11/23/2009 - 14:36

A technical evaluation of the Fordow fuel enrichment plant

Ivan OelrichIvanka Barzashka

Ivanka Barzashka

Barzashka is a research associate at the Centre for Science and Security Studies, King's College, London, and an...

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Ivan Oelrich

An independent defense analyst, Oelrich was the former vice president of the Strategic Security Program at the...

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Editor's note: Since the publication of this article, the authors and David Albright and Paul Brannan of the Institute for Science and International Security have had a lively online exchange disagreeing over estimates for the enrichment capabilities of Iran's IR-1 centrifuges. A discussion about this debate by Bulletin columnist Joshua Pollack can be found on the blog, Arms Control Wonk. Links to the back-and-forth include Albright and Brannan's original reaction; Oelrich and Barzashka's response; and Albright and Brannan's rebuttal.

When Iran's Fordow fuel enrichment plant first became public on September 25 at the G-20 meeting in Pittsburgh, the underground facility, located near the holy city of Qom, was widely portrayed as proof that Tehran was pursuing nuclear weapons. In particular, U.S. President Barack Obama, French President Nicolas Sarkozy, and British Prime Minister Gordon Brown claimed that the clandestine enrichment plant's "size and configuration" were "inconsistent with that of a peaceful program."

For its part, Tehran has steadfastly denied that it's pursuing nuclear weapons and rejects accusations that it hid the Fordow enrichment plant from the international community. Iran has defended its lack of disclosure and the nature and location of the facility (in a bomb-proof tunnel, under a mountain, near a military base) by citing its legal right under the Nuclear Non-Proliferation Treaty to enrich uranium, persistent Israeli military threats, and a different interpretation of its obligations to reveal new facilities to the International Atomic Energy Agency (IAEA) under the Subsidiary Arrangements to its Safeguards Agreement.

Because it has been exposed, the Fordow facility is now subject to IAEA inspection, just as any other declared Iranian nuclear facility. (The IAEA's technical assessment of Fordow also plays a wider political role, to determine whether Iran has violated its obligations under the Safeguards Agreement and arbitrate between Western accusations and Iranian claims of a peaceful nuclear program.) According to IAEA Director-General Mohamed ElBaradei, inspectors who visited the site in late October didn't find anything immediately alarming. But according to the IAEA report, larger questions regarding the chronology and purpose of the site still remain. (Note: The link is to a leaked "restricted" version of the report.)

The facility's capacity. The October inspection confirmed that so far construction corresponds to the design specifications for the facility provided by Tehran to the IAEA. Iran ultimately plans to install about 3,000 centrifuges at Fordow, which is consistent with U.S. estimates. The inspection revealed that none of the centrifuges had been installed but that footings and piping were in place. Although Iran has mentioned that it may install more advanced centrifuges in the future, current plans call for IR-1 machines, the well-understood design that the Iranians operate at their Natanz enrichment facility. This substantially narrows the uncertainty in estimating Fordow's potential enrichment capacity. Since centrifuge cascades used for nuclear fuel differ in arrangement from those used for bomb material, inspectors have photographed the cascade piping to evaluate whether it's consistent with declared enrichment levels and the declared number of machines. Their conclusions are forthcoming.

What is known about the facility's size, however, is perplexing. It will be 6 percent of the ultimate capacity of Natanz, making it, as Western nations have pointed out, far too small to be useful for enriching fuel for civilian nuclear reactors. In fact, it would take almost 90 years for the cascades at Fordow to fuel a single 1,000-megawatt commercial nuclear power plant for just one year. Therefore, many nuclear experts have indicated that Fordow was more likely designed to be a clandestine facility devoted to enriching uranium for weapons, in accord with U.S. statements that the facility is inconsistent with a peaceful nuclear program.

