A recent mock terrorist infiltration conducted at the Lawrence Livermore National Laboratory (LLNL), located near San Francisco, showed that fissile material necessary for building nuclear weapons was not hard to obtain. In Building 332, the faux-invaders found access to approximately 2,000 pounds of weapons-grade uranium and deadly plutonium, a surplus bountiful enough to build at least 300 nuclear weapons. The simulated attack also revealed problems with the lab’s hydraulic system which controls the Gatling gun responsible for protecting the facility.

Voices from Capitol Hill, across party lines, called the incident “an embarrassment to those responsible for securing the nation’s nuclear facilities,” and called for immediate steps to correct the lab’s major security weaknesses. Danielle Brian, Executive Director of the Project on Government Oversight, explained the danger of allowing terrorists access to the wealth of nuclear materials at Livermore. She argued that terrorists willing to sacrifice their lives would not need to escape the lab safely with apprehended fissile materials. “They could simply detonate it as part of an improvised nuclear device on the spot.” With nearly seven million residents within 50 miles of the lab, the possibility of such a detonation has led many experts to urge the lab to choose a more remote location for nuclear material.

The laboratory undergoes staged attacks annually, and the faux foes are timed to see how much damage real invaders could inflict. Can the attackers evade the lab’s security system just in time to build a “dirty bomb” for immediate detonation? Can they hold off the lab’s armed guards long enough to quickly construct a rudimentary device with a destructive capability akin to the bombs dropped on Hiroshima and Nagasaki? Or, would it be best to simply rush past the out-of-order Gatling gun and leave the lab altogether, fissile materials in tow, to use a nuclear device in the heart of San Francisco?

Located above an irrigation canal, less than two miles from elementary schools, a pre-school, a middle school, a senior center, and a major highway junction, Livermore’s security defects have invigorated opposition to the storage of nuclear weapons materials at the lab. Marylia Kelley, executive director of Tri-Valley CARES, a nuclear weapons watchdog group, argued that the fissile materials at Livermore “simply cannot be made safe and secure.” She explained that the Livermore community, consisting of 81,000 residents, strongly desires that the plutonium and highly enriched uranium be moved elsewhere.

The stores of weapons-grade uranium and plutonium across the street are not the only thing inducing anxiety among Livermore’s residents. The lab’s security system, assuming that its components are in working order, also serves to stir unease in the suburban homes nearby. The laboratory’s Gatling guns, which were purchased by the National Nuclear Security Administration (NNSA) just after the Department of Energy approved doubling the lab’s plutonium storing capacity, each release the force of a dozen armed guards, firing 4,000 rounds per minute and taking down targets up to a mile away. Former Administrator of the NNSA, Linton Brooks, explained that the guns “leave no doubt about the outcome” in the event of a military-style air or ground attack on the lab.”

Kelley, of Tri-Valley CARES, referred to “children on bicycles and skateboards … people walking their dogs,” along the western perimeter of the lab, and questioned the transformation of the science laboratory into a fortified arsenal, prepared for military style attacks. In a residential neighborhood, she argued, “you can’t just indiscriminately open fire.” The Gatling guns are supposed to be tested regularly, and no explanation has been given for their malfunction.

While the security failures exposed at Livermore seem unacceptable to most, many experts believe that many more exist, and remain undiscovered due to inherent flaws in the “force-on-force” simulated attacks. The mock intrusions generally occur at night or on weekends when the lab’s employees are safe at home and not susceptible to hostage-taking, and when the defenders are given advance notice of the attack. The staff-free corridors of the laboratory during these simulations do not give the defenders accurate practice at securing the lab, as they do not have to distinguish their firing between innocent bystanders and intruders. The “force-on-force” exercises also do not assess the lab’s capability of withstanding an attack from a rogue aircraft passing along one of the flight paths to or from one of the nearby airports.

In a press release on the newly exposed security flaws, the Department of Energy (DOE) explained that the “force-on-force” simulation revealed both positive aspects of the security system and others “requiring corrective action.” A spokesperson told Time that the DOE does not believe the nuclear materials at Livermore are at risk, but is “interested in examining any deficiencies.”

As long as there are those who seek access to the US’ stores of plutonium and uranium at Livermore, and those who build their lives on the suburban streets around the lab, perhaps the DOE should examine the prospect of transplanting its fissile material fortress, rather than waiting for new deficiencies to emerge, or simulated failures to become real tragedies.

Rachel Hitow is the Nuclear Age Peace Foundation’s Washington, DC Intern.