The power stations generated 60TWh of electricity in 2012 from its 15 nuclear reactors and was almost 50 per cent higher than the output in 2009.
A £300 million annual investment, in addition to £350 million being spent on plant operations every year, has been accredited with the increase in output, reducing the number of unplanned outages.
Vincent de Rivaz, EDF Energy chief executive, said: “This will help postpone the energy gap in the short term, but underlines the need to move forward with plans to build the next generation of nuclear stations to provide reliable energy for the long term.”