The operator of the Dounreay nuclear complex in Caithness has been ordered to clean up its act by regulators following a fire that caused a radioactivity leak.
The incident in part of the Prototype Fast Reactor (PFR) facility on October 7, led to an “unauthorised release” of tritium.
The Office for Nuclear Regulation (ONR) said it had been concerned by poor compliance and “unacceptable behaviours of personnel”.
Dounreay Site Restoration Limited (DSRL) has been served with an improvement notice by ONR
The company has been told to make appropriate improvements to preventative and protective measures for the decommissioning of the sodium tank farm by June 30 next year.
ONR deputy chief inspector Richard Savage said: “The incident revealed several concerns, notably a poor compliance culture and unacceptable behaviours of personnel on site.
“We are looking for evidence of improvements to effective planning, control and monitoring that will prevent future incidents occurring, and protect the public during the decommissioning of the plant.”
Trace amounts of tritium were released into the environment and DSRL said it did not pose a risk to the public.
No-one at the plant, which is being decomissioned at a cost of £1.6billion, was hurt in the early morning blaze that was extinguished by the site’s fire brigade within 30 minutes.
The Scottish government and WWF Scotland have raised concerns about the incident.
Highland MSP Rob Gibson is demanding “straight” answers over the escape of radioactivity.
Mr Gibson, who is also convener of the Scottish Parliament’s Rural Affairs, Climate Change and Environment, said he was “concerned” about the release of tritium.
He is meeting the Nuclear Decommissioning Authority to find out the environmental impact of the escape.
DSRL managing director Mark Rouse said: “Our investigation identified unacceptable behaviours and practices that fell well short of our values and standards.
“It is important to take the time to ensure as many lessons are learned from this incident as possible.
“We are determined to improve our behaviours and compliance to ensure that we always meet the high standards expected on a nuclear site.”