nuclear-news

The two twin-reactor plants at Heysham 1 and Hartlepool have been shut down since August amid safety fears following the discovery of cracks in one boiler structure at Heysham.

The ageing reactors are likely to be restarted in coming months at just 75pc-80pc of their usual output in order to prevent high temperatures causing further cracks, EDF said on Friday.

The move will further worsen the risk of power shortages this winter and next.

The temporary closure of the plants, which produce enough power to meet about 4pc of peak winter demand, has already forced National Grid to invoke emergency measures to bolster power supplies this winter, by paying mothballed power stations to fire up.

EDF warned in September that the reactors – initially expected to be shut for two months – would only be restarted gradually between the end of October and late December, once safety checks on each reactor’s eight boilers were finished.

On Friday it further revised the likely dates of the restarts. The restart of the reactor with cracks has been pushed back a month, from the end of November to the end of December. Two other reactors have been pushed back from the end of October to November 9, and the fourth reactor has been brought forward from November 30 to November 22………

The cracks at Heysham 1 are in a “boiler spine”. The Office for Nuclear Regulation said that the spine “supports the weight of an entire boiler and its failure could lead to water entering the reactor vessel”.

“The potential worst consequences of water entering the reactor vessel is an over-pressurisation of the reactor which could result in lifting of the reactor pressure relief valves. If this was to occur co-incidentally with fuel damage then there could be a direct path to the environment and a release of radiation,” it said……..

As well as firing up mothballed power plants, National Grid is also using emergency plans to pay factories to switch off on winter weekdays to ease demand to help ensure households’ lights are kept on. http://www.telegraph.co.uk/finance/newsbysector/energy/11169625/Nuclear-reactor-heat-turned-down-to-stop-boilers-cracking.html