Iran nonetheless possesses a whole bunch of kilograms of extremely enriched uranium and retains the technical capability to provide extra. Whereas the modalities of a remaining settlement are to be negotiated within the second part of talks, the MoU states that either side have agreed to take steps to downblend Iran’s uranium stockpile. U.S. President Donald Trump stated final week that the U.S. would “go and get” Iran’s extremely enriched uranium “in some unspecified time in the future” and “dilute” (downblend) it both in America or in Iran.
Paragraph 8 of the MoU states: “The Islamic Republic of Iran reaffirms that it shall not procure or develop nuclear weapons… The 2 events additionally agreed to resolve the disposition of stockpiled enriched materials pursuant to a mechanism… with the minimal methodology to be down-blending on website beneath the supervision of the Worldwide Atomic Power Company.”
Downblending is a expertise used to make uranium much less pure. It’s troublesome to purify uranium, and extremely pure uranium can be utilized to make nuclear bombs. So downblending removes the quantity of uranium-235 obtainable to make a bomb and will increase the time required to take action. This period, known as the breakout time, is a cornerstone of contemporary nuclear non-proliferation.
Thus, the worldwide group’s belief in Iran’s promise to not pursue a nuclear weapon is determined by how effectively it implements downblending within the coming months, amongst different components.
Uranium in nature consists primarily of two isotopes: uranium-238 and uranium-235. Of those, solely uranium-235 is fissile, that means it may well maintain a nuclear chain response. Nonetheless, the pure focus of uranium-235 in uranium is barely 0.72%. The remaining 99.28% is uranium-238. Purification means enriching the focus of uranium-235 to larger ranges.
Downblending is the other of enrichment. Right here, enriched uranium is blended with depleted (reverse of enriched) or pure uranium to provide uranium with lower than 5% uranium-235. E.g. the 2015 Iran deal allowed Iran to complement uranium as much as 3.67%. Uranium of this purity can be utilized in some easy reactors to provide electrical energy however to not make a bomb.
The enriched uranium feedstock is normally saved because the compound uranium hexafluoride (UF6), which is a strong at room temperature. In step one, the metal cylinders containing UF6 are positioned in an industrial oven known as an autoclave and heated to 80-110° C, turning the compound to gasoline. Gases are simpler to combine than solids.
Second, one other supply of uranium known as the blendstock is ready. It might have 0.7% uranium-235 (pure uranium), 0.2-0.3% (depleted uranium), 1% uranium-235 (barely enriched) or a distinct stage. The extent is predicated on want. For example, downblending 90% enriched uranium to five% will want a bigger amount of depleted uranium than pure uranium. The blendstock can be gaseous.
The enriched feedstock and the blendstock are pumped right into a junction known as a mixing tee. The principle problem right here is mass circulate management: to attain a goal enrichment, the ratio of the 2 gases should be good. If an excessive amount of feedstock will get in, the ultimate gasoline will probably be too excessive in uranium-235.
Engineers use thermal mass circulate meters, which decide the lots by measuring the warmth switch traits of the flowing gases. Then automated values modify the circulate. To make sure the gases combine, the mixing tee makes use of inside mixers, known as baffles, to create turbulence.
When the blended gasoline exits the mixing tee, it passes via a web-based enrichment monitor (OLEM). The OLEM makes use of sodium iodide to sense the quantity of gamma rays emitted by the gasoline. Uranium-235 has an power signature at 186 keV (round 3 × 10^-14 joules). OLEM tracks the depth of gamma rays with this signature. If it exceeds an agreed-upon restrict, the system will set off failsafe valves that shut off the complete circulate. That is finished to maintain the ability from producing extra of the non-compliant materials.
In truth, the ability can be match with cameras housed in tamper-proof casings and which report 24/7.
The gasoline is then solidified by cooling it in a product cylinder.
This isn’t the final step, nevertheless. The downblended uranium nonetheless exists as UF6 — which can be the feedstock for the method that enriches uranium. Because the function of downblending is to extend the quantity of effort wanted to make a bomb, the UF6 is lastly moved to a reconversion plant, the place the gasoline reacts with steam and hydrogen. The response replaces the fluorine atoms with oxygen, producing uranium dioxide (UO2), a darkish powder.
The uranium in UO2 can’t be enriched immediately. It needs to be transformed to UF6 first in a conversion plant. The emissions from such a plant may be detected by satellites and on floor inspections.
The final step is IAEA verification. IAEA inspectors acquire a small bodily pattern of the UO2 powder and ship it to their laboratory in Seibersdorf, Austria, the place thermal ionisation mass spectrometry is used to verify the extent of uranium-235 to 4 decimal locations. Second, the IAEA applies seals on the cylinders that may’t be tampered with out leaving again indicators.
Whereas the crux of downblending is the bodily mixing, downblending the method contains the management programs in order that it may well present verifiable proof that the uranium has certainly change into much less pure. And that in flip is why the U.S.-Iran memorandum will relaxation as a lot on diplomatic assurances as on the technical implementation.
Revealed – June 19, 2026 09:14 am IST
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