Experience with the TÜV pipe monitoring system at the Grohnde nuclear power station

Abstract

A special pipe monitoring system has been developed by TÜV Rheinland during the construction, commissioning and operation of the Grohnde nuclear power station. On the basis of measurements during construction and commissioning a basic monitoring system has been developed, using not only a system of sophisticated sensors that had been permanently installed from the beginning but also a large number of quite simple additional sensors. Measurements were taken before, during and after inspections and led to the discovery of unexpected and high stresses during service as well as to long-term changes over a period of years. Special measurements were taken with high temperature strain gauges and thermocouples to identify problems such as temperature layering. A special on-line measuring device was developed and used for the continuous monitoring of temperatures during operation. All these measurements help to identify out areas with high stresses or service conditions giving rise to high loads, in order on the one hand to prevent damage and on the other hand to prove that the pipes are functioning within their design parameters without problems.