A History of the Centrifuge

To make a uranium-based weapon, technicians have to take uranium ore and extract certain rare types of atoms. One tool that does that is a centrifuge: a metal tube that spins at nearly the speed of sound. Hear a history of the high-speed gas centrifuge.

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Another nation suspected of working to develop nuclear weapons is Iran. Iran seems determined to build thousands of centrifuges for civilian use, it says, which is one reason that Iran faces a dispute with the United States. For a uranium-based weapon, technicians have to take uranium ore and extract certain rare types of atoms. And one tool for doing that is these centrifuges. They're metal tubes that spin at close the speed of sound. NPR's David Kestenbaum has this report on the curious history of a device at the center of international negotiations.

DAVID KESTENBAUM reporting:

You've probably got a centrifuge in your house--that nifty salad spinner that dries lettuce or your washing machine. The first centrifuge that successfully separated individual atoms of different weights was made by Jesse Beams in 1934. He was working at the University of Virginia, initially in an office right by the picturesque central lawn where today you can find students throwing around a baseball. Beams' centrifuge spun a lot faster than a washing machine. Houston Wood is in the engineering department at the university. He says Beams is a legend there.

Mr. HOUSTON WOOD (University of Virginia): So when you have something spinning at high speed and it breaks, it makes a loud noise. And so he was breaking a lot of them. And so I think the president of the university at the time said, `We want to move you to another facility.' And so they moved him up to Observatory Hill.

KESTENBAUM: Beams filled the centrifuge with a gas. As the tube spun furiously, it pushed the heavier atoms to the outer walls. The United States considered using centrifuges during the Manhattan Project, turning uranium into a gas and spinning it, but they decided the technology wasn't good enough yet. It was the Russian nuclear weapons program that eventually made the centrifuge really sing. The lead researcher was an Austrian prisoner they'd captured named Gernot Zippe.

Mr. GERNOT ZIPPE (Researcher): For me, it was the only way to survive and I decided I would do my best, and if it would be successful, I hoped that this method will not be chosen to make the nuclear weapons. But finally, it turned out after seven years, the centrifuge was chosen for making the nuclear weapons for the Russians.

KESTENBAUM: Zippe's centrifuges spun for months on end without fail, and they used a clever trick. They heated the uranium gas so it would circulate, further helping to strip out the light atoms from the heavier ones. Houston Wood at UVA says this made the centrifuges 10 times better. And today, he says, they are the method of choice for enriching uranium. Run the centrifuges for a while, and they produce uranium good enough to make electricity in a reactor. Run them a little while longer, and they make highly enriched uranium suitable for a bomb. The centrifuge's advances made the world a little more dangerous because centrifuges are easy to hide. The previous method for processing uranium, called gaseous diffusion, required massive amounts of electric power which meant huge power lines that were easy to spot. At one point, the US uranium enrichment plants were the largest consumers of electricity in the country. Centrifuges consume far less power and Wood says you could hide one in your garage.

Mr. WOOD: The United States' point of view, when I was working on the project, was to protect the technology, not allow it to leak out even to our allies. Gas centrifuge technology was part of the most highly sensitive and most highly protected--and to my knowledge, there hasn't been any leak from our technology into the public domain or into the world domain.

KESTENBAUM: Making enough enriched uranium for a bomb still isn't easy. It requires hundreds of centrifuges linked together, operating reliably for a year. Neither Houston Wood nor Zernot Zippe say they regret working on the centrifuge. Zippe, after the Russians released him, helped start an international organization called Uranko(ph) that uses centrifuges to process uranium for nuclear power. Uranko is also where the Pakistani scientist, A.Q. Khan, worked. Khan stole plans for centrifuges started a global black market which put the machines in the hands of Libya and Iran. `Still,' Zippe says, `the world is a better place because of centrifuges. Every technology cuts two ways,' he says. `With a knife, you can peel potatoes or you can kill your neighbor.'

Mr. ZIPPE: Centrifuges can make very cheap nuclear fuel for the power stations and is able to make highly enriched uranium for nuclear weapons. The ghost is out of the bottle. You cannot stop and take again.

KESTENBAUM: Houston Wood also has good things to say about nuclear power. But he says if he could change the laws of physics so that neither the power plants nor the bombs would work, he'd do it. David Kestenbaum, NPR News.

INSKEEP: David's a science correspondent for NPR and you're hearing him on MORNING EDITION from NPR News.

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