W9 (nuclear warhead)

A W9 nuclear artillery shell was tested during the Upshot-Knothole Grable shot in 1953 with a yield of 15 kilotons, about the same strength as the Little Boy bomb dropped on Hiroshima during World War II.

The W9 was an American nuclear artillery shell fired from a special 11 inch howitzer. It was produced starting in 1952 and all were retired by 1957.

Description

The W9 was 11 inches (280 mm) in diameter, 55 inches (138 cm) long, and weighed 850 pounds (364 kg). It had an explosive yield of 15 kilotons.

The W9 was a gun-type nuclear weapon, utilizing around 50 kilograms of highly enriched uranium in one large rings assembly and one smaller "bullet", which was fired down a tube by conventional explosives into the rings assembly to achieve critical mass and detonate the weapon.

The W9 units which were retired in 1957 were recycled into lower yield T-4 Atomic Demolition Munitions. These were the first (semi) man-portable nuclear weapons.

Tests

The W9 is only the second gun-type nuclear weapon known to have been detonated; the first was the Little Boy nuclear weapon used in World War 2.

The W9 artillery shell was test fired once, in Upshot-Knothole Grable on May 25, 1953. Yield was the expected 15 kilotons.

Subsequently, the W33 nuclear artillery shell was test fired twice during its development process. These four detonations are the only identified gun-type bomb detonations.

See also

• Nuclear artillery
• List of nuclear weapons

External links

• Allbombs.html list of all US nuclear weapons models at nuclearweaponarchive.org