Arak IR-40 heavy water reactor, Iran. Image credit: Nanking2012. CC BY-SA 3.0 accessed via Wikimedia Commons.
An undervalued success story from the 2015 negotiations on the nuclear deal with Iran is the effective blockade of Tehran’s ability to collect plutonium for an atomic bomb. The nuclear deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), has not only effectively curtailed the Iranian program, but could, if adjusted accordingly, provide guidance for the construction of research reactors that would reduce the risk of proliferation worldwide.
There are two ways to get the fissile material to fire an atomic bomb. The first is to enrich uranium and the second is to recover plutonium from the spent fuel of a reactor. The JCPOA blocked both routes. Now Iran’s advancing enrichment program is the main obstacle to diplomats trying to revive the deal, and these talks have dragged on for months as the program progresses.
Many nuclear weapons, including those used on Hiroshima, are based on uranium. However, every country that has a nuclear weapon has produced and segregated plutonium for weapons. Iran has not reopened that path despite efforts by its conservatively dominated parliament to pressure the United States to lift sanctions in exchange for compliance with the nuclear deal. In December 2020, Iran passed a nuclear law mandating a return to a threatening research reactor design. So far, Iran has not complied with this law because the changes to the original design under the JCPOA have made the reactor even more efficient. This suggests that even in its weakened state, the JCPOA continues to provide permanent solutions to potential proliferation problems. Its revival may further cement those gains as a “longer and stronger” deal is sought.
The inherent problem with nuclear reactors. Here is the riddle to nuclear negotiations with both Iran now and possibly with other countries in the future: if there is enough time, all civil research reactors will produce enough plutonium for a nuclear weapon that could be reprocessed in its spent fuel or separated from irradiated uranium. Some, like the Iranian heavy water research reactor Arak, are particularly well suited for plutonium production in their original form, but also have civil uses such as the production of medical radioisotopes and the testing of nuclear fuels and materials. Argentina, Brazil, South Korea, Sweden and Taiwan all considered acquiring reprocessing plants but eventually objected to the proliferation potential due to the international response. There is no public evidence that Iran has a reprocessing plant.
Since the Trump administration pulled out of the JCPOA, Iran has introduced advanced centrifuges and stored uranium. This means that the time for Iran to trace a nuclear weapon via the enriched uranium route has been significantly reduced. However, the spent fuel path has not been reactivated as Iran has not undertaken any work to rebuild the Arak heavy water research reactor to its original design or to reprocess it. Iran’s hedging strategy, ostensibly to put pressure on negotiations to revive the JCPOA, suggests that nuclear brinksmanship with uranium enrichment allows flexibility that plutonium does not.
How did the JCPOA prevent plutonium recovery? Initially, the Arak heavy water research reactor posed a serious proliferation threat because it was a plutonium producing machine. As originally planned, the Arak reactor could produce enough plutonium in its spent fuel to make one or two atom bombs a year. Construction of the Arak reactor was completed by the start of the nuclear talks, and the inclusion of a construction freeze actually delayed the completion of the 2013 Joint Action Plan that preceded the JCPOA. Groups of independent scientists, including Ali Ahmad, Frank von Hippel, Alexander Glaser, and Zia Mian, proposed new designs for the reactor, which would be based on low-enriched uranium.
Finally, Iran made the following proposal for the Arak reactor: operate the reactor at half its original capacity; change the core size (height from 3.4 to 1.1 meters and core diameter from 3.4 to 2.4 meters); and only use up to 3.67 percent enriched fuel or low enriched uranium. The new design reduced plutonium production from 11 kilograms (24.25 pounds) per year to about 1.2 kilograms (2.65 pounds) per year, which means it would take Iran much longer than a year to produce one for one Nuclear weapon to produce sufficient quantity.
The JCPOA also demanded that Iran send its spent fuel elements containing plutonium for the Arak reactor, probably to Russia, on a permanent basis, so that at no point would Iran be able to use the Arak reactor to recover plutonium. This is the crucial stipulation which, if generalized, could spell an end to civil research reactors covering a secret interest in nuclear weapons. As long as spent fuel can be accumulated, plutonium production for a nuclear weapon remains on the table.
Lessons from the JCPOA. Behrouz Kamalvandi, spokesman for the Iranian Atomic Energy Agency, said: “Our experts believe that the converted reactor is more efficient for research and we should complete it. That means that the construction of a reactor like the original reactor has to start over in a different location. ”That statement says it all. Not only has the JCPOA achieved a much less dangerous reactor, but it is in Iran’s interest to keep that as it is a more efficient design. To restore plutonium’s path to an atomic bomb, Iran would have to start over somewhere else.
Around 220 research reactors are in operation in 53 countries around the world. Some still use fuel that is about 93 percent enriched, but the international community has made great strides in converting these reactors to low-enriched uranium. Looking to the future, the modifications made to the Arak reactor could set a technical standard for any new heavy water research reactor construction.
An equally important component is the agreement to ship spent fuel elements to another country. Here’s the problem: most countries do not accept spent fuel because it could pose a radiological hazard and is an unpopular domestic policy. With research reactors producing so little spent fuel, these concerns can be allayed at any new negotiation, even if it is difficult to predict in the short term.
Transporting spent fuel to nuclear weapon states is the most logical answer given the potential for reclaiming plutonium for a nuclear weapon. However, the United States is struggling to dispose of its own weapons-grade plutonium, which it produced between 1944 and 1994, so it is not currently clear who has the capacity or the political will to shoulder this burden.
Nonetheless, interest in preventing further proliferation may deserve general global guidelines for new construction, including engineering restrictions and spent fuel disposal. Russia has signaled its willingness to accept spent fuel even though it is already facing major challenges from its own nuclear waste. Both the United States and Russia already have levels of plutonium in excess of what is needed for their weapons programs, so accepting spent fuel would not pose a proliferation risk. Should the Arak agreement become standard, it would also help normalize the JCPOA’s verification regime and act as a deterrent for non-compliance.
This is another area where the JCPOA could set a new gold standard for non-proliferation agreements. Negotiating its future has as much to do with appeasing the local audience as it is with the merit of the deal. But while important issues are being cleared up, US politicians and political experts should not lose sight of some of their lesser-known achievements, which have undoubtedly made the world a safer place, and look for ways to apply them elsewhere.
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