The first nationally televised U.S. nuclear test, Upshot–Knothole Annie also served as a civil defense study measuring a 16 kt blast's effects on houses, shelters, and vehicles.
Key Facts
- Device yield
- 16 kilotons kt
- Detonation height
- 90 meters above ground m
- Test date
- 17 March 1953
- Closer house distance
- 3,500 feet from hypocenter ft
- Farther house distance
- 7,500 feet from hypocenter ft
- Observer distance
- 7.5 miles from blast (troops/officials) miles
By the Numbers
Location
Cause → Event → Consequence
During the Cold War, the United States sought both to advance its nuclear arsenal and to assess civilian preparedness against atomic attack. The Federal Civil Defense Administration partnered with the military to study how ordinary structures and vehicles would fare under a nuclear detonation, feeding public anxiety about Soviet nuclear capability.
On 17 March 1953, a 16 kt Mark 5 fission bomb was detonated 90 meters above the Nevada Test Site as part of Operation Upshot–Knothole. The blast, known as Annie, was broadcast live on national television and simultaneously served as Operation Doorstep, a civil defense experiment testing two wooden houses, eight bomb shelters, mannequins, and fifty instrumented automobiles.
The FCDA concluded that automobiles at least ten blocks away with open windows offered relative safety, and that a well-constructed basement could survive a nearby detonation. The closer house was destroyed while its basement remained intact; the farther house was damaged but standing. The live kinescope recording remains a rare audio-visual record of an actual atomic detonation.