Some good news came through over the weekend—Iran agreed to a set of limits on its nuclear power activities that will make it somewhat more difficult for it to develop nuclear weapons. While this agreement (with the five permanent members of the UN Security Council and Germany) is only for six months, it is intended to be the first step to a “comprehensive solution.” And it is certainly a step in the right direction.
The Nuclear Power-Nuclear Weapons Linkage
At the heart of the Iranian issue is the fact that some types of nuclear power facilities can be used to make the materials needed for a nuclear weapon—plutonium or highly enriched uranium. Uranium ore contains less than 1% of the isotope U-235, which is the one needed for both reactor fuel and nuclear weapons. Most power reactors use uranium enriched to 3-4% U-235, whereas uranium enriched to 20% or greater can be used to make nuclear weapons. Weapon-grade uranium, which is most desirable for nuclear weapons, has 90% or more U-235. An enrichment facility that is used to make reactor fuel—such as those Iran operates at Natanz and Fordow—can also be used to make weapon-grade uranium.
All power reactors produce plutonium, but it is imbedded in radioactive fuel rods that must be “reprocessed” to extract the plutonium, which can then be used for reactor fuel or weapons.
Thus, any country that has enrichment or reprocessing facilities can make the materials needed for nuclear weapons. For countries without nuclear weapons, like Iran, these facilities are monitored by international inspectors. If a country started to use the material for nuclear weapons, the inspectors and the world would likely know. The question then becomes how long it would take to build a weapon and how much time the world has to respond. A separate issue is the ability of a country like Iran to make nuclear weapons covertly, without alerting inspectors.
What the Deal Does
Iran has been enriching uranium to 5% U-235, which could provide fuel in the future for its nuclear power reactors at Bushehr, and to 20% U-235 to provide fuel for its research reactor in Tehran. It would take somewhat more time for Iran to produce weapon-grade uranium if it started with 5% rather than 20% enriched uranium. Iran has also been building a small reactor at Arak, which could be used to produce plutonium.
Probably the most important parts of the agreement are:
- Iran agreed to dilute part of its stock of 20% enriched uranium to 5% and convert the rest into a form that can’t be further enriched without additional processing. It also agreed to not enrich additional uranium to more than 5%, and to put limits on its enrichment capability. This increases the length of time it would take Iran to enrich enough uranium for one nuclear weapon—by one estimate from 4-6 weeks to 8-9 weeks. While still uncomfortably short, Iran has also agreed to accept enhanced monitoring of its nuclear program. This will provide greater confidence that Iran cannot covertly use these facilities to produce materials for weapons.
- Iran agreed to halt work on its Arak reactor and to not reprocess or build a reprocessing facility.
The Longer Term Plan
The new agreement makes clear that under a longer term, comprehensive solution, Iran could continue to enrich uranium, but would have constraints on its activities. As long as Iran maintains an enrichment facility, it will have the ability to throw out the inspectors and make material for weapons. The goal is to increase the amount of time it would take Iran to do so. With enough constraints, the breakout time could be many months—which would be an important achievement.
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