How to ensure Iran never resumes reprocessing

After more than a decade of tensions over Tehran’s nuclear program, the 2015 Iran nuclear deal—formally known as the Joint Comprehensive Plan of Action (JCPOA) —provided the international community a verifiable means to ensure that Iran’s nuclear program would be peaceful in nature. The deal was the result of a hard-fought, two-year negotiation that involved Iran, the European Union, and the P5+1 (the five permanent members of the UN Security Council, plus Germany). Though the negotiation leading to the JCPOA took place over a significant stretch of time—indeed, it was built on the foundation of talks that began in 2003—it’s important to remember that the deal contains critical concessions regarding Iran’s production of plutonium, which the United States had been seeking from Tehran since the 1970s, when the two countries were allies.

Shah Mohammad Reza Pahlavi, prior to his overthrow in 1979, sought to enrich uranium, ostensibly for civilian nuclear power. But he also insisted on Iran’s right to reprocess spent nuclear fuel, which ultimately produces weapons-usable plutonium. The United States staunchly objected—and it is often overlooked that reprocessing was for years a major sticking point between the United States and the Iranian monarch. The disagreement wasn’t formally resolved until the JCPOA effectively blocked Iran’s pathway to a plutonium-based nuclear weapon.

The agreement’s firm provisions against reprocessing, however, extend only until 2031. Critics of the deal often use this sunset provision to argue that the JCPOA delays but does not eliminate Iran’s ability to develop nuclear weapons. These critics ignore the reality that, if the Iranians were to return to reprocessing after 2031, they would have to start from scratch. They would have to contend with intrusive monitoring arrangements that will persist after 2031. And they would have to decide—unlike other nations that have foregone reprocessing—that the technology makes economic, technical, and environmental sense after all. On paper, the JCPOA’s reprocessing provisions don’t last forever. In practice, they very well might.

A long-running dispute. In the late 1950s, amid President Eisenhower’s Atoms for Peace program, the United States and Iran first agreed to undertake nuclear cooperation, with Washington providing Tehran nuclear technology, materials, and training. In 1967, the United States supplied Iran a five-megawatt nuclear reactor known as the Tehran Research Reactor, which was used to produce medical isotopes. Washington also provided the highly enriched uranium needed (at the time) to fuel the reactor.

As oil prices spiked in the 1970s, so did Iran’s nuclear ambitions. In 1974—the same year India first successfully tested a (plutonium-based) nuclear weapon—the US embassy in Paris sent a cable to the State Department in Washington, as well as to other embassies, in which the Shah was reported to have said in an interview with the French weekly “Les Informations” that Iran would “certainly” possess a nuclear weapon one day. Though Iran quickly denied a desire to develop nuclear weapons, the United States grew increasingly concerned about the risks of a nuclear-armed Tehran. Such concerns were specifically heightened by Iran’s apparent insistence on independently reprocessing spent nuclear fuel from its current and future power reactors.

When spent nuclear fuel is removed from a reactor, most of its fissionable isotopes (uranium-235 and plutonium-239) have not been used up. Reprocessing recovers the unused uranium and plutonium. Advocates of reprocessing argue that recovering uranium and plutonium reduces the need for mining and enriching uranium because the recovered materials can be re-used as fuel in commercial nuclear reactors. PUREX—short for plutonium uranium extraction—is the process most often employed to recycle these materials. It results in pure streams of uranium and plutonium. But notably, PUREX is also the standard way to obtain weapons-usable plutonium from spent nuclear fuel. As such, and in line with broader US nonproliferation objectives, Washington opposed Iran’s position on independent reprocessing. Instead, the United States in 1974 proposed an alternative that would allow for a reprocessing plant located in Iran but operated under multinational (including US) ownership and control. Such an arrangement would have reduced the risk that Iran might utilize plutonium for military purposes. Iran rejected that proposal. Independent reprocessing would become perhaps the most contentious nuclear issue in the two nations’ relations for years to come.

According to a declassified 1975 State Department document, Iran was adamant about reprocessing because it wanted to ensure that its mastery of the “complete nuclear fuel cycle” would not be inhibited. Despite Tehran’s insistence on this point, in 1976 the Ford administration sought the Shah’s commitment to a “major act of nuclear statesmanship: namely, to set a world example by foregoing national reprocessing” as international concerns grew regarding nations’ ability to obtain plutonium-based nuclear weapons. Meanwhile, Iranian officials argued that “Iran should have the full right to decide whether to reprocess” and the “right to effective control of the management and operation of … reprocessing facilities.” In 1978, the Carter administration and Iran finally reached an understanding on reprocessing whereby Iran would not reprocess spent fuel, or enrich uranium supplied by the United States, “unless the parties agree.” This would have ensured a US veto over Iran’s activities—but the events leading to the 1979 Islamic Revolution prevented the agreement from being formally approved and signed.

In the decades that followed the revolution, Iran’s nuclear program eventually expanded. It included a clandestine, organized weapon design program that was largely halted in 2003. It was characterized more broadly by concealment and by periodic revelations of previously undeclared facilities. These included the 2002 revelations that Iran was not only pursuing covert enrichment but was also constructing a heavy water reactor, perfectly suited for producing plutonium (near Arak, about 150 miles southwest of Tehran). In 2003, Iranian authorities formally declared to the International Atomic Energy Agency the construction of the Iran Nuclear Research Reactor, maintaining that the reactor’s purpose was “research and development and the production of radioisotopes for medical and industrial use.” However, experts estimate that if the facility had been operationalized as Iran had planned, it could have produced one to two bombs’ worth of weapons-usable plutonium annually.

