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Iran’s Unyielding Pursuit Of Nuclear Weapon Capabilities

LINK TO VIDEO With less than five months before the American Presidential elections, U.S. relations with the Islamic Republic of Iran seem to be moving on two parallel routes leading to heating up and cooling down. There has been a prisoner swap, with express calls on the American side to enlarge this opening for a comprehensive deal focusing on the nuclear dimension but not limited to it; but at the same time there are credible reports that the Iranian regime is moving its uranium stockpile dangerously close to a weapons-grade quantity. Do these currents contradict or complement one another? Panel: – Jonathan Hessen, Host. – Amir Oren, Analyst. – Olli Heinonen Former Deputy General IAEA and a Distinguished fellow, Stimson center, Washington DC (New York, USA). – Mr. Meir Javedanfar, Iran lecturer, IDC Herzliya (Central Israel).

  • Iran’s violations of nuclear limitations in the JCPOA continued. Iran’s stock of low enriched uranium (LEU) grew by about 50 percent, to 2324.9 kilograms of low enriched uranium (hexafluoride mass), all enriched below 5 percent, or the equivalent of 1571.6 kilograms (uranium mass).
  • Enrichment capacities did not grow at the Natanz and Fordow Fuel Enrichment Plants during this reporting period. Total enrichment capacity increased by only about five percent, reflecting the deployment of more advanced centrifuges at the Natanz Pilot Fuel Enrichment Plant.
  • Breakout timelines decreased slightly from the last reporting period to an average of 3.5 months, with a minimum of at least 3.1 months. These values reflect greater certainty that Iran possesses sufficient enriched uranium to make enough weapon-grade uranium (WGU) for a nuclear weapon. Iran does not yet possess enough LEU for a second nuclear weapon, but if it did, it could produce the second one more quickly than the first.
  • A companion IAEA Iran safeguards report, NPT (Nuclear Non-Proliferation Treaty) Safeguards Agreement with the Islamic Republic of Iran, which will be discussed in a separate Institute report, makes the startling finding: “The Agency notes with serious concern that, for over four months, Iran has denied access to the Agency, under Article 4.b.(i) and Article 5.c of the Additional Protocol, to two locations and, for almost a year, has not engaged in substantive discussions to clarify Agency questions related to the possible undeclared nuclear material and nuclear-related activities in Iran.”

Advanced Centrifuges

Iran continued to take steps during the IAEA reporting period to violate the JCPOA’s limitations on advanced centrifuges. The following summarizes the deployment of advanced centrifuges in the six lines at the Natanz Pilot Fuel Enrichment Plant, or PFEP, their enrichment status, and their enrichment capacity, if known, as of the last reporting period.

Iran was no longer remixing the product and tails (waste), but collecting it separately, meaning that Iran accumulated enriched uranium at the PFEP. As of May 20, 2020, 483.1 kilograms (uranium mass) of uranium enriched up to two percent had been collected from lines 2 and 3 of the six lines at the PFEP. The IAEA does not provide the average enrichment of this material, although it can be safely assumed that it varies from just above natural uranium (0.71% uranium 235) up to 2% uranium 235. (This average value matters because the amount of separative work to make, for example, a quantity of two percent enriched uranium, is several times the amount needed to make that same quantity of one percent enriched uranium.) The IAEA did not reveal how much enriched uranium was collected in lines 4, 5, and 6 of the PFEP.

Lines 2 and 3 contained a variety of centrifuge types and numbers, many accumulating enriched uranium. The following is a summary, as of the end of the last reporting period, of all the centrifuges installed in lines 2 and 3, or about 90 in total, that were accumulating enriched uranium (so far about 483.1 kg, as mentioned above):

  1. Up to 20 IR-4 centrifuges in a cascade;
  2. Up to 10 IR-5 centrifuges in a cascade;
  3. Up to 30 IR-6 centrifuges, in a centrifuge cascade of 10 IR-6 centrifuges and another of 20 IR-6 centrifuges;
  4. Up to 20 IR-6s centrifuges; and
  5. Up to 10 IR-s centrifuges.

According to the IAEA report, as of June 1, Iran was testing the following single centrifuges with uranium hexafluoride in lines 2 and 3, but not accumulating enriched uranium:

  1. one IR-2m centrifuge;
  2. one IR-3 centrifuge;
  3. two IR-4 centrifuges;
  4. one IR-5 centrifuge;
  5. three IR-6 centrifuges;
  6. one IR-6m centrifuge;
  7. one IR-6s centrifuges;
  8. one IR-6sm centrifuge;
  9. one IR-7 centrifuge;
  10. two IR-8 centrifuges;
  11. two IR-8s centrifuges;
  12. one IR-8B centrifuge;
  13. two IR-s centrifuges; and
  14. one IR-9 centrifuge.

Iran was also accumulating enriched uranium in lines 4, 5, and 6, in redeployed IR-2m and IR-4 centrifuge cascades (164 centrifuges each) and an IR-6 cascade (135 centrifuges). The IAEA did not specify how much enriched uranium had been produced so far, or its level of enrichment. This enriched uranium is likely included in the IAEA’s aggregate, reported amount of enriched uranium enriched up to 4.5 percent.

