focused on maintenance and operation of its functions, and strengthening its response abilities in cooperation with the national government. This annual report summarized these activities of JAEA/NEAT in the fiscal year 2012.
Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Miyajima, Tsukasa*; Honda, Yosuke*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.255 - 259, 2013/08
no abstracts in English
Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.
Proceedings of 34th International Free Electron Laser Conference (FEL 2012) (Internet), p.161 - 164, 2012/08
Katagiri, Hiromi; Okuno, Hiroshi; Sawahata, Masayoshi; Ikeda, Takeshi; Sato, Sohei; Terakado, Naoya; Nagakura, Tomohiro; Nakanishi, Chika; Fukumoto, Masahiro; Yamamoto, Kazuya; et al.
JAEA-Review 2011-037, 66 Pages, 2011/12
When a Nuclear emergency occurs, Nuclear Emergency Assistance & Training Center (NEAT) of JAEA gives technical advice and information, dispatch specialists as required, supplies emergency equipment and materials to the National Government and local governments. NEAT provides various lectures and training courses concerning nuclear disaster prevention for those personnel taking an active part in emergency response organizations at normal time. NEAT also researches on nuclear disaster prevention and cooperates with international organizations. Concerning about the assistance to the Accident of Fukushima No.1 Nuclear Power Station caused by the Great East Japan Earthquake at 11 March, 2011, JAEA assisted activities including environmental radiation monitoring, environmental radioactivity analyses, resident public consulting etc., with its full scale effort. NEAT served as the center of these supporting activities of JAEA.
Sugihara, Shinji*; Tanaka, Masahiro*; Tamari, Toshiya*; Shimada, Jun*; Takahashi, Tomoyuki*; Momoshima, Noriyuki*; Fukutani, Satoshi*; Atarashi-Andoh, Mariko; Sakuma, Yoichi*; Yokoyama, Sumi*; et al.
Fusion Science and Technology, 60(4), p.1300 - 1303, 2011/11
The purpose of this study is to develop the technique to evaluate the environmental tritium behavior of the nuclear facility origin. Tritium concentrations of river water, precipitation and ground water around the NIFS site were determined by low background liquid scintillation measurement system combined with the electrolysis using solid polymer electrolyte. The electric conductivity and flow rate of the river and isotopic ratio of oxygen and hydrogen of water samples were also measured. The tritium concentrations in precipitation showed the seasonal variation and the range were 0.09-0.78 Bq/L. The tritium concentrations of river water and ground water were almost constant, 0.34 and 0.24 Bq/L respectively. The simple dynamic model for the site around the NIFS facilities was developed using measured data, and the behavior of tritium was simulated.