The first of three new replacement steam generators was delivered for installation at unit 5 of France’s Gravelines nuclear plant on 13 March. The Gravelines NPP comprises six 900MWe pressurised water reactors commissioned between 1980 and 1984.

Installation of new steam generators was initially planned for 2016 but was delayed after discrepancies were found in the manufacturing files of the original equipment.

Owner-operator EDF had intended to replace all three steam generators during the unit’s third 10-year in-service inspection, which began in April 2016. However, when the replacement steam generators were delivered from Areva's Le Creusot forge, discrepancies were found in their manufacturing records.

The unit was allowed to restart in late July 2017 after EDF made repairs to certain tubes within the existing steam generators. This work involve repairing almost 1800 'sleeves' over the affected tubes. The French Nuclear Regulatory Authority (ASN) had considered the sleeves to be strong enough to ensure the tightness of the primary circuit and meet the production standards.

EDF said the new steam generators would be installed during the next routine outage.