Erosion by cavitation on safety-related piping systems of French PWR units

The first time traces of erosion inside of the pipe of the residual heat removal system was noticed during routine maintenance at Fessenheim-1 in 1982. After this, the similar damages were discovered in pipes of some other units. In studies and further inspections were launched to analyse the risk on the other units and systems. The present conclusions are that many systems of many units may be concerned, depending on the shape of the pipelines and operating conditions. So, the specific maintenance program was set up to recommend particular operating procedures and to study possible modifications for long term solutions. This paper discusses various problems of corrosion-erosion in pipelines: The possible incidents, the results of the inspections and analysis and their effects on maintenance and operation instructions, and the tentative long term solutions