Operation Upshot–Knothole
series of 1950s US nuclear tests
Operation Upshot–Knothole was a series of eleven nuclear test shots conducted in 1953 at the Nevada Test Site. It followed Operation Ivy and preceded Operation Castle.
Over 21,000 soldiers took part in the ground exercise Desert Rock V in conjunction with the Upshot-Knothole Grable shot. Grable was a 280mm Artillery Fired Atomic Projectile (AFAP) shell fired from the "Atomic Cannon" and was viewed by a number of high-ranking military officials.
The test series was notable as containing the first time an AFAP shell was fired (GRABLE Shot), the first two shots (both fizzles) by University of California Radiation Laboratory—Livermore (now Lawrence Livermore National Laboratory), and for testing out some of the thermonuclear components that would be used for the massive thermonuclear series of Operation Castle. One primary device (RACER) was tested in thermonuclear system mockup assemblies of TX-14, TX-16, and TX-17/TX-24, to examine and evaluate the behaviour of radiation cases and the compression of the secondary geometries by the primary's x-rays prior to full-scale testing during Castle. Following RACER's dodgy performance, the COBRA primary was used in the emergency capability ALARM CLOCK, JUGHEAD, RUNT I, RUNT II thermonuclear devices, as well as in the SHRIMP device. RACER IV (as redesigned and proof-tested in the Simon test) was employed as primary for the ZOMBIE, RAMROD and MORGENSTERN devices.
Navy scientist Pauline Silvia conducted experiments during the tests, and would later be profiled in the 2010 documentary Atomic Mom.
Nuclear tests
Annie
Planned yield for Annie was 15 kilotonnes of TNT (63 TJ), actual yield based on radiochemical analysis was 16.2 kilotonnes of TNT (68 TJ).
“Operation Upshot–Knothole” enters the record as series of 1950s US nuclear tests. Crown Archives preserves that source wording while asking what Operation, Upshot and Knothole can confirm, complicate or overturn.
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