“No material or sensitive information at Lawrence Livermore National Lab is at risk, and the security at the site remains strong,” he said.
All plutonium at the facility will be removed in four years, he said.
The NNSA said in a statement Friday that a recent “security assessment” identified several areas needing improvement.
Lawrence Livermore is part of the nuclear weapons complex and conducts research on plutonium pits used in nuclear weapons.
Laboratory spokeswoman Susan Houghton said some personnel were reassigned as a result of the security review and one immediate step will be to increase the training of the protective force officers. “We’ve accelerated training, and we’re training against more real-world threats,” she said.
The anti-nuclear group Project on Government Oversight (POGO), which monitors security at Energy Department facilities, said in a statement that the penetration drill shows the problems of security at the facility.
“The hydraulic system used to raise the gun from its hiding place inside the back of a small truck failed, making it impossible for the gun to be fired,” POGO said, noting that the group has been critical of the deployment of the gun because of its one-mile range that poses a danger to nearby residences.
The group also stated that special response teams of armed security guards were involved in tactical failures during the drill.
“It is important to emphasize that Livermore’s security problems are not the fault of the guard force, who have complained about their lack of training and poor tactics,” said POGO senior investigator Peter Stockton. “In fact, two security officers were fired for raising these problems.”
Time magazine, which first reported the penetration drill in its Monday editions, stated that the attacking force was able to penetrate Building 332, which contains about 2,000 pounds of plutonium and weapons-grade uranium.
The mock terrorists gained access to a payload of simulated fissile material inside the facility.
A POGO report on Lawrence Livermore security problems last year stated that contract security guards are not equipped to adequately secure the site and have limited capabilities to communicate with local police.
“As a result, coordinating an effort to recapture stolen [special nuclear material] is virtually impossible,” the report said.
A POGO report from March stated that the laboratory has been unable to meet U.S. government security requirements and was given a waiver from the Energy’s nuclear security administration.
“This action comes at a time when experts warn that the threat of nuclear terrorism is growing,” the report said.