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Dechenaux, B.*; Brovchenko, M.*; Araki, Shohei; Gunji, Satoshi; Suyama, Kenya
Annals of Nuclear Energy, 223, p.111555_1 - 111555_11, 2025/12
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Ishii, Junichi; Seki, Masakazu; Aizawa, Eiju; Sumiya, Masato; Maekawa, Tomoyuki; Arakaki, Yu; Hasegawa, Kenta; Araki, Shohei; Izawa, Kazuhiko; Gunji, Satoshi
Proceedings of Nuclear Criticality Safety Division 2025 Conference (NCSD 2025) (Internet), p.39 - 48, 2025/09
The removal of fuel debris is one of the most important and challenging tasks in the decommissioning of power reactors damaged in the 2011 accident at Fukushima Daiichi Nuclear Power Plant (1F). The Japan Atomic Energy Agency (JAEA) has implemented a renewal program of the Static Experiment Critical Facility (STACY), transitioning it from a homogeneous solution system to a heterogeneous water-moderated system, in order to verify the criticality calculations that consider the fuel debris from the 1F accident. The first criticality of the modified STACY was achieved in April 2024. After a series of performance inspections, an experimental campaign for the investigation of fuel debris characteristics was started in August 2024. In this paper, we describe the main equipment of the modified STACY. In addition, the experimental equipment for the debris-simulated core configuration is also introduced.
Maekawa, Tomoyuki; Seki, Masakazu; Sumiya, Masato; Araki, Shohei; Murakami, Takahiko; Hasegawa, Kenta; Yoshikawa, Tomoki; Mori, Takashi*; Ishii, Junichi; Kobayashi, Fuyumi; et al.
no journal, ,
As previously reported, to clarify critical characteristics of fuel debris, the Static Experiment Critical Facility (STACY) is being converted to the heterogenous thermal system using fuel rods and light water moderator from the homogenous system using solution fuel. Seismic reinforcement of the support structure of the core tank started in 2022. This report presents progress on manufacture and construction of the modified STACY in 2021 and 2022.
Arakaki, Yu; Izawa, Kazuhiko; Gunji, Satoshi; Araki, Shohei; Suyama, Kenya
no journal, ,
JAEA has been modifying the Static Experiment Critical Facility (STACY) to experimentally study on the criticality characteristics of fuel debris. Although arbitrary detectors or activation samples can be placed in the core of STACY, they must be contained in sheath tubes (insertion tubes) that have been approved by the regulatory authorities. This report presents the status of the design study of the insertion tube for the experiments in the modified STACY.
Yoshikawa, Tomoki; Araki, Shohei; Arakaki, Yu; Izawa, Kazuhiko; Gunji, Satoshi; Suyama, Kenya
no journal, ,
In order to clarify the criticality characteristics of fuel debris, we plan experiments in the Static Experiment Critical Facility (STACY) by using concrete and steel simulating the structural materials of the core of the Fukushima Daiichi Nuclear Power Plant. In order to carry out the experiments, it is necessary to obtain a construction permit for the core with the debris structural material simulant mentioned above. In this presentation, we present the analysis results and the feasible core configuration for obtaining the certification from the regulatory body.
