A manufacturing facility in Avonmouth has closed temporarily after 19 employees tested positive for Covid-19 over the weekend.
The site is owned by construction giant Balfour Beatty, which is making nuclear-grade concrete segments for huge tunnels being built under the Bristol Channel for Hinkley Point C.
The company said it was working with Public Health England and Bristol City Council and had carried out a "deep clean" of the plant.
It also said it was using the NHS track and trace app and it had "so far shown no impact" on the main construction site at Hinkley Point.
"Having engaged with Public Health England and Bristol City Council we have now taken the responsible decision to close the facility until further notice to reduce the potential further spread of Covid-19," the company said in a statement.
"We continue to engage with all those affected and remain committed to the health, safety and wellbeing of all those who work with and for us, as well as the general public."
Balfour Beatty's sites have remained open in line with government guidelines during the coronavirus pandemic.
The company said it had been carrying out "preventative health and safety measures" such as enhanced hygiene and cleaning, and daily briefings on Covid-19 practices including the controls around two-metre working.
It also said it was carrying out temperature checks for all individuals on arrival at its sites and had put in place changes to working practices including at its shared facilities to maintain social distancing.
The news comes as another eight people living in the West of England tested positive for coronavirus.
The eight positive tests, including five for people living in Bristol, have been added to the Government statistics in the last 24 hours, to 4pm on Sunday, July 26, although the tests themselves may have taken place in the last few days.
For Bristol, the five new cases recorded on Sunday brings the total number of cases to 1,318
