Python primary

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According to researcher Chuck Hansen, the W-34 Python was a gas-boosted fission primary used in several designs of American thermonuclear weapons.

Primary is the technical term for the fission bomb trigger of a thermonuclear or fusion bomb, which is used to compress, heat and ignite the fusion fuel in the thermonuclear secondary.

Hansen's research indicates that the W-34 Python primary was used in the US B28 nuclear bomb, W-28 nuclear warhead, W-40 nuclear warhead, and W-49 nuclear warhead, and as a boosted fission warhead without a thermonuclear second stage in several other weapons. These were the Mk-45 ASTOR wire-guided 21 inch, submarine launched heavyweight torpedo; the Mk-101 Lulu NDB; the Mk-105 Hotpoint laydown bomb. Additionally, an anglicised W-34 Python known to the British as 'Peter' was manufactured in Britain as the primary for Red Snow, itself an anglicised W-28 warhead. Peter was also proposed as a replacement for the Red Beard warhead housed in a Red Beard carcass, and as an ADM for the British Army in Germany. The W-34 used the melt-cast HE Cyclotol, a variant of HMX as the material for its implosion lenses, and this relatively unsophisticated explosive that pre-dated PBX explosives was perhaps a reason why the British adopted this warhead, since they were attempting to deploy a thermonuclear warhead for their strategic bombers quickly, and the British were well-versed in the manufacture, storage and use of these melt-cast explosives.

Declassified British military documents also refer to a 'Low-Yield-Python' and the Genie Air-to Air Missile being considered by the UK for their interceptors, suggesting that there was a design linkage with the W-25 low-yield warhead of the Genie. There is no hard evidence as yet, but the 11 kT yield of the W-34 Python would degrade to a figure comparable with the W-25 without the gas-boosting.

Historical evidence indicates that these weapons shared a reliability problem, which Hansen attributes to miscalculation of the reaction cross section of Tritium in fusion reactions. The weapons were not tested as extensively as some prior models due to a mid-1960s nuclear test moratorium, and the reliability problem was discovered and fixed after the moratorium ended. The flaw was apparently common with the W-44 Tsetse primary design.

Characteristics of these weapons are: