Welding issues found at French nuclear sites: Update

Adds comments from ASN

French state-controlled utility EdF has notified the country's nuclear safety authority, ASN, of deviations in the manufacture of some steam generator welds for its nuclear reactors, it said today.

The "deviation from technical standards" in the detensioning heat treatment on the welds was reported to EdF by French manufacturer Framatome and concerns operational parts and new components yet to be installed at nuclear sites, EdF said.

Twenty steam generators manufactured by Framatome since 2008 are potentially affected, ASN said today, adding "investigations are ongoing". EdF and Framatome are in the process of identifying the affected components and "ascertaining their fitness for service" and the utility has passed its initial findings to ASN, EdF said. It did not provide further details of the sites affected or whether the discovery would force plants off line for maintenance.

EdF operates all of France's 63.13GW nuclear fleet. The discovery of irregularities at Framatome's Creusot Forge factory — which makes components for nuclear plants — forced several French reactors off line for safety checks in 2016-17. And unrelated anomalies in welds at EdF's new 1.6GW Flamanville 3 nuclear reactor have delayed its start-up by more than two years to the end of 2022.

In a separate case, ASN ruled last month that metal parts manufactured by French firm Aubert and Duval for the country's nuclear plants are fit for purpose despite irregularities.

French front-quarter power contracts trading in the over-the-counter market took support today from the resulting uncertainty surrounding nuclear availability for the period.

The November and December base-load contracts closed at €61.70/MWh and €65.15/MWh, which was €7.20/MWh and €9.80/MWh above yesterday's close, respectively. And the fourth-quarter 2019 contract closed at €58.60/MWh, or €7.45/MWh above its closing assessment yesterday, while October closed €5.25/MWh above at €49/MWh.