WASHINGTON -- When the word first hit the scientific community a few months ago, it was all some physicists could do to keep from laughing. Iraq, it seemed, had been trying to whip up enough enriched uranium for a nuclear weapon by using a technological dinosaur known as a calutron.
To the Nobel laureates who had cut their teeth on such stuff, the idea was almost quaint, and almost certainly preposterous. Sure, the calutron had been a mainstay nearly a half-century earlier in the Manhattan Project, jump-starting efforts to produce the world's first atomic bomb. But it is a bulky machine that gulps electricity and gives little in return -- the creaky old jalopy of a dawning nuclear age.
A few days later, the snickering stopped. Further word showed that Iraq's old jalopy had been souped up with the latest in computer technology and precision equipment. Instead of being five to 10 years away from building a nuclear weapon, as the United States had estimated before the Persian Gulf war, Iraq was only a year away, United Nations inspectors concluded.
But even more worrisome was this: For all Iraq's ingenuity in refining the calutron technique, basic calutron technology is declassified, and some authorities think that the Iraqi exercise will provide an example for other countries aspiring to join the exclusive nuclear arms club. "I think we have to worry now that the North Koreans might try this, and the Iranians," said Leonard Spector, senior associate of the Carnegie Endowment for International Peace and a leading authority on nuclear proliferation.
Mr. Spector made that remark in an interview several weeks ago, and it proved prophetic when U.S. officials confirmed that Iran appeared to be working on its own calutrons, apparently with the help of China.
The calutron surprise is one of many lessons learned from the dismantling of the Iraqi nuclear program. Experts around the world are now assessing the blind spots that allowed much of the Iraqi program to remain hidden. They are also pondering anew which country might be next in line to build a bomb, and they are scrambling to find better ways to thwart such efforts.
As with any would-be nuclear nation, Iraq expended its greatest efforts trying to obtain the enriched uranium needed for a bomb -- the "critical mass" necessary for unleashing the horrific energy of an uncontrolled chain reaction. Once that is achieved, the other steps, while still requiring great expertise, are comparatively simple.
Iraq's nuclear program probably began in the mid-1970s, but the impetus for its expansion came in 1981 when low-flying Israeli jets in a surprise raid destroyed the Osirak nuclear reactor, the centerpiece of the Iraqi program. Iraq then redoubled its efforts, and recent U.N. inspections have shown that by the time the war began in January, Iraq was working to enrich uranium at least three ways: with the surprising calutrons, which extract high-grade uranium from lesser stuff by using large electromagnets; with centrifuges, which whirl high-grade uranium out of gases in high-speed cylinders; and by chemical extraction.
The Iraqis were also working on an implosion technique used to set off a chain reaction in a nuclear weapon and a missile program to carry the weapon to its target. But because of the Osirak setback, Iraq's drive for secrecy was as strong as its drive for success. The country hoodwinked the world's most sophisticated spy satellites and intelligence networks.
Nuclear sites camouflaged
Part of the reason the intelligence community was fooled is that "we weren't looking for it," said Gary Milhollin of the Wisconsin Project on Nuclear Arms Control, a Washington-based research organization. U.S. intelligence resources in the Middle East were more worried about neighboring Iran, and most satellites passing over that part of the world were guided into orbits crossing the Soviet Union.
Even after the gulf war began, extra satellite overflights failed to detect major pieces of the Iraqi program. David Kay, leader of the first six of the United Nations' postwar nuclear inspection teams, discovered several reasons why.
At the twin calutron facilities at Tarmiya and Al-Sharqat, he said, the huge electrical cables that might have given away the purpose of the site were buried in tunnels leading several miles to a power plant. Tarmiya also employed large "absolute filters" that screened any possibly irradiated particles from outgoing air. Such particles might have been detected by satellites or by sensors in neighboring countries. Both facilities were laid out in odd configurations -- a sacrifice of efficiency for the sake of subterfuge.