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The International Atomic Energy Agency (IAEA) has an extremely difficult time in evaluating alleged nuclear weapons studies in Iran. While it has done an excellent job in verifying the nuclear material production activities in Iran’s uranium enrichment plants, the IAEA also appears to be willing to risk its technical credibility by insisting on visiting a military site called Parchin, near Tehran. The IAEA renewed its call to be granted access to Parchin during the past week’s negotiations with Iran on a new framework agreement for resuming its investigation of suspected military nuclear activities in the country. For its part, Iran has dismissed the IAEA’s concerns about the Parchin site, claiming that it was sufficiently inspected by the agency in 2005.
The IAEA is focusing on one particular building at Parchin on the basis of member state intelligence contained within its recent report on Iran’s alleged weapons program. This building is said to hold a massive steel chamber designed to contain explosives development tests for implosion-type uranium bombs. The IAEA believes that such a chamber is a unique indicator of nuclear weapons development. The use of such a chamber is actually rare in historical nuclear weapons development and quite inappropriate for Iran. In fact, the IAEA has already reported that the most interesting alleged large-scale nuclear weapons high explosive tests were not conducted at Parchin, but hundreds of kilometers away at site called Marivan.
Parchin is a huge ammunition and explosives plant with perhaps 1000 buildings over an area of 40 square kilometers. Despite the fact that the entire plant shows many classical signatures of explosive operations, the IAEA has chosen to focus on one building alone. The IAEA states in its report that a very large chamber for containing explosive tests was said to have been installed at Parchin and then covered up by a building. It also claims that commercial satellite imagery is consistent with this but the earliest commercial satellite imagery shows only a finished building. The only way the IAEA could make this claim would be if it possessed earlier classified imagery. The IAEA further bolsters its case by using reports from unnamed human sources.
The massive steel explosives containment chamber in the building is said by the IAEA to be able to contain an explosion of 70 kg of high explosives. This is a world-class facility, especially as it was designed 15 years ago with the help of a former Soviet engineer. It is more likely that the container will hold about 10 kg of high explosives detonation. In any case, there are few if any tests involving uranium and high explosives that Iran needs to conduct in a container that is only there to hide traces of uranium.
In fact, the chamber is far too small to contain explosive proof tests of a full scale mock-up, and far too big to contain smaller tests of research interest. Thus, a container of this size is irrelevant to an Iranian nuclear weapons program. Some say that a container for explosives tests is a clear and unequivocal indication of nuclear weapons development. This is incorrect. Most nuclear weapon development tests have been carried out in the open air for obvious technical reasons. The IAEA is therefore risking its technical reputation on tenuous premises.
The reported chamber at Parchin is too big or too small but not the right size. It was designed and built in the late 1990s when Iran might have had a different set of requirements for nuclear weapon design. The most critical experiments Iran might have done in the alleged chamber are far too large for its unbelievable 70 kg high explosive capacity. But those same experiments were done at another test site near Marivan, hundreds of kilometers away, as described in great detail by the IAEA.
The container described by anonymous sources has a massive concrete collar around the middle to contain the huge blast and make it useful for experiments. This collar makes it difficult if not impossible to make the scientific measurements that Iran needs to make in the chamber that was designed. Flash x-ray, optical and especially neutron measurements would be difficult or impossible because of the collar.
The container has wash-down systems and a vacuum pump system that are appropriate for nanodiamond production rather than for explosives tests. It was supposed to have been built by an Iranian company with the capability to build relatively thin-walled pressure vessels for the oil industry. This company could not build a small chamber appropriate to contain a large blast so they would have built a larger, but thinner-walled chamber, to offset the weakness of their vessels.
Since November 2011 there have been press reports that the Parchin site has been ‘sanitized’ to remove traces of uranium. Uranium signatures are very persistent in the environment. Stories that bulldozers are being used to sanitize the chamber are irrelevant. If Iran is using hoses to wash contamination across a parking lot into a ditch, there will be enhanced opportunities for uranium collection if teams are allowed access. If an explosion chamber has been used with uranium and explosives, uranium will be detected no matter how hard the Iranians work to clean it. If a chamber using explosives and uranium has been used inside this building, the IAEA will find the particles as surely as they did in the aftermath of the Syrian reactor bombing.
Ultimately the IAEA is trying to force Iran to grant access to a military site where they have been told that nuclear-related activities have taken place. It is unlikely that the alleged chamber is being used for nuclear activities, if it even exists. If the IAEA succeeds in visiting the site and does not find evidence of nuclear weapons activities, its credibility will be seriously damaged and it will be unable to persuasively make the case for visits to more serious sites of concern inside Iran.