Monitoring the filling level of the RPV using stationary EMUS-probes

Today the filling level in the reactor pressure vessels (RPV) of a boiling water reactor is measured exclusively by the approved differential pressure method based on a comparison of columns of weights. Because of the high importance which the filling level in the RPV respresents for the safety of a nuclear power plant, a physically diverse measuring method has been searched for which satisfies the following requirements: -unequivocal signal generation, - sufficient precision, -good time behavior, -possibilty of installation in existing plants. A binary working ultrasonic method, with which discrete marks of the filling level in the RPV can be surveyed, fulfils these requirements. (-z-)