Particular importance of nuclear valves and fittings: The French PWR experiment

In spite of a good availability of French nuclear power plants, the accidental shutdowns due to valves are one of the main reasons of the outages (more than 12 percent of unexpected shutdowns) of EDF PWRs. The improvements made over the past few years must not cover up the increasing number of inspections and maintenance operations which are necessary to the upkeep of valves and fittings and also to prevent their aging. This shows the specific importance of nuclear valves and fittings (about 12,000 valves and fittings per unit) and even more so, regarding the so-called main valves (about 800 items per unit) for the guarantee of safety and availability of the power plants in operation (48 PWR units in service by the end of 1989). This is why the Research and Development Division performs on behalf of EDF's other technical departments, the necessary development studies and qualification tests, either by its own means (test facilities at Les Renardieres Center) or with the assistance of other specialized laboratories