A deal, Joint Comprehensive Plan of Action (JCPOA), was reached in 2015 between Iran and P5+1 (US, UK, France, China, Russia and Germany).
The deal came after years of tension over Iran’s alleged efforts to develop a nuclear weapon. Iran insisted that its nuclear programme was entirely peaceful, but the international community did not believe that. [BBC]
A deal summary by Belfer Center for Science and International Affairs, Harvard Kennedy School
Uranium Enrichment
Uranium is required to produce nuclear power and create nuclear weapons. However, the naturally-occurring form of the element does not have a sufficient level of a common fissile isotope U-235 to set off a nuclear reaction.
The amount of U-235 in uranium must be increased through a process of enrichment.
Uranium enriched to between 3 and 4 percent can be used for nuclear power plant fuel, but it must be enriched to around 90 percent for use in weapons.
Iran previously reached a near 20% level enrichment before the deal.
When uranium is mined it typically has about 140 atoms of U-238 for every atom of U-235. Refining it to a purity of 3.67% means using centrifuges to remove 114 unwanted atoms of U-238 for every atom of U-235. Boosting its purity to 20% means removing 22 more unwanted atoms of U-238 per atom of U-235, while going from there to weapons-grade material means removing just four more per atom of U-235. [TheGuardian]
Cap: Stockpile of Low-enriched Uranium
JCPOA set a limit of 3.67 percent enrichment and a stockpile limit of 300kg (660lbs) for 15 years (until 2031).
The United States said in 2015 the deal reduced Iran’s stockpile of enriched uranium by 98 percent, to less than the amount needed for one weapon from enough for about 10. [france24]
Limit: Enrichment capability
Iran had two facilities – Natanz and Fordo – where uranium hexafluoride gas was fed into centrifuges to separate out the most fissile isotope, U-235.
Much of Natanz is deep underground and Fordow is buried inside a mountain, which is widely believed to protect them from aerial bombardment.
The deal allows Iran to continue enrichment at Natanz but with constraints. It turns Fordow into a “nuclear, physics and technology centre” where centrifuges are used for purposes other than enrichment, like producing stable isotopes.
First-generation centrifuges installed in Iran is capped at 6,104, reduced from 19,138.
Plutonium Track
Spent fuel from a heavy-water reactor contains plutonium suitable for a nuclear bomb.
Iran had been building a heavy-water nuclear facility near the town of Arak.
Under the JCPOA, the core of that reactor has been removed and filled with concrete to make it unusable
The reactor is being redesigned so as to “minimise the production of plutonium and not to produce weapon-grade plutonium in normal operation”
Iran will not be permitted to build additional heavy-water reactors or accumulate any excess heavy water until 2031.
