The guards here carry assault weapons and are authorized to "shoot to kill." Visitors must don goggles and yellow radiation suits after passing through metal detectors and soaring barbed-wire fences.
Getting into building 371 here at the Rocky Flats nuclear weapons plant is a tense, hour-long process, reminiscent of a scene from Mission Impossible.
Few Americans have ever passed into the inner sanctum of this former bomb plant, where America once produced nuclear warheads and today where most of the plant's 14.2 metric tons of plutonium is stored. But on this day, the plant has some special visitors: 10 Russian nuclear scientists have come to see how "surplus" plutonium is stored and disposed of.
There's something vaguely surreal about having America's one-time cold-war enemy tour the highest-security nuclear weapons facilities in the United States.
But Department of Energy officials hope their open-door hospitality here and at the Hanford weapons site in Washington State will smooth the path for implementing a September nonproliferation accord between the US, the Russian Federation, and the International Atomic Energy Agency (IAEA) in Vienna.
The agreement calls for the two nuclear superpowers to place their "excess" weapons-grade material under IAEA monitoring to ensure that the stock won't be reused to build new weapons. Each nation will ultimately commit to safeguarding about 50 metric tons of plutonium and highly enriched uranium from warheads dismantled since the end of the cold war.
"This is just to get the ball rolling," says Ken Luongo, the DOE arms control chief. "As a first step, we said, 'Why don't you come to the US and see what we've done?'"
The Russian visit also confirms sentiments that signing treaties is the easy part. The tough task will be in coming up with the money for implementation. Uncle Sam may soon be digging deep in his pocket to fund Russian compliance.
For its part, the US has already placed 12 tons of plutonium into special vaults, fitted with fiber-optic and chemical alarms, at Rocky Flats, Hanford, and Oak Ridge in Tennessee. IAEA inspectors check the vaults monthly.
To date, Russia hasn't dedicated any of its excess nuclear stock to IAEA monitoring - but not from lack of desire, Russian officials say.
"There is not enough money," to achieve US security and safety standards, says Nikolai Khlebnikov, a Russian atomic energy official, after touring Rocky Flats.
The situation is so desperate that the director of one Russian nuclear research center committed suicide earlier this month, reportedly in despair over the center's deep financial woes. Researchers there went unpaid for five months.
Construction of a new storage facility for Russia's surplus plutonium is now under way in the Ural Mountains, with $40 million already invested. But the final tab is likely to approach $400 million and Russia can't cover the balance, says Mr. Khlebnikov.
Meanwhile, dismantled weapons pose a real security threat in Russia. With a shaky economic and political climate, there is significant potential for fissile elements to fall into the wrong hands, experts say. Emerging nation-states and terrorists are willing to pay tens of millions for advanced weapons-grade plutonium, and a little goes a long way. A baseball-sized chunk can level a major city.
For underpaid Russian scientists, the profit motive might outweigh the concern for global safety. "There are highly skilled scientists [in Russia] who were used to being paid well, and now aren't being paid at all," says Robert Lawrence, a political scientist at Colorado State University. "So you can kind of empathize and see how they might think of walking off with a piece of plutonium."
According to former Russian national security chief Alexander Lebed, who spoke in New York last week, Russia needs a $400 million aid package to protect its nuclear arsenal from such influences. The ousted general maintains, "One not-very-clever person can create a very great headache for all the wise people of the world."
Reports of careless handling of nuclear waste in Russia also raise concerns. "Russian technology in many areas is not as advanced as the US," says Dr. Lawrence. "We don't want nuclear accidents in Russia. So if we help them, it helps us."
Long-term storage of plutonium - which has a half-life of 25,000 years - remains the preferred method of securing surplus. The DOE is now leaning toward the option of burning bomb-grade plutonium as a reactor fuel, but there is reluctance to that method in the face of greater risks of theft and technical hazards.
Even with a secure storage facility, the Russians will probably require long-range assistance to to cover the cost of plutonium maintenance. But this option riles many American conservatives. "Some people say the Russians are our recent enemy, so why should we give them money?" Lawrence says. "Hard-line skeptics are always concerned that the Russians are going to change their stance. There's always a risk, because of the [political] instability in Russia."