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CoSiYamauchi, Hiroki; Sari, D. P.*; Yasui, Yukio*; Sakakura, Terutoshi*; Kimura, Hiroyuki*; Nakao, Akiko*; Ohara, Takashi; Honda, Takashi*; Kodama, Katsuaki; Igawa, Naoki; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
Oikawa, Kenichi; Sato, Hirotaka*; Watanabe, Kenichi*; Su, Y. H.; Shinohara, Takenao; Kai, Tetsuya; Kiyanagi, Yoshiaki*; Hasemi, Hiroyuki
Journal of Physics; Conference Series, 2605, p.012013_1 - 012013_6, 2023/10
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.
Shobuda, Yoshihiro; Harada, Hiroyuki; Saha, P. K.; Takayanagi, Tomohiro; Tamura, Fumihiko; Togashi, Tomohito; Watanabe, Yasuhiro; Yamamoto, Kazami; Yamamoto, Masanobu
Physical Review Accelerators and Beams (Internet), 26(5), p.053501_1 - 053501_45, 2023/05
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)At the Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC), theoretical predictions have indicated that the kicker-impedance would excite the beam-instability. A 1 MW beam with large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) through suppression of the beam instabilities by choosing the appropriate machine parameters. However, we require other high-intensity and high-quality smaller emittance beams (than the 1 MW beam) for the Main Ring (MR). Hence, we proposed a scheme for suppressing the kicker-impedance by using prototype diodes and resistors, thereby demonstrating the effect on the kicker impedance reduction. However, the J-PARC RCS must be operated with a repetition rate of 25 Hz, which urged us to consider special diodes that are tolerant to heating. After developments, we have demonstrated that the special diodes with resistors can suppress the beam instability by reducing the kicker impedance. Enhanced durability of the prototype diodes and resistors for the 25 Hz operation was also realized. Moreover, the new diodes and the resistors have negligible effect on the extracted beam from the RCS. From a simulation point of view, the scheme can be employed for at least 5 MW beam operation within the stipulated specifications.
Watanabe, Masao; Kihara, Takumi*; Nojiri, Hiroyuki*
Quantum Beam Science (Internet), 7(1), p.1_1 - 1_10, 2023/03
A pulsed magnet system has been developed as a new user-friendly sample environment equipment at the Materials and Life Science Experimental Facility in Japan Proton Accelerator Research Complex. It comprises a vacuum chamber, a 4 K closed-cycle refrigerator for samples, and a nitrogen bath made of a stainless-steel tube with a miniature solenoidal coil. The coil is cooled by liquid nitrogen supplied by an automatic liquid nitrogen supply system, and the sample is cooled by a refrigerator. This combination facilitates the automatic high magnetic field diffraction measurement for the user's operation. A relatively large scattering angle is up to 42 degrees, which is significantly wider than the previous setup. Neutron diffraction experiments were performed on a multiferroic TbMnO
and the field dependence of the diffraction peaks was clearly observed. The new pulsed magnet system was established for a practical high magnetic field diffraction for the user program.
Sn in concrete rubbleDo, V. K.; Furuse, Takahiro; Ota, Yuki; Iwahashi, Hiroyuki; Hirosawa, Takashi; Watanabe, Masahisa; Sato, Soichi
Journal of Radioanalytical and Nuclear Chemistry, 331(12), p.5631 - 5640, 2022/12
Times Cited Count：2 Percentile：53.91(Chemistry, Analytical)Sn is one of the long-lived fission products that might have been released into the environment after the Fukushima nuclear accident in Japan in 2011. The presence of radionuclides must be monitored for the proper treatment of wastes obtained from decommissioning accident-related nuclear facilities and the surrounding environment. In the work, we propose a reliable method for verifying the presence of Sn in construction materials by combining the HCl-free solid phase extraction on TEVA resin and a selective measurement by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). The method has been optimized and characterized step by step. More than 95% of chemical recovery was achieved for Sn from typical concrete matrixes. The interference caused by an isobar Te and possible polyatomic interferences from matrixes were effectively suppressed by the developed chemical separation and the tandem MS/MS configuration. The total decontamination factor for the Te interference was of the order of 10
. The estimated method detection limit for Sn in concrete as measured at m/z = 160 was 12.1 pg g
, which is equivalent to 6.1 mBq g.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Kobayashi, Daisuke; Yamamoto, Masahiko; Nishida, Naoki; Miyoshi, Ryuta; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kato, Keisuke; Nishino, Saki; Kuno, Takehiko; Kitao, Takahiko; et al.
Nihon Hozen Gakkai Dai-18-Kai Gakujutsu Koenkai Yoshishu, p.237 - 240, 2022/07
All gloves attached to glove-box in Tokai Reprocessing Plant have a fixed expiration date and have to be replaced every 4-year. However, degrees of glove deterioration are different depending on its usage environment (frequency, chemicals, radiation, etc.), because of rubber products. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured, and the life-time of gloves are estimated. As a result, gloves without any defects in its appearance have enough physical property for acceptance criteria of new glove. The extrapolated physical property of glove is sufficiently larger than the reported values of damaged glove. No deterioration in physical properties of gloves, that are periodically replaced without any defects in its appearance, is observed and the usable life-time of the glove is estimated to be 8 years.
