Lawrence Livermore Laboratory's protective force failed to deter a mock terrorist attack during a recent security drill, according to a Time magazine report online Monday.

During the simulated night-time attack several weeks ago, a team posing as terrorists was able to defeat the lab's defenses and get hold of their target of pretend nuclear material, according to unnamed sources.

Bryan Wilkes, a spokesman for the National Nuclear Security Administration, which oversees the lab for the Department of Energy, told the Times that the initial results of the inspection were "disappointing."

But he noted that the simulated attacking force was given insider information and other advantages that "would be highly improbable in a real world scenario.

"While we have security measures in place that are working, in a number of cases they can be improved upon, and the system pointed that out," he said.

Four of the areas of the lab's security that were inspected during a routine, seven-week independent audit conducted by the Department of Energy's Office of Health, Safety and Security during April and March were rated as "effective performance," and four needed improvement.

The lab has taken action to fix problems uncovered by the inspection, said lab spokeswoman Susan Houghton.

"We've added officers, reassigned personnel, and we have accelerated our training from quarterly to daily," she said.

No nuclear material or sensitive information was ever at risk, Houghton said.

A DOE official familiar with the mock attack said that the Time report was exaggerated.

The attacking force did reach their objective, he said, and the defenders did not do as well as they could have in some areas, but the attack was unrealistic.

For one, the simulation started at the fence line of the plutonium facility known as Superblock, already well inside lab property, he said. The attack team was made up of security officers from other DOE sites and was allowed to haul in equipment, including ATVs and mock explosives.

Some members of the attack team were even positioned inside rooms in the Superblock, as if they had already cut fences, blown up walls and avoided guards. The mock attackers were also treated to a walkthrough ahead of the exercise.

"They knew exactly what was there, how to get to certain places and where the defenders would be," said the official who spoke on condition of anonymity. "It just wouldn't happen in real life."

The whole point of the force-on-force test is to really stress the system and hit the pressure points, he said.

"Things don't run perfectly in a force-on-force," he said. "That's not the point. You want to see where the stress points are. That's why you do it."

Among the problems highlighted by the Time magazine report was the failure of one of the lab's powerful Gatling guns, capable of firing 4,000 rounds per minute, to get into firing position due to problems with a hydraulic system.

The guns were added to the lab's arsenal in 2006 to bolster its ability to protect the weapons-grade plutonium and highly-enriched uranium.

"Failing an exercise like a mock terrorist attack highlights serious and unacceptable security shortcomings," said Rep. Ellen Tauscher, D-Alamo. "I have insisted that the plutonium housed at Livermore be consolidated and moved away from Livermore to a safe location away from population centers as soon as possible."

In March, the National Nuclear Security Administration said it was on track to remove the plutonium from the Livermore lab by 2012, in part to reduce security costs by consolidating special nuclear materials at fewer sites.

National Nuclear Security Administration director Thomas D'Agostino told the Times that it makes sense to move Livermore's plutonium to its sister nuclear weapons lab in New Mexico because "you don't have communities growing up around Los Alamos."

The 2012 goal is two years earlier than the previous plan, but critics still think the plutonium can and should be moved sooner.

"We think this should be the DOE's highest priority," said Marylia Kelley of Livermore-based watchdog group Tri-Valley CAREs.

Kelley believes the plutonium could be safely packaged and removed by 2010, perhaps even by the end of 2009.

The recent security test "shows that the nuclear materials at Livermore lab isn't secure and cannot be made secure," she said.