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Usami, Hiroshi; Ito, Rintaro; Tagawa, Akihiro
JAEA-Review 2024-045, 49 Pages, 2024/12
JAEA-Review-2024-045.pdf:13.38MB
The decommissioning of the TEPCO's Fukushima Daiichi Nuclear Power Station is a long-term project, and the training of young engineers and researchers who will be responsible for future decommissioning is a necessary and urgent task. Since 2016, Collaborative Laboratories for Advanced Decommissioning Science has been continuously organizing "Conferences for R&D Initiative on Nuclear Decommissioning Technology by the Next Generation (NDEC)" for students who are engaged in research activities for decommissioning. NDEC is a forum for students to present their research for the purpose of human resource development and networking among young researchers, and to increase their motivation for decommissioning research. NDEC-9 was held at "Manabi-no-Mori" in Tomioka-machi, Fukushima Prefecture, from March 21-22, 2024. This proceeding compiles the contents of report papers in the conference.
Morishita, Yuki; Usami, Hiroshi; Furuta, Yoshihiro; Aoki, Katsunori; Tsurudome, Koji; Hoshi, Katsuya; Torii, Tatsuo
Radiation Protection Dosimetry, 189(2), p.172 - 181, 2020/04
Times Cited Count：0 Percentile：0.00(Environmental Sciences)We developed a remote continuous air monitoring (RCAM) system. The RCAM system consisted of a personal air monitor and a robot. The personal air monitor (poCAMon, SARAD, Germany) had a 400 mm
ion-injected silicon detector and a membrane air filter with 25 mm-diameter. The personal air monitor provides the alpha energy spectra for any measurement time interval. Demonstration measurements were taken underground at the Mizunami Underground Research Laboratory (MIU) and at a poorly ventilated concrete building. The RCAM system was remotely operated and successfully measured the 
Rn progeny even though the relative humidity (RH) was almost 100%. In the measured alpha spectra, the peaks of 
Po (6.0 MeV alpha) and 
Po (7.7 MeV alpha) were clearly identified. Our developed monitor is promising for alpha dust monitoring in a high gamma-ray environment or contaminated areas where a worker cannot safely physically enter.
Morishita, Yuki; Usami, Hiroshi; Torii, Tatsuo
Isotope News, (765), p.10 - 13, 2019/10
This paper reports the development of an alpha particle imaging detector to detect alpha emitters originating from the Fukushima Daiichi Nuclear Power Station and the actual measurement of smear papers.
Morishita, Yuki; Torii, Tatsuo; Usami, Hiroshi; Kikuchi, Hiroyuki*; Utsugi, Wataru*; Takahira, Shiro*
Scientific Reports (Internet), 9, p.581_1 - 581_14, 2019/01
Times Cited Count：28 Percentile：92.83(Multidisciplinary Sciences)Sato, Yuki; Tanifuji, Yuta; Terasaka, Yuta; Usami, Hiroshi; Kaburagi, Masaaki; Kawabata, Kuniaki; Utsugi, Wataru*; Kikuchi, Hiroyuki*; Takahira, Shiro*; Torii, Tatsuo
Journal of Nuclear Science and Technology, 55(9), p.965 - 970, 2018/09
Times Cited Count：40 Percentile：96.70(Nuclear Science & Technology)Usami, Shin; Kishimoto, Yasufumi*; Taninaka, Hiroshi; Maeda, Shigetaka
JAEA-Technology 2018-003, 97 Pages, 2018/07
JAEA-Technology-2018-003.pdf:12.54MB
The decay heat used for effectiveness evaluation of the prevention measures against severe accidents in the prototype fast breeder reactor Monju was evaluated by applying the updated nuclear data libraries based on JENDL-4.0, reflecting the realistic core operation pattern, and setting the rational extent of uncertainty. The decay heats of fission products, the actinide nuclides such as Cm-242, and radioactive structural materials were calculated by FPGS code. The decay heat of U-239 and Np-239 was evaluated based on ANSI/ANS-5.1-1994. The calculation uncertainty of each decay heat was evaluated based on summation of uncertainty factors, C/E values of reaction rates obtained in Monju system startup test, and so on. Furthermore, the decay heat evaluation method based on the FPGS90 was verified by the comparison of the results of the decay heat measurement of the two spent MOX fuel subassemblies in the experimental fast reactor Joyo MK-II core.
