Editing Nuclear weapon design (section)

===Lawrence Livermore===
{{Main|Lawrence Livermore National Laboratory}}
With its original mission no longer available, the Livermore lab tried radical new designs that failed. Its first three nuclear tests were [[fizzle (nuclear test)|fizzles]]: in 1953, two single-stage [[uranium hydride bomb|fission devices with uranium hydride pits]], and in 1954, a two-stage thermonuclear device in which the secondary heated up prematurely, too fast for radiation implosion to work properly.{{Citation needed|date=June 2021}}

Shifting gears, Livermore settled for taking ideas Los Alamos had shelved and developing them for the Army and Navy. This led Livermore to specialize in small-diameter tactical weapons, particularly ones using two-point implosion systems, such as the Swan. Small-diameter tactical weapons became primaries for small-diameter secondaries. Around 1960, when the superpower arms race became a ballistic missile race, Livermore warheads were more useful than the large, heavy Los Alamos warheads. Los Alamos warheads were used on the first [[intermediate-range ballistic missile]]s, IRBMs, but smaller Livermore warheads were used on the first [[intercontinental ballistic missile]]s, ICBMs, and [[submarine-launched ballistic missile]]s, SLBMs, as well as on the first [[multiple independently targetable reentry vehicle|multiple warhead]] systems on such missiles.<ref>Sybil Francis, ''Warhead Politics: Livermore and the Competitive System of Nuclear Warhead Design'', UCRL-LR-124754, June 1995, Ph.D. Dissertation, Massachusetts Institute of Technology, available from National Technical Information Service. This 233-page thesis was written by a weapons-lab outsider for public distribution. The author had access to all the classified information at Livermore that was relevant to her research on warhead design; consequently, she was required to use non-descriptive code words for certain innovations.</ref>

In 1957 and 1958, both labs built and tested as many designs as possible, in anticipation that a planned 1958 test ban might become permanent. By the time testing resumed in 1961 the two labs had become duplicates of each other, and design jobs were assigned more on workload considerations than lab specialty. Some designs were horse-traded. For example, the [[W38 (nuclear warhead)|W38 warhead]] for the [[Titan (rocket family)|Titan]] I missile started out as a Livermore project, was given to Los Alamos when it became the [[SM-65 Atlas|Atlas]] missile warhead, and in 1959 was given back to Livermore, in trade for the [[W54]] [[Davy Crockett (nuclear device)|Davy Crockett]] warhead, which went from Livermore to Los Alamos.{{Citation needed|date=June 2021}}

Warhead designs after 1960 took on the character of model changes, with every new missile getting a new warhead for marketing reasons. The chief substantive change involved packing more fissile uranium-235 into the secondary, as it became available with continued [[uranium enrichment]] and the dismantlement of the large high-yield bombs.{{Citation needed|date=June 2021}}

Starting with the [[Nova (laser)#Fusion in Nova|Nova]] facility at Livermore in the mid-1980s, nuclear design activity pertaining to radiation-driven implosion was informed by research with ''indirect drive'' laser fusion. This work was part of the effort to investigate [[Inertial confinement fusion#Nuclear weapons|Inertial Confinement Fusion]]. Similar work continues at the more powerful [[National Ignition Facility]]. The [[Stockpile stewardship#Stockpile Stewardship Management Program|Stockpile Stewardship and Management Program]] also benefited from research performed at [[National Ignition Facility#Stockpile experiments, 2013–2015|NIF]].{{Citation needed|date=June 2021}}