ALEXANDRIA, VA. — Materials for the third and final Nightshade subcritical plutonium test at the Nevada National Security Site have shipped out from the Los Alamos National Laboratory ahead of a shot planned for the fall, the head of the lab’s weapon’s program said here this week.
Nightshade C had been scheduled to fire in Nevada by September, Los Alamos has said. The previous test in the series, Nightshade B, fired in June.
“The samples have been made and shipped” for Nightshade C, Bob Webster, Los Alamos’ deputy director for weapons, told Nuclear Security & Deterrence Monitor here Wednesday at the Exchange Monitor’s annual Nuclear Deterrence Summit.
Subcritical tests explosively compress plutonium inside of a steel sphere deep underground at the Nevada National Security Site. Such tests aim to bring the material to the brink of a nuclear fission chain reaction without producing a nuclear yield. The resulting data helps the NNSA determine if plutonium has retained its destructive capacity as it ages.
The Nightshade series began with Nightshade A, which fired on Nov. 3 and was the first subcritical test the National Nuclear Security Administration had gotten off in more than a year. The Nightshade series was delayed after the previous subcritical test, Lawrence Livermore National Laboratory’s Ediza, leaked some radiation from a breach in its underground containment sphere after a 2019 shot.
Livermore’s next subcritical series is called Nimble, Bradley Wallin Livermore’s program director for weapon physics and design and weapons and complex Integration, told Nuclear Security & Deterrence Monitor here Wednesday. The first Nimble shot was notionally scheduled for Spring 2022, Wallin said.
