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Kurata, Masaki; Okuzumi, Naoaki*; Nakayoshi, Akira; Ikeuchi, Hirotomo; Koyama, Shinichi
Journal of Nuclear Science and Technology, 59(7), p.807 - 834, 2022/07
Times Cited Count：11 Percentile：96.15(Nuclear Science & Technology)Immediately after the 1F-accident, various attempts have been made to evaluate the fuel debris characteristics toward the decommissioning of 1F. The present review outlines those attempts. In the years immediately following the 1F-accident, the knowledge obtained from the 1F-site (especially from the damaged reactors of Units 1, 2 and 3) was extremely limited. The approximate location of fuel debris was investigated by muon tomography, and its characteristics were roughly estimated based on the past findings such as the results of the Three Mile Island-II accident investigation in the United States, which gave us information of prototypical accident scenarios and debris characteristics for pressurized water reactor accident. After that, various internal investigation robots were developed, and from 2017, investigation of the inside of the reactor containment vessel was started using these robots. Consequently, these three units were found to have core damage status and debris distribution that were rather different from what had been expected based on the typical accident scenario of a pressurized water reactor. In parallel, a small amount of U-bearing particle was recovered from the smear samples of these robots. The analysis of these particles is ongoing to get information relevant to fuel debrsi body. Furthermore, international collaboration is ongoing mainly under OECD/NEA, including accident analysis and debris characterization. From now on, one need to further understand 1F-accident scenario and progress debris characterization based on these 1F-site information.
Ando, M.*; Hirano, Masashi
Nihon Genshiryoku Gakkai-Shi, 44(2), p.162 - 172, 2002/00
no abstracts in English
Watanabe, Norio; *; Muramatsu, Ken
2nd Int. Conf. on Containment Design and Operation,Conf. Proc., Vol. l, 14 Pages, 1990/00
no abstracts in English
Maruyama, Yu; Abe, Yutaka; *; Soda, Kunihisa
JAERI-M 89-054, 142 Pages, 1989/05
no abstracts in English
Washiya, Tadahiro; Kurata, Masaki; Ashida, Takashi; Torii, Tatsuo
no journal, ,
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS) carried out several international cooperation to gather the knowledge and expertise on decommissioning and accident management. The cooperation fields are radioactive waste management in the decommissioning, characterization of fuel debris, investigation on core degradation process and remote monitoring technology etc.. In this presentation current activities and results on the international cooperation will be reported.
Chiyatani, Keiji
no journal, ,
Japan Atomic Energy Agency (JAEA) established Collaborative Laboratories for Advanced Decommissioning Science (CLADS) in 2015. The main roles of JAEA/CLADS are to promote research and development (R&D) and human resource development towards the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F) of Tokyo Electric Power Company Holdings through collaborative efforts with academia-industry- government. Current R&D activities on risk reduction in decommissioning, accident progression evaluation and fuel debris characterization, remote system and sensing technology, and radioactive waste management for the decommissioning of the 1F are introduced.
Yamaji, Akifumi*; Furuya, Masahiro*; Oishi, Yuji*; Sato, Ikken; Li, X.*; Fukai, Hirofumi*; Madokoro, Hiroshi
no journal, ,
no abstracts in English
Li, X.; Yamaji, Akifumi*; Sato, Ikken*; Yamashita, Takuya
no journal, ,
This study presents a numerical evaluation of possible core material discharge behavior from the RPV lower head region including the penetrations (Control Rod Drive (CRD) Housing) in 1F Unit-2 with Lagrangian-based MPS method. Two-dimensional geometry is established to model CRD housing with simplified inner structures inthe center of RPV, with surrounding RPV walls and RPV insulation below. The initial temperature distribution/boundary conditions referenced the results from accident progression and global RPV CFD analysis (Series presentations (2), (5), and (7)). The results show that local CRD housing melting assumed at 15%Zr-85%Fe eutectic temperature (1523 K) before global RPV failure could result in melt discharge into the pedestal, which is consistent with the accident progression analysis and plant internal investigation results.
