W54

The W54 was one of the smallest nuclear warheads deployed by the United States. It was a very compact implosion-type nuclear weapon design, designed for tactical use and had a very low yield for a nuclear weapon.

The W54 was designed by Los Alamos Scientific Laboratory and built by the United States Atomic Energy Commission. Around 400 units were manufactured from 1961 until early 1962 and were deployed until at least 1971.

The earliest identified nuclear tests of devices corresponding to the W54 characteristics were the Pascal-A and Pascal-B test detonations in 1957, in the Operation Plumbbob nuclear test series. These were both intended to have very low yield, but overshot to higher yields (tens and hundreds of tons of TNT).

These were followed by tests of the XW-51 design, which evolved into the XW-54 in the Operation Hardtack I test series in 1958 (Hardtack Quince and Hardtack Fig). These were both described as fizzles, or test failures.

A number of XW-51/XW-54 tests followed in the 1958 Operation Hardtack II test series, including Hardtack II Otero, Bernalillo, Luna, Mora, Colfax, Lea, Hamilton, Dona Ana, San Juan, Socorro, Catron, De Baca, Chavez, Humboldt, and Santa Fe. By this time, the XW-51 / XW-54 design had been test-fired more times than any preceding US nuclear weapon prior to its successful introduction in service, indicating the difficulty of successfully making this small and low-yield design work reliably and safely.

Further testing followed in the 1961 Operation Nougat test series, probably including Nougat Shrew, Boomer, Ringtail, and possibly others. By this time the W-54 design was performing consistently as expected at low yields.

There were four distinct models of the basic W54 design used, each with different yield, but the same basic design. These were:

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