Iran’s Centrifuges: The Long Road Towards a Nuclear Bomb

This photo released on Nov. 5, 2019, by the Atomic Energy Organization of Iran shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. (Atomic Energy Organization of Iran via AP, File)
This photo released on Nov. 5, 2019, by the Atomic Energy Organization of Iran shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. (Atomic Energy Organization of Iran via AP, File)
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Iran’s Centrifuges: The Long Road Towards a Nuclear Bomb

This photo released on Nov. 5, 2019, by the Atomic Energy Organization of Iran shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. (Atomic Energy Organization of Iran via AP, File)
This photo released on Nov. 5, 2019, by the Atomic Energy Organization of Iran shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. (Atomic Energy Organization of Iran via AP, File)

The UN nuclear agency has confirmed that Iran plans to install around 6,000 new centrifuges to enrich uranium, according to a report seen by AFP on Friday.

“Iran informed the Agency that it intended to feed” around 6,000 centrifuges at its sites in Fordo and Natanz to enrich uranium to up to five percent, higher than the 3.67 percent limit Tehran had agreed to in 2015.

The Iranian decision came in response to a resolution adopted on November 21 by the UN nuclear watchdog that censures Tehran for what the agency called lack of cooperation.

On Thursday, Iran had threatened to end its ban on acquiring nuclear weapons if Western sanctions are reimposed.

The country’s foreign minister, Abbas Araghchi, said in an interview that the nuclear debate inside Iran is likely to shift towards the possession of its own weapons if the west goes ahead with a threat to reimpose all UN sanctions,

What are centrifuges?

They are precise devices with cylinders that rotate much faster than the speed of sound, to collect enriched uranium atoms.

To explain how centrifugation works, rotating cylinders are much like medical laboratory equipment used to test blood.

The high rotation speeds exert a rotational force that separates the various components of blood as a function of their density and quantity in the sample.

In the case of uranium, the centrifuge operates using the familiar principle of centrifugal force. This force separates two gases of unequal masses in a spinning cylinder or tube. The heavier uranium-238 isotope collects at the outer edges of the cylinder while the lighter uranium-235 collects near the axis of rotation at the center.

Around 20 kg of uranium enriched to a 90% purity level would be needed for a single nuclear weapon. It would take about 1,500 SWU to produce a weapon-equivalent of 90 percent-enriched uranium from this enriched uranium.

At Fordo, Iran is currently using the two only operating cascades of IR-6 centrifuges there to enrich to 60% from 20%.

There are 1,044 centrifuges active at the Fordo uranium enrichment plant, Iran's President Masoud Pezeshkian said.

He had earlier asked the Iran Atomic Energy Agency to begin inserting uranium gas into newly activated advanced centrifuges.

Early this month, a spokesperson for the US State Department said Iran's expansion of uranium enrichment activities in defiance of key nuclear commitments is "a big step in the wrong direction”.

His statement came after Tehran announced it would start injecting uranium gas into centrifuges at Fordo.

Dispute

The Nuclear Non-Proliferation Treaty, signed in 2015 between Tehran and Western countries, says advanced centrifuges for uranium enrichment could operate until January 2027.

The difference between the first generation of centrifuges (IR-1) and the other generations is speed. The latest generation, IR-6, could enrich uranium up to 10 times faster than the first-generation IR-1, according to Iranian officials.

During the heyday of its nuclear program, Iran operated a total of 10,204 first-generation IR-1 centrifuges at the Natanz and Fordo facilities. But under the deal, Iran's commitments included operating no more than 5,060 IR-1 centrifuges for a period of 10 years.

Although the centrifuges that Iran installed before the 2015 nuclear deal were of the first generation, Tehran’s recent uranium enrichment activity at nuclear sites has reached disturbingly advanced levels, potentially increasing the nuclear proliferation risk.

Major centrifuge activities in Iran

May 2008: Iran installed several centrifuges including more modern models.

March 2012: Iranian media announced 3,000 centrifuges at Natanz.

August 2012: The International Atomic Energy Agency announced that Iran had installed large parts of the centrifuges at Fordo.

November 2012: An IAEA report confirmed that all advanced centrifuges had been installed at Fordo, although there were only four working centrifuges, and another four fully equipped, vacuum tested, and ready to go.

February 2013: IAEA says Iran has operated 12,699 IR-1 centrifuges at the Natanz site.

June 2018: Iran’s supreme leader revealed Tuesday that it ultimately wants 190,000 nuclear centrifuges — a figure 30 times higher than world powers allowed under the 2015 deal.

September 2019: Iran mounted 22 IR-4, one IR-5, 30 IR-6, and three IR-6 for testing, outside the treaty boundaries.

September 2019: Iran announced it started operating advanced and fast centrifuges to enrich uranium.

November 2024: Iranian Foreign Minister Abbas Araghchi announces that his country will operate several thousand advanced centrifuges.

November 2024: Iranian state television broadcasts AEOI Chief Mohammad Eslami announcing that “gasification of a few thousands of new generation centrifuges has been started.”



