UK nuclear power plant operator, EDF Energy, has announced that it will shut three of its advanced gas-cooled reactors over the next few days to carry out detailed inspections of the boilers.
The news comes after planned inspections at the Heysham 1 Reactor 1 confirmed a defect in the boiler spine of one of eight boilers.
The potential problem with the boiler spine was first highlighted during a planned inspection outage in 2013. The reactor was returned to service in early 2014 on reduced load with the affected boiler quadrant isolated pending further investigations.
Detailed inspections of the affected boiler spine began in June and have now confirmed a defect in the location indicated by the initial findings. The reactor now remains shut down while work continues to characterise the nature of the defect.
EDF Energy says that although routine inspections of other boiler spines have not previously indicated any similar defects, it has taken the "conservative decision" to shut down Heysham 1 Reactor 2 and Hartlepool Reactors 1 and 2 that are of similar design to carry out further inspections in order to satisfy itself and the UK nuclear regulator that the reactors can be safely returned to service.
Initial estimates suggest that these investigations will take around eight weeks.
No other nuclear power plants are affected as they have different designs, EDF Energy said.
As a result of the outages, EDF Energy has revised its maximum theoretical output before unplanned losses for 2014 to around 61 TWh. In 2013, the UK nuclear fleet generated 71 TWh of electricity, the highest level since 2006. Nuclear power is responsible for approximately 20% of total UK generation.
