Dounreay leak probe launched as Scottish Environment Protection Agency announce investigation into incident

Scotland's environmental regulator has launched an official investigation into a leak of caustic material at Dounreay this week.

The incident at the Dounreay nuclear facility on Wednesday evening was contained and the environmental impact is thought to be minimal, according to the site owners.

The Scottish Environment Protection Agency (SEPA) said that the leak of tritium, a radioactive isotope of hydrogen which is historically used in a variety of industrial processes, presents a "low radiological hazard".

However, the agency said that a formal investigation would be launched into the incident at the site, which is operated by Dounreay Site Restoration Ltd (DSRL).

Dr Paul Dale, radioactive substances manager at SEPA, said: “Shortly after midnight [Thursday, April 21] SEPA was notified of an incident at the decommissioning Dounreay nuclear site at Thurso in the Scottish Highlands.

"Specialist SEPA officers were in liaison with the site operators overnight and understand that the incident occurred at a sodium storage facility associated with the Prototype Fast Reactor building, currently being decommissioned.

"Further updates have been received today and we understand that there was a small release of process chemicals from the system and a release of tritium, which presents a low radiological hazard, may have occurred.

"DSRL continue to investigate and SEPA will be updated as further information becomes available."

He added: “Whilst from initial information we consider the risk to the public or the environment to be extremely low, SEPA has launched a formal investigation and will provide further updates as appropriate."

DSRL said the incident occurred at the Prototype Fast Reactor complex.

A spokesperson said: "At approximately 8pm on April 20, site emergency personnel responded to a call at the sodium storage tanks at the Prototype Fast Reactor complex.

"A planned reaction of material inside a tank resulted in an excursion, causing the release of a small amount of caustic liquor. No-one was injured and damage was confined to components in the tank.

"We believe the environmental impact is low. Emergency personnel kept the tank under observation as a precaution.

"SEPA and the Office for Nuclear Regulation have been informed of the occurrence, and DSRL is commencing its own investigation of the circumstances."

A spokesperson for the ONR said: "We have been made aware of an incident at the Dounreay site [on April 20] that resulted in site emergency personnel attending to a call at the sodium storage tanks at the Prototype Fast Reactor complex.

"ONR is content that Dounreay responded appropriately in accordance with their established arrangements and the system is now stable.

"Our inspectors are in close contact with Dounreay and will continue to monitor the situation, including Dounreay’s investigation into the incident."

Dounreay's operators were taken to task recently over several "near miss" industrial mishaps with incidents occurring between April and November last year involving crane-lifting operations. It resulted in DSRL and site contractor Graham receiving enforcement letters from the Office for Nuclear Regulation (ONR). The regulator warned that the breaches of compliance would lead to stronger action if improvements were not made.