Monitoring the filling level of the rpv using stationary emus-probes

The determination of the filling level and the initiation of growth of bubbles in vessels and pipes containing fluids is an essential component of monitoring during operation.The ultrasonic pulse-echo-method is a measuring procedure suited for this purpose and applicable from the outside. Piezoelectric ultrasonic transducers can be used in principle at a temperature of 300°C, but in practice these transducers are not preferred because of the expense and inconvenience in coupling them to the vessel wall.These problems are solved using lectro agnetic- ltrasonic-(EMUS-)transducers. Due to physical reasons a longitudinal wave is generated in the fluid by the refraction of a shear wave in the vessel-wall. The filling level is measured in a pitch and catch-technique by a mirror reflection of the longitudinal wave at a construction element inside the vessel. This paper reports on laboratory investigations concerning the applicability of the technique and first experiences with an EMUS-prototype system installed in a nuclear power plant.