The redeployed cascades of 164 IR-2m and IR-4 centrifuges in lines 4 and 5 of the PFEP represent Iran’s most successful advanced centrifuge types. When previously operated in a production-scale cascade, each IR-2m centrifuge had an enrichment capacity of about 3.7 separative work units (SWU) per year. The total cascade thus has an estimated enrichment capacity of about 607 SWU per year. This is equivalent to about 675 IR-1 centrifuges operating in production cascades, where each IR-1 is assumed to have a capacity of 0.9 SWU per year. The IR-4 has a lower capacity than the IR-2m, estimated here as ten percent lower, or about 3.3 SWU per year per centrifuge. The production cascade would have a total output of about 540 SWU per year, or equivalent to about 600 IR-1 centrifuges. These two cascades represent a total capacity of about 1147 SWU/year, or the equivalent of about 1275 IR-1 centrifuges.

Line 6 at the PFEP held 135 IR-6 centrifuges in a single cascade (up from 72 during the last reporting period). Iran stated earlier that the line will hold 164 IR-6 centrifuges in a cascade. The IR-6 has a single machine estimated capacity of 6.8 SWU per year. No recent data are available publicly on its performance in this cascade. Assuming that the cascade value would be about 90 percent of the capacity achieved by an IR-6 operating by itself, 135 IR-6 centrifuges in cascade would have an output of about 826 SWU per year, and a cascade of 164 IR-6 would have total capacity of about 1000 SWU per year, or the equivalent of about 1115 IR-1 centrifuges.

Line 1 currently holds an inoperable cascade of IR-1 centrifuges. However, Iran reportedly announced planned modifications of line 1 that include removal of the inoperable centrifuges, apparently to clear space for upcoming R&D activities.
In addition, according to the quarterly report, Tehran was violating an additional JCPOA limitation by conducting mechanical testing of centrifuges at the Tehran Research Centre and a workshop at Natanz. According to the IAEA report, “On 27 May 2020, the Agency verified that, for periods of four to ten days, Iran had conducted mechanical testing of up to six IR-4 centrifuges simultaneously, and up to ten IR-6 centrifuges simultaneously” at these two locations.

As can be seen, Iran is developing a large number of centrifuges simultaneously, an unusual practice. The centrifuges at the PFEP include: IR-1, IR-2m, IR-3, IR-4, IR-5, IR-6, IR-6m, IR-6s, IR-6sm, IR-7, IR-8, IR-8s, IR-8B, IR-s, and IR-9. No information was provided in the IAEA report on how well these centrifuges work, their failure rates, or why so many of them are being developed. Typically, a centrifuge program with such characteristics is likely failing at developing a commercially viable centrifuge, although several of these centrifuges could work adequately in a nuclear weapons program, where efficiency, low failure rates, and low cost are not priorities.

n the breakout estimate, the following conditions are assumed:

  • An enrichment capacity at the Natanz and Fordow Fuel Enrichment Plants, as drawn from the latest IAEA report. The enrichment contribution from advanced centrifuges at the Pilot Fuel Enrichment Plant is not included, as their use in a breakout would be complicated and likely not contribute to reducing breakout timelines;
  • Only LEU stocks above two percent enriched are used. Stocks of less than two percent enriched uranium are not used, since to do so would require additional modifications of the cascades to handle the lower enrichments, likely significantly slowing or contributing only slightly, rather than speeding up breakout timelines; and
  • Iran redeploys its 1000 IR-2m centrifuges, removed from the Natanz FEP prior to the JCPOA’s Implementation Day; however, the rest of the centrifuges deployed are IR-1 centrifuges from Iran’s existing stock. Iran may in fact deploy additional advanced centrifuges, but this effect is not included in this estimate, as none of the dozen advanced centrifuge types Iran is testing at the PFEP stands out as Iran’s clear centrifuge of choice, many assessed as performing poorly.
  • This breakout calculator utilizes a modified form of the well-known four-step enrichment process that was developed under A.Q. Khan for Pakistan’s centrifuge program and transferred to other countries, such as Iran. Using all four steps, Iran would enrich natural uranium to 3.5 percent in step one, then to 20 percent in step two, 60 percent in step three, and finally to weapon-grade uranium in step four. Currently, Iran can achieve weapon-grade uranium in three steps, starting with its existing LEU stockpiles.

Under these conditions, the breakout calculator gives an estimate of 3.1 months, with no initial set-up time added. Doing so would lengthen the estimate to about 3.5 months. In addition to the IR-2m re-deployment, a major factor is that most of the LEU is already enriched to 4.5 percent instead of 3.5 percent, a significant change from estimates performed before the JCPOA’s Implementation Day, since this one percent increase in enrichment can provide up to a 15 to 20 percent reduction in breakout time to produce 25 kilograms of weapon-grade uranium. The greater enrichment level also means that the production of 25 kilograms of weapon-grade uranium requires less LEU than if it were enriched to 3.5 percent: 900 kilograms of 4.5 percent LEU vs. 1250 kilograms of 3.5 percent LEU in hexafluoride mass. This last condition is particularly significant here, since it means that the existing amount of LEU is enough to reach the requisite amount of weapon-grade uranium without the need to also use some natural uranium to make a portion of the needed WGU. As a result, the process is strictly a three-step one instead of a three-step followed by a four-step one. This ability to use only three steps to reach weapon-grade, instead of four, is why the media often discusses a key threshold of about 1000 kg of LEU as significant