原子力発電給水流量計校正のための高レイノルズ数実流校正設備 : 不確かさ評価および実流校正試験(流体工学,流体機械)

概要

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Since 1990s, an uprate of the thermal output has been carried out in USA using a method of measurement uncertainty recapture called as MUR. The principle of the MUR method is based on reduction of the measurement uncertainty of the feedwater flow rate measurement using an ultrasonic flowmeter with high accuracy. Since the measurement uncertainty of thermal output can be reduced using this type of flowmeter, the thermal output can be increased within the reduced value of the uncertainty. The ultrasonic flowmeter used in a feedwater loop should be calibrated under the same condition of a nuclear power plant because of its correction factor is strongly affected by the condition of the flow field such as Reynolds number. To realize an actual flow calibration of feedwater flowmeter used at nuclear power stations at Reynolds numbers of up to 18 million, a new test facility is constructed at National Metrology Institute of Japan (NMIJ). This paper describes a calibration method and uncertainty evaluation of the new facility. As a result of evaluation, the expanded uncertainty k=2 of the facility is 0.077%. Some results of calibration of flowmeter are also presented in this paper.
2008-02-25