Preventing Iran from developing nuclear weapons has been near the top of the U.S. diplomatic agenda for years now, and stories about Iran's efforts—and the negotiations to undo them—have dominated newspaper coverage in many nations. Almost all this attention has focused on Iran's reactor in Bushehr and on its enriched uranium fuel, involving a process that could easily produce weapons-grade uranium. So too have Western sanctions and recent secret carrot-and-stick proposals made by the five-plus-one group (the permanent members of the U.N. Security Council plus Germany). Uranium enrichment is high on the agenda of the group's talks this week in Geneva with Iran, with a U.S. envoy in attendance for the first time.
Amid all this fuss, a second—and potentially more worrisome—nuclear reactor has gone almost completely overlooked by the West. This facility is located in the city of Arak. Like the one in Bushehr, the Arak reactor is officially nonmilitary. Its purpose is not to generate electricity (or weapons) but to produce radioactive isotopes used in medical diagnostics and procedures. That sounds downright humanitarian. But the Arak reactor would be just as capable of serving up fuel—in this case, plutonium—needed for weapons. And yet the reactor has been largely ignored by negotiators from the United States and other countries.
The Arak reactor could be used to make medical isotopes, which play a key role in diagnosing and treating diseases, such as radiation therapy for cancer. But the reactor is large for that purpose. At 40 megawatts, it could satisfy a significant part of the world's demand for medical isotopes all by itself. And it could also produce five to 10 kilograms of weapons-grade plutonium each year—enough for one or two nuclear weapons.
The procedure used to make weapons fuel, moreover, would be largely the same as that for medical isotopes. To get isotopes out of radioactive material in an isotope reactor, technicians use "hot cells"—a shielded room close to the reactor with a thick lead-glass window and robot arms. They can just as easily use the same setup to extract plutonium—the stuff of bombs—from spent fuel.
The Arak reactor is the same type that India and Israel used to make plutonium for their nuclear weapons, and is a cousin of the one North Korea uses. These reactors differ from most other nuclear-power reactors in that they use "heavy" water instead of ordinary water to cool the reactor core. Heavy water, which has a heavier form of hydrogen, called deuterium, in the water molecule, allows the reactor to operate with natural uranium as fuel rather than enriched uranium. That means there's no need to build and operate tens of thousands of centrifuges round the clock—which the Bushehr plant needs to make its fuel. In a heavy-water reactor, all you need to do is pop uranium fuel pellets in one end of a tube that runs through the reactor core. Spent-fuel pellets, containing plutonium, medical isotopes and other radioactive material, will pop out the other end.
Heavy-water reactors are expensive and rare, and for this reason they haven't been as much of a proliferation risk as light-water reactors. But once the reactors are operating, it's difficult, without close and continuous inspection, to tell if they're being used for medical or weapons purposes. The world learned of India's weapons program only after New Delhi set off a "peaceful" nuclear explosion in the 1970s. Similarly, though U.S. officials had fretted over North Korea's efforts, they learned the truth only in 1993 when Pyongyang kicked out IAEA inspectors, withdrew from the Non-Proliferation Treaty and began extracting plutonium.
Ironically, Iran has made a more convincing case for the nonmilitary use of the Bushehr plant (to generate electricity) than for the Arak one. Iran needs more electric power because its population and per capita GDP are increasing. With the price of oil and natural gas near record highs, it makes sense for Iran to produce electricity cheaply using nuclear power, saving oil and gas for sale to outsiders. There's also some logic behind Iran's desire to enrich its own uranium. Iran can't trust the Americans and Europeans to supply the fuel, for obvious reasons. Nor can it rely on Russia, which seems to have no qualms about cutting off a nation's energy supply for political purposes. Those are currently the only sources of enriched uranium.
The commercial case for producing medical isotopes isn't quite so clear. There certainly is a market for them. Canada, for example, produces about half the world's supply. Some of these isotopes have very short lifetimes and so have to be rushed by jet from where they're made to where they're used. Creating more sources distributed around the world would thus be a generally good thing. But the market for such isotopes in Iran and the Middle East isn't large enough to justify a plant like the one in Arak. I visited Iran recently; its people are impressive and it has a vibrant economy that is limited by an inadequate infrastructure. Spending a very large amount of money on both the plant to produce the heavy water and on the reactor seems to be a strange economic choice.
Iran is nevertheless moving forward. A heavy-water plant is up and running. The reactor itself is under construction and is scheduled for completion in five years; after an additional three to five years of testing, it would be ready to start making isotopes (or plutonium).
To be safe, any nuclear deal with Iran needs to include its plutonium program as well as its uranium one. The IAEA should make closer and more frequent inspections of the isotope-separation facility and the disposal of the spent fuel than what's required by the Non-Proliferation Treaty. Western negotiators need to worry about what's going on in Arak. There's more than one ball in the air.