But Fordow may be too small even for that. In theory, the plant is conveniently sized to manufacture enough highly enriched uranium (HEU) for one nuclear weapon per year, if it were to use already enriched, reactor-grade uranium as the feedstock. This scenario, a favorite among nonproliferation experts, would require enriched uranium to be sneaked out of the Natanz facility, which has been under safeguards since it became operational in 2003. The IAEA's goal for detection of a "significant quantity" of uranium, that is, enough to be of worry for making a bomb, is one month--much shorter than the time it would take the cascades at Fordow to enrich such an amount. If Iran did want to enrich uranium for a weapon, it would be far easier to oust inspectors from Natanz and proceed with much more rapid HEU enrichment there. The Fordow option would be more plausible if it used machines with a significantly higher separative capacity than the IR-1 centrifuges--a possibility that will need revisiting when the devices actually are installed at Fordow.

Since it would be difficult to divert enriched material from Natanz, Fordow still could be used to enrich natural uranium to HEU levels (although it would take four years to enrich enough natural uranium for just one bomb, hardly a viable breakout option). To remain undetected, this would require a covert uranium hexafluoride conversion plant, which converts uranium to gas for use in the cascades. So far, no clandestine Iranian conversion facility has been detected. (Iran's only known conversion plant is at Isfahan, and it is under safeguards.)

The facility's purpose. In its initial statement to the IAEA, Iran described Fordow as a pilot plant protected by "passive defense" systems. Tehran has justified placing the facility in a hardened mountainside tunnel as a response to barely veiled threats by the United States and overt threats by Israel to destroy its nuclear program. In another letter, cited in the agency's report, Iran described the facility as a so-called contingency enrichment plant, designed to prevent enrichment from being suspended in the event its declared nuclear facilities were destroyed by military attack.

The Iranian Revolution Document Center [in Farsi], a pro-government Iranian research institute dedicated to documenting and analyzing the Islamic Revolution, suggests that Fordow's strategic purpose is to deter an attack on Natanz. Even though Fordow is much smaller than Natanz, this makes some sense. Such an attack would not be meant to cripple Iran's commercial nuclear fuel production, but to stop a weapons program. If Fordow is invulnerable and could alone carry a weapons program forward, the value of attacking Natanz is greatly diminished--although Fordow's limited enrichment capability is still an issue.

Another more disturbing possibility is that Iran has a number of similar secret facilities--along with the required uranium hexafluoride conversion plants--and that Fordow is simply the only one to have been discovered. The IAEA report raises this possibility, but says that Iran has declared to the agency that it has no other undeclared nuclear facilities. Any further discoveries would be hard to explain away as being for peaceful purposes--and we doubt that Iran would make such a blanket statement in light of its poor track record at hiding its nuclear facilities. It also is possible that Fordow was the first of several planned secret facilities, and that, with its discovery, Iran has put further plans on hold. From a technical perspective, it's too soon to know how Fordow fits in with Iran's larger nuclear ambitions. Although the facility's capacity is not viable for large-scale nuclear fuel production by itself, it is not ideal for weapons production either.

The facility's legality. The chronology of Fordow's planning and construction is important to know whether Iran has met even its own recognized obligations to the IAEA. If Tehran's story is inconsistent, it shows an intent to deceive the agency (with the implication, of course, that it was covering up a covert weapons program). According to the IAEA, Iran should have declared the facility as soon as it decided to construct it, as it is legally obligated to do under revised Code 3.1 rules of the Subsidiary Arrangements to its Safeguards Agreement. But Tehran unilaterally withdrew from these provisions in March 2007 to protest what it thought was unfair censure by the U.N. Security Council. Under the version of Code 3.1 that Iran does recognize, it is obligated to declare any nuclear facility six months before material is introduced. Iran announced Fordow in a letter to the agency on September 21 and stated later that the plant would become operational in 2011, meaning that it was well within its obligations as it recognizes them.