Hamamoto, Shimpei; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Sekita, Kenji; Watanabe, Shuji; Furusawa, Takayuki; Iigaki, Kazuhiko; et al.
Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03
Times Cited Count：2 Percentile：53.91(Nuclear Science & Technology)Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, the Japan Atomic Energy Agency adapted High-Temperature engineering Test Reactor (HTTR) to meet the new regulatory requirements that began in December 2013. The safety and seismic classifications of the existing structures, systems, and components were discussed to reflect insights regarding High Temperature Gas-cooled Reactors (HTGRs) that were acquired through various HTTR safety tests. Structures, systems, and components that are subject to protection have been defined, and countermeasures to manage internal and external hazards that affect safety functions have been strengthened. Additionally, measures are in place to control accidents that may cause large amounts of radioactive material to be released, as a beyond design based accident. The Nuclear Regulatory Commission rigorously and appropriately reviewed this approach for compliance with the new regulatory requirements. After nine amendments, the application to modify the HTTR's installation license that was submitted in November 2014 was approved in June 2020. This response shows that facilities can reasonably be designed to meet the enhanced regulatory requirements, if they reflect the characteristics of HTGRs. We believe that we have established a reference for future development of HTGR.
Ikami, Takaya*; Watanabe, Yuki*; Ogawa, Hiroki*; Takenaka, Mikihito*; Yamada, Norifumi*; Ouchi, Makoto*; Aoki, Hiroyuki; Terashima, Takaya*
ACS Macro Lett (Internet), 10(12), p.1524 - 1528, 2021/12
Times Cited Count：7 Percentile：48.3(Polymer Science)Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count：6 Percentile：51.19(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
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
JAEA-Technology-2021-014.pdf:5.87MB
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.
Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
Times Cited Count：2 Percentile：14.88(Chemistry, Multidisciplinary)The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 
C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl
TaOCl
DbOCl. From the obtained experimental results, thermochemical data for DbOCl were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
Somekawa, Hidetoshi*; Basha, D. A.*; Singh, A.*; Tsuru, Tomohito; Watanabe, Hiroyuki*
Philosophical Magazine Letters, 100(10), p.494 - 505, 2020/10
Times Cited Count：9 Percentile：53.43(Materials Science, Multidisciplinary)The damping capacity in the vicinity of {10
2} twin boundaries was measured before and after annealing by nano-dynamic mechanical analysis. The subsequent annealing process led to a lower damping capacity in all magnesium binary alloys, which was in contrast to the results in pure magnesium. This is on account of the segregation of solute atoms in incoherent twin boundaries. The alloying elements, which have the characteristic of a low segregation energy for twin boundaries, effectively prevents the damping capacity degradation.
Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nomura, Kazunori; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Hagura, Naoto*; Kubota, Toshio*
Nuclear Instruments and Methods in Physics Research B, 477, p.54 - 59, 2020/08
Times Cited Count：5 Percentile：45.45(Instruments & Instrumentation)Kubo, Shigenobu; Chikazawa, Yoshitaka; Ohshima, Hiroyuki; Uchita, Masato*; Miyagawa, Takayuki*; Eto, Masao*; Suzuno, Tetsuji*; Matoba, Ichiyo*; Endo, Junji*; Watanabe, Osamu*; et al.
Mechanical Engineering Journal (Internet), 7(3), p.19-00489_1 - 19-00489_16, 2020/06
The authors are developing the design concept of pool-type sodium-cooled fast reactor (SFR) that addresses Japan's specific siting conditions such as earthquakes and meets safety design criteria (SDC) and safety design guidelines (SDGs) for Generation IV SFRs. The development of this concept will broaden not only options for reactor types in Japan but also the range and depth of international cooperation. A design concept of 1,500 MWt (650 MWe) class pool-type SFR was thought up by applying design technology obtained from the design of advanced loop-type SFR, named JSFR, equipped with safety measures that reflect results from the feasibility study on commercialized fast reactor cycle systems and fast reactor cycle technology development, improved maintainability and repairability, and lessons learned from the Fukushima Daiichi Nuclear Power Plants accident.
Xe ions on proton, deuteron, and carbon targetsSun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.
Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06
Times Cited Count：5 Percentile：52.72(Physics, Nuclear)The spallation and fragmentation reactions of Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.
Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nomura, Kazunori; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Kubota, Toshio*
QST-M-23; QST Takasaki Annual Report 2018, P. 59, 2020/03
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：8 Percentile：56.2(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Saha, P. K.; Hotchi, Hideaki; Shobuda, Yoshihiro; Harada, Hiroyuki; Tamura, Fumihiko; Watanabe, Yasuhiro; Takayanagi, Tomohiro
Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.171 - 173, 2019/06
