Most of the commentary and analysis of Iran’s nuclear weapons program focuses on the uranium enrichment facilities at Natanz and Fordow. As more and more centrifuges are installed and brought online at each of those facilities, Iran’s ability to enrich fissile material, specifically the uranium isotope used in nuclear bombs (U-235), advances. This results in serious problems for the IAEA and the international community. Iran becomes able to increase its stockpile of near-20% U-235 more quickly, and to shorten the length of time needed to make enough weapon-grade uranium (90% U-235) for one Significant Quantity (SQ). [A SQ is enough 90% U-235 for one medium-yield, or a few low-yield, nuclear bombs.]

If Iran is indeed working toward making one or more nuclear bombs, using weapon-grade uranium (WGU) as the fissile material, Iran faces one major obstacle. As soon as Israel and/or the United States become convinced that Iran is close to gaining enough WGU for a bomb, a military strike on Natanz and Fordow becomes likely. Iran would need to “breakout” (rush to make WGU from 20% U-235) before such a strike destroys those facilities. But no matter how many centrifuges Iran installs, the oversight of the IAEA means that Iran cannot breakout quickly enough. The IAEA would detect the breakout attempt.

Iran can shorten the time needed for a nuclear breakout by increasing its stockpile of near-20% U-235 gas. According to a report (PDF) by ISIS (Institute for Science and International Security), a Washington, D.C. think tank, a stockpile of 240 kg of near-20% U-235 gas would allow Iran to breakout, making enough WGU for at least one nuclear bomb, in only one month (Table 8, p. 18).

The U.S. and Israel understand these limitations. And so they might choose to make a military strike on Natanz and Fordow based on their assessment of how much 20% U-235 gas Iran has stockpiled, even before a breakout begins. The figure of 240 kg of 20% U-235 is often mentioned as the red line for a strike. Once Iran reaches 240 kg of 20% enriched uranium, a military strike could occur before Iran has time to enrich that stockpile to weapon-grade purity (90%).

A larger stockpile of 20% U-235 might shorten the breakout time by several days, but at least two weeks is needed to reconfigure the centrifuge cascades to enrich the gas to 60% and then to 90% U-235. Then additional time is needed for the enrichment process itself. So there is a lower limit on the amount of time Iran needs to make WGU. They cannot do so in less than about three weeks.

Iran’s problem in moving from 20% to 90% U-235 is two-fold. (1) Stockpile too much 20% U-235 gas, and a military strike is likely. (2) No matter how much 20% U-235 Iran stockpiles, a military strike can occur more quickly than a breakout can be completed.

The solution to the first problem has been for Iran to convert some of its 20% gas into uranium oxide “fuel plates”. This form of the radioactive material is used to make radioactive isotopes for medical purposes. Once it is in oxide form, it would be difficult to convert back to gas for further enrichment in a nuclear weapons program. In 2012, Iran reported to the IAEA, and the IAEA verified, that 96.3 kg of 20% U-235 gas was converted to a metal oxide, effectively reducing Iran’s stockpile of gas that could be used for a nuclear breakout (IAEA GOV/2012/55 p. 4). This conversion lowered Iran’s stockpile of 20% gas, thereby moving Iran away from the red line of 240 kg.

The international community expressed relief. Many commentators evaluated this action by Iran as a positive development. It seemed as if Iran had backed away from the red line of 240 kg of 20% U-235, allowing the West to continue diplomatic efforts instead of military intervention.

However, I opined that Iran may have deceived the IAEA, by obtaining uranium oxide plates from another nation (such as China). Some of the gas would have been used up in the machinery that converts gas to the oxide plates, as a way to deceive inspectors. But a large portion of it might have been diverted, once inspectors had left, to a third secret enrichment facility. And that may be Iran’s solution to the second problem.

A recent ISIS report mentions the possibility of a secret third uranium enrichment facility:

“Yet, there is another possibility. Iran could deploy advanced centrifuges at the Fordow enrichment plant or possibly at a third enrichment site. Its advanced centrifuges, principally the IR-2m and perhaps the IR-4 models, are expected to achieve about 3-4 times the enrichment output of the IR-1 centrifuges.” (Iran’s Evolving Breakout Potential)

If such a facility exists and if it uses the more advanced IR-2m centrifuges, then Iran could install a relatively small number of centrifuges (less than 1,000) there, in order to breakout covertly. The only issue would then be moving the 20% U-235 gas to the covert facility without detection. One way to accomplish that goal would be to claim to be converting the gas to uranium oxide metal plates.

As I’ve said in previous posts, if Iran once again claims to be converting 20% U-235 gas to metal oxide plates, this would most likely indicate a deception and a covert breakout. And now, according to a Reuters news report, Iran is again claiming to have converted more 20% U-235 gas to the oxide form: Iran says it is converting uranium, easing bomb fears

Why is it so hard to believe that Iran would convert 20% U-235 gas to the solid metal form, uranium oxide? Iran has gone to great lengths to manufacture 20% U-235 gas. Iran has spent billions of dollars, and at the same time has endured increasingly harsh economic sanctions, over the course of many years. If Iran only wanted 20% U-235 for medical purposes, a deal with the West could easily be struck to provide Iran with uranium oxide, or with the medical isotopes themselves, in exchange for limiting enrichment to 5%. Also, as a recent ISIS report details, Iran’s current stockpile of near-20% U-235 greatly exceeds any conceivable use, other than as a step toward making weapon-grade uranium: Iranian Production of 19.75 Percent Enriched Uranium: Beyond Its Realistic Needs

Given that Iran is enriching uranium gas to the near-20% U-235 level as a means to making nuclear weapons, why would they convert large amounts of that gas to the oxide form? They would not. The cost of the 96.3 kg of near-20% U-235 gas that Iran claimed to have converted to uranium oxide in 2012 is easily in the billions of dollars, not counting the billions of dollars of harm to the Iranian economy. The only explanation that makes sense is that Iran has deceived the IAEA (much as Iraq deceived the U.N. during the “oil for food” program), and the 20% gas was diverted to a third secret enrichment facility.

The assessment of many news commentators, that Iran converted the gas to oxide to forestall a military strike is only partly correct. In my view, Iran most likely feigned converting the 20% U-235 gas to metal oxide because a large stockpile of 20% gas is a red line for a military strike. The current Iranian regime would never willingly give up its stockpile of 20% U-235, which was obtained at so great a cost, and which is so essential to fulfill their ambition to become a nuclear power.

Unfortunately, this new announcement by Iran, that it has converted more 20% U-235 to metal oxide, might be an indication that the previous quantity of 20% gas has already been converted, at a third secret facility, to 90% U-235 (Weapon-Grade Uranium). Some of the 96.3 kg of gas would have been lost in the process of deceiving IAEA inspectors. But if only 75 kg of 20% gas were recovered and sent to the third enrichment facility, it would produce approximately 37.5% of one Significant Quantity (SQ) of WGU. But since one SQ is enough WGU for at least 3 low-yield bombs, Iran may already have enough WGU for one nuclear bomb. It will be interesting to learn, in the coming days, just how much near-20% U-235 gas Iran claims to have converted to metal oxide, and whether that amount of material would be sufficient for an additional nuclear bomb.

by
Ronald L. Conte Jr.
Roman Catholic theologian and
translator of the Catholic Public Domain Version of the Bible.