According to U.S. officials, however, the timeline is much shorter--the facility was "at least a few months, perhaps more" from operation, suggesting that Iran would be in violation of its own recognized obligations and that the 2011 date was retroactively fabricated to put the facility in compliance. Although there was no comment by inspectors on whether the facility's construction seemed consistent with a declared 2011 operational date, the IAEA report concluded that Fordow was at an "advanced stage of construction" with centrifuge mounts, piping, and auxiliary equipment already installed. At Natanz, Iran took about a year to complete the installation of the facility's initial 3,000 centrifuges. But it brought them online as they were being set up rather than wait for all 3,000 machines to be set in place, so initial operation began in less than a year. Either way, it would be difficult to prove that Fordow could become operational in less than six months because Iran always could stall construction to match its stated schedule of 2011.

When the decision to construct Fordow was made and when actual construction started also remains unclear. Washington believes that construction began before 2007, meaning that, even by Iran's standards, it should have been declared to the IAEA much earlier. According to Iran, Fordow was part of a wider Iranian initiative to construct generic contingency centers based on increased military threats. Iran maintains that it acquired "one of those constructed and prepared centers" in late 2007, indirectly confirming that construction of the tunnel in which the enrichment plant is located had commenced prior to 2007. It denies, however, that the site was previously slated for an enrichment plant. The question is, was the tunnel constructed with a centrifuge plant in mind?

Moreover, if design work for the facility started in 2006, as the United States maintains, and U.S. intelligence was positive that it was intended to be "a covert centrifuge facility," why did the 2007 National Intelligence Estimate conclude that Iran had halted its nuclear weapons program in 2003? It's possible that U.S. intelligence identified that construction was taking place, but it lacked information on what was being built at Fordow. This is not inconsistent with Iran's story that in 2007 nothing was at the site except for an empty tunnel that didn't have a specified nuclear use.

The facility's political implications. The revelations regarding Fordow have fueled suspicions that Iran has built a clandestine enrichment facility as part of its nuclear weapon "breakout" plan. Contrary to Western speculation, initial IAEA inspections at the facility revealed no smoking gun, but the episode raises many questions and exacerbates worries about Iran's intentions.

Although the IAEA flatly rejects Iran's unilateral withdrawal from its revised Code 3.1 requirements, the agency was relatively mild in its latest report, merely claiming that the Fordow declaration is "inconsistent with [Iran's] obligations." The agency also abstained from making comments on the chronology or how close to completion the facility was. It seems as though the IAEA was providing leeway for Iran to explain itself or at least is allowing Tehran to further cooperate in the future.

It's also possible that Iran was not trying to deceive the international community. Even though Iran's actions appear suspicious, one legitimate explanation is that Tehran acted strictly by what it perceives to be its most narrow and legal obligations. Iran might be acting this way out of national pride and because it feels that it is being unfairly discriminated against, rather than a desire to cover-up a covert weapons program. Of course, Iran's actions also can be explained as an attempt to deceive. A physical inspection of Fordow can't prove intent one way or the other. To do so, the IAEA needs access to the papers that document the decision to build Fordow in the first place.

Based on past experience with Iran over the Natanz enrichment facility, essential questions such as the chronology of development and the role of the facility will be answered only gradually, if at all. (Previously, the IAEA was able to make substantial progress in uncovering Iran's uranium enrichment program in part because Tehran had signed and agreed to implement the Additional Protocol, which allows inspections to facilities not included in the Safeguards Agreement--such as uranium mines and centrifuge workshops. Iran has since refused to ratify the Additional Protocol and suspended its application. With limited access to additional facilities, the agency will have a harder time detangling the facts behind Fordow than it did with Natanz.)

What is known about Fordow is this: It is neither ideal for commercial nor for military purposes, and Iran's contingency and deterrence arguments are weak. The facility's size and capacity would make the most sense if it were part of a network of clandestine nuclear facilities, but Iran has formally declared it has no other undeclared facilities. This is significant since if additional hidden facilities are discovered, there will be no innocent explanation. Fordow, however, could be the first of a network of clandestine plants, and decisions to construct them could legally (according to Iran) be made in the future. In any event, it is good news that Fordow was discovered and that it will now be under IAEA safeguards. With Fordow under watch, the risks that it could be used to secretly enrich uranium for a nuclear weapon are far smaller than what was already possible at its declared Natanz facility.