Work is underway on a £28 million maintenance project at EDF Energy's Torness power station in East Lothian.
The scheme, known as a 'statutory outage', is carried out on each of the facility's reactors every three years.
The period allows workers to carry out inspections and pieces of work which would not be possible when the reactor is in operation.
More than 600 extra workers will join the 750 strong workforce for the maintenance phase, which is set to last nine weeks.
Workers will carry out more than 12,000 separate pieces of work which have been planned over the last two years. Projects include inspections of the reactor vessel internals, exchange of the turbine high pressure rotor and replacement of auxiliary cooling water pipework systems.
Station Director, Paul Winkle, said: "This is the first statutory outage since we announced last year that Torness will continue to produce low carbon electricity until 2030; an additional seven years. The outage will give us the chance to do inspections and carry out pieces of work that are not possible when the reactor is operating.
"It is also a great boost for the local economy. We are bringing in an additional 600 workers who will be staying in local hotels and B and B's, eating in the area's restaurants and using taxi firms. It is great that our investment in the power station can also benefit local community."
(LM)
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