Nuclear Device Assembly Facility In Nevada Desert May Be A Ticking Time Bomb (Updated)

One of the most important and high-security facilities in the Department Of Energy’s sprawling nuclear infrastructure portfolio could be a radiation hazard just waiting to occur according to the Chairman of the Defense Nuclear Facilities Safety Board. 

The fortress-like Device Assembly Facility (DAF) sits about 60 miles northwest of Las Vegas within the highly-security Nevada National Security Site (NNSS)—previously called the Nevada Test Site—near Yucca Dry Lake. 

The NNSS is surrounded by the Nevada Test and Training Range (NTTR) with shadowy neighbors like Area 51. The entire area continues to have massive strategic importance as evidenced by a recent Russian surveillance flight directly over the NNSS that occurred according to the rules of the Open Skies treaty.

NNSS Powerpoint

It turns out that the area is at a much higher risk to powerful seismic activity than the DAF’s designers realized decades ago. Considering that the potentially seismically vulnerable installation houses nuclear material and high explosives, and these compounds are manipulated inside the facility, a large quake could have terrible consequences. The issue was first reported on by Gary Martin of the always great Las Vegas Review Journal.

In an official letter to DOE secretary Rick Perry, Chairman Bruce Hamilton states the following:

“The Defense Nuclear Facilities Safety Board is concerned that the Department of Energy has not adequately addressed the seismic hazards for the Device Assembly Facility at the Nevada Nationatinal Security Site. The DAF probabilistic seismic hazard analysis update in 2007 identified a significant seismic hazard increase… A seismically induced high explosive violent reaction could result in unmitigated dose consequences to the offsite public… The facility continues to operate without accounting for the increase in seismic hazard and without evaluating whether the credited structures, systems, and components can perform their safety function during and after a seismic event.”

Here is the full letter:

DNFSB via Scribd

The Device Assembly Building is a low-slung, partially buried, extremely high-security, bunker-like structure that is ringed by rows of security fencing and flanked by turrets. Internally it is comprised of various compartments including nuclear storage and device assembly areas, labs, and administrative offices. It was built in the 1980s and has quietly supported America’s nuclear deterrent enterprise ever since, with a history that includes acting in conjunction with live tests at the National Test Site before such events were officially curtailed in 1992.

The DAF near Yucca Flats and deep within the NNSS. , DOE

An official DOE factsheet offers a fascinating description of the foreboding facility:

“For 41 years, nuclear weapons testing was the primary mission during which nuclear testing operations occurred in a safe, remote, and secure environment. These operations included assembly, disassembly, modification, staging, transportation, maintenance, repair, retrofit, and testing of nuclear devices. 

The mission of the DAF continues evolving since the nuclear weapons testing moratorium began in October 1992. Current missions are an integral part of the U.S. Department of Energy National Nuclear Security Administration’s Stockpile Stewardship Program, which includes work to support subcritical experiments, special nuclear material staging, and emergency response training. 

The DAF is a collection of more than 30 individual steel-reinforced concrete buildings connected by a rectangular common corridor. The entire complex, covered by compacted earth, spans an area of 100,000 square feet. Safety systems include fire detection and suppression, electrical grounding, independent heating, ventilation and air conditioning systems with high-efficiency particulate air filters, alarm systems, and warning lights. 

In operational areas, pairs of blast doors, designed to mitigate the effects of an explosion, are interlocked so that only one door may open at a time. The operational buildings in the DAF include assembly cells, high bays, assembly bays, one of which houses a glove box, and one of which houses a downdraft table, and radiography bays. 

Staging bunkers provide space for staging nuclear components and high explosives. All materials packages arrive or depart the DAF through one of two shipping and receiving bays. The support buildings include vaults for staging explosives, or special nuclear material decontamination areas and an administration area with office space, a conference area, personnel changing and shower rooms, and a machine shop. In addition, two buildings provide laboratory space, one for conducting instrumentation and environmental testing and the other for observing operations in an adjacent assembly cell.

