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Maybe you remember some earlier discussion of “Iran’s new-generation centrifuges”:http://www.totalwonkerr.net/1984/the-black-bellows. The IAEA introduced the subject to us back in “Feb. 2008”:http://www.isisnucleariran.org/assets/pdf/IAEA_Report_22Feb2008.pdf:

bq. 44. On 8 November 2007, Iran stated that it “agreed that exchanging of the new centrifuge generation information” would be discussed with the Agency in December 2007 (GOV/2007/58, para. 33). On 13 January 2008, the Director General and Deputy Director General for Safeguards visited an AEOI R&D laboratory at Kalaye Electric, where they were given information on R&D activities being carried out there. These included work on four different centrifuge designs: two subcritical rotor designs, a rotor with bellows and a more advanced centrifuge. Iran informed the Agency that the R&D laboratory was developing centrifuge components, measuring equipment and vacuum pumps with the aim of having entirely indigenous production capabilities in Iran.

So, just how “indigenous”:http://www.totalwonkerr.net/2002/p-is-for-persian are these designs, exactly? Do they have an identifiable lineage?

For glimmerings of insight into this question, we must turn to the indefatigable Mark Hibbs, who has had a few articles on related subjects in recent years.

According to MH in the Jan. 29, 2007 issue of _NuclearFuel_, Pakistan developed not just the by-now-familiar P-1, based on URENCO’s SNOR and CNOR machines, and not just the P-2, based on URENCO’s G-2, but also a P-3 and P-4, starting in the mid-1980s.

(As an aside, this might explain why Khan and his associates were prepared to start selling the earlier technology: it was obsolete. Old machines were being replaced, and those elements of the supply chain that were devoted to their components and materials (e.g., CNOR bearings) would no longer serve a purpose for Pakistan, KRL, or Khan — except to make some money.)

Hibbs writes:

bq. While individual segments of Pakistan’s aluminum P-1 model had a throughput of less than 1 SWU/year, P-2, which features two maraging steel rotor tube segments, had a throughput of about 5 SWU/yr. P-3, the first of two later centrifuges, according to the intelligence information, is a four-tube model with a throughput of just under 12 SWU/yr. A successor model, P-4, may have a throughput slightly over 20 SWU/yr, the information indicates.

It should come as no surprise, by now, that the P-3 and P-4 were based on URENCO models, the four-tube 4-M and the six-tube TC-10, also known as SLM, according to MH in the Feb. 15, 2007 issue of _Nucleonics Week._

It’ll certainly be interesting to learn how much the IR-4 — apart from having carbon-fiber rotors — resembles the P-3. Certainly, to judge by what Hibbs writes, the IAEA had its suspicions.

Another possibility, though, is that the IR-4 is basically an upgraded, carbon-fiber version of the P-2, owing nothing in particular to the P-3 or P-4.

As for the “more advanced centrifuge” mentioned by the IAEA last year, we’ll just have to wait and see.

_Edited lightly for clarity._