On May 14, the Lawrence Livermore National Laboratory completed the first in the Nimble series of underground subcritical experiments at the Nevada National Security Site, according to a press release.
The subcritical experiment was conducted at the Principal Underground Laboratory for Subcritical Experimentation, also known as the U1a Complex.
In June 2023, a senior Livermore official
told the Monitor that Nimble was a three-shot series of experiments, the first of which was called Nob Hill and scheduled to fire in late fiscal year 2023, which ended on Oct. 1.
Since the U.S. unilaterally stopped detonating nuclear weapons to test them in 1992, the National Nuclear Security Administration (NNSA) and predecessor agencies have used subcritical experiments, which the agency says produces no self-sustaining nuclear chain-reaction, to determine whether U.S. nuclear weapons have retained their design destructive yield as they age.
A version of this story first appeared in Defense Daily affiliate publication Exchange Monitor.