Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji
JAEA-Technology 2021-014, 80 Pages, 2021/09
In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.
Saito, Wataru*; Hayashi, Kei*; Huang, Z.*; Sugimoto, Kazuya*; Oyama, Kenji*; Happo, Naohisa*; Harada, Masahide; Oikawa, Kenichi; Inamura, Yasuhiro; Hayashi, Koichi*; et al.
ACS Applied Energy Materials (Internet), 4(5), p.5123 - 5131, 2021/05
Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.
JAEA-Technology 2020-020, 73 Pages, 2021/03
The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.
Okayasu, Satoru; Harii, Kazuya*; Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Ishida, Masahiko*; Ieda, Junichi; Saito, Eiji
Journal of Applied Physics, 128(8), p.083902_1 - 083902_7, 2020/08
Hayashi, Kei*; Saito, Wataru*; Sugimoto, Kazuya*; Oyama, Kenji*; Hayashi, Koichi*; Happo, Naohisa*; Harada, Masahide; Oikawa, Kenichi; Inamura, Yasuhiro; Miyazaki, Yuzuru*
AIP Advances (Internet), 10(3), p.035115_1 - 035115_7, 2020/03
Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Kawasaki, Ikuto; Okane, Tetsuo; Yamagami, Hiroshi; Yaita, Tsuyoshi; Harii, Kazuya; Ieda, Junichi; Okayasu, Satoru; et al.
JPS Conference Proceedings (Internet), 30, p.011192_1 - 011192_6, 2020/03
High energy X-ray photoelectron spectroscopy (HAXPES) measurements were carried out for the Spin Seebeck system Pt/YFeO(YIG). This system was found to show anomalous Hall effect, possible due to the formation of intermetallic compounds between Fe and Pt. To reveal this possibility, we have measured the Fe 1s photoelectron peaks by using HAXPES. It was found that the Fe ions consist of Fe in YIG and metallic Fe. The formation of the metallic state is consistent with the proposed origin of the anomalous Hall effect. Other spectra such as Pt 4f will be presented at the conference.
Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.
Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12
Negative muonium atom (ee, Mu) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu were 10/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu averaged energy: it was 0.20.1keV.
Ito, Daisuke*; Kurisaki, Tatsuya*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.6430 - 6439, 2019/08
In core disruptive accident of sodium-cooled fast reactor, cooling of residual fuel debris formed in the reactor core is one of important factors to achieve in-vessel retention of the fuel. To clarify the feasibility of the cooling which is called "in-place cooling", characteristics of gas-liquid two-phase flow in the debris bed must be well understood. Since the debris bed can be formed in a confined flow channel in the core, effect of the channel wall cannot be neglected. Thus, this study aims to clarify the effect of the wall on two-phase flow characteristics in the debris bed, which was simulated as a particle bed packed in a pipe. The pressure drop was measured and compared with results by previous models, and porosity and void fraction distributions were measured by X-ray radiography. Then, the pressure drop evaluation model was modified considering the wall effect, and the applicability of the models was discussed.
Sakai, Kenji; Obayashi, Hironari; Saito, Shigeru; Sasa, Toshinobu; Sugawara, Takanori; Watanabe, Akihiko*
JAEA-Technology 2019-009, 18 Pages, 2019/07
Construction of Transmutation Experimental Facility (TEF) is under planning in the Japan Proton Accelerator Research Complex (J-PARC) program to promote R&D on the transmutation technology with using accelerator driven systems (ADS). ADS Target Test Facility (TEF-T) in TEF will develop spallation target technology and study on target materials with irradiating high intensity proton beams on a lead-bismuth eutectic (LBE) target. For safe and efficient beam operation, a general control system (GCS) will be constructed in TEF-T. GCS comprises several subsystems, such as a network system (LAN), an integral control system (ICS), an interlock system (ILS), and a timing distribution system (TDS) according to their roles. Especially, the ICS plays the important role that executes integral operations in the entire facility, acquires, stores and distributes operation data. We planned to develop a prototype of the ICS, to evaluate its concrete performances such as data transmission speeds, data storage capability, control functions, long-term stability of the system, and to utilize them for design of the actual ICS. This report mentions to product the prototype of ICS and to apply it to remote operations of instruments for developing LBE target technology.
Kurisaki, Tatsuya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 3 Pages, 2018/11
In the evaluation of the in-place cooling which is for the residual core materials in the severe accident of sodium-cooled fast reactors, pressure loss of two-phase flow in debris bed is one of the important factors. Although Lipinski model is already proposed for the pressure loss evaluation, the accuracy would decrease when the porosity is not homogeneous. Thus, experiment to measure the pressure loss in a packed bed of non-homogeneous porosity distribution was conducted, and the Lipinski model was modified dividing the cross section to evaluate the pressure loss in it. As a result, it was confirmed that agreement of the experimental values with the values by modified Lipinski model was better than that with the original Lipinski model.
