Following the US pulling out of the JCPOA agreement last year, Iran has announced it may resume Uranium enrichment, up to a level of 20% of U-235 (the more-active isotope, as opposed to U-238). The plan allows Iran to enrich to 3.67% U-235, for use in power plants.

Now, 20%-enriched Uranium can be used for (quicker) further enrichment to weapons-grade Uranium at around 80% or 90% U-235. And it can even theoretically itself be used in a weapon, although this is "not practical" as a design.

But - are there civilian uses of further-enriched Uranium? And specifically:

  • Are there benefits for using 20%-enriched Uranium for power generation?
  • Is there non-weapons research that uses 20%-enriched Uranium?
  • How was Iran using the 20%-enriched Uranium it had produced before the deal (if it was using it at all)?
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    You know what uranium is, right? It's this thing called nuclear weapons, and other things, including some bad things. But nobody talks about that.
    – Obie 2.0
    May 10, 2019 at 4:47
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    " You know what uranium is, right? It’s this thing called nuclear weapons. And other things. Like lots of things are done with uranium. Including some bad things. But nobody talks about that. "
    – Evargalo
    May 10, 2019 at 12:15
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    @Evargalo: I don't understand your comment.
    – einpoklum
    May 10, 2019 at 13:53
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    @einpoklum : I was quoting a genius that is alas often misunderstood. Go to n°7 here : vox.com/2017/2/16/14640772/president-trump-quotes-presser
    – Evargalo
    May 10, 2019 at 15:48
  • @Evargalo: Actually, stupidity and ignorance notwithstanding, Trump does make a good point there about the way his stance vis-a-vis Russia is interpreted. But that would be off-topic for this question.
    – einpoklum
    May 10, 2019 at 16:22

2 Answers 2


Partial answer: It's usable as reactor fuel

20% enrichment is also referred to as "High-assay Low-Enrichment Uranium" (HALEU). It has various benefits when used as a fuel in some reactors; see the Centrus page on HALEU.

Apparently, it is already in use in existing research reactors in the US, for example - after 10 tonnes of the material had been produced by the Idaho National Lab. In Iran, there's a research reactor in Tehran for which 20%-enriched Uranium could be used as fuel; and apparently, Ali Akbar Salehi, head of the nuclear program, has said that's what Iran plans to do. IIANM they had the same plan before the JCPOA negotiations process as well, and it got postponed/set aside by the agreement; now they'll resume it.

According to the World Nuclear News website, many advanced reactor designs will require fuel from Uranium enriched to the 20% level. So it is quite conceivable that Iran may have planned energy-production uses for 20%-enriched Uranium.

I can't speak to whether it actually has working reactors, or planned reactors, which use such fuel.


US HALEU (High-assay Low-Enrichment Uranium) reactors are intended to be fairly mobile. Basically the DOD is currently the only (US) customer. So claiming this has non-bomb uses is one thing. Claiming it has non-military uses (presently) is quite another. (Nevertheless, a HALEU reactor would be much bigger than a HEU reactor used on military naval craft.)

according to Dr. Everett Redmond, senior technical advisor of the NEI’s New Reactor & Advanced Technology division, the DOE’s announcement is a significant leap in the right direction because no commercial facilities to make HALEU on a commercial scale or transportation infrastructure associated with uranium hexafluoride above 5% exist worldwide.

On the other hand

Massachusetts-based fuel company Lightbridge is developing HALEU for use in commercial fuel. It has said it wants to demonstrate the fuel in a research reactor at a U.S. national laboratory in 2020, as well as a commercial nuclear power plant powering a U.S. city by 2021.

Also the Bulletin of the Atomic Scientists doesn't find plausible (contra to the OP's own anwer) that Iran could use HALEU as fuel for their research reactor. Instead it says:

If Iran’s claim that it’s enriching uranium to produce fuel for its research reactor is suspect, then we must examine the possibility that Tehran is intentionally moving toward a weapons capability. Although 20 percent enrichment is legal under the Nuclear Non-Proliferation Treaty, it brings Iran a step closer to producing 90 percent enriched, bomb-grade uranium.

A stockpile of 20 percent enriched uranium increases the breakout threat in two ways. First, by starting with 20 percent LEU–rather than the current stock of 3.5 percent–Iran cuts the time required to produce a bomb’s worth of material by more than one-half. Second, a higher degree of enrichment means that a smaller quantity of material presents a weapons threat.

To make a bomb’s worth of highly enriched uranium, Iran would need to start with more than 5 tons of natural uranium or about 1 ton of its 3.5 percent LEU. But if it starts enriching with 20 percent enriched uranium, it would only need 130 kilograms. (All of these numbers depend on assumptions about the amount of uranium 235 lost in the waste, which tends to be high in Iran’s operations.)

Also Iran has been working on and off on the HALEU for at least 6 years, when few considered HALEU commercially viable, including Iran's president:

What has raised the world’s suspicions is that Iran continues to produce 20 percent enriched uranium despite the fact that this exceeds its civilian needs and, as President Mahmoud Ahmadinejad acknowledged in September [2011], does not make economic sense. [...]

Iran’s entire uranium-enrichment program is now [2012] being devoted to producing 20 percent enriched uranium.

That changed with the deal, of course.

In case there's still doubt about the intent of this latest Iranian conditional announcement (to resume enirchment to HALEU levels), it coincides with another (conditional) annoucement to resume the work on the heavy water version of the research reactor, which is considered plan B for making weapons-grade material (plutonium in the latter case).

  • 1. Your third quoted paragraph doesn't say it is implausible Iran could use HALEU as reactor fuel. 2. Did Ahmedinajaad actually state that use of 20%-enriched fuel makes no economic sense? 3. About the Arak reactor - it is the apparently intended replacement for the Tehran research reactor, and Iran agreed to more-or-less scrap it as part of the JCPOA. It's dual-use technology - it has civilian uses, but it also produces plutonium which can be used to make a bomb.
    – einpoklum
    May 10, 2019 at 6:54
  • @einpoklum: I can't find a direct quote from Ahmadinejad on that. Let me ask a question here about that... May 10, 2019 at 7:25
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