抄録
In liquid metal cooled fast breeder reactors, electromagnetic-flowmeters (EMFs) have been extensively used. To calibrate any performance degradation, it is desired to develop an appropriate method without taking the EMF out of the system. A correlation method is applied for calibration in in-service conditions. The flow rate is obtainable from the propagation velocity of the voltage fluctuation. However, the propagation velocity of the fluctua tion is larger than the mean flow velocity.
In this paper, the relationship between the flow velocity distribution and the fluctuation frequency is considered and a method of correcting the propagation velocity is proposed based on fluid mechanics. In the case of the 12 in. diameter EMF in "JOYO" reactor, the fluctuation propagates with the average velocity in the region from the pipe center to 0.79 times the inner radius. Then the calculated correction factor which transforms the propagation velocity of the fluctuation to the mean flow velocity is 0.937 and fairly agreed with the measured data. The calibration error of the correlation method does not exceed ±2%. The accuracy of 2% is comparable with that of the calibration by real flow in test loop.