Aratani, Hidekazu*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Kawada, Moeki*; Kanai, Yuina*; Yamagami, Kohei*; Fujioka, Shuhei*; Hamamoto, Satoru*; Kuga, Kentaro*; Kiss, Takayuki*; et al.
Physical Review B, 98(12), p.121113_1 - 121113_6, 2018/09
Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Matsuba, Kenichi; Kamiyama, Kenji
Nuclear Engineering and Design, 334, p.90 - 95, 2018/08
Two-phase flow through porous media must be well understood to develop a severe accident analysis code not only for light water reactor but also sodium-cooled fast reactor. When a core disruptive accident occurs in sodium-cooled fast reactor, the fuel inside the core become melted and interacts with the coolant. As a result, gas-liquid two-phase flow will be formed in the debris bed, which may have porous nature depending on the cooling process. In such condition, the local porosity and its distribution are very important to characterize two-phase flow field in the porous media. In this study, X-ray radiography was applied to measure the local porosity in the packed bed of spheres. The radial profiles were estimated from the chordal profiles measured by the X-ray method and compared with the previous porosity model. In addition, the void fraction radial profiles were also obtained in air-water two-phase flow.
Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Ito, Daisuke*; Rivera, M. N.*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 10 Pages, 2017/09
Nava, M.*; Ito, Daisuke*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07
Ito, Daisuke*; Nava, M.*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 2017 Japan-US Seminar on Two-Phase Flow Dynamics (JUS 2017), 4 Pages, 2017/06
Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Hamamoto, Shimpei; Nemoto, Takahiro; Sekita, Kenji; Saito, Kenji
JAEA-Technology 2015-048, 62 Pages, 2016/03
The decarburization may take place depending on the chemical impurity composition in helium gas used as the primary coolant in High-Temperature Gas-cooled Reactors, and will significantly reduce the strength of the alloy. The ability to remove impurities by a helium purification system was designed according to the predicted generation rate of impurities so as to make the coolant become the carburizing atmosphere. It has been confirmed that the coolant becomes the carburizing atmosphere during the operation period of the High Temperature engineering Test Reactor (HTTR). However, it is necessary to consider changes of generation rates of impurities since lifetime of commercial reactor is longer than the life of the HTTR. To avoid the influence of the change of generation rate, the control of removal efficiency of impurity in the helium purification system was considered in this study. To reform the decarburizing into the carburizing atmosphere, it is effective to increase the H and CO concentration in the coolant helium. By controlling the efficiency of the Cooper Oxide Trap (CuOT), it is possible to increase the H and CO concentrations. Therefore, an experiment was carried out by injecting the gas mixture of H and CO into the existing purification system of HTTR to investigate the dependencies of temperature and impurity concentration on the removal efficiency of CuOT. The experimental results are described as the following, (1) By adjusting the temperature of helium at the CuOT within a range from 110C to 50C, it is possible to reduce the removal efficiency of H sufficiently. (2) Temperature change of helium gas in the CuOT is sufficiently reduced by the cooler located at the downstream of the CuOT, which does not affect the primary cooling system of HTTR. As the results, the applicability of removal efficiency control of CuOT was verified to improve the decarburizing atmosphere for the actual HTGR system.
Kobayashi, Masato*; Saito, Masahiko*; Iwatani, Takafumi*; Nakayama, Masashi; Tanai, Kenji; Fujita, Tomo; Asano, Hidekazu*
JAEA-Research 2015-018, 14 Pages, 2015/12
JAEA and RWMC concluded the letter of cooperation agreement on the research and development of radioactive waste disposal in April, 2005, and have been carrying out the collaboration work based on the agreement. JAEA have been carrying out the Horonobe URL Project which is intended for a sedimentary rock in the Horonobe town, Hokkaido, since 2001. In the project, geoscientific research and research and development on geological disposal technology are being promoted. Meanwhile, The Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry has been promoting construction of equipments for the full-scale demonstration of engineered barrier system and operation technology for high-level radioactive waste disposal since 2008, to enhance public's understanding to the geological disposal of HLW, e.g. using underground facility. RWMC received an order of the project in fiscal year 2014 continuing since fiscal year 2008. Since topics in this project are included in the Horonobe URL Project, JAEA carried out this project as collaboration work continuing since fiscal year 2008. This report summarizes the results of the research on engineering technology carried out in this collaboration work in fiscal year 2014.
Kitayama, Takumi*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Matsuda, Makoto; Sataka, Masao*; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*
Nuclear Instruments and Methods in Physics Research B, 354, p.183 - 186, 2015/07