Ex-intel, atomic chiefs: Why are there so many Iran nuke estimates?

Former IDF intelligence chief Amos Yadlin and former Israel Atomic Energy Official Ephraim Asculai explain why there are so many estimates for the Iran nuke breakout timeline.

VIEW OF a damaged building after a fire broke out at Iran’s Natanz Nuclear Facility, in Isfahan on July 2. (photo credit: ATOMIC ENERGY ORGANIZATION OF IRAN/WANA VIA REUTERS)
VIEW OF a damaged building after a fire broke out at Iran’s Natanz Nuclear Facility, in Isfahan on July 2.
Between the US, IDF Intelligence, the Mossad and others, the length of time it would take Iran to break out to a nuclear weapon if it wanted to now ranges from three months to two years.
How can estimates from highly knowledgeable nuclear experts diverge to such a great extent – and who is right?
There are a series of variables that make each position defensible, former IDF Intelligence chief Amos Yadlin and former Israel Atomic Energy official Ephraim Asculai said Monday in an Institute for National Strategic Studies paper. Yadlin is executive director of the INSS, where Asculai is a senior fellow.
They recommend a middle position, estimating that the Islamic Republic is eight months to a year from a nuclear bomb. But their in-depth explanation of the variables is just as important as their conclusion.
The first variable is how quickly Tehran can enrich and weaponize enough uranium for a bomb.
When the 2015 Iran nuclear deal was signed, estimates were based on the ayatollahs using around 20,000 centrifuges to enrich uranium. But the vast majority were slow IR-1s.
The Islamic Republic now has a small but increasing number of functional advanced IR-4s and IR-6 centrifuges, which can enrich at a much faster speed.
This could be a game changer in terms of time. But Yadlin and Asculai point out that “functional” does not mean full-speed enrichment of uranium. Many of these advanced centrifuges are at different stages of functionality.
How fast uranium can be enriched to achieve 25 kilograms at a 90% weaponized level will vary greatly depending on whether hundreds of advanced centrifuges are fully functional or only dozens, with the other hundreds more for show.
If Tehran has advanced in enrichment, according to all parties, how could there now be two-year estimates for breakout when some estimates before were only one year, the authors ask.
According to the position paper, part of the answer is simply measuring different things.
IN 2015 and earlier, most experts were focused solely on how long it would take Iran to enrich enough uranium for a nuclear weapon.
But enrichment is only one stage. After enrichment, Iran must have the capacity to cause a nuclear detonation and must have the ability to deliver a nuclear warhead to a target.
Here, there are even more variables.
US intelligence believes these so-called weaponization activities stopped in 2003 and that it would take the Islamic Republic 18 months to accomplish them.
This position is defensible since there is a long list of weaponization activities and tests that must be carried out in an exact manner or any effort to explode and deliver a nuclear weapon will fail.
Within this calculation are the variables of safety, how quickly Iran could revamp its weaponization program and to what extent it has covert facilities that could carry out weaponization tests without Israeli and Western intelligence knowing.
The middle position would be that Iran did not finish all the weaponization activities before halting in 2003, but it did finish many of them, carefully recorded the results and will not need to go back to anywhere near square one.
For example, a May 2019 report by the Institute for Science and International Security noted that documents the Mossad appropriated from Iran in 2018 said major experiments relating to detonation were performed starting in February 2003 in the Taleghan chamber at the Parchin nuclear facility.
According to the Mossad-acquired documents, “The Iranian Nuclear Archive shows that Iran planned on using a relatively sophisticated neutron source, or initiator, to trigger a chain reaction in the weapon-grade uranium core of its nuclear weapons.”
“This source was made by combining natural uranium and deuterium into uranium deuteride (UD3),” said the May 2019 report.
Furthermore, the report said, “The work on the neutron initiator does not appear to have been completed on schedule, but continued in the reoriented nuclear-weapons program that may continue into the present.”
It describes the detonation process that Iran was practicing at Parchin: “High explosives compress the nuclear core and the initiator at its center, producing a spurt of neutrons” that flood the core of the uranium, initiating the chain reaction.
But measuring the neutrons being emitted is both incredibly difficult and critical.
After all of that, no one knows how far along Iran got in its measurements of the neutrons, and that is only one weaponization issue.
DEBATES CONTINUE about how much of a covert program Tehran has maintained.
The Mossad helped discover three nuclear sites that the International Atomic Energy Agency did not know about: at Turquzabad, Mariwan-Abadeh and one near Tehran.
But are there more than even the Mossad might have missed?
Many US and IDF intelligence analysts believe any large covert program would have been found by American, Israeli and others’ satellites, as well as other spying means, along with the many IAEA inspectors in Iran.
They point out that Iran has been very public with its nuclear violations in front of IAEA inspectors since May 2019.
This is a crucial variable because if there are covert sites, Iran could perform weaponization tests and enrich uranium in parallel instead of waiting to start weaponization until it finishes enriching the uranium and announces it is breaking out to a bomb.
Most estimates assume that Iran will forgo many of the Western-style safety measures if it is rushing to a nuclear weapon, so the time such measures would take are often mostly discounted.
The middle estimate assumes five months for enriching uranium and then between three to seven months for weaponization, some of which would be done in parallel.
The most hawkish estimates assume that Tehran finished nearly all of its weaponization by fall 2003, has significant covert facilities to finish remaining weaponization activities and can complete all of them while enriching uranium with a large fleet of advanced centrifuges.
Estimates would then put a nuclear weapon at three to six months away.
The authors caution that since Iran is now enriching uranium to the 20% level, all of these estimates will get shorter since the length of time to weaponize the uranium will be less.