The containment vessel that blew a leak during a subcritical nuclear test last year in Nevada was not properly designed or procured, the Department of Energy’s Los Alamos National Laboratory concluded in a final report about the accident.
The independent federal Defense Nuclear Facilities Safety Board (DNFSB) summarized the lab’s unreleased report in a recent monthly review of the Nevada National Security Site, where the underground test — dubbed Ediza — took place.
Personnel from Los Alamos National Laboratory in New Mexico and Mission Support and Test Services, the management and operations contractor for the former Nevada Test Site, “were not trained and qualified as subcontract technical representatives, which resulted in less than adequate procurement and quality oversight of the manufacturing process,” the DNFSB stated in its report, dated March 6.
Likewise, “the vendor responsible for building the confinement vessel did not have prior experience manufacturing vessel weldments to the appropriate American Society of Mechanical Engineers requirements.”
Los Alamos designed the test, which was conducted in the underground U1a Complex.
Subcritical tests produce no yield, but explosively compress plutonium almost to the point of a fission chain reaction. Observing that compression allows DOE’s semiautonomous National Nuclear Security Administration to determine whether the nuclear-weapon material is aging as expected — an important consideration when the U.S. produces no new plutonium and is still a few years away from being able to cast more than a handful of fissile nuclear-warhead cores annually.
Los Alamos disclosed in January that the Ediza vessel leaked because a diagnostic port blew open during the Feb. 13, 2019 test, releasing a small amount of radioactive material. It took about a month to decontaminate the U1a zero room, the site of the Ediza test, Los Alamos said. The lab said it collected usable data from the test, that the contamination was limited to the zero room, and that the incident did not delay other subcritical tests in the Nightshade series, which is scheduled to continue this year.
The Ediza vessel has been entombed in the U1a Complex.