What to Know about the Tensions between Iran and the US before Their Third Round of Talks

The flags of US and Iran are displayed in Muscat, Oman, 25 April 2025. Iran and US will hold third round of nuclear talks on 26 April 2025, in Muscat. (EPA)
The flags of US and Iran are displayed in Muscat, Oman, 25 April 2025. Iran and US will hold third round of nuclear talks on 26 April 2025, in Muscat. (EPA)
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What to Know about the Tensions between Iran and the US before Their Third Round of Talks

The flags of US and Iran are displayed in Muscat, Oman, 25 April 2025. Iran and US will hold third round of nuclear talks on 26 April 2025, in Muscat. (EPA)
The flags of US and Iran are displayed in Muscat, Oman, 25 April 2025. Iran and US will hold third round of nuclear talks on 26 April 2025, in Muscat. (EPA)

Iran and the United States will hold talks Saturday in Oman, their third round of negotiations over Tehran’s rapidly advancing nuclear program.

The talks follow a first round held in Muscat, Oman, where the two sides spoke face to face. They then met again in Rome last weekend before this scheduled meeting again in Muscat.

Trump has imposed new sanctions on Iran as part of his “maximum pressure” campaign targeting the country. He has repeatedly suggested military action against Iran remained a possibility, while emphasizing he still believed a new deal could be reached by writing a letter to Iran’s 85-year-old Supreme Leader Ali Khamenei to jumpstart these talks.

Khamenei has warned Iran would respond to any attack with an attack of its own.

Here’s what to know about the letter, Iran’s nuclear program and the tensions that have stalked relations between Tehran and Washington since the 1979 revolution.

Why did Trump write the letter? Trump dispatched the letter to Khamenei on March 5, then gave a television interview the next day in which he acknowledged sending it. He said: “I’ve written them a letter saying, ‘I hope you’re going to negotiate because if we have to go in militarily, it’s going to be a terrible thing.’”

Since returning to the White House, the president has been pushing for talks while ratcheting up sanctions and suggesting a military strike by Israel or the US could target Iranian nuclear sites.

A previous letter from Trump during his first term drew an angry retort from the supreme leader.

But Trump’s letters to North Korean leader Kim Jong Un in his first term led to face-to-face meetings, though no deals to limit Pyongyang’s atomic bombs and a missile program capable of reaching the continental US.

How did the first round go? Oman, a sultanate on the eastern edge of the Arabian Peninsula, hosted the first round of talks between Iranian Foreign Minister Abbas Araghchi and US Middle East envoy Steve Witkoff. The two men met face to face after indirect talks and immediately agreed to this second round in Rome.

Witkoff later made a television appearance in which he suggested 3.67% enrichment for Iran could be something the countries could agree on. But that’s exactly the terms set by the 2015 nuclear deal struck under US President Barack Obama, from which Trump unilaterally withdrew America.

Witkoff hours later issued a statement underlining something: “A deal with Iran will only be completed if it is a Trump deal.” Araghchi and Iranian officials have latched onto Witkoff’s comments in recent days as a sign that America was sending it mixed signals about the negotiations.

Yet the Rome talks ended up with the two sides agreeing to starting expert-level talks this Saturday. Analysts described that as a positive sign, though much likely remains to be agreed before reaching a tentative deal.

Why does Iran’s nuclear program worry the West? Iran has insisted for decades that its nuclear program is peaceful. However, its officials increasingly threaten to pursue a nuclear weapon. Iran now enriches uranium to near weapons-grade levels of 60%, the only country in the world without a nuclear weapons program to do so.

Under the original 2015 nuclear deal, Iran was allowed to enrich uranium up to 3.67% purity and to maintain a uranium stockpile of 300 kilograms (661 pounds). The last report by the International Atomic Energy Agency on Iran’s program put its stockpile at 8,294.4 kilograms (18,286 pounds) as it enriches a fraction of it to 60% purity.

US intelligence agencies assess that Iran has yet to begin a weapons program, but has “undertaken activities that better position it to produce a nuclear device, if it chooses to do so.”

Ali Larijani, an adviser to Iran’s supreme leader, has warned in a televised interview that his country has the capability to build nuclear weapons, but it is not pursuing it and has no problem with the International Atomic Energy Agency’s inspections. However, he said if the US or Israel were to attack Iran over the issue, the country would have no choice but to move toward nuclear weapon development.

“If you make a mistake regarding Iran’s nuclear issue, you will force Iran to take that path, because it must defend itself,” he said.

Why are relations so bad between Iran and the US? Iran was once one of the US’s top allies in the Middle East under Shah Mohammad Reza Pahlavi, who purchased American military weapons and allowed CIA technicians to run secret listening posts monitoring the neighboring Soviet Union. The CIA had fomented a 1953 coup that cemented the shah’s rule.

But in January 1979, the shah, fatally ill with cancer, fled Iran as mass demonstrations swelled against his rule. The revolution followed, led by Khomeini, and created Iran’s theocratic government.

Later that year, university students overran the US Embassy in Tehran, seeking the shah’s extradition and sparking the 444-day hostage crisis that saw diplomatic relations between Iran and the US severed. The Iran-Iraq war of the 1980s saw the US back Saddam Hussein. The “Tanker War” during that conflict saw the US launch a one-day assault that crippled Iran at sea, while the US later shot down an Iranian commercial airliner that the American military said it mistook for a warplane.

Iran and the US have see-sawed between enmity and grudging diplomacy in the years since, with relations peaking when Tehran made the 2015 nuclear deal with world powers. But Trump unilaterally withdrew America from the accord in 2018, sparking tensions in the Middle East that persist today.