The breakthrough. The parties negotiating the JCPOA reached agreement on July 14, 2015. Iran, in accordance with the deal, has since removed the core of the Arak reactor and rendered it inoperable by filling it with concrete. Under the accord, Iran is required to redesign the reactor so as to “minimize the production of plutonium and not to produce weapon-grade plutonium in normal operation”—and also, for the lifetime of the reactor, to ship all its spent fuel outside the country. The United States cochairs the working group responsible for overseeing and approving the redesign, giving Washington clear influence over the process.

Collectively, these provisions ensure that Iran’s potential plutonium pathway to a nuclear weapon is verifiably and indefinitely blocked at Arak. Under the terms of the JCPOA, Iran also cannot, for a duration of 15 years from the deal’s 2016 “Implementation Day”:

• engage in any spent fuel reprocessing
• engage in any R&D for spent fuel reprocessing
• build any additional heavy water reactors
• develop, acquire, or build a reprocessing facility

To pursue plutonium production, Iran would need to design and construct a new reactor from scratch—itself a long-term process—some time after 2031.

While some provisions related to the disposition of spent fuel and reprocessing are not explicitly “forever commitments” from Iran, the United States and its international partners have a real opportunity to ensure—indefinitely—that Iran does not produce weapons-usable plutonium. For starters, as part of the deal, Iran declared in writing its intent to indefinitely refrain from all four activities outlined above.

While not iron-clad, Iran’s declaration of intent gives the international community a basis for future engagement with Iran and with international partners on this issue (assuming the JCPOA remains in place). Tehran’s declared intent also gives the international community a stronger basis for scrutinizing any actions inconsistent with Iran’s stated intent. Likewise, the United States can continue to engage with countries that carry out nuclear cooperation with Iran, such as Russia and China, to ensure that they continue insisting that fuel contracts for Iran’s reactors include provisions for shipping out of the country all plutonium-bearing spent fuel, as is done today with the Bushehr power reactor. The United States may also wish to encourage other partners, such as Japan, to engage Iran regarding their experience with the immense economic, safety, and environmental costs of reprocessing.

Reprocessing trends among states with nuclear power sectors will also reduce Iran’s ability to claim it has been singled out as a nation that must indefinitely forego reprocessing. Of the 31 countries worldwide that operate commercial nuclear power plants, only a handful reprocess their spent nuclear fuel—and among those, only Japan lacks nuclear weapons. Some nations, including the United States, have independently reprocessed spent nuclear fuel in the past, but no longer do so. In 1977, the Carter administration announced that the United States would indefinitely discontinue reprocessing commercial spent nuclear fuel, and urged other nuclear nations to follow suit. This shift was due in part to the cost of reprocessing, but also to increased instances of nations’ obtaining plutonium-based nuclear weapons from reprocessed fuel. Today, 95 percent of the world’s nuclear warheads—belonging to countries ranging from the United States and Russia to North Korea—rely on plutonium.

Reprocessing involves key technical and economic drawbacks that may also encourage Iran to refrain from pursuing the technology after 2031. The PUREX process is dangerous and technically demanding, and creates a significant amount of highly toxic, radioactive waste. PUREX requires that highly radioactive spent nuclear fuel be dissolved in nitric acid. That solution must then be mixed with the organic chemicals tributyl phosphate, ferrous sulphamate, and kerosene. This procedure isotopically separates the waste into individual streams of material. But the organic chemicals used cannot easily be disposed of. Once the organic chemicals are combined with the radioactive spent fuel, the result is a noxious, liquid mess that is difficult to handle and dispose of. Additionally, any person in close proximity to spent nuclear fuel, if unshielded from radioactivity, will receive a lethal radiation dose within moments.

Economically, reprocessing is very costly, making it a weak alternative to uranium mining and enrichment (unless the cost of mining uranium increases tenfold). Reprocessing is also expensive compared with other means of managing spent fuel. For example, simply storing spent fuel is 10 to 50 times cheaper than reprocessing, and also far simpler. Although reprocessing is a way of “recycling” uranium and plutonium, PUREX creates a larger quantity of waste than does simply storing spent fuel. Additionally, reprocessing does not reduce the need for nations to develop long-term solutions—for example, a geologic repository—for nuclear waste management. Quite literally, when considering every pragmatic argument about whether to employ the technology—technically, economically, and environmentally—reprocessing spent nuclear fuel is not an attractive option.

Therefore, when nations express an interest in reprocessing today, the international community—due to the technology’s economic, environmental, and proliferation-related implications—assesses their intentions through narrowed eyes. As such, most nations with commercial nuclear power enterprises have refrained from reprocessing. Additionally, key historical examples suggest that once nations decide to stop reprocessing, they refrain from it indefinitely. As part of the JCPOA, Iran has decided to forgo reprocessing—and hence production of weapons-usable plutonium—until at least 2031. It has also formally declared an intention to forego reprocessing after 2031. Given all this—as well as the significant technical, economic, and political drawbacks of reprocessing—the international community may be able to ensure indefinitely that Iran cannot develop a plutonium-based nuclear weapon.

Outspoken critics of the JCPOA tend to maintain a selective focus on what they view as the agreement’s shortcomings—and on hypothetical scenarios regarding Iran’s nuclear program after 2031, when enrichment and plutonium separation restrictions expire. But intrusive transparency and monitoring arrangements will continue. It’s easy to lose sight of the tremendously significant restrictions that will constrain Iran’s nuclear program for years to come—including the critical restrictions on plutonium production that the United States has been seeking for decades, since the time of the Shah. The United States shouldn’t squander the opportunity that will be available over the coming years. It is an opportunity for Washington and its international partners to build on the diplomatic success of the JCPOA—and use the tools at their disposal (including creative thinking) to shape the future trajectory of Iran’s nuclear program.