Application of monitoring system using electromagnetic acoustic transducers for wall thickness measurement to Fukushima Daiichi nuclear power plant Unit 4 spent fuel pool cooling piping
高木 敏行 Toshiyuki TAKAGI 内一 哲哉 Tetsuya UCHIMOTO 浦山 良一 Ryoichi URAYAMA 鈴木 聡則 Akinori SUZUKI
EMAT monitoring system nuclear reactor cooling pipe wall thinning radiation area
In the decommissioning measures of Fukushima Daiichi Nuclear Power plant (1F), it is important to ensure the thermal stability of the reactor and the whole system by the cooling system in order to prevent criticality of fuel and fuel debris. However, wall thinning is concerned due to the corrosion in the piping of the cooling system. In order to maintain the safety of the system, it is necessary to manage the piping thinning. In this study, the EMAT thickness monitoring system, which can measure thickness change automatically by remote control, is applied to the spent fuel pool circulation cooling system piping of 1F Unit 4. Four EMAT probes are arranged with different circumferential locations of the downstream pipe of the orifice, other four probes are on the upstream, and another one is installed on the standard specimen. As a result, it was shown that EMAT system can monitor piping wall thickness change.