Concerns over uranium waste earmarked for low-level waste pits at Dounreay

Dounreay's operators are being pressed to rule out dumping bomb-grade uranium on its site.

Concern about the prospect has been raised as a result of plans to dig up historic waste held in a near-surface cluster of pits near the DFR dome-shaped reactor.

If the option is adopted, the material is earmarked to go to the low-level waste dump, to the immediate east of the plant.

Dounreay Stakeholder Group (DSG) is concerned to ensure that this would not include the long-lived radio-nuclides present in the pits.

A member of the group has calculated this could be as much as three-quarters of a tonne of highly fissile uranium-235; a tonne-and-a-half of uranium-238; and a kilogramme of plutonium.

Given their half-lives stretch into hundreds of thousands of years, DSG points out the substances would easily outlive the designed lifetime of the dump.

Its disquiet is reflected in notes of a recent meeting between DSG representatives and Scottish Environment Protection Authority's (Sepa's) Dounreay official Stuart Ballantine.

It read: "The radio-nuclides will still be present in the wastes after coastal erosion impacts in approximately 10,000 years. In fact, long, long after that.

"This is really not something that should be put into the LLWF (Low Level Waste Facility) unless as a last resort (and makes the safety arguments), as it will certainly impact future generations and the future environment."

DSG is seeking an assurance that should Dounreay's site licence company DSRL move the pit waste to the dump that the uranium and plutonium content be filtered out.

DSRL has yet to decide whether or not to transfer the waste from the cluster of six pits to the £110 million dump, which was commissioned in 2014.

It has planning permission to build six vaults. Four are designed to take waste from decommissioning activities at the site and the other two – not yet built – have been provisionally earmarked for the waste from the pits.

DSRL has applied to Sepa for a variation in its permit for the dump. A public consultation on the application is due to be launched shortly.

A DSRL spokesman said: "Our mission is to safely decommission Dounreay to the point of site closure with minimum impact on people and the environment during and after these activities.

"While no decision has yet been made regarding the future of the legacy waste pits, our environmental safety case (ESC) can demonstrate that any low-level waste that we dispose of into the LLW disposal facilities will be safe for the long term.

"Sepa will be assessing the ESC as part of their review of our application to vary the permit."

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