Up to 30 reactors in France are to have bearings replaced in emergency coolant pumps after operators Electricité de France (EdF) discovered a common fault.

Following a series of special tests, EdF has undertaken a programme of technical modifications to the cooling pumps of its 900 MW reactors and reported a level 2 common cause event to the French Nuclear Safety Authority (ASN).

The problem concerns reactor cooling pumps used in accident situations, the motors of which have failed to perform to specifications such that the pumps have proved to be unreliable after several dozen hours of use.

Although the nuclear reactors could be cooled, if necessary, through normal operating procedures combined with complementary techniques, says EdF, the company has nonetheless decided to make modifications by replacing the bearings of the pump motors by the end of March 2006.