EDF Energy initially gave a mid-October restart date for the four nuclear units which were taken offline in early August due to safety concerns over the boiler design of the units.
But on Thursday morning the company said it plans a “phased return” between the end of October and the end of December 2014, which will hit its total annual nuclear output by as much as 5 per cent.
The delayed capacity return comes following National Grid’s decision earlier this week to take extra measures to guard against the heightened risk of blackouts, as a string of recent unplanned outages threatens to halve the expected supply margins for this winter.
In addition to the nuclear outages, which removed around 2.5GW from the UK’s generation supply, the UK has lost SSE’s fire-damaged Ferrybridge coal-fired power plant.
SSE says it expects one of its units to return to service by November at the earliest while the unit most badly affected is only expected to return in March next year.
EDF Energy took the four reactors offline in August after a crack was found in a boiler at Heysham-1. As a safety precaution all units of the same design were removed from service for safety inspections, but a statement from the company said no further faults have been found.
“During the coming weeks the programme team will focus on completing the inspections and work to build a robust case for the safe continuing operation of the boilers. This ‘safety case’ is subject to approval from the independent nuclear regulator, the ONR (Office for Nuclear Regulation),” EDF Energy said.
Investment analysts at RBC Capital estimate that the delayed return of nuclear output could double the expected hit to EDF Energy’s earnings by an additional £150 million.
UK power market traders told Utility Week that the delay pushed already bullish morning pricing levels for winter power contracts higher.
According to one trader: “It’s certainly given the market an extra reason to move up.”