The Energy Department cannot meet its own post-Sept. 11 security standards to repel a terrorist force at the Ft. Knox of uranium, a facility in Tennessee that stores an estimated 189 metric tons of bomb-grade material, agency officials acknowledged.
The material is stored in five masonry and wood-frame buildings at the Y-12 facility, a key part of the nation's nuclear weapons infrastructure at the Oak Ridge site near Knoxville.
The Energy Department's National Nuclear Security Administration is building a secure facility, due to be completed in 2009, to warehouse the material. Until then, the Energy Department has given itself an "extension," or waiver, on meeting security requirements at the site.
The risk is that terrorists will gain access to highly enriched uranium and then within minutes construct a crude but powerful improvised nuclear device, or IND. It is believed such a device could have a yield equal to that of the Hiroshima atomic bomb.
The issues at Y-12 were disclosed in a report by the Project on Government Oversight, a Washington, D.C., group that has urged the Energy Department in recent years to strengthen security at all of the nation's nuclear weapons sites.
Officials at Y-12 acknowledged they were not meeting the security requirements but rejected the concerns raised by the organization. Y-12 spokesman Steven Wyatt said the facility's security force could effectively defend the site and prevent terrorists from constructing a weapon.
"There are better odds that an asteroid would hit Oak Ridge than the likelihood that terrorists would have the access and time to build and detonate an IND," Wyatt said.
After the Sept. 11 attacks, the department quadrupled in several steps the number of terrorists that it assumed it would have to repel at all of its nuclear weapons facilities. The number is classified, but it is believed to be in line with the number of terrorists who executed the attacks on the World Trade Center and the Pentagon.
Then last year, the agency watered down the number of assumed attackers. Even with the weaker standard, the department decided it could not fully guarantee that a highly trained terrorist assault team could be repelled at Y-12 without millions of dollars in additional expenses.
At the Tennessee site, the department has 527 guards, provided by the private security firm Wackenhut Services Inc. To meet the federal security standard -- known as a "design basis threat" -- would have required a force of 800 guards, said Peter Stockton, one of the key authors of the report and a former security consultant to the Energy Department.
The issue has caused political headaches at the highest levels in the department.
Early this year, Linton F. Brooks, chief of the nuclear security agency, told his staff they would have to find a way to explain to Congress why the agency was failing to request money to upgrade security.
"We all know that is because [the Bush administration's Office of Management and Budget] denied funding, but since we will be defending the administration's position, we won't be able to say that," Brooks told his subordinates in an e-mail in January.
"I think there is serious risk to our credibility if we say nothing," he wrote.
After weighing various proposals from his staff on how to spin the agency's decision not to meet its security standards, Brooks warned, "The only thing I think we absolutely must avoid is misleading the Hill."
An analysis by the watchdog group found that a terrorist assault team would have more firepower than the Wackenhut guards. It also showed that an improvised nuclear device would destroy much of Knoxville and cause an estimated 60,000 deaths.