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The core of Iran’s Tehran Research Reactor glows (center) in this 2010 photo.

The Asahi Shimbun via Getty Images

Iran’s plans for research reactor fuel imperil revival of nuclear deal

Iran is forging ahead with plans to manufacture a sophisticated uranium fuel for a research reactor in Tehran. The government’s announcement last week, which specialists said was not wholly unexpected, represents a further breach of the 2015 Iran nuclear deal and comes at a critical point in negotiations to reboot the pact before Iran’s hardline president-elect, Ebrahim Raisi, assumes power on 8 August.

“Iran is pursuing a strategy of brinkmanship,” says Andrea Stricker, a nonproliferation analyst at the nonprofit Foundation for Defense of Democracies. “It is using civil-use justifications as a pretext to brazenly advance its nuclear weapons–related knowledge.” Iran says the reactor will be used to produce medical isotopes.

The Trump administration in 2018 pulled out of the agreement, which restrained Iran’s nuclear program in return for relief from economic sanctions. President Joe Biden has vowed to rejoin the pact, but Iran remains at odds with the United States and other signatories, including China, France, Germany, Russia, the United Kingdom, and the European Union. Iran ratcheted up the pressure last week, announcing it will follow through on a long-standing aim of making uranium silicide fuel for the Tehran Research Reactor (TRR) at the Atomic Energy Organization of Iran (AEOI). Iran would irradiate uranium silicide pellets in the reactor to produce medical isotopes, primarily molybdenum-99. Mo-99 decays into technetium-99m, which is commonly used in diagnostic procedures for cancer and heart disease.

The TRR has a complex history. The United States provided the reactor to Iran in 1967 under the Atoms for Peace program—along with bomb-grade, highly enriched uranium to fuel it. HEU shipments ceased after Iran’s revolution in 1979, forcing Iran to convert the reactor to run on low-enriched uranium (LEU). Following revelations about Iran’s covert nuclear activities, Iranian officials in the late 2000s failed to persuade the International Atomic Energy Agency (IAEA) to authorize a sale of LEU fuel for the TRR. In 2011, AEOI then started to produce LEU fuel, enriched to 20% of the fissile isotope uranium-235. That milestone, experts noted, represents 90% of the process required to make bomb-grade uranium—–and it precipitated the crisis that led to the nuclear deal.

Beginning 1 year after Trump pulled out of the deal, Iran has taken several steps to resume nuclear activities prohibited under the agreement, including experimenting with advanced centrifuges and enriching uranium to higher levels of uranium-235. In recent negotiations to revive the nuclear deal, Iran sought assurances it could import uranium silicide pellets—but no country that makes the state-of-the-art research reactor fuel “was ready to provide Iran with a such a definite guarantee,” Kazem Gharibabadi, Iran’s permanent representative to IAEA, tweeted last week. With uranium silicide, he says, “The quality and quantity of [medical isotopes] will be remarkably enhanced.”

Manufacturing silicide fuel for the TRR breaches the deal’s 15-year moratorium on uranium metallurgy, as an intermediate step in the process involves working uranium metal. It also involves a technical challenge that few other countries have mastered, Gharibabadi boasts. With a thermal conductivity higher than traditional fuel made from uranium oxide, uranium silicide is deemed more efficient and safer. Manufacturing it will make Iran “one of the leading countries in the field of nuclear technology,” he says.

The United States and other Western powers that negotiated the nuclear deal with Iran don’t see it that way. “It’s another unfortunate step backwards for Iran,” Department of State spokesperson Ned Price told reporters.

The last round of talks in Vienna on a return to the nuclear deal wrapped up on 20 June, and it’s unclear when the next round will be held. Although negotiators have hoped to agree to terms before Raisi takes the reins, “I don’t think it’s necessarily a hard deadline,” says Naysan Rafati, a senior Iran analyst at the International Crisis Group. “Iran’s major national security decisions, including key issues like the nuclear talks, involve more than the president and his immediate team,” he says. Even if negotiations drag out past 8 August, Rafati predicts, “A return could still be in the cards.”