Iran Moves Toward Breaching Nuclear Limits

July/August 2019
By Kelsey Davenport

Iran is moving closer to the limits on its nuclear program set by the 2015 multilateral nuclear deal after threatening in May to breach certain caps, but Tehran has not yet crossed those thresholds. The United States, however, has already accused Iran of violating the accord, an assertion disputed by other parties to the agreement.

Iran announced on May 8 that it would no longer adhere to stockpile limits for low-enriched uranium and heavy water set by the nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA). The announcement was a response to the U.S. decision in May 2018 to reimpose sanctions and withdraw from the agreement. (See ACT, June 2019.)

According to a May 31 report from the International Atomic Energy Agency (IAEA) on Iran’s implementation of the nuclear deal, Iran moved closer to the caps on enriched uranium and heavy water set by the deal, but did not exceed them.

The agency reported that as of May 20, Iran had stockpiled 174 kilograms of uranium enriched to 3.67 percent uranium-235, which is less than the 202 kilograms permitted by the JCPOA. In its previous report in February, the IAEA reported that the stockpile was 168 kilograms.

Behrouz Kamalvandi, spokesman for the Atomic Energy Organization of Iran (AEOI), said on June 17 that Iran was quadrupling its uranium-enrichment capacity and would breach the limit set by the deal within 10 days.

Exceeding the limit of uranium enriched to 3.67 percent U-235 would reduce the so-called breakout time, or the time it takes Iran to produce enough nuclear material for a weapon, but it does not pose an immediate risk. Currently, due to restrictions put in place by the nuclear deal, the United States estimates that timeline at 12 months.

Any reduction in the 12-month timeline will depend on how quickly Iran continues to enrich and stockpile uranium. Tehran would need to produce about 1,050 kilograms of uranium hexafluoride gas enriched to 3.67 percent U-235 to produce enough weapons-grade material (more than 90 percent-enriched U-235) for one bomb.

Kamalvandi also said that Iran was increasing its production of heavy water and would exceed the JCPOA’s 130-metric-ton cap in two-and-a-half months. According to the IAEA, Iran had 125 metric tons as of May 26.

Heavy water is used to moderate the reactions that occur in certain types of reactors, including Iran’s unfinished reactor at Arak.

The IAEA also reported that Iran had installed 33 advanced IR-6 centrifuges, of which 10 are being tested with uranium, at its Natanz plant. Iranian President Hassan Rouhani announced in April that Iran would install 20 additional IR-6 machines at the facility.

Past IAEA reports have not indicated the specific number of IR-6 centrifuges installed at the facility, but stated that Iran was conducting its research and development (R&D) activities using advanced centrifuges in accordance with a confidential plan submitted to the agency.

That language did not appear in the May report, which stated that technical discussions on the IR-6 centrifuges are “ongoing.”

Citing the number of installed IR-6 centrifuges, Jackie Wolcott, U.S. ambassador to the IAEA, said on June 11 that Iran “is now reported to be in clear violation of the deal.” Other countries still party to the agreement argue that Iran’s actions fall into a gray area not explicitly covered by the accord.

According to the JCPOA, Iran is permitted to conduct mechanical testing on up to two IR-6 centrifuges and can test with uranium using “single centrifuge machines and its intermediate cascades.” Iran cannot withdraw any enriched material from the centrifuges.

The deal does not specify what constitutes an intermediate cascade, but states that, after eight-and-a-half years, or beginning in July 2024, Iran can “commence testing” of up to 30 IR-6 centrifuges.

Additional detail is likely found in the confidential R&D plan that Iran submitted to the IAEA. Alleged copies of the plan leaked in 2016 suggest that Iran can test about 10 IR-6 centrifuges for the first four years of the deal and then move to a cascade of 20 machines until year eight and a half, when it is permitted to test up to 30.

It does not appear to be clear in either the nuclear deal or leaked copies of the R&D plan how far ahead of those time frames Iran is permitted to install the additional IR-6 machines.

Russian President Vladimir Putin said on June 6 that inspectors have not found “a single violation” of Iran’s nuclear commitments.

An official from a country party to the JCPOA told Arms Control Today on June 13 that Tehran is “pushing the limits” of the deal but the IR-6 installation is not likely a violation. The official said that it is for the JCPOA Joint Commission to “resolve any ambiguities or compliance questions” and it is premature for states to make judgments on the IR-6 dispute before the commission can consider the issue.

The commission was set up to oversee implementation of the deal and resolve any compliance issues. It is comprised of the parties to the deal, so the United States is no longer a participant. The next commission meeting is scheduled for June 28.

Wolcott said the commission is “treating this issue with the seriousness it deserves.”