Skip to main content

UF6 Cylinders

Iran is reported to have produced some 400 kilograms of uranium enriched to 60% in the isotope U-235, enough with further enrichment to “weapon grade” (~90%) for up to 10 nuclear weapons. A big question now: what has happened to that stockpile since the beginning of the Israeli bombardment? 

Here’s background on the form of the uranium and how it is stored and transported. 

Uranium hexafluoride (UF6) is the gas used in centrifuge uranium enrichment. It sublimes at 56.5°C (134°F) under atmospheric pressure. It can be liquefied and solidified for storage and transport. 

UF6 is stored and transported in steel cylinders designed to contain the corrosive and radioactive UF6. Large 48Y cylinders are used for natural (0.7% U-235) and depleted UF6 and smaller 30B cylinders (photo) for low enriched UF6.

High enriched uranium (20% or more U-235) hexafluoride is stored and transported in specialized cylinders, which are designed to prevent “criticality.” 

IAEA inspectors routinely verify the amount and enrichment of uranium in UF6 cylinders at enrichment facilities (photo of enrichment verification).
 

Iran was producing 20% and 60% uranium at Natanz and at Fordo. And some of the stockpile was said to be stored at Isfahan. At Natanz, the above ground part of the enrichment facilities, producing 60%, was destroyed in the first Israeli attack. Some UF6 cylinders may have been torn open, releasing some UF6 to the atmosphere. The IAEA has reported that radiation levels near the Natanz facility have not changed. At Isfahan, several facilities were destroyed or damaged in the first attack. Some UF6 cylinders may have been destroyed and some UF6 released to the atmosphere. The underground Fordo was not attacked; 60% uranium was being produced there, and the stockpile was not affected. 

As Israeli bombardment continues, and with a possible MOAB attack on Fordo (and possibly on Natanz), and with IAEA inspectors gone, the Iranians have had time to take action to protect the UF6 cylinders, probably by moving them to safer locations. Israel is no doubt using its on-the-ground agents to try to determine where the UF6 cylinders are. 

And that’s where this key factor stands today - the amount and whereabouts of Iran’s 60% and 20% UF6 cylinder stockpile. If Iran retains enough of that stockpile, it has the possibility to “break out” along with withdrawing from the NPT. A number of non-Iranian commentators believe that would be the proper strategic decision for Iran, especially if President Trump takes the U.S. to war with Iran, at the side of Israel.

Comments

Post a Comment

Popular posts from this blog

‘New war with Israel at any moment’, ‘still digging through rubble’

The news about Iran has taken an ominous tone in the last couple days. Here is some reporting and commentary.  Newsweek on August 18, 2025, reported that Yahya Rahim Safavi, senior military adviser to Supreme Leader Ali Khamenei, said ‘ We are not in a ceasefire; we are in a stage of war. No protocol, regulation, or agreement has been written between us and the U.S. or Israel. A new war with Israel could break out at any moment .’  Yonah Jeremy Bob commented in The Jerusalem Post on August 19, 2025, that ‘ Khamenei can either “drink from the poisoned chalice” of diplomatic concessions … or face more airstrikes, possibly next time some targeting him directly ’.   Bob also noted that ‘ right now Iran is still digging through rubbl e’. The U.S. attacked Fordow, Natanz and Esfahan on June 22. Two months of digging. No surprise that there has been no public news about that.
Post a Comment
Read more

Assessing possible outcomes of the snapback mechanism

The initiation by the E3 of the 30-day snapback mechanism in the UN Security Council makes everything more difficult and there is great uncertainty about the outcome. Will it be peaceful with a new nuclear deal with Iran, negotiated by the U.S., endorsed by the UNSC and verified by IAEA, or will Iran withdraw from NPT with further military action by Israel and the U.S.?                 To perhaps shed a little light on what the outcome will be, here is my analysis of how the players - Iran, U.S. and E3 - may be assessing the acceptability of the range of outcomes. Four levels of acceptability were used: 1 Fully acceptable; 2 Less acceptable; 3 Just acceptable; and 4 Not acceptable. Four near term 30-day outcomes are listed, and two optimistic outcomes with an interim U.S.-Iran agreement reached within a 6-month extension.                 For the 30-day near term, the best outcome would b...
Post a Comment
Read more

‘Making nuclear fuel’ under the NPT

It is with some hesitation that I take issue with the latest publication of the renowned Henry Sokolski and Sharon Squassoni on August 15 in the Bulletin of Atomic Scientists, titled: “ Actually, the NPT doesn’t guarantee a right to make nuclear fuel .”  But someone should defend the IAEA and international safeguards! Here are points in question.            ‘ The [NPT] treaty was designed to prevent dangerous bombmaking activitie s.’  NPT is far more complex than that. It is common to state the three pillars of NPT: nuclear disarmament; nuclear nonproliferation; and peaceful uses of nuclear technology. Nonproliferation involves the commitment of non-nuclear states not to pursue nuclear weapons and to accept IAEA inspection to confirm that commitment is being followed. Perhaps Sokolsky intends to refer to INFCIRC/153, which lays out how IAEA and the state cooperate to carry out that confirmation. If so, INFCIRC/153 is not designed to ‘prevent’...
Post a Comment
Read more