Surge (expansion) tanks of emergency diesel generators were found corroded.Inadequate maintenance lead to not identify the corrosion and as consequence manage it. Their condition was such that their expected seismic resistance was not ensured.
Both of the two EDGs were concerned on Paluel reactors 1 and 2, which is relevant to an INES level 2 event.
The event is rated level 1 on the INES scale for the earthquake resistance deficiencies of the surge tanks of one emergency diesel generator set of the Nogent 1, Penly 1, Belleville 2, Cattenom 2 and Paluel 3, reactors, given that only one generator set out of the two is affected.
The corroded surge tanks of the reactors concerned were repaired or replaced between August and October 2017.
This event is different from the one reported on 20 June 2017 (event ID 2017/24), which was related to EDGs auxiliary systems’ ground anchors.
Event date: Thu, 09-11-2017