PARIS (Reuters) - French nuclear regulator ASN has ordered utility EDF to urgently make the steel “anchors” for the emergency diesel generators at its Bugey and Fessenheim nuclear plants more earthquake resistant.
The back-up generators, of which there are two per reactor, provide auxiliary power for reactor safety systems, including cooling the spent-fuel pool in the event of grid failure.
The generators sit on steel anchors that have be able to withstand an earthquake.
ASN gave EDF until Nov. 6 to fix the anchors of both backup generators for Bugey 3 and at least one of Bugey 4. The second Bugey 4 backup generator should be fixed by Nov. 29, ASN said In a decision published on its website on Monday.
the anchor of at least one of the generators at Fessenheim 2 should be reinforced by Dec. 31 and the second one by Jan. 31, it added. Fessenheim 2 has been offline since June 2016 and is due to restart on Jan 31, 2018.
ASN said that on Fessenheim 1 and Bugey 2 and 5 the problem had already been fixed.
EDF said on Oct. 16 it had widened a probe into the quake resistance of all backup generators at its twenty 1,300 megawatt (MW) capacity reactors to also include two of its 34 900 MW capacity reactors: Fessenheim and Bugey.
The ASN had said in June the probe covered both design and maintenance problems, which were generic to all the reactors, as well as local problems relating to the poor conditions or assembly of the anchors.
It had added that in the case of an earthquake and the outage of the reactor’s external power source, the operation of the emergency diesel generator sets could no longer be guaranteed as a result of the failure of their auxiliary systems which were not quake-resistant.
ASN has classified the issue as “Level 2” on the international nuclear and radiological event scale (INES), where Level 1 is the lowest level of risk while 7 is the highest.
EDF, which on Friday trimmed its 2017 nuclear power output and earnings targets after postponing the restart of its Tricastin nuclear power plant, has said production would not be affected while the anchor issues are resolved.
Reporting by Bate Felix; Editing by Geert De Clercq and Alexander Smith