Safety concerns over Dounreay electrical items and low-risk radioactive leak
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Dounreay's regulators have flagged up safety concerns about some of the site's elderly electrical equipment.
The condition of a number of transformers and other plant is the subject of an enforcement letter from the Office for Nuclear Regulation (ONR).
Operators, Magnox Ltd, have also been sent a warning letter about a small leak of radioactive tritium from a drum of alkali metal stored at the prototype fast reactor towards the end of last year.
The actions were confirmed at last week's meeting of Dounreay Stakeholder Group (DSG).
ONR inspector James Francis said the concerns emerged during an electrical safety inspection. He said the radiological checks were rated green but the conventional electrical safety was flagged amber.
"There was equipment dating back to the 1950s and 1960s which was still in use and had known safety concerns surrounding it," he said.
Mr Francis said Magnox has withdrawn the equipment from use and has responded to the enforcement letter with an improvement programme.
He added: "We're reasonably content with their response to the enforcement letter."
John Crouden, who attended the meeting as a member of the public, was concerned how the electrical issue had escalated to the stage where enforcement action had begun.
"Have the risk assessments not been robust enough?," he asked.
Assurance director Barry Cran said it has taken steps to address the concerns.
He said: "The letter is about two very specific things. It was about how certain switchgear of a particular type and a particular vintage was operated, and the suitability and operation of a couple of transformers and a package of work associated with them.
"We have replied with a plan of action for the transformers and have taken steps to change our risk assessment of the electrical equipment."
Mr Cran said the switchgear had been operated well below its rated values.
The enforcement action relating to the Electricity and Work Regulations and the Health and Safety at Work Act followed an inspection on March 21-23.
The warning letter about the sodium tank leak was issued after the Scottish Environment Protection Agency (Sepa) completed its investigation early last month.
Its probe got under way after plant managers notified it of the leak of the radioactive gas from a sodium drum in November.
Dounreay site inspector Stewart Ballantine said: "It related to a very small release of tritium. There was a worst-case assessment done and it was many orders of magnitude below the public dose limit."
The watchdog rated the risk to the public or the environment to be extremely low.
Gillian Coghill, who chairs DSG's site restoration sub-group, said how stockpiles of sodium at the site are stored needs to be treated as a matter of urgency.
"It is something that is going to need to be addressed very quickly," she said. "It can't just be one drum leaking – there must be more than one."
Mac MacGill, Dounreay's chief of staff and security resilience director, said it was working with Sepa to address the issue.
He said: "We recognise that this is not just a single drum. We have other things to deal with."
The incident followed a leak from the sodium tank farm at the prototype fast reactor in April last year.
Sepa found that the plant operators had breached its authorisation and earlier this year issued a final warning letter to DSRL.
DSG later heard that Magnox is taking action to prevent a recurrence of the recent incident when clinical waste from the site was dumped at the Seater landfill site.
Sepa launched an investigation after four bags containing personnel monitoring and analytical procedures ended up at the dump on March 17.
Mr Ballantine said: "We have been engaging with the site and have been advised of corrective action."
DSG chairman, local Highland councillor Struan Mackie, said he is eager to understand what had gone wrong.
He said: "I haven't heard much back from Highland Council and I'm keen to see what comes through from the regulator's perspective."
