Materials shortages, technology changes and other factors have pushed major enhancements to a nuclear-weapon testing facility in Nevada back three years and inflated the overall project cost to $1.8 billion, according to the National Nuclear Security Administration’s 2024 budget request.
Supply chain disruptions and other problems caused by the COVID-19 pandemic also contributed to the project delays, which could run up against the military’s schedule for fielding new and refurbished nuclear warheads in the 2030s.
Once scheduled to be complete by fiscal 2027, the Enhanced Capability for Subcritical Experiments (ECSE) project at the Nevada National Security Site’s U1a underground complex, which includes installing a sophisticated new x-ray camera to measure explosive plutonium tests, is now slated for completion in late fiscal 2030.
“During project design, challenges resulted in multiple design modifications under appropriate change control,” according to the request. “The growth in the project’s estimated costs have been driven by … technology changes – incorporation of more advanced technology, to include full solid state pulsed power, to provide expanded capabilities and flexibility to meet the data needs for the Subcritical Experiment program in support of multiple weapon systems.”
Upgrading the agency’s subcritical experiments capability involves expansion of the Nevada site’s existing underground laboratory to accommodate the large modern diagnostic systems necessary to evaluate plutonium implosion system experiments that help maintain the U.S. nuclear weapon stockpile.
As recently as last year, the NNSA listed fiscal year 2026 as the target date for commencing subcritical experiments with the new Scorpius x-ray imager at the expanded U1a complex.
Scorpius, within the Advanced Sources and Detectors program, passed its critical decision three milestone on Nov. 30. Its Critical decision four milestone is scheduled for the third quarter 2030, or no later than April 2031. Critical decision three signals the beginning of construction, critical decision four the end.
A key milestone schedule for the program included in the NNSA budget documents lists fiscal year 2031 as the target date for beginning subcritical experiments in the U1a complex, using Scorpius and other Advanced Sources and Detectors (ASD).
The NNSA requested a total of $279.6 million for ASD in its fiscal 2024 budget request.
Scorpius is designed to capture data during subcritical experiments on weapons-grade plutonium used in the primary stage of nuclear weapons. NNSA planned to use the device for validation of the W80-4 and certification of W87-1 warheads, to be carried by the Long Range Standoff Cruise Missile and Intercontinental Ballistic Missiles, respectively.
Both the ECSE and preparations for NNSA’s first exascale high-performance computing system are “required to meet W80-4 LEP confirmation experiment and reduce uncertainty in the W87-1 modification certification,” according to the budget documents.
NNSA did not answer a request for comment this week about how the ECSE upgrades would affect modernizations of those weapons. In February, Marvin Adams, NNSA’s associate administrator for defense programs, told the Exchange Monitor that if Scorpius isn’t ready when prospective users want it to be, those people will have to make do with the tools that are available.
The Lawrence Livermore National Laboratory and the Los Alamos National Laboratory, the respective design labs for the W80-4 and W87-1 programs, hoped to use Scorpius and the other planned upgrades at U1a for work on those weapons. Los Alamos also hopes the new U1a facilities will be available before development of the Navy’s new W93 intercontinental ballistic missile warhead begins in earnest. First delivery of that weapon is due in the mid-2030s.
