Improvements in availability and reliability of reactors under the French nuclear programme

In 1984, French PWRs attained remarkable levels of availability, which placed them among the best in the world. However, this result could still be improved upon (average age of reactors is only 3.5 years). One way of achieving such an improvement is to reduce the number of chance trips. Under the French policy of reactor standardization, the Electricite de France (EDF) now has a homogenous group of 31 (soon to be 34) 900 MW PWRs, which means that feedback is highly effective. In particular, statistical analysis of all incidents since 1982 has made it possible to identify and to classify in descending order of responsibility the causes of trips, which are grouped according to five study topics. The paper describes some of the 31 main types of action taken. These demonstrate one of the advantages of the very high level of standardization adopted in France: the general introduction of any important modification can be preceded by in-depth studies and tests on an operating reactor. Frequently, their costs are acceptable only because they can be distributed over 34 identical reactors. (author)