MetNet Opinions

Estimated Enrichment Capacity of the Natanz Site

http://www.exportcontrols.org/cascades.html

As mentioned above, the two underground structures have a combined area of over 60,000 square meters, implying a substantial floor area for centrifuges. Such a large facility is intended to hold tens of thousands of centrifuges and is consistent with Iranian government statements that it wants to produce low enriched uranium for nuclear power reactors. However, such a large facility could also be used to make highly enriched uranium for nuclear weapons. Iran could also secretly possess or build another, much smaller facility to make highly enriched uranium.

The Iranian government has announced that over the next 20 years it wants to build several nuclear power reactors for a total capacity of 6,000 megawatts of electricity. Tehran has also stated that it wants to be self-sufficient in the nuclear area, implying that it wants to produce the low enriched uranium it would need for at least some of these reactors. It does not appear to want to produce all its low enriched uranium fuel. For example, it has announced that it will buy low enriched uranium from Russia for the Bushehr power reactor that Russia is providing.

To be fully self-sufficient in the production of low enriched uranium for an installed capacity of 6,000 megawatts of electricity, Iran would need an enrichment capacity of about 600,000 separative work units (SWU) each year. The two underground structures at Natanz do not appear large enough to achieve this enrichment capacity, but Iran may be trying to provide a significant fraction of this anticipated capacity over the next two decades. Based on a combined surface area of about 60,000 square meters, these enrichment halls are crudely estimated to be able to hold about 50,000 centrifuges, where each centrifuge requires on average roughly one square meter of floor space. Substantially more centrifuges could be located in the halls, particularly if the centrifuges are packed more tightly or stacked vertically. If each centrifuge has an enrichment capacity of up to 5 SWU per year, the total capacity of this facility when finished is estimated to be up to 250,000 SWU per year. This is a rough estimate that reflects extensive uncertainties about both the underground structures and Iran’s centrifuges. In addition, advanced countries, such as Japan, have encountered difficulties in building reliable centrifuges on such a large scale, meaning that Iran may fail in its bid to build such a large centrifuge plant.

This capacity is far larger than needed for a nuclear weapon program, supporting Iran’s statement that the facility is aimed at producing low enriched uranium for nuclear power reactors. Nonetheless, such a facility could use a relatively small fraction of its capacity, say 10,000 SWU per year, to make enough highly enriched uranium for three nuclear weapons a year, while using the remaining capacity to produce low enriched uranium. In addition, if a country can make an enrichment plant of this size, it can make enough machines to outfit another secret enrichment plant with a capacity of 10,000 SWU per year involving several thousand machines. IAEA safeguards could detect such clandestine activities, but the IAEA must have far more extensive inspection rights than Iran has been willing to provide the IAEA so far.

Recent media reports have stated that Natanz is intended to house only 5,000 centrifuges. This number may reflect an interim goal for this site, perhaps the capacity Iran wants to achieve in the next few years.