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Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Fujita, Natsuko; Yokoyama, Tatsunori; Ogita, Yasuhiro; Fukuda, Shoma; Nakajima, Toru; Kagami, Saya; Ogata, Manabu; et al.
JAEA-Review 2023-017, 27 Pages, 2023/10
JAEA-Review-2023-017.pdf:0.94MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2023. The objectives and contents in fiscal year 2023 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
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：0 Percentile：0.01(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.
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, p.9_1 - 9_10, 2019/01
Times Cited Count：7 Percentile：39.29(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.
Onoue, Ryuji; Kawamata, Takanori; Otsuka, Kaoru; Sekine, Katsunori; Koike, Sumio; Gorai, Shigeru; Nishiyama, Yutaka; Fukasaku, Akitomi
JAEA-Review 2012-010, 116 Pages, 2012/03
JAEA-Review-2012-010-01.pdf:65.41MBJAEA-Review-2012-010-02.pdf:81.33MBJAEA-Review-2012-010-03.pdf:87.98MBJAEA-Review-2012-010-04.pdf:45.25MB
JMTR is a light water moderated and cooled tank-type reactor, and its thermal power is 50 MW. The JMTR is categorized as high flux testing reactors in the world. The JMTR has been utilized for irradiation experiments of nuclear fuels and materials, as well as for radioisotope productions since the first criticality in March 1968 until August 2006. JAEA is decided to refurbish the JMTR as an important fundamental infrastructure to promote the nuclear research and development. And The JMTR refurbishment work is carried out for 4 years from 2007. Before refurbishment work, from August 2006 to March 2007, all concerned renewal facilities were selected from evaluation on their damage and wear in terms of aging. Facilities which replacement parts are no longer manufactured or not likely to be manufactured continuously in near future, are selected as renewal ones. Replace priority was decided with special attention to safety concerns. A monitoring of aging condition by the regular maintenance activity is an important factor in selection of continuous using after the restart. In this report, renewal of the cooling system within refurbishment facilities in the JMTR is summarized.
Onoue, Ryuji; Kawamata, Takanori; Otsuka, Kaoru; Koike, Sumio; Nishiyama, Yutaka; Fukasaku, Akitomi
JAEA-Review 2011-018, 17 Pages, 2011/06
JAEA-Review-2011-018.pdf:2.71MB
JMTR is a light water moderated and cooled tank-type reactor, and its thermal power is 50 MW. The JMTR is categorized as high flux testing reactors in the world. The JMTR has been utilized for irradiation experiments of nuclear fuels and materials, as well as for radioisotope productions since the first criticality in March 1968 until August 2006. JAEA decided to refurbish the JMTR as an important fundamental infrastructure to promote the nuclear research and development. The refurbishment work was started from 2007, and restart is planned in 2011. Renewal facilities were selected from evaluation on their damage and wear in terms of aging. Facilities whose replacement parts are no longer manufactured or not likely to be manufactured continuously in near future, are selected as renewal ones. Replacement priority was decided with special attention to safety concerns. A monitoring of aging condition by the regular maintenance activity is an important factor in selection of continuous using after the restart. In this report, renewal of the cooling system within refurbishment facilities in the JMTR is summarized.
Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.
JAEA-Technology 2009-030, 165 Pages, 2009/07
JAEA-Technology-2009-030.pdf:69.18MB
The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.
Kawamata, Takanori; Otsuka, Kaoru; Sekine, Katsunori; Onoue, Ryuji; Koike, Sumio; Nishiyama, Yutaka
no journal, ,
no abstracts in English
Sr/
Sr ratios inside the Toki granite, Central Japan; Implication for the intrusion and cooling process of a granitic plutonYuguchi, Takashi; Tsuruta, Tadahiko; Kunimaru, Takanori; Nishiyama, Tadao*
no journal, ,
no abstracts in English
Yuguchi, Takashi; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*; Sueoka, Shigeru; Hattori, Kentaro*; Sakata, Shuhei*; Ishibashi, Masayuki; Kunimaru, Takanori; Nishiyama, Tadao*
no journal, ,
no abstracts in English
Yuguchi, Takashi; Iwano, Hideki*; Hattori, Kentaro*; Sakata, Shuhei*; Sueoka, Shigeru; Danhara, Toru*; Hirata, Takafumi*; Ishibashi, Masayuki; Kunimaru, Takanori; Nishiyama, Tadao*
no journal, ,
no abstracts in English
