New Technologies Underscore Nuclear Proliferation Challenges
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JEFFREY KAYE: It’s been 60 years since the United States developed and used the world’s first nuclear bombs. In the decades since at least nine nations have come to possess atomic weapons, and concern grows as more countries develop nuclear programs. At the United Nations, diplomats from 190 countries are winding up a month-long conference reviewing the state of nuclear proliferation.
MOHAMED ELBARADEI: We need a better control over proliferation-sensitive parts of the nuclear fuel cycle, activities that involve uranium enrichment and plutonium separation.
JEFFREY KAYE: Nuclear programs in Iran and North Korea, two nations whose military ambitions concern Europe and the U.S., have raised particular alarm.
SCOTT McCLELLAN: Well, I would say that these reports that we are seeing of Iran enriching uranium and possessing more advanced centrifuge designs raise serious concerns.
JEFFREY KAYE: We came to New Mexico, the birthplace of the atomic bomb, to better understand nuclear technology — what it means to enrich uranium, to process plutonium and to possess centrifuge designs.
At Sandia and Los Alamos National Laboratories, scientists and engineers continue to work on America’s nuclear arsenal, and to try to contain the international spread of atomic weapons.
CHARLES LOEBER: This was the “fat man.” It was a plutonium weapon.
JEFFREY KAYE: Engineer Charles Loeber spent more than 37 years designing and producing nuclear weapons. We met Loeber at the National Atomic Museum in Albuquerque.
On display are replicas of generations of American nuclear weapons, from the 10,000-pound bomb nicknamed “Fat Man” that destroyed Nagasaki, to a 1960 atomic weapon, the 76-pound “Davy Crockett” that could be fired from the back of a jeep.
JEFFREY KAYE: Has bomb technology changed dramatically?
CHARLES LOEBER: Well, the basic physics has not changed at all.
JEFFREY KAYE: What has changed is how easy it’s become to acquire sophisticated nuclear technology. The raw material for both nuclear bombs and nuclear energy is uranium, a mineral that’s about as common in nature as tin.
After uranium ore is mined, to be used as a fuel in bombs and in most reactors, it has to be purified, or enriched. The goal of uranium enrichment is to separate light from heavy uranium. Light uranium is more capable of fission. That’s when the nucleus of an atom is split and energy released.
CHARLES LOEBER: That’s nuclear fission, and that goes back to Einstein’s equation. If you can split it, it turns out some of the mass disappears as it splits into smaller particles, and you release lots of energy.
JEFFREY KAYE: Atomic bombs require highly enriched uranium. The uranium needed for most nuclear reactors, which produce power, is less pure.
CHARLES LOEBER: It’s also enriched uranium, but enriched to a much lower level, typically 3 or 4 percent enrichment in a reactor versus roughly 90 percent in a nuclear weapon. So, it’s the degree of enrichment that makes the difference.
JEFFREY KAYE: The enrichment method used in the U.S. converts uranium to gas then pumps it through hundreds of filters. The lighter molecules pass through faster than the heavier ones. Most other countries, including Iran, use centrifuges to separate the molecules.
CHARLES LOEBER: You spin something very fast, the heavier isotope tends towards the outside of the centrifuge versus the lighter one, and you can get this separation. Centrifuge has an advantage over gaseous diffusion in that it’s much more energy efficient. You could have a much smaller plant.
JEFFREY KAYE: Because highly enriched uranium can now be made so efficiently, monitoring enrichment programs is one key to controlling the spread of nuclear weapons. The challenge for nuclear inspectors is to figure out whether Iran, for instance, is enriching uranium just for electricity, as it claims, or for making atomic bombs, as the American and some European governments suspect.
JEFFREY KAYE: From the point of view of someone concerned about arms control, is any enrichment facility suspect?
C. PAUL ROBINSON: Oh, of course.
JEFFREY KAYE: Physicist C. Paul Robinson is a former director of Sandia National Laboratories. He also led nuclear weapons programs at Los Alamos, and served as a U.S. arms control negotiator in the late 1980s.
C. PAUL ROBINSON: We have worried about certain countries that would produce civilian fuel enrichment during the daylight hours. But in the evening hours and weekends, the valve configuration would be moved to recycle that material and increase it up into the weapons range.
JEFFREY KAYE: Iran says that its enrichment is for peaceful purposes. How can anyone tell the difference whether it is for peaceful or lethal purposes?
C. PAUL ROBINSON: Strictly by declaring its purpose I don’t think you can. I believe that’s why monitoring is essential.
JEFFREY KAYE: Robinson says that by checking how centrifuges are hooked up, inspectors can often tell what the equipment is producing.
C. PAUL ROBINSON: If you put the plumbing in such a way as to make multiple passes, you can climb the ladder of enrichment to weapons-grade quantities. And that’s called a cascade. How you configure the centrifuges, what is the input, what is the output lets you determine the purpose of the cascade.
JEFFREY KAYE: Not all nuclear weapons are made from uranium. The bomb dropped on Nagasaki in 1945 used plutonium, the material North Korea is using in its weapons program. North Korea expelled arms control inspectors in late 2002, but U.S. experts believe since then it’s made several plutonium bombs. The nation gets plutonium by reprocessing the uranium fuel rods used in its Yongbyon nuclear reactor.
CHARLES LOEBER: You simply shut down the reactor, you take out those fuel rods. They could then use chemistry to separate the plutonium from the uranium. We did this 60 years ago. It’s not unreasonable to think a country like North Korea could make an implosion weapon like “fat man” with plutonium.
JEFFREY KAYE: Robinson says that by monitoring a reactor’s operations, inspectors can get a good idea of whether weapons-grade plutonium, called Plutonium 239, is being made. In the case of North Korea, satellite photos of a cooling tower at the Yongbyon nuclear reactor show it with steam and without steam at different times, indicating the plant has been turned on and off.
C. PAUL ROBINSON: A tip-off that they were shutting it down, and undoubtedly to replace fuel pins at a constant rate to produce materials. If one is building a nuclear reactor but changing fuel elements out at some frequency, it’s probably a military program.
JEFFREY KAYE: Compounding the challenge for nuclear watchdogs are leaps in technology.
C. PAUL ROBINSON: Centrifuges that are the size of a small barrel.
JEFFREY KAYE: A small barrel?
C. PAUL ROBINSON: Yes. And so, just think of all the barrel-sized things that are shipped around the world.
JEFFREY KAYE: Just to make sure I’m clear, you could do everything in a barrel-sized centrifuge that would be necessary to produce highly enriched uranium?
C. PAUL ROBINSON: Oh, you need hundreds of them. But the basic component is shipped individually, wrapped individually.
JEFFREY KAYE: Nuclear components have been hot items on an international black market. Revelations of the activities of this man, Abdul Quadeer Khan, the former head of Pakistan’s nuclear weapons program, were a wake-up call for arms control officials. Khan headed a network that reportedly supplied centrifuge equipment and plans to Libya, Iran and North Korea. As nuclear technologies spread, so do its perils.
MOHAMED ELBARADEI: Some estimates indicate that 40 countries or more now have the know-how to produce nuclear weapons, which means that if they have the required fissile material, high-enriched uranium or plutonium, we are relying primarily on the continued good intentions of these countries.
JEFFREY KAYE: There are an estimated 19,000 tons of highly enriched uranium in stockpiles around the world. That’s enough to make nearly a million nuclear bombs.