What is "dounreay"

Dounreay (; ) ( Ordnance Survey ) is on the north coast of Caithness, in the Highland area of Scotland and west of the town of Thurso. Dounreay was originally the site of a castle (now a ruin) and its name derives from the Gaelic for 'fort on a mound.' Since the 1950s it has been the site of two nuclear establishments, for the development of prototype fast breeder reactors and submarine reactor testing. Most of these facilities are now being decommissioned.