Iran’s Growing Stockpile

The latest chess match between Iran and six major powers in Baghdad ended last week without any declared breakthrough. This is not entirely surprising. Talks were unlikely to make significant headway with Iran offering to sacrifice a pawn — 20 percent enriched uranium — in exchange for the queen — the lifting of oil sanctions. Negotiations are scheduled to continue, with a new round set for Moscow in mid-June. But pressures are also building up, which risks a confrontation instead of a settlement.

In the meantime, the International Atomic Energy Agency’s (IAEA) report on Iran, released May 25, reveals new information, most notably the presence of uranium particles enriched to 27 percent, well above the declared 20 percent enrichment level at the Fordow underground enrichment plant. Right now, the key question that the IAEA is trying to answer is how much uranium was enriched to 27 percent and over what period of time the enrichment took place.

During the enrichment process, rows of centrifuges, known as cascades, produce increasingly higher concentrations of the uranium-235 isotope. It is unclear at this stage whether the higher levels reported represent a technical glitch during the start-up of a cascade (when spikes of higher enrichment can take place), or a sign of something more sinister. The spike could have been caused by an operator who changed the cascade’s operating parameters — in particular the rate at which uranium hexafluoride (UF6) gas is fed into the centrifuges — during the start-up phase or at some other time. Another potential cause is cross-contamination, meaning that the particles originated from elsewhere, such as contaminated equipment. This could indicate unknown enrichment activities in Iran. It could also be a problem in the sample analysis. But the IAEA’s method of duplicating samples taken and testing in multiple laboratories makes this an unlikely explanation.

The "spike" scenario demonstrates the current IAEA inspection system’s limited ability to detect real-time enrichment levels. From when the samples are taken, tested and answers sought, there can be a time lapse of up to six months. The reason for the delay is the time needed for the analysis of uranium particles, which is done in dedicated laboratories in Vienna and elsewhere, as well as the follow-up clarification process.

As an additional measure, the IAEA could install continuous online monitors to the feed and withdrawal lines of the enrichment route, giving better and timelier information about the operation of Iran’s plants. Once installed, this equipment could also be monitored remotely from Vienna. Timelier information is particularly important when a facility operates at an enrichment level as high as 20 percent, which is unusual for commercial enrichment plants.

The international community’s concerns surrounding the production and stockpile of enriched uranium in Iran, including at the 3.5 percent level, can best be understood by looking at the full context. Iran’s uranium enrichment capacities, in both the Fordow and the Natanz plants, are increasing. To date, the two facilities have produced 6 tons of UF6 enriched to 3.5 percent — five times the amount foreseen for the first fuel swap deal for the Tehran Research Reactor in fall 2009, and an amount sufficient for five nuclear weapons, if further enriched.

The monthly production of 3.5 percent UF6 at Natanz has increased from 170 kg in February 2012 to 220 kg 3.5 percent enriched UF6 today, but this can be attributed to the higher number of centrifuges and not to better performance. Either way, the result by the end of this year could be a cumulative inventory of 7.5 tons of low-enriched UF6 — enough for half a dozen nuclear weapons.

Meanwhile, Iran has about 150 kg of UF6 enriched to 20 percent. The installation and commissioning of additional cascades at Fordow indicates that by the end of this year, the inventory of 20 percent enriched UF6 could be as high as 300 kg — an amount sufficient for more than one nuclear weapon. In further enriching 20 percent uranium to higher levels, Iran could turn this material to nuclear weapon components in a couple of months. The IAEA might be able to detect that at locations it inspects. But not immediately.

Iran’s increasing enrichment capacity, together with information it reportedly has on a crude design of a nuclear weapon, show that Iran is positioning itself as a virtual or latent nuclear weapon state. Given the risks involved for a potential breakout scenario, a stringent nuclear verification regime in Iran is as vital as it is challenging. A more intrusive and timely inspection system, as well as Iran’s agreement to follow the Additional Protocol of the Non-Proliferation Treaty, would be required.

But that’s not all. First and foremost, Iran must clear up the military ambiguities surrounding its nuclear program — most notably issues related to high explosives testing and neutron initiators. Since these alleged activities relate closely to nuclear material, they cannot be dealt with in isolation or at some later date. Iran needs to provide a full and complete declaration of its nuclear material and all linked activities if it is to proceed with its civilian nuclear program. The clock is ticking.