Qualification measurement techniques for flow quantities in heavy liquid metals

For the transmutation of radioactive waste. Accelerator driven systems (ADS) are under investigation in European research projects. One of the explored concepts utilizes the heavy liquid metals (HLM) lead or lead-bismuth as coolant for such a system. The thermohydraulic design as well as the future operation demands measurement techniques to acquire relevant flow quantities within HLM flows. Because of the differences of HLM compared to sodium regarding the physical and chemical properties, the knowledge from the previously developed technology can not generally be transferred. Thus, a systematic investigation of different physical principles for the measurement of flow rate and local velocity fields were performed in the Karlsruhe Lead Laboratory (KALLA) of the Forschungszentrum Karlsruhe. Volumetric, magnetic inductive and ultrasound transit time methods for the flow rate measurement, a differential pressure pitot probe and the ultrasound doppler velocimetry (UDV) for local velocity measurements were investigated in a fully developed turbulent lead-bismuth pipe flow. During the application of the flow rate measurement techniques in liquid lead-bismuth primarily technological problems were solved, whereas for the measurement of the local velocity field a considerable progress was achieved especially related to the attainable resolution in position and time compared to available liquid metal measurement techniques. Particularly, the ultrasound doppler velocimetry allowed to measure velocities in the viscous sublayer of the turbulent boundary layer as well as the determination of statistical quantities of the turbulent there. The main result of this report is the availability of qualified measurement techniques for heavy liquid metal operated loop systems. (orig.)