ISIS (Institute for Science and International Security) is a Washington D.C. think tank that covers a wide range of topics. But they have a particular concern for Iran’s progress toward obtaining nuclear weapons. The main site is ISIS-online.org and their Iran nukes specific site is ISISnuclearIran.org. On 8 Oct 2012, they released their latest assessment of Iran’s nuclear capability: “Iran’s Evolving Breakout Potential” (PDF). In this Report, ISIS evaluates how long it would take Iran to “breakout”, meaning to rush to make Weapon-Grade Uranium (U-235 of 90% purity or better).

Currently, Iran only purifies uranium to 20% (technically, ~19.75%) — as far as we know. The IAEA (International Atomic Energy Agency) “safeguards” Iran’s uranium enrichment activities, and Iran insists that these activities are for peaceful purposes: nuclear power and radioactive isotopes for medicine. But, as the ISIS Report of 15 June 2012 argued, Iranian production of 19.75% uranium is beyond its realistic needs, unless Iran is working toward making a nuclear weapon. Iran is known to purify uranium at two locations: Natanz and Fordo (near Qom). According to the IAEA and ISIS, as of August 2012, Iran currently possesses over 5,000 kg of uranium gas purified to 3.5%, and, “Between the two enrichment sites, Iran has produced 189.4 kilograms of 19.75 percent LEU hexafluoride.” (ISIS 30 Aug 2012).

The current ISIS Report (8 Oct 2012) assesses how long it would take Iran to make enough 90+% U-235 using the gas centrifuges at Natanz and/or Fordo, given the state of their enrichment program as of August 2012. There are many variables and the Report considers multiple scenarios. The basis for the analysis is how quickly Iran can make enough uranium gas to produce 25 kg of U-235 metal of 90% or better purity. This amount of metal is considered one significant quantity (SQ) by ISIS, i.e. enough for one implosion nuclear bomb of a certain yield.

Now let me summarize the worst case scenario in the ISIS Report:

Suppose that Iran decides to refuse further IAEA inspections, and to breakout: to rush to make weapon-grade uranium (WGU). These IAEA inspections are not continuous. So if Iran breaks out, they might get a week or so head start, before inspectors show up for an inspection and are turned away. How quickly can Iran make 1 SQ of WGU? The fastest time, which is the worst case scenario in the Report, requires a stockpile of 20% U-235 gas.

At the Natanz facility alone, with a 180 to 230 kg stockpile of 20% U-235, it would take 1.4 to 1.7 months to make 1 SQ.

At the Fordo facility alone, with 200 to 220 kg 20% U-235, it would take 2.0 to 2.2 months to make 1 SQ.

If both facilities worked together to make 1 SQ (Natanz enriching to 60% and Fordo to 90%), with 190 to 200 kg U-235, it would take 1.3 to 1.4 months to make 1 SQ of Weapon-Grade Uranium.

To purify uranium quickly, Iran would need to spend some time reconfiguring the centrifuges at both facilities into tandem cascades (2 sets of centrifuges working together, which increases efficiency). ISIS estimates that this set up would take about 1 month to accomplish. So the actual uranium enrichment time is only 0.3 to 0.4 months. The figure 1.3 to 1.4 months includes the 1 month set up time.

After producing enough 90% uranium gas, Iran must turn the gas into metal, then machine the metal into a hollow sphere. Finally, they must complete the assembly of the whole bomb. And this is only a bomb, not a missile. Developing a working nuclear missile would take longer still. ISIS gives no precise estimate for the time to make a bomb or a missile. The 1.3 to 1.4 month figure is only for enough WGU gas.

“The estimates in this report do not include the additional time that Iran would need to convert WGU into weapons components and manufacture a nuclear weapon. This extra time could be substantial, particularly if Iran wanted to build a reliable warhead for a ballistic missile. However, these preparations would most likely be conducted at secret sites and would be difficult to detect. If Iran successfully produced enough WGU for a nuclear weapon, the ensuing weaponization process might not be detectable until Iran tested its nuclear device underground or otherwise revealed its acquisition of nuclear weapons.” [ISIS 8 Oct 2012]

Once Iran has enough WGU gas, a military strike might not be successful at stopping them from making a working nuke. The gas enrichment occurs at two known facilities. But the rest of the process of making a nuke can occur almost anywhere. Israeli Prime Minister Benjamin Netanyahu pointed this out in his 27 Sept 2012 UN speech:

“For Iran, amassing enough enriched uranium is far more difficult than producing the nuclear fuse.

For a country like Iran, it takes many, many years to enrich uranium for a bomb. That requires thousands of centrifuges spinning in tandem in very big industrial plants. Those Iranian plants are visible and they’re still vulnerable.

In contrast, Iran could produce the nuclear detonator – the fuse – in a lot less time, maybe under a year, maybe only a few months.

The detonator can be made in a small workshop the size of a classroom. It may be very difficult to find and target that workshop, especially in Iran. That’s a country that’s bigger than France, Germany, Italy and Britain combined.

The same is true for the small facility in which they could assemble a warhead or a nuclear device that could be placed in a container ship. Chances are you won’t find that facility either.

So in fact the only way that you can credibly prevent Iran from developing a nuclear weapon, is to prevent Iran from amassing enough enriched uranium for a bomb.” (Full Transcript)

Once Iran has enough WGU for a bomb, a military strike on their enrichment facilities would be unlikely to prevent them from making a nuclear bomb. Instead, such a strike would almost guarantee a nuclear retaliation by Iran as soon as the bomb were assembled. Therefore, Israel and/or the U.S. must prevent Iran from making enough 90% U-235 gas in order to prevent them from making a nuclear bomb.

Iran needs 190 to 200 kg of 20% uranium gas and 1.3 to 1.4 months in order to make 1 SQ of 90% uranium gas.

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