Iran Approaches the Nuclear Weapons Threshold
11/09/2011 – by Richard Weitz
The International Atomic Energy Agency (IAEA) has written its latest quarterly assessment of Iran’s nuclear program and things don’t look good.
The report and other comments by the IAEA and its member governments indicate that Iran has made considerable progress In the three pillars required to have a nuclear weapons capacity: producing sufficient weapons-grade fissile material—normally highly enriched uranium (HEU) or plutonium—to fuel the explosion; designing and physically assembling nuclear explosive devices using this material; and acquiring a means to deliver the weapon to a target—normally by designing and building a small nuclear warhead that can be carried by a ballistic missile or warplane.
The November 8 report was written by IAEA Director General Yukiya Amano and his staff from information received from the agency’s monitors and analysts as well as intelligence provided by national governments. The report says ten national governments provided some intelligence, which the agency then tried to verify independently. The report says it includes only the information that could be so verified.
Like earlier IAEA reports on Iran, the most recent report again complains that Iranian authorities have failed to fulfil the multiple Security Council resolutions requiring Tehran to provide the IAEA with all the information required for it to verify that Iran’s nuclear program has been for exclusively peaceful purposes. Iranians resolutely deny any effort to make nuclear weapons but have conducted so many deceptive and clandestine nuclear activities as to sow doubt among many observers.
This latest IAEA report finds that Iran continues to enrich larger quantities of low-enriched uranium (LEU) at the Fuel Enrichment Plant (FEF) and the Pilot Fuel Enrichment Plant (PFEP), both located at Natanz. The FEF concentrates on manufacturing LEU whose proportion of the fissile isotope Uranium-235 has been artificially raised to 3.5%, which is suitable for use in most commercial nuclear reactors. As of early November, Iran was using 37 cascades at the FEF containing of 6,208 IR-1 centrifuges, with another 2,000 or so devices off-line, probably for repair.
The PFEP, besides experimenting with new centrifuge models, is producing uranium fuel enriched to 20% Uranium 235 for use as fuel in Tehran Research Reactor (TRR), which has almost exhausted its original fuel supply. Since this above-ground cascade began operating in February 2010, Iran has fed a total of 765.5 kg of 3.5% LEU, producing 79.7 kg 20% uranium.
Tehran and its foreign partners tried to negotiate a uranium swap agreement whereby Iran would surrender large quantities of its 3.5% LEU in exchange for foreign fuel rods containing the 20% LEU. After these negotiations failed, Iran decided to try to produce the 20% LEU fuel rods itself. It has demonstrated the capacity to produce the 20%-enriched LEU but not the fuel assemblies needed to power the reactor.
Still, being able to manufacture 20% U-235 makes it easier for Iran to produce weapons-grade uranium, which is normally enriched to 90%. According to IAEA calculations, Iran has already manufactured sufficient LEU, almost 5,000 kilograms, to make several nuclear weapon if this LEU were enriched further to weapons-grade high-enriched uranium (HEU).
Both these facilities at Natanz are subject to IAEA surveillance and containment, as required by Iran’s IAEA Safeguards Agreement (INFCIRC/214), which entered into force on May 15, 1974. The IAEA has generally been able to monitor these sites, but the Security Council has prohibited Iran from engaging in such uranium enrichment until Iran clarifies IAEA concerns that Iranians have engaged in nuclear weapons research.
Iran is a party to the Nuclear Non-Proliferation Treaty (NPT), which prohibits Iran from engaging in such research, and authorizes the IAEA to ensure the compliance of all parties with their treaty commitments.
Interestingly, while the volume of both types of enriched LEU continues to accumulate, the pace at which Iran is producing this material is not. This stagnation, evident for some time now, may be related to the Stuxnet virus and other clandestine sabotage operations. Or it could be that Iran is trying to proceed surely but slowly towards achieving a nuclear weapons potential to avoid precipitating a strike against these facilities before it has a more developed nuclear capacity.
Unfortunately, this pause may not last long. The IAEA notes that Iran continues to make progress developing more efficient enrichment machines designed to overcome the reliability problems found with the current IR-1 devices. These first-generation centrifuges, based on Pakistan’s P-1 centrifuges acquired through A.Q. Khan’s illicit procurement network, have been the sole device in operation in Iran since Iran started manufacturing LEU in February 2007.
Iran has been developing and testing several new and presumably more efficient centrifuge models at its testing facility at the PFEP. The Iranians informed the agency earlier this year that Iran intend to begin deploying two of these next-generation centrifuges, the IR-4 and IR-2m, soon at FEP. Since they operate more efficiently and require less physical space, these centrifuges can also more easily be used at clandestine sites.
They might also be able to produce HEU more easily than the problematic IR-1. Once the second-generation centrifuges enter into operation on a large scale, Iran’s enrichment uranium production—and potential bomb-making material–could soar.
