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 [calendar year] 2020,” a spokesperson for the nuclear-weapon facility told Nuclear Security & Deterrence Monitor by email this week.
The lab spokesperson declined to say when, or whether, each test is scheduled to 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 so far about one month behind schedule; it was once 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. The tests are funded under the Research, Development, Test, and Evaluation portion of the NNSA’s weapons budget, in an account called Dynamic Materials Properties that also includes other plutonium research. Congress approved $128 million for Dynamic Materials Properties in the current fiscal 2020, an $8 million raise from 2019 but nearly $6 million less than the 2020 request.
The 2017 notional schedule also included a test called Nightshade L, but that experiment has been dropped, the Los Alamos spokesperson said this week.
It can takes weeks or months to reset the U1a complex after a subcritical test.
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.
