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Oto, Tsutomu; Asano, Norikazu; Kawamata, Takanori; Yanai, Tomohiro; Nishimura, Arashi; Araki, Daisuke; Otsuka, Kaoru; Takabe, Yugo; Otsuka, Noriaki; Kojima, Keidai; et al.
JAEA-Review 2020-018, 66 Pages, 2020/11
JAEA-Review-2020-018.pdf:8.87MB
A collapse event of the cooling tower of secondary cooling system in the JMTR (Japan Materials Testing Reactor) was caused by the strong wind of Typhoon No.15 on September 9, 2019. The cause of the collapse of the cooling tower was investigated and analyzed. As the result, it was identified that four causes occurred in combination. Thus, the soundness of the cooling tower of Utility Cooling Loop (UCL cooling tower), which is a wooden cooling tower installed at the same period as the cooling tower of secondary cooling system, was investigated. The items of soundness survey are to grasp the operation conditions of the UCL cooling tower, to confirm the degradation of structural materials, the inspection items and inspection status of the UCL cooling tower, and to investigate the past meteorological data. As the results of soundness survey of the UCL cooling tower, the improvement of inspection items of the UCL cooling tower was carried out and the replacement and repair of the structural materials of the UCL cooling tower were planned for safe maintenance and management of this facility. And the renewal plan of new cooling tower was created to replace the existing UCL cooling tower. This report is summarized the soundness survey of the UCL cooling tower.
Ono, Masato; Iigaki, Kazuhiko; Sawahata, Hiroaki; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Kondo, Toshinari; Kojima, Keidai; Takada, Shoji; Sawa, Kazuhiro
Journal of Nuclear Engineering and Radiation Science, 4(2), p.020906_1 - 020906_8, 2018/04
On March 11th, 2011, the 2011 off the Pacific coast of Tohoku Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the High Temperature Engineering Test Reactor (HTTR) had been stopped under the periodic inspection and maintenance of equipment and instruments. A comprehensive integrity evaluation was carried out for the HTTR facility because the maximum seismic acceleration observed at the HTTR exceeded the maximum value of design basis earthquake. The concept of comprehensive integrity evaluation is divided into two parts. One is the "visual inspection of equipment and instruments". The other is the "seismic response analysis" for the building structure, equipment and instruments using the observed earthquake. All equipment and instruments related to operation were inspected in the basic inspection. The integrity of the facilities was confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the results of inspection of equipment and instruments associated with the seismic response analysis, it was judged that there was no problem for operation of the reactor, because there was no damage and performance deterioration. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015. Additionally, the integrity of control rod guide blocks was also confirmed visually when three control rod guide blocks and six replaceable reflector blocks were taken out from reactor core in order to change neutron startup sources in 2015.
Ono, Masato; Iigaki, Kazuhiko; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Hamamoto, Shimpei; Nishihara, Tetsuo; Takada, Shoji; Sawa, Kazuhiro; et al.
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 12 Pages, 2016/06
On March 11th, 2011, the Great East Japan Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the HTTR had been stopped under the periodic inspection and maintenance of equipment and instrument. In the great earthquake, the maximum seismic acceleration observed at the HTTR exceeded the maximum value in seismic design. The visual inspection of HTTR facility was carried out for the seismic integrity conformation of HTTR. The seismic analysis was also carried out using the observed earthquake motion at HTTR site to confirm the integrity of HTTR. The concept of comprehensive integrity evaluation for the HTTR facility is divided into two parts. One is the inspection of equipment and instrument. The other is the seismic response analysis using the observed earthquake. For the basic inspections of equipment and instrument were performed for all them related to the operation of reactor. The integrity of the facilities is confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the result of inspection of equipment and instrument and seismic response analysis, it was judged that there was no problem to operate the reactor, because there was no damage and performance deterioration, which affects the reactor operation. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015.
Hashimura, Hirohiko; Uryu, Mitsuru; Yamazaki, Toshihiko; Nakanishi, Ryuji; Kirita, Fumio; Kojima, Keidai
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Kirita, Fumio; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kojima, Keidai
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Kojima, Keidai; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kirita, Fumio
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Nakanishi, Ryuji; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Kirita, Fumio; Kojima, Keidai
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Uryu, Mitsuru; Kirita, Fumio; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kojima, Keidai
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Kirita, Fumio; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kojima, Keidai
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Kojima, Kazuki; Kojima, Keidai; Fujita, Masateru; Hashimura, Hirohiko; Takaji, Kazuhiko*; Maenaka, Toshinobu*
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Nitta, Yoshiaki*; Kojima, Keidai; Sashima, Yuta*; Sanada, Yasushi*
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Yamazaki, Toshihiko; Nakanishi, Ryuji; Kirita, Fumio; Kojima, Keidai; Takahashi, Rei
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Kojima, Keidai; Sanada, Yasushi*
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Kirita, Fumio; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kojima, Keidai
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Nakanishi, Ryuji; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Kirita, Fumio; Kojima, Keidai
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Hashimura, Hirohiko; Uryu, Mitsuru; Yamazaki, Toshihiko; Nakanishi, Ryuji; Kirita, Fumio; Kojima, Keidai
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Kitazawa, Yuki; Yamazaki, Toshihiko; Nakanishi, Ryuji; Kojima, Keidai
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