Iran’s nuclear program is a major topic in President Joe Biden’s meetings this week with leaders in the Middle East. The most challenging part of producing nuclear weapons is making the materials that fuel them, and Iran is known to have produced uranium that is of a weapons grade.
I asked the conversation Professor Brandeis University Gary Samourwho has worked on nuclear arms control and nonproliferation in the United States government for more than 20 years, to explain why uranium enrichment is so important to Iran’s nuclear ambitions and where Iranian efforts stand now.
A series of gas centrifuges at a US uranium enrichment plant in Beketon, Ohio in 1984. Iran uses similar technology to enrich uranium. US Department of Energy
What does uranium enrichment mean?
Natural uranium has two major isotopes, or forms whose atoms contain the same number of protons but different numbers of neutrons. About 99.3% uranium-238 and 0.7% uranium-235. The uranium-235 isotope can be used to generate nuclear energy for peaceful purposes, or nuclear explosives for military purposes.
Enrichment is the process of separating and increasing the concentration of uranium-235 to higher levels above natural uranium. In general, low levels of enriched uranium, such as 5% uranium-235, are commonly used to fuel nuclear reactors. Higher levels of enrichment, such as 90% uranium-235, are more favorable for nuclear weapons.
For military purposes, why are higher levels of enrichment important?
The higher the level of enrichment, the less nuclear material needed to produce a nuclear weapon.
The International Atomic Energy Agency He defines 25 kilograms (55 pounds) of 90% enriched uranium as the “significant amount” necessary for a simple nuclear weapon. But larger quantities of low-enriched uranium can also be used.
From a nuclear weapons design point of view, smaller amounts of highly enriched nuclear material are more desirable because this reduces the size and weight of the nuclear weapon and makes it easier to deliver. As a result, modern uranium-based nuclear weapons typically use uranium enriched from 90% to 93% uranium-235, which is known as weapons-grade uranium, as the primary fuel.
What did Iran achieve before the 2015 nuclear deal?
The 2015 nuclear deal Between Iran and the United States, China, France, the United Kingdom, Russia and Germany have placed significant limits on Iran’s nuclear program, in exchange for the relief of a number of international sanctions. When the deal was adopted, Iran had mastered the basic technology of enriching uranium with gas centrifuges—cylinders that spin uranium in gas form at very high speeds to separate the heavier U-238 isotope from the lighter U-235 isotope.
at the two major enrichment facilities, Natanz And the FordIran was operating about 18,000 first-generation IR-1 centrifuges and about 1,000 second-generation IR-2 centrifuges. It has also accumulated stockpiles of approximately 7,000 kilograms (about 15,430 pounds) of low-enriched uranium (less than 5%) and about 200 kilograms (440 pounds) of 20% enriched uranium.
Based on these capabilities,breakout timeTo produce about 25 kilograms (55 pounds) of 90% enriched uranium — enough for one nuclear weapon — it is estimated in a month or two.
The time of the breach is not intended to indicate that Iran would necessarily decide to produce weapons-grade uranium at these inspected facilities, because the risk of detection and potential international backlash is very high.
How did the nuclear deal restrict Iran’s activities?
The 2015 nuclear deal placed physical limits on Iran’s enrichment program for 10 to 15 years, including the number and types of centrifuges Iran could operate, the size of its stockpile of low-enriched uranium and its maximum level of enrichment.
For 15 years, no enrichment will take place at Fordow, and Iran’s stockpile of low-enriched uranium will be limited to 300 kilograms (660 pounds) with a maximum enrichment of 3.67%. For 10 years, the centrifuges will be limited to about 6,000 IR-1 centrifuges at Natanz.
In order to meet these physical limits, Iran Shipped to Russia Most of its stock is low-enriched uranium and its entire stock is 20% enriched uranium. like that Dismantled for storage inside Iran Most IR-1 centrifuges and all more advanced IR-2 centrifuges. As a result of these restrictions, Iran’s “breakthrough time” has been extended from a month or two before the deal to about a year after the deal.
However, after the tenth year of the deal, Iran was allowed to begin replacing the IR-1 centrifuges at Natanz with more advanced models, which were allowed to continue research and development during the first decade of the deal. Given the installation of these more powerful centrifuges, the breakthrough time would likely have been reduced to about a few months by the fifteenth year of the deal.
As part of the agreement, Iran also agreed to strengthen international inspections and monitoring of its nuclear facilities.
What has Iran done since President Trump withdrew the United States from the nuclear deal in 2018?
Since the United States Withdrew from the nuclear dealIran gradually exceeded the limits of the agreement. increased its stock of enriched uranium by 5%; resumed production of 20% enriched uranium; Production of 60% enriched uranium began, and enrichment resumed at Fordow; and manufacture and install advanced centrifuges in both Natanz and Fordow.
Iran has also begun to restrict international monitoring of its nuclear facilities. In June 2022, for example, Iran announced that it would separate cameras installed under the 2015 nuclear deal to monitor its nuclear facilities.
As a result of this increasing stockpile of enriched uranium and the use of advanced centrifuges, the estimated penetration time for Iran has been reduced to a few weeks. However, Iran has not yet decided to start producing enriched uranium (90%) that is used to make weapons, although it is technically capable of doing so.
Most likely, Iran is acting cautiously because its leaders are concerned that producing weapons-grade uranium would trigger a strong international response, which could range from additional sanctions to a military attack.
About the author:
Gary SamourProfessor of the Practice of Politics and Director of the Crown Prince’s Family at the Crown Center for Middle Eastern Studies, Brandeis University