W78

Missile warheadUnited StatesThermonuclear (staged)

No freely licensed photo of this device yet.

Yield · TNT equivalent335–350 kt

Key specs

Country: United States
Design: Thermonuclear (staged)
Type: Missile warhead
Length: 1.72 m
Diameter: 540 mm
In service: 1979 – present
Number built: 1,083

Overview

A warhead of about 335–350 kt in the Mk 12A re-entry vehicle of the Minuteman III, still deployed alongside the W87. It is to be replaced by the new W87-1.

Effect radii: estimates

Calculated for 350 kt

Fireball, maximum radius: ≈ 630 m
Initial radiation, 500 rem (5 Sv): ≈ 2.6 km
Blast 5 psi: most buildings collapse: ≈ 5 km
Thermal: third-degree burns: ≈ 7.4 km
Blast 1 psi: windows shatter: ≈ 16 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

Sources

Complete List of All U.S. Nuclear Weapons, Nuclear Weapon Archive (Carey Sublette)
W78, Wikipedia