A number of contractors working on a major maintenance project at Sizewell B have been forced to self-isolate after coming into contact with a person who tested positive for Covid-19.

EDF said the contractors had tested negative before starting work at the nuclear power station site earlier this month.

The person the workers came into contact with was not a Sizewell worker - and they were made aware through track and trace.

They continued to be tested during the isolation period, which ended today, allowing them to return to work.

EDF says it has "robust" Covid testing measures and safety precautions in place at Sizewell B, where several hundred extra contractors are working.

The company has considerably reduced the number of workers who would normally work on an outage project and cut the scope of the work being done while the power plant is off-grid.

East Anglian Daily Times: The Turbine Hall at Sizewell BThe Turbine Hall at Sizewell B (Image: Archant)

The contractors - believed to be less than a dozen - self-isolated at their temporary accommodation in Thorpeness.

An EDF spokeswoman said: "Sizewell normally employs an additional 1,200 workers during an outage but has reduced the scope of work and the additional staff and contractors needed. The outage is now reduced to four weeks with under 750 additional contractors.

"This decision has been taken to protect the public and employees and contractors during the ongoing pandemic."

These changes have been undertaken with the approval of the independent regulator ONR (Office for Nuclear Regulation).

The station introduced robust measures to protect everyone at Sizewell B from January 2020.

The measures have included establishing a test facility for all staff; moving to a shift pattern to typically halve the number of workers on site at any one time; asking vulnerable workers to shield; supporting working from home when possible; and installing thermographic cameras, Perspex screens and additional hand cleaning facilities.

The company has also moved meetings to Skype and Zoom; reduced non-essential footfall on site; enhancing its cleaning regime; and introduced mandatory face masks and observance of social distancing.

During the shutdown, power station workers will complete 8,000 routine maintenance and inspection tasks and replace a third of the fuel.

Major work being undertaken includes maintenance of one of the steam turbines and generators, and there will also be routine servicing of valves, pumps and motors, as well as a full suite of testing.