On Tuesday, in the latest challenge to the deal over Iran’s nuclear program reached last October, the House of Representatives held a hearing in which several Republicans accused the Obama administration of lying. This is part of a continuous effort over the last few months by members of Congress and by the presumptive Republican nominee Donald Trump to cast doubt on the agreement between Iran and the P5+1 countries and undermine its implementation. But these critics have done almost nothing to answer the most important questions: What has the nuclear deal actually achieved? And what are its potential shortcomings?
Trump shows no comprehension at all of the Joint Comprehensive Plan of Action—as the deal is officially called. He discusses it as if was a financial arrangement in which we “gave” the Iranians $150 billion and got nothing back. In reality we gave back $150 billion that we had confiscated. Critics in Congress give the impression that they have no understanding of the technical aspects of the deal but that it must be bad because it involves Iran.
In fact, enough time has passed since the deal that one can begin to make a rational assessment about how successful it has been at limiting Iran’s nuclear capacity and bringing its program under international oversight. On February 26, for example, the International Atomic Energy Agency (IAEA) released its own such report. While it might be argued that the IAEA is a little too optimistic, the overall impression the report gives is that the nuclear arrangements agreed to by Iran are working well. My own view is that the deal has been more successful than I expected, although there are flaws.
The deal has already significantly reduced Iran’s supply of both centrifuges and nuclear fuel. During the height of their nuclear program the Iranians had more than 18,000 centrifuges operating to enrich uranium. Most of these were outmoded but newer versions were being built. The number has now been reduced to about 5,000 that can be used to enrich small amounts of uranium.
Construction of the advanced models has stopped. At the time of the deal, the Iranians had enriched over sixteen thousand kilograms of low-enriched uranium hexafluoride. This is a compound that is solid at room temperature but is heated to a gas when it is fed into centrifuges. Of this about 3,500 kilograms were used to make 20 percent enriched uranium. (20 percent is the maximum allowed by the non-proliferation regime.) Some four thousand kilograms of the 16,000 were also used to create uranium oxide, which can be used to make a metal. The rest was used to make uranium or uranium hexafluoride that was enriched to less than 4 percent.
But the Joint Plan stipulates that for fifteen years the Iranians can maintain a stock of only 300 kilograms of low-enriched uranium, and on December 28, a Russian ship took some 11,000 kilograms of Iran’s uranium stockpile—in various forms and in various degrees of enrichment—to Russia. (One of the silliest comments on this came from Trump, who tweeted: “The Iran deal is terrible. Why didn’t we get the uranium stockpile—it was sent to Russia”—apparently unaware that uranium hexafluoride is both toxic and radioactive.)
The Joint Plan has removed the main rationale Iran has used for producing 20-percent-enriched uranium. For many years the Iranians were claiming that the production was necessary to fuel the small Tehran Research Reactor, but they already have enough to last for the indefinite future so this explanation is no longer tenable.
Furthermore, the nuclear deal has had a significant effect on Iran’s production of plutonium—which along with enriched uranium is one of the two materials that can be used to make a fission bomb. (A hydrogen bomb uses nuclear fusion but it must be triggered by a fission bomb.) Plutonium does not exist naturally on Earth so it must be manufactured in reactors, which produce it in their spent fuel. The Iranians were constructing a reactor at Arak that seemed especially designed to make plutonium. It ran on natural uranium and used heavy water to slow down neutrons, a process that enhances fission.
For years the Iranians did not allow adequate inspections of the Arak reactor. This has now changed. The original design of the reactor has been scrapped and a more suitable reactor is being built with the aid of the Russians and the Chinese. The Russians will supply the fuel and take away the spent fuel. They have already been doing this successfully with the Iranian power reactor at Bushehr. The Iranians will ship most of their heavy water out of the country. This too is a significant advance since for many years the IAEA was never allowed to inspect Iran’s production of heavy water.
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All of this is to the good, as far as the control of nuclear materials goes. But there are other reasons for concern that cannot so easily be measured by counting centrifuges or kilograms of enriched uranium. I think that the main one is that the Iranians will not come clean on what the IAEA calls “previous military dimensions.” The Iranian government claims that whatever it had been doing it stopped in 2003—but it does not say what it had been doing. There is also skepticism that it really stopped its activities in 2003. It is clear to me that one of the things the Iranians had been doing was designing nuclear weapons.
It is surprising how few people such a program would require. In the case of Pakistan’s nuclear weapons program, there were about a half-dozen, with only a primitive computer to use. One of them was a friend and colleague, the Pakistani physicist Riazuddin, who spent several months in the United States looking at open sources and led the effort. I think the Iranians have the plans for a Chinese weapon design, which they purchased along with prototype centrifuges from A. Q. Khan. It is also much easier to hide people than nuclear technology. There is almost no way that such a small group of theorists can be found if the host country doesn’t want them to be, which I think is what is happening in Iran.
How serious is this? As long as we can keep the Iranians from getting the fissile material—separated uranium and plutonium—I do not think it is a primary concern. Without the Joint Plan we would have the prospect of a country with both the knowledge and the material to make a bomb.
Postscript: What are the Remaining Centrifuges For?
As I noted, the Joint Plan allows Iran to operate 5,060 centrifuges of the old IR-1 type in its facility at Natanz. The reason for this curious number is that these centrifuges are arranged in cascades which can have as many as 174 centrifuges. In a July 22, 2015, report for the Institute for Science and National Security, David Albright raised some caution about this arrangement. The agreement imposes a fifteen-year limit of 300 kilograms of 3.67 percent enriched uranium. But Albright notes that this system can produce one hundred kilograms a month! Hence the cap would be reached almost immediately. Any excess could be down-blended to natural uranium or sold abroad. But there are now various reliable sources of enriched uranium—including Russia, which initially supplied eighty-five tons of enriched uranium for the power reactor at Bushehr. In view of this, the production of a few hundred kilograms at Natanz is not likely to be very attractive commercially. The Iranians could choose not to use Natanz to enrich more uranium but this is something the IAEA needs to monitor carefully.
On a somewhat different matter, the Arak reactor, which is now being reconfigured to use a light-water moderator, required in its previous configuration tons of so-called “heavy water” in which the hydrogen is replaced by heavy hydrogen that has an extra neutron in its nucleus. Making heavy water is a very inefficient process. To make one pound of reactor-grade heavy water requires 340,000 pounds of ordinary water. Iran now has only a very limited use for its supply of heavy water and on April 22 the United States announced that it would buy thirty-two metric tons for $8.6 million. This has many uses in laboratories such as Oak Ridge.
—May 23, 2016
