British Energy has reported a huge rise in quarterly profits after fears about supply shortages forced up electricity prices earlier this year.
The nuclear power generator, which was on the brink of collapse in 2002 but has since restructured, saw first quarter profits rise 85% to £210m.
Wholesale prices soared this spring after a fire at a UK's largest gas storage facility prompted supply fears.
But British Energy said it was worried about lost production at its plants.
Losses from unplanned stoppages and non-routine events rose to 3.4 terrawatt hours (TWh), from 2.3 TWh for the same period last year.
This amounted to 20% of total generation output over the period.
Price boost
The firm pledged to focus on improving reliability at its plants, which include eight nuclear stations in the UK.
The company was financially restructured in 2004 after facing collapse, relisting on the stock market in 2005.
Soaring demand for electricity over the winter and spring boosted the firm, with achieved prices rising £11.20 per megawatt hour to £35.90.
In the three months to the end of June, the firm's revenues rose to £729m from £521m for the same period last year.
"I am pleased with our financial results benefiting from strong electricity prices," said chief executive Bill Coley.
"However, I am not pleased with the level of unplanned losses. We are sharply focused on improving losses over the remainder of the year."