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Shirafuji, Masaya; Hasegawa, Rie; Akutsu, Narumi*; Maruyama, Hajime; Miyaji, Noriko
Dai-44-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2023/11
To maintain transparency in the use of nuclear materials in Japan, it is important for operators to appropriately respond to safeguards activities conducted by the IAEA/Japan. Failure to appropriately respond to these activities could have significant impacts, such as raising suspicion from the international community about the misuse of nuclear materials by not only the operators but also Japan. To appropriately respond to safeguards activities, JAEA has conducted some activities such as education on safeguards for all employees and case study activities for the employees engaged in responding to safeguards activities. This paper focused on case study activities that started in FY2022. In FY2022, we created documents based on scenarios with problems in safeguards responses in order to promote understanding among participants. We also conducted a questionnaire survey for participants, and we evaluated the result of the questionnaire. The evaluation results showed that the case study activities contributed to raising awareness of safeguards responses, although there were improvements. After making improvements, we are conducting these activities again in FY2023. Since case study activities are expected to be effective if carried out continuously, we plan to continue them in combination with other activities.
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.
Kawasaki, Masatsugu; Nakajima, Junya; Yoshida, Keisuke; Kato, Saori; Nishino, Sho; Nozaki, Teo; Nakagawa, Masahiro; Tsunoda, Junichi; Sugaya, Yuki; Hasegawa, Rie; et al.
JAEA-Data/Code 2017-004, 57 Pages, 2017/03
JAEA-Data-Code-2017-004.pdf:2.34MB
In emergency situation of nuclear facilities, we need to estimate the radiation dose due to radiation and radioactivity to grasp the influence range of the accident in the early stage. Therefore, we prepare the case studies of dose assessment for public exposure dose and personal exposure dose and contribute them to emergency procedures. This document covers about accidents of nuclear facilities in Nuclear Science Research Institute and past accident of nuclear power plant, and it can be used for inheritance of techniques of emergency dose assessment.
Riemer, B. W.*; Wendel, M. W.*; Felde, D. K.*; Sangrey, R. L.*; Abdou, A.*; West, D. L.*; Shea, T. J.*; Hasegawa, Shoichi; Kogawa, Hiroyuki; Naoe, Takashi; et al.
Journal of Nuclear Materials, 450(1-3), p.192 - 203, 2014/07
Times Cited Count：14 Percentile：72.55(Materials Science, Multidisciplinary)Populations of small helium gas bubbles were introduced into a flowing mercury experiment test loop to evaluate mitigation of beam-pulse induced cavitation damage and pressure waves. The test loop was developed and thoroughly tested at the Spallation Neutron Source (SNS) prior to irradiations at the Los Alamos Neutron Science Center - Weapons Neutron Research Center (LANSCE-WNR) facility. Twelve candidate bubblers were evaluated over a range of mercury flow and gas injection rates by use of a novel optical measurement technique that accurately assessed the generated bubble size distributions. Final selection for irradiation testing included two variations of a swirl bubbler provided by Japan Proton Accelerator Research Complex (J-PARC) collaborators and one orifice bubbler developed at SNS. Bubble populations of interest consisted of sizes up to 150 
m in radius with achieved gas void fractions in the 10
to 10
range. The nominal WNR beam pulse used for the experiment created energy deposition in the mercury comparable to SNS pulses operating at 2.5 MW. Nineteen test conditions were completed each with 100 pulses, including variations on mercury flow, gas injection and protons per pulse. The principal measure of cavitation damage mitigation was surface damage assessment on test specimens that were manually replaced for each test condition. Damage assessment was done after radiation decay and decontamination by optical and laser profiling microscopy with damaged area fraction and maximum pit depth being the more valued results. Damage was reduced by flow alone; the best mitigation from bubble injection was between half and a quarter that of flow alone. Other data collected included surface motion tracking by three laser Doppler vibrometers (LDV), loop wall dynamic strain, beam diagnostics for charge and beam profile assessment, embedded hydrophones and pressure sensors, and sound measurement by a suite of conventional and contact microphones.
Futakawa, Masatoshi; Kogawa, Hiroyuki; Hasegawa, Shoichi; Ikeda, Yujiro; Riemer, B.*; Wendel, M.*; Haines, J.*; Bauer, G.*; Naoe, Takashi; Okita, Kohei*; et al.
Journal of Nuclear Materials, 377(1), p.182 - 188, 2008/06
Times Cited Count：28 Percentile：85.1(Materials Science, Multidisciplinary)no abstracts in English
Kogawa, Hiroyuki; Hasegawa, Shoichi; Futakawa, Masatoshi; Riemer, B.*; Wendel, M.*; Haines, J.*
Journal of Nuclear Materials, 377(1), p.195 - 200, 2008/06
Times Cited Count：3 Percentile：23.55(Materials Science, Multidisciplinary)In beam test was carried out at the LANSCE-WNR to investigate pressure wave mitigation in mercury targets for the MW-class spallation neutron sources under international collaboration between SNS and JSNS. A mercury loop with micro bubble generator was used for the target. The loop target consists of the rectangular pipe which was made of stainless steel. The total length of the loop is about 2 m. Strain sensors were set on many points of loop to measure the strain on the pipe wall caused by the pressure wave. The maximum strain at 350 mm apart from the proton bombarded point appeared after 5.5 ms after the proton bombardment. The wave propagation velocity was slower than the stress wave and the pressure wave propagation velocities and became 65 m/s in the IBBTL. Numerical analysis result shows that the maximum strain at 350 mm apart from the proton bombarded point appeared at 5.5 ms after proton bombardment as well as the experimental due to interaction between liquid and solid.
Nakajima, Junya; Yamada, Katsunori; Hasegawa, Rie; Umeda, Masayuki; Seki, Masakazu; Muto, Yasushi; Sawahata, Katsunori
no journal, ,
STACY (Static Experiment Critical Facility) has been under remodeling work. During the demolition work of the previous model of STACY, we conducted radiation management for both internal exposure and external exposure taking the characteristics of the previous model into consideration. As a result, any contamination and internal exposure of the all workers was detected, and external exposure of the all workers were less than the detection limit.
