What Might the Iranians Have Tested at Parchin?

The Parchin story continues to complicate. Gareth Porter would like to believe that there is no explosives testing chamber at all, and indeed we have no photographic proof that one is there. This somewhat undermines Porter’s earlier story, however, of the quest for nanodiamonds at Parchin. Jim White continues to argue that if a uranium deuteride initiator was tested in a steel container there, the steel would have been activated by the neutrons produced. Both argue that the cleanup activities that continue to be reported by David Albright’s Institute for Science and International Security.

There is a lot that we don’t know about Parchin, and all attempts in the media to figure out what went on there are speculation based on very few facts. That includes Porter, White, AP correspondents, David Albright, and our own Susan Voss and me.

Much of the speculation turns on technical details. So it’s important to get those technical details right. Let’s assume that there is indeed an explosives testing chamber of roughly like what Susan analyzed. What might it have been used for?

Four possibilities have been put forward. Another, testing conventional explosives like shaped charges, is possible, but I won’t consider it here. In the United States, clean air laws have made it necessary to do many kinds of explosives testing in containment like the vessel that has been skechily described at Parchin. It’s unlikely that the Iranians have similar laws or that they would apply them to military activities.

Other purposes of containment would be concealment of the tests or recovery of valuable starting materials (like plutonium or enriched uranium) or products (like nanodiamonds).

Three of the possibilities have to do with nuclear weapons design. The fourth is Porter’s belief that the Iranians have been making nanodiamonds, with the aid of Vyacheslav Danilenko.

The other three can be confusing, because all can be (and have been) categorized by the media as “triggers” for nuclear weapons. But the three are quite different, and reporters would benefit by understanding that.

Neutron Initiators
A nuclear weapon has a higher yield if the fissionable material is hit with a burst of neutrons as it is being compressed. Neutron initiators provide those neutrons. Jim White focuses on a uranium deuteride initiator design, but there is also reason to believe that the Iranians have looked at a polonium-beryllium design. Polonium is highly radioactive; beryllium and uranium are also hazardous. So testing in a container makes sense.

Multipoint Initiation System
The assembly or compression of fissionable material in a nuclear weapon requires precise timing of shaped charges, called a multipoint initiation system. Both timing and arrangement of the charges need to be tested. A test system is usually a fairly large load of explosives, but contains little hazardous material in comparison to the other two possibilities. However, the size of the explosion might be something to conceal in a container.

Hydrodynamic Experiments
These are experiments to determine the properties of materials under the high pressures generated by the multipoint initiation systems. Many different configurations are possible, depending on what is to be determined. Some of these experiments will involve uranium, a reason for containment.

Albright, Porter, and White all have been following recent activities at the Parchin site that look like the Iranians may be cleaning things up, apparently in response to the IAEA’s request to visit the site and take samples. I regard the concerns as something of a sideshow; now that the Iranians have been washing something out with water, demolishing buildings, and shoving dirt around, there is no way that an IAEA inspection can support the Iranians’ claim that nothing untoward has been done there. Questions will remain, no matter what the findings.

What the IAEA Might Find at Parchin
All three types of test might have been done at Parchin. The multipoint initation system tests would be the largest, and it appears that the explosive chamber has been sized for them. There is no reason smaller tests couldn’t be done inside such a chamber.

When I was in charge of environmental cleanup at Two Mile Mesa, one of the sites was where the very first ever polonium-beryllium neutron initiators might have been tested. We were pretty sure we found the site from descriptions in old memos. There was no reason to test for polonium. With a half-life of 138 days, it is pretty much gone after 1380 days, or a little less than four years. Finding polonium inside or around the Parchin container would suggest a more recent test.

[News just coming across claiming that Yasser Arafat may have been killed eight years ago by polonium. The amounts given are very, very small. I would like to know what the detection and error limits are.]

Beryllium should be detectable, particularly inside a container. Uranium, from neutron initiators or hydrodynamics experiments, should also be detectable. However, sufficient earthmoving could change that.

White has been arguing that neutron initiator tests would have activated the cobalt in the steel vessel itself via the neutrons released during the test. This will depend on how much cobalt is in the steel, the energies of the neutrons produced, and the capture spectrum for cobalt-59. Without calculations based on that information, I’d say that finding a cobalt-60 signature in the vessel would suggest neutron initiator experiments, but not finding it wouldn’t prove they hadn’t been done.

Damage to the interior of the container might provide clues as to the size of explosions within it.

Presumably the IAEA has more information. Sampling could provide evidence that one or more of these kinds of test have taken place, but there is no way now that they could dismiss the possibility of testing. Documentary evidence, if Iran were willing to provide access to all documents, might provide that kind of clean bill of health.