But as witches’ brews go, this is all pretty thin gruel. The true security nightmare is a nuclear weapon locked in a trunk in the parking lot at Washington’s Union Station. Even a crude atomic bomb could level buildings for miles around ground zero. The resulting fireball would radiate at the speed of sound, incinerating every bit of steel, concrete and human flesh in its path and igniting a holocaust that would make Dresden look like a birthday candle.
What’s keeping a terrorist group from going nuclear? Building an atomic bomb requires two things: knowledge and material. Knowledge has not been in short supply since the Manhattan Project tests at Alamogordo, N.M. A terrorist might start with the $23 hardback “The Los Alamos Primer.” On page 25 are the once top-secret data on the minimum amount of uranium needed to sustain a chain reaction. Page 44 explains how to build a reflector to halve the amount of fissionable material required. Page 57 details how to shoot a slug of uranium into a bomb’s core and trigger the nuclear explosion. And if the terrorist had a sense of irony, he might check out the 1986 book “Preventing Nuclear Terrorism”: it contains the exact weights of uranium or plutonium needed for a bomb.
The biggest barrier to nuclear terrorism has been material. A bomb needs plutonium or enriched uranium-products too expensive to produce and, until recently, very difficult to steal. With the disintegration of the Soviet Union, however, thousands of nuclear-weapons workers are out of jobs and out of money. But not out of ideas. Last fall two Russians and a Belarusian swiped 5.5 pounds of semi-enriched uranium pellets from a top-secret plant somewhere in Russia, stuffed them into a lead container and drove 1,200 miles to Brest, Belarus. (Police arrested them before they could strike a deal with their Polish buyers.) German investigators uncovered more than 100 nuclear-smuggling schemes last year, compared with 35 in 1991. “What you’re talking about with smuggling is the guys guarding the back fence [of an ex-Soviet nuclear facility land making $10 a month,” says David Kay, who headed the United Nations nuclear-inspection team in Iraq after the gulf war. “As you disassemble weapons, of course you should worry.”
None of the uranium smuggled out of the ex-Soviet states so far has been weapons grade (a purified form of the element, called uranium-235, that sustains a chain reaction). The one known attempt to slip a small quantity of bombgrade uranium out of Russia was foiled. But what troubles Kay and others is that smuggling routes are being established. “The customs people don’t have a clue if their intercepts are the whole universe or much less,” says Kay, now at the Uranium Institute in London. The most worrisome routes are not the well-monitored ones to the West but those through Kazakhstan or Georgia to Iraq, Iran, Afghanistan, India and Pakistan. U.S. officials say they have credible evidence that Iranian front companies have tried to acquire nuclear materials from Kazakhstan.
Terrorists don’t have to produce anything like the complex and efficient bombs in the U.S. and Russian arsenals. Their task would be cruder: create a critical mass in order to make the nucleus of the plutonium or uranium atoms fission and release enormous energy. Either of two simple bomb designs could reprise Hiroshima:
In a gun-type bomb, a slug of uranium shot from a modified gun barrel boosts a chunk of uranium to critical mass (diagram). “If you use weapons-grade uranium, you would need about 50 kilograms [114 pounds]-a little bigger than a soccer ball,” says David Albright of the Institute for Science and International Security, a think tank in Washing-ton. That assumes the bomb is surrounded by a reflector, a shell of iron or graphite a few inches thick that bounces neutrons back to the core to sustain the chain reaction. Ordinary machine tools could turn uranium into the requisite sphere; working the metal poses little risk of radiation exposure or explosion. A timer, available at any electronics store, could be wired to the device to shoot the projectile at the desired hour. A guntype bomb could produce a 15-kiloton blast the size of the Hiroshima bomb. Even if the reaction fizzled short of a mushroom cloud, the shower of radiation from a small blast could kill a few thousand people.
In an implosion bomb, specially shaped charges studding a sphere of uranium squash it into a critical mass (diagram). An “initiator” encased in the fuel provides an extra boost to the chain reaction; a few grains of the element polonium, available in many university physics labs, and lithium, for sale at chemical-supply houses, would work. About 20 pounds of plutonium-239 (or half that with a reflector) would sustain a chain reaction, producing a one-kiloton explosion that could topple skyscrapers. That 20 pounds might not even be missed: the chief engineer of a Russian plant that reprocesses spent uranium into plutonium says, because of bookkeeping uncertainties, 33 pounds of plutonium could vanish every three months without anyone knowing it. “And even if terrorists just have high explosives packed around five to seven kilograms of plutonium,” says Albright, “the radioactivity would be terrifying.”
A team might need no more than a year to master bomb design and obtain uranium. Then it could assemble a workable nuclear bomb “in a few days,” says David Fischer of the International Atomic Energy Agency in Vienna. But he calls that scenario “extremely unlikely. Metallurgist terrorists and physicist terrorists are not easy to come by.” Maybe so, but no one is doing much to choke off the potential supply. “Nuclear-engineering departments at many American universities are being kept alive by foreign students, including Iraqis, Iranians and Libyans,” says Paul Leventhal of the Nuclear Control Institute in Washington. “There’s the concept of academic freedom, but there’s also the question of who we’re educating and why.”
Under disarmament treaties, the ex-Soviet Union will dismantle 2,000 nuclear warheads a year until well into the next century; that will mean moving six tons of plutonium and 30 tons of uranium from easily counted missiles to hard-to-inventory stockpiles. Can anyone monitor it all? While the United States measured uranium stockpiles down to the microgram, the Soviets-claiming a lack of sophisticated measuring devices-counted barrels of bomb-grade uranium and pits (softball-size units) of plutonium. Given that imprecision, says Kay, “skimming is relatively easy when you’re disassembling weapons. Anyone who tells you no material is missing either doesn’t know what he’s talking about or is deluding himself.”
The world is not yet awash in the fuel for bombs. But the spigot has been turned.
