Dounreay Site Restoration Ltd (DSRL) publishes an annual inventory of nuclear material at the site and as the decommissioning continues, the balance is starting to show a slight gain.

The company is taking pains to point out this is not because Dounreay is producing more nuclear waste, but rather that the waste previously chalked up as ‘material unaccounted for’ is being found.

Last year, the clean-up operation found around 1.5kg of uranium-235, a material which can be used to make nuclear weapons.

According to an official statement, the extra nuclear waste is coming from two sources.

First, tiny amounts of fissile material caught up in nooks and crannies of inaccessible pipework and equipment are being identified.

Second, there is an ongoing programme of opening up old sealed drums of waste, to check whether the recorded contents match up with reality.

Over two hundred waste drums full of material produced during historic operations were inspected, assayed and repacked for safe long-term storage.

During the work, operators opened up the old packaging and confirmed that there was more uranium trapped in the waste than had previously been measured.

Decommissioning engineer Bob McKiddie said: “The equipment that we are using to assay the waste is far more accurate than that available when the drums were originally packed.

“We had suspected that the historical results had under-estimated the uranium content in a number of waste items. The repackaging work has resulted in an overall gain in the amount of uranium declared.

“The figures from the repackaging work show that material previously considered ‘lost’ was in fact safely packaged as waste.”

Sam Bond

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