Area 12 held 61 nuclear tests between 1957 and 1992, one of which involved two detonations. All tests were conducted below Rainier and Aqueduct mesas.
Area 12 was the primary location for tunnel tests and used almost exclusively for that purpose.
The tunnel complexes mined into Rainier and Aqueduct Mesa include the B -, C -, D -, E -, F -, G -, I -, J -, K -, N -, P -, and T - Tunnel complexes, and the R - and S - shafts.
