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Hipwell pounced upon the question like a farmer on a bargain.

“Different kinds of uranium, my dear man. Funny stuff, uranium. Very rare. From a thousand tons of uranium ore, all you get is a block the size of a cigar box. Yellowcake. It’s called natural uranium, with an isotope number of 238. You can power an industrial reactor with it, but not make a bomb. Not pure enough. For a bomb you need the lighter isotope, uranium-235.”

“Where does that come from?” asked Paxman.

“It’s inside the yellowcake. In that one cigar-box-size block there is enough uranium-235 to stick under one fingernail without discomfort. The devil is getting the two separated. It’s called isotope separation.

Very difficult, very technical, very expensive, and very slow.”

“But you said Iraq is getting there,” pointed out Sinclair.

“He is, but he’s not there yet,” said Hipwell. “There’s only one viable way of purifying and refining the yellowcake to the required ninety-three percent pure. Years ago, in the Manhattan Project, your chaps tried several methods. They were experimenting, see? Ernest Lawrence tried one way, Robert Oppenheimer tried another. In those days they used both methods in complementary fashion and created enough uranium-235 to make Little Boy.

“After the war the centrifuge method was invented and slowly perfected. Nowadays only this method is used. Basically, you put the feedstock into a thing called a centrifuge, which spins so fast that the whole process has to be done in a vacuum or the bearings would turn to jelly. Slowly the heavier isotopes, the ones you don’t want, are drawn to the outer wall of the centrifuge and bled off. What’s left is a little bit purer than when you started. Just a little bit. You have to do it over and over again, thousands of hours, just to get a wafer of bomb-grade uranium the size of a postage stamp.”

“But he is doing it?” pressed Sir Paul.

“Yep. Been doing it for about a year. These centrifuges ... to save time we link them in series, called cascades. But you need thousands of centrifuges to make up a cascade.”

“If they’ve been going down that road since 1982, why has it taken so long?” asked Terry Martin.

“You don’t go into the hardware store and buy a uranium gas diffusion centrifuge off the shelf,” Hipwell pointed out. “They tried at first but were turned down—the documents show that. Since 1985 they have been buying the component parts to build their own on-site. They got about five hundred tons of basic uranium yellowcake, half of it from Portugal. They bought much of the centrifuge technology from West Germany—”

“I thought Germany had signed a whole range of international agreements limiting the spread of nuclear bomb technology,” protested Paxman.

“Maybe they have. I wouldn’t know about the politics,” said the scientist. “But they got the bits and pieces from all over the place. You need designer lathes, special ultrastrong maraging steel, anticorrosion vessels, special valves, high-temperature furnaces called ‘skull’ furnaces because that’s what they look like, plus vacuum pumps and bellows—this is serious technology we are talking about. Quite a bit, plus the know-how, came from Germany.”

“Let me get this straight,” said Sinclair. “Has Saddam got any isotope separation centrifuges working yet?”

“Yes, one cascade. It’s been functioning for about a year. And another one is coming on stream soon.”

“Do you know where all this stuff is?”

“The centrifuge assembly plant is at a place called Taji—here.” The scientist passed a large aerial photo over to the American and circled a series of industrial buildings.

“The working cascade seems to be underground somewhere not far from the old wrecked French reactor at Tuwaitha, the reactor they called Osirak. I don’t know whether you’ll ever find it with a bomber—it’s certainly underground and camouflaged.”

“And the new cascade?”

“No idea,” said Hipwell. “Could be anywhere.”

“Probably somewhere else,” suggested Terry Martin. “The Iraqis have been practicing duplication and dispersal ever since they put all their eggs in one basket and the Israelis blew the basket away.”

Sinclair grunted.

“How sure are you,” asked Sir Paul, “that Saddam Hussein cannot have his bomb yet?”

“Very,” said the physicist. “It’s a question of time. He hasn’t had long enough. For a basic but usable atomic bomb, he will need thirty to thirty-five kilograms of pure uranium-235. Starting cold a year ago, even assuming the working cascade can function twenty-four hours a day—which it can’t—a spinning program needs at least twelve hours per centrifuge. You need a thousand spins to get from zero percent pure to the required ninety-three percent. That’s five hundred days of spinning. But then there’s cleaning, servicing, maintenance, breakdowns. Even with a thousand centrifuges operating in a cascade now and for the past year, you’d need five years. Bring in another cascade next year—shorten it to three years.”

“So he won’t have his thirty-five kilograms until 1993 at the earliest?” interjected Sinclair.

“No, he can’t.”

“One final question: If he gets the uranium, how much longer to an atomic bomb?”

“Not long. A few weeks. You see, a country undertaking to make its own bomb will have the nuclear engineering side running in parallel. Bomb engineering is not all that complicated, so long as you know what you are doing. And Jaafar does—he will

know how to build one and trigger it. Dammit, we trained him at Harwell. But the point is, on a time-scale alone, Saddam Hussein cannot have enough pure uranium ready yet. Ten kilograms, tops. He’s three years short, minimum.”