Castle Bravo ("Shrimp")

TX-21 "Shrimp" (Castle Bravo)

Test deviceUnited StatesThermonuclear (staged)

Castle Bravo ("Shrimp") — Photo: Federal government of the United States Restored by: Bammesk · Public domain · background removed

Yield · TNT equivalent15 Mt

Key specs

Country: United States
Design: Thermonuclear (staged)
Type: Test device
Weight: 10.66 t
Length: 4.56 m
Diameter: 1.37 m
Number built: 1

Overview

The TX-21 "Shrimp", the first US test of a dry-fuel thermonuclear device using lithium deuteride, fired at Bikini Atoll on 1 March 1954. Expected to yield about 5 Mt, it produced 15 Mt, the largest explosion the United States has ever set off.

The designers had not foreseen that lithium-7 would also take part in the reactions. Fallout spread over more than 18,000 km² of the Pacific: people on Rongelap and Utirik suffered radiation sickness and were evacuated, and the 23 crew of the Japanese fishing boat Daigo Fukuryū Maru were contaminated; one of them died months later. The disaster fuelled worldwide calls to end atmospheric testing.

Effect radii: estimates

Calculated for 15 Mt

Fireball, maximum radius: ≈ 2.9 km
Initial radiation, 500 rem (5 Sv): ≈ 5.2 km
Blast 5 psi: most buildings collapse: ≈ 18 km
Thermal: third-degree burns: ≈ 35 km
Blast 1 psi: windows shatter: ≈ 54 km

Estimated ground ranges for an air burst at the optimum height over flat, open ground, computed from the yield with standard scaling laws. These are not measurements: real effects depend on the height of burst, terrain, buildings and weather.

Formulas from: Glasstone & Dolan, The Effects of Nuclear Weapons (1977), chapter II; Carey Sublette, Nuclear Weapons FAQ, section 5

Tests and use

Date	Event	Site	Yield
Mar 1, 1954	Castle BravoSurface shot on an artificial island off Namu; three times the expected yield.	Bikini Atoll, Marshall Islands	15 Mt

Test footage

Archive films hosted on YouTube. Nothing loads from YouTube until you press play; the player then comes from youtube-nocookie.com.

atomcentral · youtube.com

Sources

Castle Bravo, Wikipedia