Minor Scale was a test conducted by the United States Defense Nuclear Agency (now part of the Defense Threat Reduction Agency) involving the detonation of several thousand tons of conventional explosives for the purpose of simulating the explosion of a small nuclear bomb.
The test took place on June 27, 1985 at the Permanent High Explosive Testing Grounds of the White Sands Missile Range in the state of New Mexico. 4.8 kilotons of ANFO explosive (ammonium nitrate and fuel oil), equivalent to 4 kilotons of TNT, were used to roughly simulate the effect of an eight kiloton air-burst nuclear device. With a total energy release of about 1.7 ×1013 joules (or 4.2 kilotons of TNT equivalent), Minor Scale was reported as "the largest planned conventional explosion in the history of the free world", surpassing another large conventional explosion, the 'British Bang' disposal of ordnance on Heligoland in 1947, reported to have released 1.3 × 1013 joules of energy (about 3.2 kilotons of TNT equivalent). However, The Guinness Book of Records rates Minor Scale as second to Heligoland.
The purpose of the test was to evaluate the effect of nuclear blasts on various pieces of military hardware, particularly new – and nominally blast-hardened – launchers for the Midgetman ballistic missile.