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The W52 was a
Researcher Chuck Hansen claims based on his research into the US nuclear program that the thermonuclear W52 and (fission-only) W30 warheads both use a common primary or fission first stage, and that this design was nicknamed the Boa primary.
Three models of the W52 were produced, the Mod 1, Mod 2, and Mod 3. A warhead test was performed in 1963, which failed, showing that the Mod 1 and Mod 2 versions of the W52 were essentially duds. The Mod 3 was subsequently redesigned to work properly.
The design failures of the Mod 1 and 2 W52, along with early problems with the W45 and W47 warheads, are still an active part of the debate about the reliability of the US nuclear weapons force moving into the future, without ongoing nuclear testing.