Major refuelling and maintenance work is taking place at the Sizewell B nuclear power station – with both its electricity-producing turbines closing down this week as part of the project.

Around 1,500 specialist workers – many staying in the area and giving guest houses, restaurants, pubs and shops a huge economic boost ahead of the summer season – have joined the regular 520-strong workforce.

Turbine Generator 1 was taken off-line yesterday and Turbine Generator 2 will be brought off-line on Friday at 9am. Refuelling was last carried out in December 2014.

A spokeswoman for EDF Energy said: “The station is brought off-line every 18 months for this work to take place.

“Sizewell B has one reactor and two turbine generators which produced enough power for 2.6million homes last year.

“An additional 1,500 specialist workers will assist Sizewell B employees to complete over 13,000 tasks in addition to refuelling the reactor.

“Preparation work for the outage begins at least two years ahead of refuelling the reactor as part of a 10-year strategic outage plan for the station.”

The tasks being carried out include extensive tests on the pressure vessel “heart” of the Sizewell B reactor.

Anti-nuclear groups had pressed for an earlier examination of the vessel after faults were found in two similar power stations in Belgium in 2012. However, the Office for Nuclear Regulation (ONR), the UK safety watchdog, ruled there was no need for early testing at Sizewell and the work could be carried out this year as part of the routine inspection.

EDF has pledged to carry out extra ultra-sonic tests to establish beyond doubt that the Sizewell B vessel is safe.

Pressure vessel faults at Belgium’s Doel and Tihange reactors are thought to have occurred during the manufacturing process. The Sizewell B vessel came from a different manufacturer and underwent exhaustive testing before and during installation.

It is the 14th routine outage at the power station since it began generating electricity in 1995 and has been planned in consultation with National Grid to try to ensure there is no risk to national electricity supplies.