This Letter presents an ultrasonic waveguide sensor for measuring fluctuations in a liquid level using leaky longitudinal wave L(0,2) in a coolant loop system. A 20% cold-worked D9 fuel pin clad tube of 1000 mm long, 6.6 mm outer diameter and 0.45 mm wall thickness was used as a waveguide on which the L(0,2) mode was transmitted/received along the axial direction at 500 kHz. When the waveguide got introduced into a coolant loop and partially immersed in a non-viscous liquid (water/liquid sodium), the amplitude of L(0,2) mode got reduced due to leakage. The rate of leakage depends on the characteristics of the waveguide and the embedding liquid medium. By utilising this physical property of L(0,2) mode, it is possible to predict the variations in liquid level during dynamic conditions. Experimental measurements were carried out on a mock-up test loop in which water was used as embedding liquid and two artificial notches were made on the waveguide at different depths were used as reference levels. The time-amplitude signals were monitored and the reflected energies from the bottom end of the waveguide and the notches were used as the threshold and reference amplitudes respectively for identification of water level.

中文翻译：

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用于回路系统液位测量的超声波波导传感器的开发

这封信提出了一种超声波波导传感器，用于使用冷却剂回路系统中的泄漏纵波L（0,2）测量液位波动。使用长度为1000毫米，外径为6.6毫米，壁厚为0.45毫米的20％冷加工D9燃料针复合管作为波导，在500℃沿轴向方向发射/接收L（0,2）模式。千赫。当将波导引入冷却剂回路中并部分浸入非粘性液体（水/液体钠）中时，由于泄漏，L（0,2）模式的振幅会减小。泄漏率取决于波导和嵌入液体介质的特性。通过利用L（0,2）模式的这种物理特性，可以预测动态条件下液位的变化。实验测量是在一个模拟测试回路上进行的，其中将水用作包埋液，并在波导上制作了两个不同深度的人工缺口作为参考水平。监视时间振幅信号，并将来自波导底端和槽口的反射能量分别用作阈值和参考振幅，以识别水位。