The Graduation Characteristic Research For Sodium Level Gauge

The coolant to be used in China Experimental Fast Reactor (CEFR) to transfer heat away from the nuclear core is liquid sodium. It is necessary to know the level of liquid sodium accurately in the reactor vessel and many associated tanks to assure proper operation. The methods of measurement of liquid sodium level are summarized and researched in this paper. The characteristic of various methods, such as the float type level gauge, the ultrasonic level gauge, the contact type sodium level gauge, the resistance-tube type sodium level gauge, the inductance type single point sodium level gauge, the measurement system of mutual inductance type that follows sodium level, the discrete inductance type sodium level gauge, and the mutual inductance type sodium level gauge, are summarized. Their operation principle, graduation characteristic, merits and demerits when they are used to measure the sodium level in CEFR are introduced emphatically. The mutual inductance type sodium level sensor, which has been developed with the participation of author, and its graduation characteristic are described emphatically. The component construction and their performances of the intelligent type sodium level gauge and its graduation calibration facility are presented. They can be operated in the temperature limit 100~550C. Its graduation characteristic calibration test is described. The temperature effect is analyzed. The graduation characteristic equation using the medium temperature as the parameter is given. The calibration errors are analyzed. The measurement system using this sodium level gauge is presented. The tests show that the intelligent type sodium level gauge possesses good linearity. The accurate sodium level measurement data can be obtained by means of its on-line compensation function of the temperature effect. Moreover, it possesses the self-inspection, the electric shutoff protection, the setting of full-scale, the thermocouple breaking alarm, the two upper limits and two lower limits alarms, the standard analog output signal and the digital output signal. Therefore, it is applicable particularly to the instrument measure systems of LMFBR. Thebasic error of this intelligent type sodium level gauge is 1.9% of measuring range. It has been presented that the sodium level with great measuring range can be measured by superimposing transducers. Moreover calibration test of level gauge on active service can be carried out by means of the inductance type single point sodium level sensor.