Iran's Nuclear Numbers - OZY | A Modern Media Company

Iran's Nuclear Numbers

Iran's Nuclear Numbers

By Emily Cadei

An Iranian technician works at the Isfahan Uranium Conversion Facilities (UCF), 420 kms south of Tehran, 03 February 2007.
SourceBehrouz Mehri/Getty Images


Because whether Iran has nuclear weapons or not has a huge impact on the Middle East and the rest of the world.

By Emily Cadei

As world powers kick off a pivotal round of negotiations with Iran over its nuclear program in Geneva this week, attention will be focused on one figure: Iran’s level of uranium enrichment. Specifically, the United States and its Western allies insist that Iran cease enriching uranium to 20 percent, which they say gets it far too close to weapons-grade material for a nuclear bomb. Iran says it needs the 20 percent uranium for its medical research reactor, but experts say it’s stockpiling far more uranium than necessary for that.

It’s an oft-discussed issue in the coverage of Iran’s nuclear program, but the science behind it is not. Here are the basics for all you out there who aren’t nuclear physicists.

Less than 1%

The amount of uranium-235 — the “fissile isotope” capable of generating a nuclear reaction — that is found in uranium ore in its natural state. When scientists “enrich” uranium, they are increasing the concentration of this isotope. So the level of enrichment refers to the percentage of uranium-235 atoms in the uranium. 


The threshold of enrichment at which uranium is considered “weapons grade” and can be used to make modern nuclear bombs.


The threshold at which uranium goes from being considered “low enriched” (LEU) to “highly enriched ” uranium (HEU). In the centrifuge plant design that experts believe Iran has obtained, there are four steps in the enrichment process — from 5 to 20 to 60 percent and then to 90 percent weapons-grade uranium — and “each step requires less work,” explains Christina Walrond, a research analyst on Iran’s nuclear program at the Institute for Science and International Security. Once a country stockpiles uranium enriched to 20 percent, “It’s much faster to ‘break out,’ or make weapons grade uranium,” says Walrond. 

186 kilograms

240-250 kilogramsThe amount of uranium Iran has now enriched to 20 percent, according to the latest International Atomic Energy Agency report , raising international suspicions. Iran’s leaders say they need the uranium for medical research, but this amount is far more than necessary for the country’s one research reactor, according to Walrond. The amount of 20-percent enriched uranium experts estimate Iran would need to be able to “break out” and quickly build one nuclear weapon, possibly before being detected by other countries.


The number of first-generation centrifuges — machines used to enrich uranium — that Iran has installed in its Fordow and Natanz nuclear facilities. Just over half, 10,190, are currently in the process of enriching uranium, Walrond says.


The number of next-generation centrifuges Iran has installed but not yet started to use at Natanz, per the IAEA report.

Walrond estimates these new centrifuges have an enrichment capacity that is three to five times that of Iran’s older model centrifuges, and her organization is urging world powers to focus on them as well. “It can’t just be a negotiation about the level of enrichment; it also has to be about the number and the types of centrifuges,” she says.

For now, however, enrichment is “at the center of the negotiations,” as Secretary of State John Kerry told reporters on October 10. Iran will be meeting with the P5 Plus 1 — the five permanent members of the United Nations Security Council plus Germany – in Geneva. The P5 Plus 1 will have to decide whether they could live with a deal that allows Tehran to continue to enrich uranium to 5 percent.Hardliners in the Uniter States and Israel (including Prime Minister Benjamin Netanyahu) argue that Iran should halt all enrichment. Given the fact that Iran’s leaders have threatened to wipe Israel off the face of the earth, you can understand why their neighbors are nervous about any nuclear capability.

Iran’s leaders deny they are building weapons and insist that they have the right to ”peaceful nuclear technology.

Something – or someone – will have to give.

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