Centrifuges at core at nuclear development for nations
The small slender cylinders spin at twice the speed of sound, driving the heavier gas outward with a force a million times greater than gravity, leaving an isotope behind that can light cities – or level them. Such uranium centrifuges appear to be key to North Korea’s revived nuclear bomb program. In Iraq, centrifuges will be the first things U.N. inspectors look for when they return. And elsewhere in coming years this precision technology may spread to still more hands in what the atomic energy industry foresees as a “nuclear renaissance.”
It’s a rebirth some would resist in the name of arms control.
“It will become a very substantial problem,” Pakistani physicist Zia Mian, a leading nonproliferation advocate, said of growing access to these tools for enriching uranium.
For electric utilities, centrifuges are the most cost-efficient way to produce fuel for an expansion of nuclear energy to replace coal- and oil-burning linked to global warming.
For those who want doomsday weapons, however, the appeal of uranium gas centrifuges lies in their compactness. A centrifuge plant for a small but significant nuclear weapons program could be hidden in a building the size of a warehouse, said a U.S. government physicist in the front ranks of the fight against nuclear proliferation.
This scientist, discussing official concerns on condition of anonymity, noted that both North Korea and Iraq discarded weapons programs using plutonium, the other bomb material, because they were difficult to hide. “Centrifuges are what people go to when frustrated with other methods,” he said.
The danger was clear last June when the U.N. nuclear agency disclosed its concerns that sensitive equipment or design documents may have been taken from a research institute in the former Soviet republic of Georgia.
That institute at Sukhumi on the Black Sea, abandoned for nine years in territory controlled by rebels, was the site of breakthroughs in gas centrifuge development by German and Soviet scientists in the decades after World War II.
The principle was simple: The centrifugal force of spinning separates materials by driving the heavier of them to an outer wall first. But the technology is complex: arrangements of vacuums, zero-friction bearings using electromagnets, minute balancing mechanics, thin-walled cylinders of strong but superlight materials.
Uranium gas is fed into the upright “rotor,” a cylinder typically three to six feet tall and several inches wide. It spins on its axis at up to 70,000 revolutions per minute, separating the heavier uranium-238 from the rarer U-235, the isotope whose nucleus produces energy when split in the process called fission.
The mixture is pumped through hundreds of centrifuges to boost its U-235 content to over 3 percent – the level needed for power generators. If extended, the process can produce uranium that is 90 percent U-235 -required for nuclear bombs.
Free-lancing German engineers brought classified centrifuge technology to Baghdad in 1988-89 as Iraq moved toward a nuclear weapon. United Nations inspectors later dismantled that plant, but after a four-year absence they’ll look for signs of centrifuge rebuilding on their expected return later this year.
In the early 1990s, the same Germans helped Brazil build centrifuges to produce fuel for nuclear submarines, raising proliferation concerns in Latin America.
Earlier, a Pakistani engineer in Western Europe’s nuclear industry brought back to his homeland the knowledge – and reportedly plans – for centrifuge technology.
Pakistan now has dozens of nuclear bombs.
Some believe North Korea’s new weapons plans, disclosed last week, may be all-Korean, based on old, widely known centrifuge technology. Others believe Pakistan helped. American officials say they don’t know. “There are a lot of countries that may have been assisting,” said Condoleezza Rice, U.S. national security adviser.
Russia, China, Japan and India have centrifuges. Ukraine disclosed it developed its own with help from scientists who fled Georgia’s Sukhumi institute. Israel reportedly enriches uranium for bombs. Iran, believed seeking weapons capability, has tried to buy centrifuges from Russia. The United States, meanwhile, is re-emphasizing centrifuges over gaseous diffusion, a more cumbersome enrichment technology.
“It can be as simple as having someone who knows how to do it. That’s what’s really spreading around,” said American physicist David Albright, a former U.N. inspector in Iraq.
The industry hopes so. Steve Kidd, research chief for the industry’s London-based World Nuclear Association, said all the world’s uranium enrichment may be done by centrifuges within 20 years.
Zia Mian, at Princeton University, fears that will put enrichment equipment in too many Third World hands. “Then there’s only the decision of a sovereign government to do what they want with it.”
Such fears are overblown, said Kidd. He questioned whether “rogue states” really will master the technology and concluded, “Any attempt to damn commercial centrifuge plants by association is, in my view, quite wrong.”