The assembly cells were named Gravel Gerties after a 1950s comic-strip character. Modeled after the structure at Pantex Plant, these are where hands-on assembly and disassembly of U.S. nuclear weapons and devices would take place. They provide the maximum environmental and personnel protection in the event of an inadvertent high-explosive detonation. 

The cells are designed to absorb the blast pressure from a detonation of explosives equivalent to 250 kilograms (or 660 pounds) of TNT. Should a detonation occur, the Gravel Gertie would minimize release of nuclear material and its spread to other areas of the facility and to outside areas. 

The DAF is a national asset. The design of the facility and its safety features makes the DAF well-suited to address new national challenges – such as the National Criticality Experiments Research Center (NCERC) to the NNSS- which supports maintaining the nation’s nuclear stockpile. Additionally, the DAF is used to prepare subcritical experiments and target chambers for the Joint Actinide Shock Physics Experimental Research facility experiments. 

Currently, the United States is not conducting nuclear tests. However, in 1992 the then President in a Decision Directive pledged to maintain an underground test readiness program in the event that nuclear testing resumes. 

The DAF is located in the interior of the NNSS and its remoteness provides a substantial safety zone for the general public and adds to the security of the facility. In addition, activities at the DAF comply with the National Environmental Policy Act and all applicable federal, state, and local regulations.”

Photos from inside the facility are very limited, but here are some that show a couple of its unique areas:

See a diagram of the Gravel Gertie here. , Top: DOE Bottom: Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (

In an interesting read posted over at Lawrence Livermore National Laboratory’s webpage, it notes that the facility would also be used to “disable nonstandard explosives, such as a clandestine nuclear device.” 

A Defense Nuclear Facilities Safety Board staff report dated November 27th, 2018 discusses the fact that the facility sits on ground that is more unstable than architects realized during its design and construction. It states:

“The Board’s staff review team is concerned that DAF continues to operate without incorporating the increased seismic hazard and without analyzing its credited safety-related SSCs to ensure that they can perform their safety function during and after a seismic event. In the DAF documented safety analysis, a high explosive violent reaction (HEVR), or a detonation of high explosives that are co-located with special nuclear material, has the highest public dose consequences that challenge the evaluation guideline and require safety class controls.”

The report goes on to talk about all the systems in place to help mitigate risk to the public during an accident and notes that these systems may not meet the current risk requirements. The same goes for the overhead crane systems, ducts, conduits, and other infrastructure contained in the facility. 

The report includes a somewhat ominous conclusion:

“The Board’s staff review team is concerned that DAF continues to operate with the increase in seismic hazard and MSTS has not adequately evaluated credited safety-related SSCs to ensure that they can perform their safety function during and after a seismic event. Seismic accident scenarios at DAF could result in significant consequences to the offsite public. Since the impact of seismic events on DAF SSCs has not been adequately characterized, DAF continues to operate with unknown risk.”

All of this is quite timely as America’s aging nuclear infrastructure is taking center stage once again as the Pentagon pivots towards focusing on what it calls “great power competition.” This includes not just modernizing America’s existing nuclear arsenal, but also adding new nuclear capabilities like low-yield tactical nuclear warheads that can be mounted on cruise and ballistic missiles. With new nuclear weapons come the need for billions of dollars worth of testing and development and they have to be assembled and maintained somewhere over the course of their service lives. 

With these developments in mind, it is quite possible, if not probable, that the DAF will see a substantial uptick in operations in the coming years, not the other way around. 

Gary Martin of the Las Vegas Review Journalnotes in his article that the Nevada Governor’s office is aware of the report and is taking it very seriously. As for revelations about elevated seismic risk to an area that houses many of America’ most secretive and sensitive installations, Martin writes:

“The most recent U.S. Geological Survey, in 2008, lists the area that includes the Nevada security site and nearby Yucca Mountain, a proposed nuclear waste repository, as one of moderate to high seismic hazard.

Two faults, the Northern Death Valley and the Black Mountains, are located near the Nevada security site and the proposed nuclear waste storage facility.

