Jeffrey LewisMore Iran Stuff

A couple of technical bits about Iran’s nuclear programs, related to whether Iran can make clean hex (maybe not, still) and whether Iran is telling the truth about the source of its plutonium (um, doesn’t look like it).


No, not the British Buffy, you perv.

Some of us were wondering whether any of Iran’s centrifuges have crashed or, if not, how Iran figured out the process to make clean uranium hexafluoride.

Well, Western diplomatic sources are telling the BBC the Iran used some old Chinese hex imported in 1991. AFP has the same story, adding that Iran might have also tried out some of its own hex:

“We think they used both, perhaps to compare the two, and certainly to demonstrate to themselves that their own UF6 is capable of being enriched without too many centrifuge problems,” the diplomat said.


A loyal reader reminds me of something that hasn’t been well reported—continuing questions related to Iran’s plutonium separation program.

Some of you may remember a little post I wrote entitled, What Are Five Years Among Friends? Iran Confirms 1998 Pu Experiments.

The gist was simple. Iran claimed that secret reprocessing research ended in 1993, which was false—experiments continued through 1998. Confronted with scientific evidence demonstrating that experiments had continued through 1998, Iran made a “clear distinction between the date of termination of the research project on plutonium and the dates of the other activities, such the ones related to purification and related waste management of the liquid.”

Clear as mud.

Anyway, in the process of figuring out when Iran’s plutonium separation experiments ended, the IAEA noticed that some of the disks had a different amount of a certain isotope of plutonium than the solution from which they were created.

The Agency’s analysis showed, in particular, that the Pu-240 content measured on eight of the discs was significantly lower than the Pu-240 content of the solution from which the plutonium deposited on the discs was said to have originated.

In other words, eight of the disks seem to have been made from a different source of plutonium, again raising questions about the completeness of Iran’s declarations.

Apparently, according to the last IAEA Board Report (full text) the Iranians are sticking by their story despite the overwhelming scientific evidence:

In the light of the Agency’s findings, the Agency cannot exclude the possibility—notwithstanding the explanations provided by Iran—that the plutonium analysed by the Agency was derived from source(s) other than the ones declared by Iran.


  1. John Field (History)

    I’m confused.

    >> …the IAEA noticed that some of the disks had a different…

    We’ve got multiple U02 targets that got irradiated, Pu-240 level could be different in each, right? Maybe there was additional acid solution that got disposed of years ago?

    Besides, why would they give IAEA disks with lower Pu-240 content than the solution? Those are the ones which would presumably have been the most stringent test of their reprocessing technique as well as best for weapons neutron experiments.

    Perhaps there is an inconsistency here, but where is the malicious intent – isn’t the Pu-240 ratio more likely a misplaced/misremembered bottle?

    Now, on the other hand, the age of the solutions seems to be a very relevant matter. This timestamps the conclusion of their experiments.

    But, for this, shouldn’t we really be talking about the Pu-241/Am-241 ratios as this is what dates the materials best? But, there is no mention of Pu-241.

    What am I missing here?

  2. pete

    can anyone explain what exactly would happen if Iran would use contaminated hex in its cascades?

  3. Josh Narins (History)

    In addition, something about scientists, in Iran or anywhere, and perfect note-taking simply doesn’t ring true.

    If Bush had to, because of Aliens or something, totally disarm his WMD, he couldn’t do it. The Pentagon is habitually off by about a trillion or two dollars worth of equipment each year, when their own auditors check.

    The IAEA, in an earlier part of the report, claims it was shown a document, but hasn’t been given a copy of that document, and is complaining.

    Thanks for your comments, Mr. Field, they help.

  4. Max (History)

    Wasn’t the ‘bit of paper’ that Iran can’t/won’t hand over, evidence of an approach to Iran by the AR Khan ‘network’, offering nuclear capabilities?………

  5. Hass (History)

    The paper was shown to the IAEA but kept by Iran.