More than 70 years' worth of information and up to 30 million digital records are to be stored at Nucleus in Wick, Caithness.
They include papers, photographs and plans from nearby Dounreay, as well as Harwell in Oxfordshire, Trawsfynydd in Snowdonia and Sellafield in Cumbria.
Nucleus will also store local archives dating back to the 16th Century.
The Nuclear Decommissioning Authority has had the striking triangular shaped building constructed at a former RAF site. The facility, which took 12-months to construct, also boasts a large public area, a reading room and community space.
Speaking at the official opening Rob Higgins, NDA's Business Services Director, said: "We are extremely happy with Morrison Construction who completed the project on time and within budget."