‘Suspicious’ blackout at Iranian nuclear site almost certain to prompt retaliation

Iran celebrated “National Nuclear Technology Day” on Saturday, and on Sunday there was a major electric power outage at its main Natanz uranium enrichment facility, possibly caused by Israel. What might happen today?

The last time there was a mysterious explosion at Natanz in central Iran, in July 2020, Israel was silent. This time, unidentified intelligence sources are being quoted in Israeli media, which are normally restricted in reporting sensitive security issues. Iran is not only being embarrassed, it is being humiliated.

Nine months ago, the explosion seriously damaged the centrifuge assembly plant at Natanz, delaying the production of new centrifuges. This time it appears that a power cut affected the whole plant, spread over several square miles of desert. On Saturday, Iran had announced a new centrifuge type, the IR-9, claimed to be 50 times more efficient than the main type in use at Natanz, the IR-1, which Tehran retained under the 2015 nuclear agreement, the Joint Comprehensive Plan of Action (JCPOA).  Talks on the U.S. re-entering the JCPOA began in Vienna last week.

IR-this or IR-that, power failures are not good for enrichment centrifuges. Each individual rotor stands vertically inside an outer case, spinning at high speed in a vacuum to reduce air resistance, while balancing on a small ball bearing and held in position at the top, contactless, by a powerful ring magnet. An induction electromagnetic motor, also contactless, causes it to spin at around 1,000 revolutions per second.

The main challenge of centrifuge design is coping with “critical velocities.” A spinning centrifuge rotor will begin to shake or resonate, depending on its design and what it is made of, at certain speeds, both as it accelerates and when it slows down. Unless designed well, it can vibrate out of control, hitting its outer casing and breaking apart. This vulnerability was the weak spot targeted by the U.S.-Israel “Stuxnet” cyberattack on Iran in 2010. An electric power failure also provides just the right circumstances for such “crashing,” as it is known. The main centrifuge hall at Natanz, built eight meters underground and covered with two meters of concrete and steel to protect it from air attack, is probably in a mess right now.

Iran’s new IR-9 centrifuge type must be seen in the context of how successful it will be in actual operation, if it is given a chance. The claim of 50 times greater efficiency relates to its ability to separate out the fissile isotope U-235, rather than its speed of operation. Its centrifuge claims are noted anyway for their hyperbole. It is far from clear whether Iran can make its existing centrifuge types work properly. The IR-1 — a copy of the type provided by Pakistani scientist A.Q. Khan — is said to have problems with critical velocities and also cannot enrich beyond 20 percent (90 percent is needed for an atomic bomb).  

The IR-2m, also being brought into operation despite the restrictions of the JCPOA, is an Iranian version of Pakistan’s P-2, which Iran could not seem to make work properly. As the person who once taught me centrifuges 101, and perhaps 201, used to say: Enrichment is almost as much an art as a science.

What happens now? Will Iran feel compelled to retaliate, as it has done in the clandestine naval war waged with Israel over the past two years, with Israel targeting its oil shipments to Syria and Iran hitting ships with Israeli connections? The latest incident, an apparent Israeli attack on the Iranian ship anchored in the Red Sea to provide support to Houthi rebels in Yemen, was all but overtly claimed by Israel.

Defense Secretary Lloyd Austin is visiting Israel until Tuesday and both the Natanz attack and the Red Sea incident almost certainly have been added to his agenda. His Israeli counterpart, Benny Gantz, another former general, told him in talks in Tel Aviv on Sunday:  “We will work closely with our American allies to ensure any new agreement with Iran will secure the vital interests of the world and the United States, prevent a dangerous arms race in the region, and protect the State of Israel.” Secretary Austin, who tweeted upon arrival that he looked forward to “a series of robust discussions,” did not mention Iran in his official remarks.

Iran so far has claimed that there were no casualties or damage from the Natanz power outage, and a spokesman for its nuclear program declined to comment on its cause. But a member of the Iranian parliament said sabotage is strongly suspected. Israeli officials worry constantly about the vulnerability of their own Dimona nuclear research facility and other possible targets. Most, if not all, are in range of Iranian missiles already provided to Tehran’s Hezbollah ally in Lebanon. The next few days, which include Israel’s Independence Day, will be tense and perhaps eventful.

Simon Henderson is the Baker Fellow and director of the Bernstein Program on Gulf and Energy Policy at the Washington Institute for Near East Policy. Follow him on Twitter @shendersongulf.