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Kitayama, Ayami; Taniguchi, Naoki; Mitsui, Seiichiro
Materials and Corrosion, 72(1-2), p.211 - 217, 2021/01
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.
JAEA-Research 2019-013, 276 Pages, 2020/03
JAEA-Research-2019-013.pdf:18.72MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.
Takiya, Hiroaki; Ishiyama, Masahiro; Tezuka, Masashi; Kitayama, Naoki
Proceedings of International Conference on Dismantling Challenges; Industrial Reality, Prospects and Feedback Experience (DEM 2018) (Internet), 8 Pages, 2018/10
In FUGEN, we had isolated the reactor core by cutting pipes of the periphery systems (e.g. reactor cooling system, heavy water system, and helium system) between 2015 and 2017, as preparation for dismantling the reactor core and taking some samples from the reactor core structures. There are three issues to be solved at this isolation work; (1) to shorten the working time at high radiation area which is 1-5mSv/h at air and 10mSv/h at contact, (2) to prevent tritium spreading to working area at cutting work because tritium air is existing with 20-30Bq/cm
inside of the heavy water system and helium system, and (3) to minimize the influence of contaminated fume for the accurate radioactivity evaluation of reactor core structure. In this study, considering these problems, we discussed the method for cutting the pipes of heavy water system and helium system at the high radiation area and carried out the pipe cutting in the way.
Suzuki, Satoru; Fujishima, Atsushi; Ueno, Kenichi; Ichikawa, Yasuaki*; Kawamura, Katsuyuki*; Fujii, Naoki*; Shibata, Masahiro; Sato, Haruo; Kitayama, Kazumi*
Nendo Kagaku, 41(2), p.43 - 57, 2001/12
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Kitayama, Ayami; Taniguchi, Naoki; Mitsui, Seiichiro
no journal, ,
no abstracts in English
Tsuchida, Daisuke; Hayashi, Hirokazu; Kitayama, Naoki; Mori, Naoto
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no abstracts in English
Kitayama, Ayami; Taniguchi, Naoki; Kimura, Wataru*; Kajiyama, Hiroshi*
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no abstracts in English
Suzuki, Hiroyuki*; Kitayama, Ayami; Mitsui, Seiichiro; Taniguchi, Naoki
no journal, ,
The environmental conditions around carbon steel overpacks in geological disposal are expected to be diverse cases depending on geological environment of the repository and may also vary depending on changes in conditions after repository closure. In this study, with the aim of understanding corrosion behavior under such environmental conditions, immersion tests with different conditions were conducted in bentonite/silica sando mixture assuming a buffer material to be constructed around the overpack under a wide range of conditions, including temperature and water quality beyond the assumed range of conventional environmental conditions, and the effects on corrosion behavior were evaluated.
Taniguchi, Naoki; Kitayama, Ayami; Kawasaki, Manabu*; Nakayama, Masashi; Ono, Hirokazu; Mitsui, Seiichiro; Suzuki, Hiroyuki*
no journal, ,
no abstracts in English
Watari, Shingo*; Kitayama, Ayami; Mitsui, Seiichiro; Taniguchi, Naoki; Kimura, Wataru*; Kajiyama, Hiroshi*
no journal, ,
The application of pure copper is being considered for the purpose of extending the life-time of disposal canisters in the direct disposal of spent fuel. Pure copper generally shows little corrosion development in aqueous solution environments with low oxygen concentrations due to its thermodynamic stability, but pure copper loses thermodynamic stability and corrosion develops depending on the sulfides conditions. In this study, immersion tests and U-bend tests were conducted to understand the corrosion progress behavior and stress corrosion cracking behavior of pure copper under the condition of sparging gas with various hydrogen sulfide concentrations to simulate the disposal environment where sulfide exists.