Taninaka, Hiroshi; Takegoshi, Atsushi; Kishimoto, Yasufumi*; Mori, Tetsuya; Usami, Shin
Progress in Nuclear Energy, 101(Part C), p.329 - 337, 2017/11
Times Cited Count：3 Percentile：26.15(Nuclear Science & Technology)The present paper describes the evaluation of the power reactivity loss data obtained in the Japanese prototype fast breeder reactor Monju. The most recent analysis on the power reactivity loss measurement (Takano, et al., 2008) is updated considering the following findings: (a) in-core temperature distribution effect, (b) crystalline binding effect, (c) logarithmic averaging of the fuel temperature, (d) localized fuel thermal elongation effect, (e) updated Japanese Evaluated Nuclear Data Library, JENDL-4.0, and (f) refined corrections on the measured value. The influences of the updates are quantitatively identified and the most precise and probable C/E value is derived together with a thorough uncertainty evaluation. As a result, it is revealed that the analysis overestimates the measurement by 4.6% for the measurement uncertainty of 2.0%. The discrepancy is reduced to as small as 1.1% when the core bowing effect is considered, which implies the importance of the core bowing effect in the calculation of the power reactivity loss.
Usami, Shin; Kishimoto, Yasufumi; Taninaka, Hiroshi; Maeda, Shigetaka
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.3263 - 3274, 2016/05
The present paper describes the validation of the new decay heat evaluation method using FPGS90 code with both the updated nuclear data library and the rational extent of uncertainty, by comparing the results of the decay heat measurement of the spent fuel subassemblies in Joyo MK-II core and by comparing with the calculation results of ORIGEN2.2 code. The calculated values of decay heat (C) by FPGS90 based on the JENDL-4.0 library were coincident with the measured ones (E) within the calculation uncertainties, and the C/E ranged from 1.01 to 0.93. FPGS90 evaluated the decay heat almost 3% larger than ORIGEN2.2, and it improved the C/E in comparison with the ORIGEN2.2 code. Furthermore, The C/E by FPGS90 based on the JENDL-4.0 library was improved than that based on the JENDL-3.2 library, and the contribution of the revision of reaction cross section library to the improvement was dominant rather than that of the decay data and fission yield data libraries.
Taninaka, Hiroshi; Kishimoto, Yasufumi; Mori, Tetsuya; Usami, Shin
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.2610 - 2621, 2016/05
Reactivity loss due to power ascension (power reactivity loss or power coefficient of reactivity) is thus an important design parameter for determining the number of CRs and plutonium content or inventory in the SFR core design, along with the burnup reactivity loss. Measurements on these reactivity losses were therefore performed during the system startup tests in the Japanese prototype SFR Monju in 1995 and analyses have been carried out for several times. The most recent analysis on the power coefficient measurement in Monju was presented by Takano (Takano, et al., 2008). The following latest findings, which have not been taken into account in the past analyses, are available at present and may affect the existing results: (a) in-core temperature distribution effect, (b) crystalline binding effect, (c) logarithmic averaging of the fuel temperature, (d) localized fuel thermal elongation effect, (e) updated Japanese Evaluated Nuclear Data Library, JENDL-4.0, and (f) refined corrections on the measured value. The influences of refining the calculational models and measured value corrections were therefore quantitatively identified in this study by considering all of these new findings. As a result, it was revealed that the analysis overestimates the experiment by 8.1% for the total uncertainty of 5.9%. Therefore, an additional effect, that is the core bowing effect, was considered in the calculation, and the discrepancy was reduced to 2.9%. The possibility of a significant contribution from the core bowing or deformation effect was thus suggested.
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Kabumoto, Hiroshi; Takeuchi, Suehiro; Matsuda, Makoto; Iijima, Akihiko*; Yoshida, Takahiro*; Usami, Takahiro*; Hida, Tetsushi*
Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.819 - 821, 2006/00
JAEA and KEK have started acceleration of radioactive nuclear beam (RNB) and stable ion beam (SNB) from TRIAC. RNB and SNB are accelerated by SCRFQ and IH linac up to the energy of 1.1MeV/u. We were planning to re-accelerate the beams in the future by superconducting booster up to an energy of 5
8MeV/u. In order to inject the beams into superconducting booster, we need a pre-booster which is capable of acceleration from 1.1MeV/u to 2.0MeV/u. We have started development of superconducting twin quarter wave resonator (twin-QWR) in FY2004, and have fabricated a prototype twin-QWR in FY2005.
