US said weeks, IDF said years - How long will it really take Iran to get a bomb?

On Wednesday reports emerged that Iran is making small amounts of uranium metal, which could be used in a core of a nuclear weapon.

PEOPLE GATHER around the water nuclear reactor at Arak, Iran, in December 2019. (photo credit: WANA NEWS AGENCY/REUTERS)
PEOPLE GATHER around the water nuclear reactor at Arak, Iran, in December 2019.
US Secretary of State Antony Blinken said in late January that Iran could be “weeks away” from having enough material for a nuclear bomb. An IDF intelligence estimate reported on February 9 that it would take Iran about two years to build a bomb if it decides to do so.
These kinds of estimates, which have been repeated over the years, often leave people confused. They also lead to contradictory headlines, some appearing to justify Israel’s concern and also appearing to justify claims that Israel is fearmongering about the Iranian nuclear weapons program.
On Wednesday, reports said that the International Atomic Energy Agency (IAEA) had found that Iran is making small amounts of uranium metal at Isfahan, which could be used in the core of a nuclear weapon. This is yet another violation of the 2015 Joint Comprehensive Plan of Action, which was supposed to stop Iran making this type of metal until 2030.
Like many things, understanding the reports requires a bit of healthy skepticism blended with expertise, and also taking the time to understand that what is being presented is not a simple zero-sum issue. Both could be true: Iran is years away from a nuclear weapon, and also could have enough material to make a weapon within weeks or months.
Think of nuclear material like bricks for a building. You can produce enough bricks to build a building, but if you don’t actually start building it then you never have a building in front of you. So you could be “weeks away” from enough bricks, but still years away from actually finishing the building.
Let’s look at what we are actually talking about. Blinken is discussing the time it would take Iran to produce enough fissile material for a nuclear weapon. As he noted on January 31, previous estimates have said Iran is months away from having enough of this material. Iran has broken parts of the JCPOA that put limits on its enrichment and stockpiles of uranium.
Over the past few years, Iran has systematically said it is enriching more material at a higher percent. Recent reports said it was enriching uranium up to 20%, more than the 3.5% it is allowed. It would need to reach upwards of 90% to get the material to nuclear grade.
The IDF assessment revealed this week presents a more optimistic picture about timelines. Iran might choose to move toward a nuclear device, but this would take time. There is lack of clarity on the mixed messaging. IDF Chief of Staff Lt.-Gen. Aviv Kochavi said in late January that a return to the Iran deal was wrong. He also threatened action against Iran if it moves toward a nuclear weapon. Iran responded with its own threats.
Then Yediot Ahronot reported on January 31 that the Mossad opposed the IDF’s position on a new nuclear deal. Add in the latest story that Military Intelligence thinks that if Iran can be prevented from reaching the 90% enrichment level, then that would be a feasible way to prevent Iran getting a bomb – and the confusion is understandable.
This leads to headlines mocking Israeli and US assessments. The Atlantic claimed Iran has been two years away from a nuclear weapon for three decades. In July 2020, the New York Times reported that Iran’s nuclear program had been set back months.
A report in 2009 looked at the confusion about Iran’s nuclear material. Reports said that Iran, which had supposedly been hiding enriched uranium at the time, had enough uranium for a bomb. What was this material? Estimated inventory of low-enriched uranium had jumped at the time to a newly estimated 209 additional kilograms. This was uranium hexflouride (UF6), which is actually 68% uranium, a report noted.
Why does this matter? The 2009 article noted that Iranians may have been “novices at the centrifuge business,” walking the reader through the fact that “containers used for UF6 can hold up to 2.5 tons of UF6, which is solid at room temperature. It is stored by pumping the gas from the centrifuges into a cylinder, where the UF6 condenses into a white solid.” 
Now a bit of math is involved. The concept of “breakout” – whereby Iran rushes to enrich uranium to get enough for a bomb – is often where the time limits are discussed, weeks or months.
