A recent assessment of security at the Energy Department’s Lawrence Livermore National Laboratory has found unspecified–but apparently serious–“vulnerabilities” in the ability of guard forces to protect weapons-usable plutonium and high-enriched uranium kept at the California nuclear weapons facility.

In a press release issued late Friday, the National Nuclear Security Administration (NNSA), the semi-autonomous DoE agency that runs the department’s nuclear weapons complex, said the security assessment by DoE’s Office of Health, Safety and Security found “several areas needing improvement.”

The press release said the assessment included a “force-on-force” exercise, which are held at sensitive DoE sites to test the ability of guard forces to repel attacking terrorists. In the exercise, a tactical security team plays the role of attacking terrorists who are seeking to gain control of nuclear materials.

Some sources told sister publication The Energy Daily that the recent Livermore exercise ended with the team of mock terrorists gaining control of a simulated load of special nuclear material that was supposed to be protected by guards.

However, other sources familiar with the exercise said that was not the case.

“The force-on-force is specifically designed to find vulnerabilities–and it did,” said one authoritative source. “It identified some vulnerabilities, but that is why you do the force-on-force.”

NNSA officials refused to characterize the severity of the failures seen in the force-on-force exercise, but the agency’s press release made it clear that NNSA brass was unhappy enough to take their concerns to the board of directors of Lawrence Livermore National Security LLC (LLNS), the new contractor recently hired by NNSA to improve operations at the facility.

“NNSA Principal Deputy Bill Ostendorff said that the initial results of the LLNL inspection highlighted a number of areas that require immediate attention, and that he expected the laboratory to work closely with the NNSA Livermore Site Office to make needed improvements,” the NNSA press release said. “In addition, senior NNSA officials have discussed these security issues with the LLNS Board of Governors.”

The press release also revealed that after the negative inspection findings by the Office of Health, Safety and Security, NNSA reviewed corrective actions being taken by LLNS and was not pleased.

“NNSA sent a team of headquarters and field security experts to assess the laboratory’s response to the inspection,” the press release said. “Although the inspectors noted several very positive areas, there were other areas requiring corrective action. NNSA is evaluating the corrective actions put into place by LLNL.”

The bad inspection findings are of particular concern to NNSA because Livermore already is regarded as one of its most vulnerable facilities due to its proximity to surrounding residential neighborhoods in the San Francisco Bay Area. Security experts say that while other NNSA facilities are hard to creep up on because they are located in isolated, rural areas, terrorists seeking to launch an attack on Livermore would have ample cover in the neighborhoods surrounding the facility, enabling them to get very close to the facility’s fences without detection.

As a result of that vulnerability, NNSA has pledged to remove plutonium and other special nuclear material from Livermore by 2012, although some antinuclear activists are suspicious that the agency does not intend to meet that deadline.

Tri-Valley CARES, a local community watchdog group at Livermore, notes that NNSA recently increased administrative limits on the amount of plutonium that can be stored at Livermore. In addition, the group says Livermore has been building a new plutonium foundry at the site to test new pit production methods for next-generation warheads.

The new security issues also are disappointing to NNSA because it hoped to address longstanding security and operational issues at Livermore by hiring LLNS, a consortium led by the University of California and Bechtel. Specifically, Bechtel was brought in by the University of California, the former operator of Livermore, to provide operational support.

NNSA also has tacitly acknowledged the security problems at Livermore by declaring that the site does not have to meet the “design basis threat” (DBT) security requirements issued by the agency in 2005 for its nuclear weapons facilities. The DBT lays out the specific terrorist threat that each NNSA site must show it can repel, including the number of attacking terrorists and their weaponry. The 2005 DBT was substantially tougher than the 2003 DBT previously in effect, reflecting concerns raised by the September 2001 terrorist attacks in New York City and the Pentagon.

NNSA officials said they waived the 2005 DBT for Livermore because it is a “non-enduring” site in regards to plutonium storage, meaning the site will be emptied of special nuclear materials. As a result, the agency says it would not make sense to invest millions of dollars needed to harden buildings and other infrastructure at the site needed to meet the 2005 DBT.

However, critics say the exemption from the 2005 DBT was necessary because it is virtually impossible for Livermore to meet the DBT requirements given its vulnerable location.