The final cost of the Hinkley Point C nuclear plant, being built in Somerset, could be as much as £35 billion, according to the French firm developing it.

The start of electricity production had been scheduled for June 2027 – but the completion date could now be up to three years later, energy giant EDF said.

A re-evaluation of the schedule and cost estimates, which have been expressed in 2015 prices, suggests that one of the two planned reactors in Somerset could be ready in 2029.

Hinkley Point construction
The steel dome being lifted onto Hinkley Point C’s first reactor building (Ben Birchall/PA)

Another evaluation assumes it could be operational a year later, while a final scenario suggests adverse conditions could see that drag on until 2031, EDF warned.

The bill for completing the project is now estimated at between £31-34 billion in 2015 values.

The firm said if the risk of an additional 12-month delay – as imagined in the final scenario – did happen, it would result in an estimated additional cost of around £1 billion in 2015 values.

The updated estimate of £31-35 billion, could see costs reach £46 billion in today’s prices.

EDF is aiming for the plant to become a major source of decarbonised electricity supply for the UK, providing around 7% of national consumption.

In a note to Hinkley project staff, Stuart Crooks, managing director of Hinkley Point C (HPC), said: “Like other infrastructure projects, we have found civil construction slower than we hoped and faced inflation, labour and material shortages – on top of Covid and Brexit disruption.”

In December last year, building work on the multibillion-pound nuclear power station reached a major milestone, with the first reactor building being lifted into place.

EDF said the achievement ended the year on a high as the 14m-tall dome sat on top of the reactor building, which is 44 metres high.

It was said that around 10,000 workers and 3,500 British companies were involved in the building Hinkley Point C.