Operation Prairie Flat was a test involving the detonation of a 500-short-ton (450 t) spherical surface charge of TNT to evaluate airblast, ground shock and thermal effects of nuclear weapons.

It was a continuation of the technical co-operation (Canada, United States, Great Britain) series of tests sponsored jointly by the respective governments.

Debris fracturing and transport were also tested as part of the effort to understand nuclear blast effects on Nike-X anti-ballistic missile sites.

[2] An additional goal of the test was to compare the blast with the previous Distant Plain Event 6 that used an equivalent but smaller 100-short-ton (91 t) configuration in order to study scaling factors.

Unlike previous 500-ton tests however, the charge was built as a sphere tangent to the ground, which would make it smaller in diameter than the 500-ton hemispheres but equal in yield.