Uncertainty Examination of New Water Flow Calibration Facility for Nuclear Power Application

A new test facility has been constructed at National Metrology Institute of Japan (NMIJ) for calibration of feed water flowmeters at nuclear power stations for Reynolds numbers of up to 16 million. This very large Reynolds number is achieved at a flow rate of 3.33 m³/s (12,000 m³/h) and water temperature of 70 degrees C in a 600 mm pipe. This new facility has four sets of pumps and reference flowmeters installed in parallel upstream of the test section. These flowmeters are calibrated at 0.83 m³/s (3,000 m³/h) one by one without dismounting from the loop by using a 50 t weighing tank; this tank has been used as the primary standard for the existing flow facility. Then the flow rate can be increased up to 3.33 m³/s (12,000 m³/h) with all of the pumps and flowmeters working at the same time. This paper describes the concept of the new facility, the fundamental uncertainty estimation, and the examination of its measurement capability.