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Takiya, Hiroaki; Kadowaki, Haruhiko; Matsushima, Akira; Matsuo, Hidehiko; Ishiyama, Masahiro; Aratani, Kenta; Tezuka, Masashi
JAEA-Technology 2020-001, 76 Pages, 2020/05
JAEA-Technology-2020-001.pdf:6.06MB
Advanced Thermal Reactor (ATR) FUGEN was operated for about 25 years, and now has been proceeding decommissioning after the approval of the decommissioning plan in Feb. 2008. The reactor, heavy water system and helium system are contaminated by tritium because of neutron absorption of heavy water, which is a moderator. Before dismantling these facilities, it is necessary to remove tritium from them for not only reducing the amount of tritium released to surrounding environment and the risk of internal exposure by tritium but also ensuring the workability. In first phase of decommissioning (Heavy Water and Other system Decontamination Period), tritium decontamination of the reactor, heavy water system and helium system started in 2008 and completed in 2018. This report shows the results of tritium decontamination of the reactor, heavy water system and helium system.
Machida, Akihiko; Saito, Hiroyuki; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.
Nature Communications (Internet), 5, p.5063_1 - 5063_6, 2014/09
Times Cited Count：55 Percentile：86.02(Multidisciplinary Sciences)Iron hydride FeH
, is thermodynamically stable only at high hydrogen pressure of several GPa. To investigate the hydrogenation process and hydrogen state in iron hydride, it is necessary to carry out the in-situ measurement under high pressure and high temperature. In this study, we performed the in-situ neutron diffraction measurement of Fe-D system using the high pressure neutron diffractometer PLANET in the MLF, J-PARC, and determined the deuterium occupying sites and occupancies in fcc-FeD. We found the minor occupation of tetrahedral sites under high pressure and high temperature. We considered the mechanism of the minor occupation based on the Quantum-mechanical calculation.
Kitamura, Koichi; Sano, Kazuya; Nakamura, Yasuyuki; Matsushima, Akira; Matsuo, Hidehiko; Ishiyama, Masahiro; Haneda, Takahiro; Tezuka, Masashi
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The decommissioning program of proto-type Advanced Thermal Reactor (ATR) FUGEN has started in 2008 as first decommissioning of the commercial-scale water reactor. It consists of four periods, considering the transportation of spent fuels and the radioactive decrease of highly activated materials. It is expected that the whole program of decommissioning will be completed until 2028.Now, the decommissioning is under the first period, spent fuels and heavy water has been carrying out from FUGEN, and a part of the turbine system with relatively low radioactive contamination has been dismantled. FUGEN has a complicated core structure consisting 224 fuel channels with pressure tubes and calandria tank, etc. and used heavy water as moderator, unlike other light water reactor. So, the dismantling technology of the reactor core and the decontamination technology of tritium in heavy water system, etc. have been studying in order to dismantle them safely. In this presentation, the contents of the decommissioning program and its current status, the studying situation of dismantling technology of reactor core using Abrasive Water Jet (AWJ) which is a candidate of cutting technologies, the examination of tritium decontamination in heavy water system, the study for C-14 penetrated into concrete structure will be presented mainly.
Katano, Yoshiaki; Matsuo, Hidehiko
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Matsushima, Akira; Ishiyama, Masahiro; Matsuo, Hidehiko; Sato, Yuji
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Kadowaki, Haruhiko; Matsuo, Hidehiko; Yamane, Naoki; Matsushima, Akira
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Ando, Koji; Kadowaki, Haruhiko; Matsuo, Hidehiko; Yamane, Naoki; Matsushima, Akira
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Kadowaki, Haruhiko; Matsuo, Hidehiko; Yamane, Naoki; Asakura, Yamato*; Matsushima, Akira
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Miyoshi, Nobuaki; Kadowaki, Haruhiko; Matsuo, Hidehiko; Matsushima, Akira
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Matsuo, Hidehiko; Iwai, Masaki
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Iwai, Hiroki; Nakamura, Yasuyuki; Matsuo, Hidehiko; Mizui, Hiroyuki; Sano, Kazuya
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Matsuo, Kimihiko*; Ishitobi, Tatsuhiko*; Oka, Hiroshi*; Iwai, Hiroki; Matsuo, Hidehiko; Nakamura, Yasuyuki; Sano, Kazuya
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Hayashi, Kenta; Ito, Kenji; Matsuo, Hidehiko; Sakai, Yasuhiro
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Yamamoto, Takashi; Matsuo, Hidehiko; Miyashita, Shinichi
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Fugen is a heavy water-moderated, boiling light water-cooled, pressure tube-type reactor with the electrical power of 165 MW. It had been operated for 25 years from March 1979 to March 2003. After ceasing its operation, decommissioning project started 2008. Currently, FUGEN is the second phase of decommissioning (Reactor Periphery Facilities Dismantling Period). Fugen in decommissioning has the risk decreased than in operation. Therefore, it have been rationalizing maintenance continuously. At the paper, report on the rationalization and improvements of the maintenance in decommissioning. After ceasing the operation, all of the spent fuels were removed from reactor to the spent fuel pool. And now, the spent fuels has low heat generation and it is not necessary to remove the heat. Therefore, we are continuing to rationalize the maintenance plan depending on the situation of decommissioning.
