ヒータ付熱電対型水位計の開発

Development of heater-and-thermocouple-type water level sensor

柴田 晃 ; 三浦 邦明*; 武内 伴照   ; 大塚 紀彰 ; 中村 仁一 ; 土谷 邦彦 

Shibata, Akira; Miura, Kuniaki*; Takeuchi, Tomoaki; Otsuka, Noriaki; Nakamura, Jinichi; Tsuchiya, Kunihiko

東京電力福島第一原子力発電所の事故においては、全電源喪失により、原子炉圧力容器内水位及び使用済燃料プールの水位が測定できなくなり、事故対策及び事故後の状況の把握に大きな困難をもたらした。このため、全電源喪失時にも、小電力で作動可能な信頼性の高い水位計の開発を行った。既存の水位計を調査し、小電力作動する信頼性の高い水位計の設計と試作を行った。また、試作した水位計を用いて、性能評価試験を行い、常温から95Cの水温範囲において20mmの精度で水位を測定できることを確認した。この結果、新型水位計を使用済燃料プールや過酷事象時の原子炉圧力容器の水位計として使用する見通しを得た。

In the Fukushima-Daiichi Nuclear Power Plant Accident, the measurements of water level in pressure vessel and spent fuel pool were impossible due to station blackout, and it resulted in difficulty for countermeasures against the accidents and for understanding of the situations of reactor core after accidents. Therefore, we started to develop a new water level sensor for l with high reliability, which works with small electric power. This report describes reviews of conventional water level sensor and design and production of new water level sensor. After production of the sensor, performance tests were performed between room temperature and about 95 C, and the it was confirmed that the sensor is able to measure water level with the accuracy of 20 mm. As the results, a perspective to use the new water level sensor as water level indicator for spent fuel pools and reactor vessels after severe accident.