Each 1300 MW French type reactor is equipped with 2 EDGs which redundantly power several safety systems in case of a loss of external power, in particular following an earthquake. EDGs are composed of an alternator, a diesel engine and auxiliary systems (cooling system, pre-lubrication, etc.).
The event is related specifically to the potential failure of auxiliary systems’ ground anchors in case of an earthquake. This includes design issues, generic to all the 1300 MW French reactors, and specific issues to some EDGs, related to poor condition or uncompliant assembly.
In case of a loss of external power following an earthquake, EDGs may not operate because of a failure of their auxiliary systems.
This event follows one that has been reported previously in March 2017 on one 1300 MW NPP (Golfech), related to EDGs cooling system expansion tank not being able to withstand an earthquake. This event was found generic to all 1300 MW French reactors and was rated INES 1. On 20 June 2017, EDF has reported that other EDGs auxiliary systems may fail in case of an earthquake.
ASN has requested EDF to strengthen all auxiliary systems ground anchors within 3 weeks for at least one of the two EDGs of each of the 1300 MW reactors. The second EDG must be strengthen with a month and a half. An ASN resolution will be taken within the next days.
The INES 2 rating concerns all of the twenty 1300 MW French reactors: Belleville, Cattenom, Flamanville, Golfech, Nogent, Paluel, Penly and Saint Alban.
Event date: Tue, 20-06-2017