A second Sellafield worker is self-isolating with suspected coronavirus.
The company confirmed at the weekend that an employee had been diagnosed with the virus and is now in self-isolation.
Around 10,000 people work at the site. Sellafield confirmed on Sunday that they were in contact with Public Health England and were "maintaining [their] focus on the safety and security" at the facility.
A spokesperson from Sellafield said "It is highly likely that more of our employees and contractors will have to self-isolate in the coming weeks."
"We recently confirmed that a Sellafield Ltd employee working at the Sellafield site had been diagnosed with Covid-19. The employee followed NHS advice and is in self-isolation.
"We can also confirm that a second Sellafield Ltd employee with suspected Covid-19 is self-isolating.
"It is highly likely that more of our employees and contractors will have to self-isolate in the coming weeks.
"We remain in close contact with Public Health England and will continue to follow their advice to protect our people, while maintaining our focus on the safety and security of the Sellafield site.
"Some areas of our business are beginning to trial home-working, and we have changed our advice on travel and meeting attendance. Further changes are likely as the situation is fast-moving.
"We will be updating our internal and external communications channels regularly to provide the most up-to-date information and advice for employees, contractors and other stakeholders.
"All employees have been and are urged to follow the official guidance from Public Health England and the Department of Health at nhs.uk/coronavirus.
"We will not comment further on individual cases."
This latest case in Cumbria comes as the government readies to instruct people over 70 to stay in strict isolation for four months, under "wartime-style" mobilisation.
According to ITV's political editor Robert Peston:
The forced requisitioning of hotels and other buildings as temporary hospitals
The requisitioning of private hospitals as emergency hospitals;temporary closure of pubs, bars and restaurants - some time after next weekend's ban on mass gatherings
Emergency manufacture by several companies of respirators that would be necessary to keep alive those who become acutely ill
The closure of schools for perhaps a few weeks, but with skeleton staff kept on to provide childcare for key workers in the NHS and police.