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.

Members of the Unite union are to walk out on Wednesday after rejecting a revised pay offer.

Unions at the nuclear power site suspended strikes planned for Wednesday and Thursday to allow for talks.