INES-event
INES 2

Level 2 incident on INES scale concerning back-up diesel generators at Tricastin nuclear power plant

ASN has rated at level 2 on INES scale an incident reported by EDF licensee on February 16, 2011 concerning back-up diesel generators at Tricastin NPP.

The failure of a back-up diesel generator has been highlighted on 7 February 2011 during a periodic test conducted at an EDF NPP. According to a preliminary analysis undertaken by EDF and its supplier the failure is due to a premature degradation of the bearing bushings. In the French NPP fleet, 26 back-up diesel generators are equipped with this type of bearing bushings which are therefore potentially sensitive. Only units 3 and 4 of the Tricastin NPP have all back up generators equipped with this type of bearing bushings. Therefore, on this site, the anomaly is rated by ASN as incident Level 2 on the INES scale.

For the rest of the concerned reactors, at least one back-up generator, either in the reactor or on the site, is equipped with a different brand of bearing bushing which do not have this defect. The anomaly on these sites has been rated by ASN at level 1 on the INES scale.

ASN has asked EDF to submit a corrective action plan. The first EDF proposals have been submitted to ASN. ASN, with the support of IRSN, is currently assessing these proposals which include the installation of new bearing bushings and the implementation of a new operating procedure for the diesel generators involved.

Location: TRICASTIN-3
Event date: Wed, 16-02-2011
Nuclear event report
Legenda & explanation