According to reports in January, the head of Iran’s Atomic Energy Organization, Ali Akbar Salehi, said that Iran was producing 500 grams of 20% enriched uranium every day.
In November 2002, the International Atomic Energy Agency (IAEA) said Iran’s stockpile of low-enriched uranium had reached 2,442.9kg. It had 2,105kg in September 2020, enriched at less than 4.5%. In 2013 the AP reported that Iran’s stockpile of enriched uranium had reached 7,000kg at up to 20% enrichment.
All of these data points and factoids add up to something – but not a bomb.
They add up to a very sophisticated country that seeks to play a nuclear game with the West and the world, one usually involving blackmail. They hold up the nuclear enrichment and basically say: “pay us to stop this.”
Iran’s nuclear program is also extensive and widespread. Natanz is estimated to have some 19,000 gas centrifuges, which are fed with uranium hexafluoride. It is adding more, and has space for some 50,000.
Under the JCPOA deal, Iran was allowed to have 5,000 IR-1 centrifuges.
Iran also has centrifuges at Fordow, once a secret facility that was discovered in 2009. Iran indicated last month that it was enriching at Fordow with up to 20% enrichment, above the 3.67% allowed.
Under the deal, Iran was supposed to reduce the 19,000 installed centrifuges to 6,104. It would leave 5,060 of those at Natanz, and the 1,000 at Fordow would be dormant.
In November, Iran began to feed UF6 into a cascade of 174 IR-2 advanced centrifuges. In November 2019, Iran also said it had some 60 IR-6 centrifuges.
Given all this information about the rate of enrichment, the amount being enriched and the size and precision of Iran’s missiles, it is clear that Iran could eventually reach the stage of having a nuclear weapon and a delivery system for it. However, many things would have to happen for that to materialize.
It is worth looking to history to see just how complex it is to make a workable nuclear weapon. The US Manhattan Project that developed a nuclear weapon took years and more than 100,000 people and enormous cost to get to the final product. In the end, the bomb had to be transported by aircraft. The US used uranium-235 in its “Little Boy” bomb.
But the US program is instructive. The US attempted to use centrifuges and uranium hexafluoride in 1941 but initially abandoned the massive process. The US had also predicted the process would require 50,000 centrifuges to produce one kilogram of uranium a day. Another process was able to produce a few hundred grams of U-235 enriched to 15% by 1944. It wasn’t until the spring of 1945 that uranium enriched to more than 85% was ready for the bomb. At the same time, a small amount of plutonium nitrate, less than 100 grams, was also initially created through reactors.
Pakistan’s nuclear program took years to enrich uranium. It knew it needed dozens of kilograms of 90% enriched uranium-235. Like North Korea, it had sought to produce plutonium, which would have needed less, but it was a more complex process. It had to put the uranium hexafluoride into centrifuges for enrichment to get to the final process and produce uranium metal. While Pakistan had enough material for weapons-grade uranium, according to reports by 1978, it took until 1988 to have the ability to make a nuclear weapon device.
What about Iran’s possible route to plutonium for bombs? A paper by Ephraim Asculai – a former senior Israeli nuclear official – notes that Iran was previously working on its IR-40 heavy water natural uranium reactor at Arak, and that the “potential for using plutonium in the core of a nuclear explosive device is serious.”
A reading of the relevant details and comparisons with other nuclear programs points to a serious hurdle for Iran. While it has an extensive network of nuclear sites – from its Bushehr power plant to its enrichment site at Fordow, the Nuclear Technology Center of Isfahan with its small nuclear research reactors, and its Arak heavy water site – the extent of all the projects and investments makes Iran’s goals both opaque and its progress sometimes hard to measure.
In the end, Iran needs to stockpile a lot of highly enriched uranium or produce plutonium, and then it will need to go through the complex process of making a nuclear devise. Only then, with testing, will it be able to put the device on a missile.
Iran has friends in North Korea who know how to do that, and it has certainly studied the Pakistani program. However, this complexity leads to the misunderstandings behind what Iran has in terms of “material,” compared with how many years away it is from a real nuclear weapon.