Development of Ultrasonic Flow Meter for Liquid Lead-Bismuth Flow

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平林 勝; 近藤 正聡*; 荒 邦章 ; 高橋 実*

Hirabayashi, Masaru; Kondo, Masatoshi*; Ara, Kuniaki; Takahashi, Minoru*

Pb-Bi冷却炉用の超音波流量計を開発している。計測原理には伝搬時間差法を適用し、計測に必要な音響物性として、温度に対するPb-Biの音速を計測した。また、温度に対する音速の実験相関式を導出した。超音波流量計の開発、試作を行った。超音波センサの振動子にはニオブ酸リチウムを使用し、500Cまでの耐熱性を確認した。水中、Pb-Bi中試験を実施し、流量計の適用性を実証した。

In Pb-Bi Cooled Direct Contact Boiling Water Small Fast Reactor, PBWFR, a development of a primary loop flow meter is required. Since an electromagnetic flow meter is not better suited to an annular channel geometry such as the primary loop of PBWFR, an ultrasonic flow meter to measure the velocity of Pb-Bi has been developed.An ultrasonic transit-time method is applied to the flow velocity measurement. To evaluate the flow velocity in this method, the sound velocity in Pb-Bi is required. Therefore the sound velocity in Pb-Bi was measured at the temperature range from 187 to 407C and the experimental correlation equation of the sound velocity was derived. An ultrasonic flow meter which consisted of the high-temperature sensors and the signal processor was developed and manufactured on trial. The piezoelectric element of the sensor was lithium niobate. The sensor was heated up to 500C and the heat resistance was confirmed. The shoe, i.e. the material wetted by Pb-Bi, of the sensor was made from high-chrome steel. The in-water and the in-Pb-Bi tests were performed and the applicability of the ultrasonic flow meter was verified.