Dounreay

Vulcan on Scotland's north coast was used for more than 50 years to test nuclear submarine reactors.

Also known as the "sphere", the 41m diameter structure at Dounreay houses a nuclear reactor.

SSEN had been monitoring for radiation on the Orkney-Caithness subsea cable project site.

The machine developed by the University of Nottingham was used to investigate part of Dounreay.

Inspectors found corroded steelwork an area at Dounreay used to store radioactive material.

Members of two unions at the nuclear power site rejected a previous offer.

It is the latest action by members of two unions at the nuclear power complex in Caithness.

Members of two unions at the nuclear power site are in a pay dispute with their employer.