Material was removed from SSEN work site before radioactive material found
Excavation material from the site of a new electricity substation in west Caithness was taken away before traces of radioactive contamination were found there.
SSEN Transmission suspended work last week after the discovery at what is earmarked to be the mainland link with the new high voltage subsea power cable between Orkney and Caithness.
The firm has made clear that the majority of the material moved off site was monitored before it left the site, which it leases from the Nuclear Decommissioning Authority.
Most of it ended up at a quarry at Skitten, near Wick, with a small quantity taken to Langland Quarry, near Hill of Forss.
The traces of radium-226 in the earthworks are thought to have derived from the control panels used by pilots of planes which operated from the World War II airfield at Dounreay.
NRS Dounreay, which runs the nearby redundant nuclear complex, has offered its help in dealing with the issue.
A spokesperson for SSEN said: “Some 6900 cubic metres of material was removed from the Dounreay West substation site to the Skitten quarry under the site procedures in place at the time.
“Of this, some 4500 cubic metres, the top soil, underwent reassurance radiation monitoring prior to excavation with no elevated radiation readings being identified.
“Some 2400 cubic metres of subsoil was removed in accordance with the site procedures in place at the time.
“A further 700 cubic metres of material was taken off site to Langland quarry following reassurance radiation monitoring prior to excavation, in accordance with the updated site procedures, again with no elevated radiation readings.”
Earlier, SSEN revealed that some preparatory work on the site has started up again while it continues to liaise with the Scottish Environment Protection Agency (Sepa) on further radiation scans.
A spokesperson said: “Some non-intrusive site activities have now recommenced, with the agreement of Sepa.
“We are in ongoing dialogue with Sepa and continue to work with them, our contractors and other relevant stakeholders, with a view to recommencing full site activities in the new year.”
The spokesperson said there has been no harm to health.
The cable across the Pentland Firth will connect Orkney to the national electricity transmission network for the first time. The £900 million project is being designed to connect up to 220 megawatts of renewable energy.