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Kawahara, Takahiro; Suda, Shoya; Fujikura, Toshiki; Masai, Seita; Omori, Kanako; Mori, Masakazu; Kurosawa, Tsuyoshi; Ishihara, Keisuke; Hoshi, Akiko; Yokobori, Tomohiko
JAEA-Technology 2023-020, 36 Pages, 2023/12
JAEA-Technology-2023-020.pdf:2.79MB
We have been storing drums containing radioactive waste (radioactive waste packages) at waste storage facilities. We have been managing radioactive waste packages along traditional safety regulations. However, over 40 years has passed from a part of them were brought in pit-type waste storage facility L. Most of them are carbon steel 200 L drums, and surface of them are corroded. For better safety management, we started to take drums out from the pit and inspect them in FY 2019. After each inspection, we repair them or remove the contents of the drum and refill new drums if necessary. In this report, we will introduce the planning, the review of the plan, and the trial operation of this project.
Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：1 Percentile：22.72(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Tsuchimochi, Akari; Suda, Shoya; Fujikura, Toshiki; Kawahara, Takahiro; Hoshi, Akiko
JAEA-Technology 2021-018, 37 Pages, 2021/10
JAEA-Technology-2021-018.pdf:2.87MB
A large amount of radioactive waste has been generated in the process of research and development in Nuclear Science Research Institute. We store the equivalent of 130,604 drums (200L) of that in our storage facilities (as of March 31, 2021) and have been developing "Radioactive Waste Information Management System" to manage them for disposal. The system started designing in FY2007 and has been in operation since FY2012. After the start of operation, it has been repaired as appropriate. In this report, we summarized the development and improvement of the system.
Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.
Earth, Planets and Space (Internet), 71(1), p.9_1 - 9_10, 2019/12
Times Cited Count：8 Percentile：40.25(Geosciences, Multidisciplinary)Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of 
10 keV.
Riyana, E. S.*; Suda, Shoya*; Ishibashi, Kenji*; Matsuura, Hideaki*; Katakura, Junichi*; Sun, G. M.*; Katano, Yoshiaki
Journal of Nuclear Science and Technology, 56(5), p.369 - 375, 2019/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectra from various reactors such as typical PWR reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta decay.
Suda, Shoya*; Ishibashi, Kenji*; Lee, E.*; Shigyo, Nobuhiro*; Ikeda, Nobuo*; Sun, G. M.*; Han, B.-Y.*; Takada, Hiroshi; Harada, Masahide
no journal, ,
Our group has experience to carry out the experiment with small electrochemical devices at heavy-water-moderated Advanced Thermal Reactor (ATR, FUGEN), and observed a clear signal increase near the reactor core. The present study is aiming at demonstrating the response of the electrochemical device to tritium amount. The experiments were performed at (1) Pressurized right Water Reactor (PWR, tritium amount of 30 g and a great quantity of beta emitters) at a distance of 26 m from the core, and (2) Tritium Process Laboratory of Japan Atomic Energy Agency (TPL, tritium amount ~10 g) at a position of 8.6 m from the source. Signal increase was observed in both measurements. Analysis made clear that the detector signal is ascribed to the amount of low-energy beta emitters of plutonium 241 and tritium in the PWR experiment while it is attributed to the quantity of tritium in the TPL measurement.
Ishibashi, Kenji*; Suda, Shoya; Takada, Hiroshi; Harada, Masahide
no journal, ,
no abstracts in English
Md produced in the 
He+
Es reactionNishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi*; Sato, Tetsuya; Ito, Yuta; et al.
no journal, ,
no abstracts in English
Suda, Shoya; Masai, Seita; Kawahara, Takahiro; Fujikura, Toshiki; Hoshi, Akiko; Wakai, Eiichi; Kondo, Keietsu; Nishimura, Akihiko; Minehara, Eisuke*
no journal, ,
no abstracts in English
Suda, Shoya; Kosuge, Atsushi; Kisohara, Naoyuki; Fujii, Mitsuki; Masai, Seita; Iseda, Hirokatsu; Minehara, Eisuke*
no journal, ,