Sen. Catherine Cortez Masto, D-Nev., said earlier this week following a Senate hearing on the Energy Department’s budget request to jump start licensing to open Yucca Mountain for nuclear waste storage that the site was “seismically unsafe.” 

America’s Nuclear weapons enterprise has controversial but deep roots in Nevada and nuclear material and warheads are constantly being transported in and out of the state by the National Nuclear Security Administration’s road-borne paramilitary force tasked with protecting their deadly cargo at all costs. This includes rolling across thousands of miles of highway in armored vehicles and heavily customized semi-trailers replete with booby traps and other active defenses. You can read all about this unique force in this past feature of ours.

The National Nuclear Security Administration also commands a small army of law enforcement agents and contractors that guard the NNSS and the DAF within it, as well as many other sensitive DOE sites across the United States. They are equipped with heavy armaments that are not traditionally found in the arsenals of other domestic law enforcement outfits. 

In the case of some sort of nuclear disaster, a number of the DOE’s radiation mapping aircraft and rapid response teams are based in Nevada at Nellis AFB, which is located on the outskirts of nearby Las Vegas. They would be absolutely key in mapping an accidental radiologic release so that officials can try to limit the impact of the disaster through evacuations and/or order citizens to shelter in place. 

The potential vulnerability of the DAF to earthquakes is just another reminder of America’s rickety nuclear infrastructure that supports the strategic deterrent. Some have said it is not a matter of if but when a major nuclear issue occurs at one of these sites due to lack of maintenance, upgrades, and a robust long-term plan for storing nuclear waste. Even concerns about security in and around America’s nuclear stockpile have been raised. Scares of multiple types have occurred recently, some of which seem to underline these concerns. 

The fact is that the dawn of nuclear age and the Cold War that followed has left the U.S. speckled with bizarre nuclear sites, most of which the average person would never know existed. But that could rapidly change if a major accident that could have been avoided occurs at one of them…

Such as an earthquake near the Device Assembly Building at a very inopportune time. 

Update: 12:00pm PDT 4/4/2017—

We received the following response to our story from the National Nuclear Security Administration: 

“The concerns expressed by the Defense Nuclear Facilities Safety Board (DNFSB) about a seismic event at DAF are based on unmitigated radiation dose consequences associated with an explosion induced by an earthquake during nuclear explosive operations when high explosives are in close proximity with large quantities of nuclear material. However, nuclear explosive operations are not authorized at the DAF.   

Authorized activities involve significantly less nuclear material than would be present for nuclear explosive operations.  Accordingly, the worst case radiation dose associated with current DAF operations, such as subcritical experiment assembly, is significantly less than established dose limits for the public and are far less than that those reported by the DNFSB. 

Because of the lower magnitude of hazardous materials involved in current operations, the Department concludes that the risks associated with DAF seismic hazards are analyzed and understood. That notwithstanding, NNSS is working to update its analysis.   

The M&O partner, Mission Support and Test Services (MSTS), at the NNSS has commissioned and completed a revision to the DAF seismic hazard sensitivity analysis, including a peer review. These improved analyses will be used to update the DAF safety analysis in the future, but risks are adequately addressed in the safety analysis for current operations. 

The half-ton of plutonium shipped from South Carolina is staged in a secure building that prohibits the introduction of high explosives and ensures adequate protection from external explosive events. This material would not be adversely impacted by a seismic event.” 

The thing that stands out with this response is that the Defense Nuclear Facilities Safety Board did account for the change in the DAF’s use and operation and still found there to be major safety issues, stating:

“However, even with removal of the nuclear explosive operations mission, DAF still will have high explosives co-located with special nuclear material. Specifically, part of DAF’s mission is to build subcritical experiments, which includes mating high explosives to special nuclear material. Therefore, the potential for seismically induced HEVR accidents is still credible at DAF. MSTS has not conducted an analysis to determine how the material (i.e., high explosives co-located to special nuclear material) will be reduced and what impacts the reduction will have on the dose consequences for HEVR accidents.”

We will reach out to the Defense Nuclear Facilities Safety Board for comment on the NNSA’s response.

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