The U.S. Department of Energy’s Los Alamos National Laboratory in New Mexico still plans this year to begin the next round of subcritical plutonium experiments, a series dubbed Nightshade.
“In order to accommodate ongoing experiment preparation, facility work, and other programmatic priorities the Laboratory is planning to execute the Nightshade A SCE [subcritical experiment] in 2020,” a spokesperson for the nuclear-weapon facility told Weapons Complex Morning Briefing by email last week.
The spokesperson did not say exactly when Nightshade A would fire. The lab conducts these underground, explosive plutonium tests at the Nevada National Security Site’s U1a complex. Compared with a notional schedule published in 2017, Nightshade is about one month behind schedule; it was slated to fire in December 2019.
The most recent subcritical test, Ediza, fired on Feb. 13, 2019, at U1a. Ediza wound up firing two months after the 2017 notional schedule said it would.
The Energy Department’s semiautonomous National Nuclear Security Administration (NNSA) plans three Nightshade tests – A, B, and C – in 2020, according to the agency’s latest budget request.
Subcritical experiments provide data the NNSA can use to determine — without the benefit of a full-scale nuclear chain reaction — whether plutonium stockpiles retain enough explosive potency to meet the design requirements of existing nuclear weapons. The United States ceased full-yield, underground explosive testing in the 1990s.
