Two months ago British Energy said that achieving full-year output targets would be “very challenging”. They look completely out of reach now after the latest in a string of setbacks for the company.

Last year it was cracked boiler tubes that caused red faces in the boardroom. Today it’s wire winding at a reactor in Hartlepool.

The fact that British Energy spots the safety problems is reassuring, but however much the management papers over the cracks, investors will be losing confidence in the company.

British Energy had been hoping to achieve 61 to 63 terawatt hours of production in the current financial year.

But five months of downtime at Heysham and Hartlepool would knock out nearly 5 terawatt hours. The hit on full-year earnings could be more than £200 million.

The shares are trading at levels last month and there is little prospect of a rally over the short term.

However, even more worrying for British Energy is the credibility issue. The Government is keen for new nuclear power plants to be built on or near existing British Energy sites and for the company to be at the centre of the projects.

Yet its problems will only strengthen the hand of foreign giants, such as RWE, that are lobbying for the right to build new plant on their own.

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