Abstract :
The Philippsburg nuclear power plant Unit 1, initially commissioned in 1979 is presently still partly equipped with safety-related isolation valves which correspond to the technical standard of the 1970s. Inspection of these valves according to todayʹs technical rules revealed that a number of these isolation valves can be upgraded in such a way that compliance with the present state of the art is achieved. However, the advanced state of wear of frequently operated valves suggested that a program should be set up for the gradual replacement of these valves, with a view to this upgrading. At present, the replacement program relates to a period from 1993–1997 with the selection of valves to be replaced depending on the signs of wear and the operational possibilities. Within this period, it is planned to replace 50% of the safety related valves with those that have been in compliance with the latest technical rules, and that have been improved with regard to that resistance to wear and ease of maintenance.
