NNSA completes subcritical experiment at PULSE facility in Nevada

WASHINGTON – On the evening of May 14, the U.S. Department of Energy’s National Nuclear Security Administration successfully executed a subcritical experiment in the Principal Underground Laboratory for Subcritical Experimentation (PULSE) facility at the Nevada National Security Site. The experiment was the first in the Nimble series, executed in partnership with Lawrence Livermore National Laboratory. The series will also be supported by Los Alamos National Laboratory.

NNSA relies on subcritical experiments to collect valuable information to support the safety, security, reliability, and effectiveness of America’s nuclear warheads, without the use of nuclear explosive testing. The Nuclear Security Enterprise will use the results of this experiment to improve our modeling and simulation capability, part of the science-based stockpile stewardship program that NNSA has led for over 30 years.

This experiment performed as predicted; consistent with the self-imposed moratorium on nuclear explosive testing that the United States has held since 1992, it did not form a self-sustaining, supercritical chain reaction. This experiment and all 33 previous U.S. subcritical experiments were consistent with the zero-yield standard of the Comprehensive Nuclear-Test-Ban Treaty. 

“The success of this subcritical experiment was made possible by collaboration across our enterprise, and our investments in science and technology,” said Dr. Marvin Adams, Deputy Administrator for Defense Programs. “As NNSA Administrator Hruby announced in June 2023, we plan to increase the frequency of these subcritical experiments so we can continue to gather important data on nuclear weapons materials, with no technical need for a return to underground nuclear explosive testing.”