Energy company bosses do not anticipate unexpected cost increases with Sizewell C – despite its sister nuclear power project’s building costs rising by up to £2.9billion.

%image(15104299, type="article-full", alt="Simone Rossi, chief executive of EDF Energy, says there will be "more cost certainty" with Sizewell C Picture: DAVID GARRAD")

French energy giant EDF Energy said the Hinkley Point C (HPC) plant in Somerset will now cost between £21.5 billion and £22.5 billion - a rise of between £1.9bn and £2.9bn.

It said the cost increase reflects "challenging ground conditions" which made earthworks more expensive than anticipated.

HPC is to be replicated on the Suffolk coast but by using identical models for the Sizewell C twin reactor EDF expects it to cost 20% less. This was expected to be around £14billion in total.

No renewed costs have yet been given for Sizewell C but the company does not anticipate the same problems as at HPC.

In an email to the leadership team, Simone Rossi, chief executive officer at EDF Energy, said: "It is also important to say that today's news has no direct read across to our follow on project at Sizewell C.

"Sizewell C will have more cost certainty with identical engineering already adapted to UK conditions, known quantities of materials and the experience gained at Hinkley Point C.

"As a follow-on copy, Sizewell C will also be cheaper to finance. This actually has a much greater impact on reducing cost to consumers than the project construction costs."

Stuart Crooks, managing director of HPC, said: "We are delivering on our milestones and although the risk of a delay has increased, the schedule is unchanged and we remain focused on delivering the first power in 2025. Getting this far has cost more money than we anticipated. Our earthworks are complete, but challenging ground conditions meant we overspent to finish them on time."

"Now that the detailed design implementation is more advanced and we have placed more of our contracts, we have a better appreciation of our future costs."

Unite assistant general secretary Gail Cartmail said: "The Government needs to swiftly learn the lessons from the Hinkley Point project, to ensure that the new nuclear power building programme, which is desperately needed in order to keep the lights on is able to proceed and be expanded."

EDF said the increased costs will have no impact on UK consumers or taxpayers.