WW2 radiation affects Highland substation project

Some work on a substation for a high voltage electricity cable between Orkney and the Scottish mainland has been suspended after the discovery of radioactive contamination.

The facility at Dounreay, near Thurso in Caithness, forms part of energy giant SSEN's £900m Orkney-Caithness 220kV link project.

The traces of radiation are believed to be from military aircraft instruments discarded in the area during or after World War Two about 80 years ago.

Dials were illuminated using a paint containing radium-226 (Ra-226) and similar contamination problems have been detected elsewhere in Scotland, including Dalgety Bay in Fife.

SSEN and Scottish Environment Protection Agency (Sepa) said the site was secure and there was no risk to the public.

The Dounreay West substation site was being monitored for radioactivity due to its war-time use.

Sepa said: "Following the identification of radium contamination at the site, SSEN has stopped work while it acquires an Environmental (Scotland) Authorisations Regulations 2018 (EASR) permit.

"An EASR permit is needed due to the presence of radium contamination at depth and the planned excavation works, beyond these depths."

SSEN said the affected areas were immediately isolated and exclusion zones put in place.

Some work has resumed after being halted earlier.

A spokesperson said: "In line with our robust environmental mitigation plans and following advice from our specialist contractor, the affected areas were immediately isolated, and exclusion zones established.

"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 link to aircraft dials was first reported by the John O'Groat Journal and Caithness Courier.

Caithness had a number of military air bases during WW2.

There was an airfield created at Dounreay but in the end was not used for flights by the RAF, according to Airfields of Britain Conservation Trust. It was later taken over by the Royal Navy.

The Dounreay experiment nuclear power complex was built nearby in the 1950s.

Once completed, the 33-mile (53km) subsea cable will connect renewable energy schemes in Orkney to the national grid to supply power to 250,000 homes.

The link from Warebeth, near Stromness, to the Dounreay substation is due to be operational in 2028.

There have been concerns about radioactive pollution at other Scottish sites in the past.

Contamination affecting Dalgety Bay is believed to be linked to aircraft that were destroyed and dumped in the area after WW2.

Sepa raised concerns about the discovery of radioactive metal in 2011.

Highland Council ordered a survey of Kingsteps Quarry at Nairn following "word of mouth" suggestions of buried planes.

Tests found no evidence of radioactive contamination in 2015.

Investigations have also been carried out in the past on sand dunes near Kinloss in Moray.

Ra-226 is a radioactive substance found in nature.

In the past it was believed it could bring health benefits and it was added toothpastes and foods.

It was used until the early 1970s in luminous paints for watches and aircraft instruments.

The substance takes hundreds of years to decay.