In the vastness of cyberspace here at Lawrence Livermore National Laboratory, where miles of cable link an array of powerful supercomputers, there is no place to hide anymore.

Every keystroke anyone logs onto this vast unclassified network is recorded. Every outgoing e-mail is searched electronically. All calls coming into the system go through a single "cyberpass," protected by a firewall. And scanners search the network for unauthorized modems and classified files that may have been transferred inadvertently from an even more secure classified system.

There is even a network scanner called "the whacker," developed by scientists at this nuclear weapons lab, that constantly searches servers and directories and shuts down "world access" entry codes to prevent foreign scientists engaged in an array of unclassified research here from gaining blanket access to all types of "sensitive" unclassified technical data.

Call it the world that Wen Ho Lee made, a cyberfortress erected since FBI agents discovered in late March that the former physicist at Los Alamos National Laboratory, another Energy Department weapons lab, downloaded massive amounts of classified data from the lab's classified network to unsecure magnetic tapes and his own vulnerable desktop computer.

Computer security officials here describe these and other cyber security measures implemented over the past nine months throughout the Department of Energy's national laboratories as the electronic equivalent of SWAT teams, clad in black fatigues and body armor, which are now also guarding Livermore's stockpile of nuclear materials.

Like the cyber security teams, these highly trained commandos recently arrived here at Livermore--and at DOE's other nuclear weapons facilities--as part of Energy Secretary Bill Richardson's security and counterintelligence crusade.

The computers, and the stockpiles, appear virtually impenetrable.

But security officials here wonder whether the computer safeguards have been pushed to a point at which they are degrading the scientific environment, especially when coupled with planned polygraph testing for 800 top nuclear scientists and a congressionally mandated moratorium on visits by foreign scientists from sensitive countries.

"We've gone way overboard," said Bing Young, chief security officer at Livermore's computing center. "We're hurting ourselves."

"We're losing people," added Young's boss, David M. Cooper, Livermore's associate director of computation. "At a certain point, they just say, 'It's not worth it, I'm not going to put myself through this.' We've lost, in just this last year, 35 or 40 people. The computer scientists can jump over to Silicon Valley and make a lot more money."

Richardson, at the start of a two-day trip to Los Alamos and Livermore, acknowledged the scientists' complaints. "We've worked hard in a very focused way to improve security," he said yesterday in New Mexico. "We've made a lot of progress, but I'm concerned about reports that I hear about recruitment and morale having suffered during this turbulent year. That's why I'm spending two days at the labs meeting with scientists and engineers to hear first-hand about their concerns and ideas."

Long before the world heard of Wen Ho Lee, who is in jail awaiting trial on 59 felony counts of mishandling top-secret information, Livermore had a system in place that most likely would have prevented anyone from downloading secrets from the lab's classified network, Cooper and Young said. Even six years ago, when Lee first started transferring weapons secrets onto portable magnetic tapes, they said, no information--classified or unclassified--could have been removed from Livermore's top-secret system without the approval of a classification specialist.

Now, Young said, that safeguard has been upgraded to absurd lengths: Not one, but two, classification specialists must approve the removal of unclassified information from the classified network to make sure no classified information is inadvertently removed. And both specialists must be screened by a rigorous Personnel Security Assurance Program that requires psychological examinations and random, periodic drug testing--the same system used to screen SWAT team members who guard plutonium and truck drivers transporting nuclear waste.

The new rules make it so hard to remove even unclassified information from the classified system that they might actually hurt security if scientists who once did all of their computations on their classified machines start doing more of it on the unclassified system just to avoid the hassle, Young said.

Cooper shares his concern. "I think we've approached absurdity in this system," he said. "At a certain point, I think you have to trust people to do the job. They walk out every day with much more in their heads than they could ever carry out in their briefcases"--or on a computer disk.

To make sure that scientists cannot evade the classification specialists by downloading classified information in the privacy of their offices, Cooper and Young said, all disk drives and printers operating on the classified network have been removed from areas that also have unclassified computers, making clandestine transfers impossible.

In another precaution, the lab has been continuously scanning all unclassified files since April for any classified information in them--and found none.

For Americans with top secret nuclear "Q" clearances, Cooper said, access to classified information has been limited this year by tightening compartmentalization so that individual scientists can only get to information they "need to know."

"Very few people at this lab know everything there is to know about a nuclear weapon," Cooper said.

For foreign scientists at the lab--who have no access to classified information and are not allowed to work in the weapons program--the new cyber security measures are even more restrictive. All of them must have individual computer security plans that only give them access to certain parts of Livermore's unclassified network on a "need to know" basis.

Scientists from sensitive countries such as China, Taiwan, Russia, Pakistan, India and Israel are denied all supercomputing privileges, as well as access to most "sensitive" unclassified information. There are now about 60 scientists from sensitive countries doing unclassified research at Livermore.

In a furor earlier this year over China's alleged theft of nuclear warhead secrets, critics on Capitol Hill faulted the national laboratories for endemically lax security and described them as virtual open college campuses. DOE officials, the critics said, had failed for decades to reconcile the desire of scientists at the labs to openly share information with the need to keep nuclear weapons secrets from failing into the hands of the nation's adversaries.

But while both Livermore and Los Alamos have been operated under contract by the University of California since the earliest days of the nation's nuclear weapons program, they seem more like Fort Knox than UC-Berkeley.

At Livermore, officials say security and counterintelligence were tight before Congress's intense focus on Chinese espionage--and now border on the obsessive.

Access to the lab compound, a gated square mile on the outer fringes of the East Bay about a 45-minute drive from San Francisco, is tightly controlled. Access to classified areas requires cleared personnel to swipe a magnetic badge through a scanner and type in a four-digit password. Three failed attempts at a password activate immediate video monitoring--and possibly a confrontation with armed SWAT police.

When reporters escorted by lab personnel visit classified sections at the lab, all classified computers must be shut down and signs are placed in the hallways that say, "Visitor Unclassified Discussions Only."

Two FBI counterintelligence agents are based at Livermore full-time, and the lab's own counterintelligence staff has grown to 13 employees. It is headed by a retired FBI expert on Chinese counterintelligence and includes retired officers from the FBI, CIA and military intelligence.

The staff's newest hire, a retired officer from the supersecret National Security Agency, which intercepts electronic communications, is focusing on counterintelligence issues involving Livermore's classified and unclassified computer networks.

Cooper, who once ran the NASA computer team that helped put a man on the moon, is concerned about the future. The computer upgrades, he said, haven't been all bad. "I think we did a good job [in computer security] before all this hit, but we have strengthened it dramatically in a number of ways," he said.

But just last week, Cooper added, a husband-and-wife team of scientists called it quits. "He was one of the best computer visualization people in the United States," Cooper said. "And he just said, 'We don't need this stuff--computer security, polygraphs, restrictions in travel, nonsense.' "

CAPTION: From left, Adrian Valenzuela, Jarald Wyatt and Kevin Morris help guard the "super block," a high-security area at Lawrence Livermore National Laboratory in Livermore, Calif.