Hinkley Point C nuclear plant to run £2.9bn over budget.

French power company EDF said the new nuclear plant it is building at Hinkley Point C will cost up to £2.9bn more than thought.

It raised its estimate for the project, in Somerset, to between £21.5bn and £22.5bn, blaming “challenging ground conditions”.

It also said the risk of the project being 15 months late had risen.

In common with many very large construction projects, the power plant is dogged by rising costs and delays.

It last raised its estimate for the project in 2017, by £1.5bn.

While EDF and China General Nuclear Power Corp (CGN), with whom it is sharing the work, are still aiming to finish the work in 2025, the chance of that being 2026 has risen, although EDF did not quantify that risk.

Because of the way that the project is being funded, taxpayers and customers will not foot the bill for the increase in costs – EDF and CGN will pay.

“Cost increases reflect challenging ground conditions which made earthworks more expensive than anticipated, revised action plan targets and extra costs needed to implement the completed functional design, which has been adapted for a first-of-a-kind application in the UK context,” the company said in a statement.