THE reactor design for the proposed nuclear power plant at Moorside, Sellafield, is taking longer than expected to get regulatory approval.

But the US firm behind the reactor, Westinghouse Electric, says it is confident the design is safe and will get the go-ahead.

NuGen wants to build three Westinghouse AP1000 reactors at Moorside with a combined output of 3.6GW, enough to power 6m homes and supply 7.5 per cent of the UK’s electricity needs.

It is due to make a final investment decision in 2018, with work starting two years later, but the timetable is based on the design being approved in January 2017. That date now looks certain to slip.

Westinghouse needs a Design Acceptance Confirmation (DAC) from the Office for Nuclear Regulation and a Statement of Design Acceptability (SoDA) from the Environment Agency.

The regulators have just issued a quarterly update warning of delays in the Generic Design Assessment (GDA) process.

Their report says: “There has been closure programme slippage and a lack of technical convergence in some areas.

“This means that we have still to agree with Westinghouse the full extent of the work required to close out all of the GDA issues.

“This lack of progress and agreement on the way forward in specific areas is disappointing so far into the closure phase.”

In response, Westinghouse issued a statement aiming to reassure politicians and NuGen that its plans remain on track.

It now hopes to complete the GDA by March 2017.

Jeff Benjamin, NuGen’s senior vice president, new plants and major projects, said: “The regulators have offered a careful perspective on the UK AP1000 plant project, providing constructive feedback.

“Westinghouse has delivered revisions or validations of all GDA resolution plans to the regulators to address their concerns.

“Westinghouse has confidence in the safety of AP1000 plant design and that it will achieve the DAC and SoDA.”

Westinghouse is building eight AP1000 reactors in the US and China, with another planned for Bulgaria. Moorside would be the first time the design has been deployed in the UK.

The company, once owned by BNFL, is now a subsidiary of Toshiba, the majority shareholder in NuGen.

If the Moorside project goes ahead, the first reactor should be on stream by 2024 and all three should be generating electrcity by 2026.

At peak construction, 6,000 people will be working on site.