knew by 1941 that only the lighter isotope, 235, would create the chain reaction we needed. The trick was to separate the point seven percent of the 235 hiding somewhere in the mass of uranium-238.
“When America entered the war, we got a big leg up. After years of neglect, the brass wanted results yesterday. Same old story. So we tried every which way to separate those isotopes.
“Oppenheimer went for gas diffusion—reduce the uranium to a fluid and then a gas, uranium hexafluoride, poisonous and corrosive, difficult to work. The centrifuge came later, invented by an Austrian captured by the Russians and put to work at Sukhumi. Before the centrifuge, gas diffusion was slow and hard.
“Lawrence went for the other route—electromagnetic separation by particle acceleration. Know what that means?”
“I’m afraid not.”
“Basically, you speed the atoms up to a hell of a velocity, then use giant magnets to throw them into a curve. Two racing cars enter a curve at speed, a heavy car and a light car. Which one ends up on the outside track?”
“The heavy one,” said Martin.
“Right. That’s the principle. The calutrons depend on giant magnets about twenty feet across. These”—he tapped the Frisbees in the photograph—“are the magnets. The layout is a replica of my old baby at Oak Ridge, Tennessee.”
“If they worked, why were they discontinued?” asked Martin.
“Speed,” said Lomax. “Oppenheimer won out. His way was faster.
The calutrons were extremely slow and very expensive. After 1945, and even more when that Austrian was released by the Russians and came over here to show us his centrifuge invention, the calutron technology was abandoned. Declassified. You can get all the details, and the plans, from the Library of Congress. That’s probably what the Iraqis have done.”
The two men sat in silence for several minutes.
“What you are saying,” suggested Martin, “is that Iraq decided to use Model-T Ford technology, and because everyone assumed they’d go for Grand Prix racers, no one noticed.”
“You got it, son. People forget—the old Model-T Ford may be old,
“Dr. Lomax, the scientists my government and yours have been consulting know that Iraq has got one cascade of gas diffusion centrifuges working, and it has been for the past year. Another one is about to come on stream, but probably is not operating yet. On that basis, they calculate Iraq cannot possibly have refined enough pure uranium—say, thirty-five kilograms—to have enough for a bomb.”
“Quite right,” nodded Lomax. “Need five years with one cascade,
maybe more. Minimum three years with two cascades.”
“But supposing they’ve been using calutrons in tandem. If you were head of Iraq’s bomb program, how would you play it?”
“Not that way,” said the old physicist, and began to roll another cigarette. “Did they tell you, back in London, that you start with yellowcake, which is called zero-percent pure, and you have to refine it to ninety-three-percent pure to get bomb-grade quality?”
Martin thought of Dr. Hipwell, with his bonfire of a pipe, in a room under Whitehall saying just that.
“Yes, they did.”
“But they didn’t bother to say that purifying the stuff from zero to twenty takes up most of the time? They didn’t say that as the stuff gets purer, the process gets faster?”
“No.”
“Well, it does. If I had calutrons and centrifuges, I wouldn’t use them in tandem. I’d use them in sequence. I’d run the base uranium through the calutrons to get it from zero to twenty, maybe twenty-five-percent pure; then use that as the feedstock for the new cascades.”
“Why?”
“It would cut your refining time in the cascades by a factor of ten.”
Martin thought it over while Daddy Lomax puffed.
“Then when would you calculate Iraq could have those thirty-five kilograms of pure uranium?”
“Depends when they started with the calutrons.”
Martin thought. After the Israeli jets destroyed the Iraqi reactor at Osirak, Baghdad operated on two policies: dispersal and duplication, scattering the laboratories all over the country so they could never all be bombed again; and using a cover-all-angles technique in purchasing and experimentation. Osirak had been bombed in 1981.
“Say they bought the components on the open market in 1982 and assembled them by 1983.”
Lomax took a stick from the ground near his feet and began to doodle in the dust.
“These guys got any problem with supplies of yellowcake, the basic feedstock?” he asked.
“No, plenty of feedstock.”
“Suppose so,” grunted Lomax. “Buy the damn stuff in K-mart nowadays.
After a while he tapped the photo with his stick.
“This photo shows about twenty calutrons. That all they had?”
“Maybe more. We don’t know. Let’s assume that’s all they had working.”
“Since 1983, right?”
“Basic assumption.”
Lomax kept scratching in the dust.
“Mr. Hussein got any shortage of electric power?”
Martin thought of the 150-megawatt power station across the sand From Tarmiya, and the suggestion from the Black Hole that the cable ran underground into Tarmiya.
“No, no shortage of power.”
“We did,” said Lomax. “Calutrons take an amazing amount of electrical power to function. At Oak Ridge we built the biggest coal-fired power station ever made. Even then we had to tap into the public grid. Each time we turned ’em on, there was a brown-out right across Tennessee—soggy fries and brown light bulbs—we were using so much.”
He went on doodling with his stick, making a calculation, then scratching it out and starting another in the same patch of dust.
“They got a shortage of copper wire?”
“No, they could buy that on the open market too.”
“These giant magnets have to be wrapped in thousands of miles of copper wire,” said Lomax. “Back in the war, we couldn’t get any.
Needed for war production, every ounce. Know what old Lawrence did?”
“No idea.”
“Borrowed all the silver bars in Fort Knox and melted it into wire.
Worked just as well. End of the war, we had to hand it all back to Fort Knox.” He chuckled. “He was a character.”
Finally he finished and straightened up.
“If they assembled twenty calutrons in 1983 and ran the yellowcake through them till ’89 ... and then took thirty-percent-pure uranium and fed it into the centrifuge cascade for one year, they’d have their thirty-five keys of ninety-three percent bomb-grade uranium ... November.”
“Next November,” said Martin.
Lomax rose, stretched, reached down, and pulled his guest to his feet.
“No, son, last November.”
Martin drove back down the mountain and glanced at his watch.
Midday. Eight P.M. in London. Paxman would have left his desk and gone home. Martin did not have his home number.
He could wait twelve hours in San Francisco to telephone, or he could fly. He decided to fly. Martin landed at Heathrow at eleven on the morning of January 28 and was with Paxman at twelve-thirty. By two P.M., Steve Laing