Another problem is the IAEA cannot be certain that Iran is not now, or will in the future, enrich uranium at other clandestine locations. For example, Iran initially concealed both the Natanz Enrichment Site and the more recently revealed Fordow Enrichment Site near Qom from the IAEA, and only informed the agency after the existence of these facilities was revealed by other sources.
Iran has also taken actions to shield its nuclear activities from a potential adversary air strike as well as making it harder for satellites and other air, space, and ground sensors to monitor its activities.
For example, Iran has begun transferring nuclear material to its underground Fordow Enrichment Site and installed cascades of advanced centrifuges there. Iran has repeatedly changed the declared designs for this facility that it provides the IAEA, which, in addition to the site’s initially secret construction, suggest its purpose was to allow Iran to manufacture nuclear weapons should the Iranian leadership decide to do so.
The IAEA already complains that Iran is not providing adequate information concerning its declared nuclear activities.
For instance, Tehran has been denying agency requests for additional information about possible additional uranium enrichment facilities as well as its laser enrichment technologies or third-generation centrifuge. Furthermore, Tehran has denied the IAEA access to various nuclear sites, such as where Iran researches, develops, and manufactures enrichment technologies and centrifuges.
Efforts to understand the history of Iran’s weapons design work—the second element of a nuclear weapons program–are also impeded by Iranian secrecy.
The report’s 13-page Annex details the information that the agency possesses regarding suspicious Iranian nuclear activities that may have military purposes. The IAEA has previously concluded that before 2003 Iran had a comprehensive and structured program to develop nuclear weapons. That year, it ceased weapons-design work but continued programs to acquire fissile material as well as the means to deliver a nuclear warhead to a target using a ballistic missile.
But now the latest IAEA report provides evidence that some weapons-design work has continued, if on a less comprehensive basis.
Among the long list of suspicious activities—all of which at least some of the countries that developed nuclear weapons also followed—several stand out.
First, two IAEA member states informed the agency that Iran used advanced computers to create sophisticated models of the behaviour of uranium cores “subject to shock compression”–something that provokes the report to comment drily that, “”The application of such studies to anything other than a nuclear explosive is unclear to the agency.” Modern nuclear warheads use high-grade explosives, tamping devices, and precise geometries around the nuclear core to minimize the size and weight of the warhead so that it can be carried by a plane or missile.
Second, the IAEA has evidence that Iran built a large explosives container at the Parchin military complex southeast of Tehran in 2000 that technicians use to conduct hydrodynamic experiments, activities that are “strong indicators of possible weapon development.” Iran concealed this vessel from IAEA inspectors.
Third, Iran keeps renaming and reorganizing the clandestine organization that before 2003 had led its comprehensive nuclear weapons program, suggesting a kind of shell game designed to conceal its existence. But the IAEA believes that the same person who led this weapons program, Mohsen Fakrizadeh, remains in charge of the current renamed and reorganized effort. The Iranian government has denied repeated agency requests to communicate with Fakrizadeh.
Some other disturbing findings are that Iran:
- Tried to obtain equipment, materials, and services that would help develop a nuclear explosive device, including high-speed electronic switches and spark gaps (for triggering and firing detonators), neutron sources, radiation detection and measuring equipment, and training courses on subjects related to developing nuclear explosive devices;
- Received nuclear explosive design information from the A Q Kahn clandestine nuclear supply network;
- Sought data on how to transform HEU into a metal usable as the nuclear core for a weapon;
- Developed exploding bridgewire detonators for detonating a nuclear explosive device;
- Conducted high-scale explosive experiments near Marivan;
- Manufactured simulated nuclear explosive components with high density materials such as tungsten;
- Researched the manufacture of small capsules suitable for carrying components filled with nuclear material;
- Conducted preliminary experiments that could be useful for testing a nuclear bomb.
Perhaps almost any one of these types of activities in isolation might be excused as a simple scientific experiment. Some could be seen as having possible civilian as well as military purposes, but the large volume of suspicious activities more convincingly lead one to conclude that Iranians are seeking at least the option to convert their growing supply of potential fissile material into a nuclear weapons stockpile.
As the report puts it, “The Agency has serious concerns regarding possible military dimensions to Iran’s nuclear program. After assessing carefully and critically the extensive information available to it, the Agency finds the information to be, overall, credible. The information indicates that Iran has carried out activities relevant to the development of a nuclear explosive device.” And some of these activities continue to this day.
In addition to acquiring potential fissile material and undertaking activities suitable for making a nuclear explosive device, Iran has also worked to improve its ballistic missile capacities in recent years—making progress in the third pillar of a nuclear weapons program.
More suspiciously, the IAEA reports that Iran studied how to fit possible nuclear payloads onto the re-entry vehicle of a Shahab 3 missile. The IAEA has evidence that Iranians technicians examined how these payloads would function during the missile’s launch and flight. They also worked on developing a prototype firing system that would allow a payload to explode in mid-air above a target (for a nuclear air burst, which could generate electro-magnetic pulse suitable for disabling electronic devices), or when the missile re-entry vehicle hit the ground.
For the report
For earlier pieces see