Maezawa, Hiroshi*; Furusawa, Yoshiya*; Kobayashi, Katsumi*; Hieda, Kotaro*; Suzuki, Masao*; Usami, Noriko*; Yokoya, Akinari; Mori, Tomoyuki*
Acta Oncologica, 35(7), p.889 - 894, 1997/01
Times Cited Count：7 Percentile：22.77(Oncology)no abstracts in English
Hieda, Kotaro*; Hirono, Taisuki*; Azami, Akira*; Suzuki, Masao*; ; Maesawa, Hiroshi*; Usami, Noriko*; Yokoya, Akinari; Kobayashi, Katsumi*
International Journal of Radiation Biology, 70(4), p.437 - 445, 1996/10
Times Cited Count：49 Percentile：95.39(Biology)no abstracts in English
Kuriyama, Masaaki; Aoyagi, Tetsuo; ; ; Ito, Takao; Inoue, Takashi; Usami, H*; Usui, Katsutomi; ; Oshima, Katsumi*; et al.
Nihon Genshiryoku Gakkai-Shi, 38(11), p.912 - 922, 1996/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
Konishi, Hiroyuki; Yokoya, Akinari; Shiwaku, Hideaki; Motohashi, Haruhiko; ; Kashihara, Yasuharu*; ; Harami, Taikan; Sasaki, Teikichi; Maeta, Hiroshi; et al.
Nuclear Instruments and Methods in Physics Research A, 372, p.322 - 332, 1996/00
Times Cited Count：72 Percentile：97.63(Instruments & Instrumentation)no abstracts in English
Oga, Tokumichi; ; ; ; Ito, Takao; ; Kawai, Mikito; ; Komata, Masao; Kunieda, Shunsuke; et al.
JAERI-Tech 95-044, 147 Pages, 1995/09
no abstracts in English
Nishitani, Takeo; Takeuchi, Hiroshi; Barnes, C. W.*; Iguchi, Tetsuo*; Nagashima, Akira; Kondoh, Takashi; Sakasai, Akira; Itami, Kiyoshi; Tobita, Kenji; Nagashima, Keisuke; et al.
JAERI-M 91-176, 23 Pages, 1991/10
no abstracts in English
Mizuno, Makoto; Dairaku, Masayuki; Horiike, Hiroshi; Kitamura, Shigeru; Komata, Masao; Kuriyama, Masaaki; Matsuda, Shinzaburo; Matsuoka, Mamoru; Oga, Tokumichi; Ohara, Yoshihiro; et al.
JAERI-M 88-088, 14 Pages, 1988/05
no abstracts in English
Watanabe, Kazuhiro; Dairaku, Masayuki; ; Horiike, Hiroshi; Inoue, Takashi; Kitamura, Shigeru; Komata, Masao; Kurashima, Toru*; Mizuno, Makoto; Oga, Tokumichi; et al.
JAERI-M 88-022, 26 Pages, 1988/02
no abstracts in English
森下 祐樹; 鳥居 建男; 宇佐美 博士
not registered
JP, 2019-066560 Patent licensing information Patent publication (In Japanese)
【課題】透過力の低い放射線を高感度で検知し、これによって放射性物質を検知する。 【解決手段】試料Sにおいては、平面状のろ紙Fの一方の側の表面に測定対象物質粒子Rが転写されている。第1検出部11はこの測定対象物質粒子Rが転写された表面側に密着して使用される。一方、第2検出部12は第1検出部11とは上下関係が反転された状態で試料Sの反対側の表面側に密着されて使用される。第1検出部11によって得られた第1スペクトルから第2検出部12によって得られた第2スペクトルを減算したエネルギースペクトルを算出することができる。このエネルギースペクトルにおいては、β線の影響が低減され、α線の影響が強調される。このため、このα線を発する放射性物質を高感度で検知することができる。
