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(This is a followup question, I suppose, to: Are there non-military uses of 20%-enriched Uranium?)

Following the US pulling out of the JCPOA agreement in 2018, and the other signatories enabling continued sanctions in breach of the agreement, Iran has resumed Uranium enrichment. At first, it officially limiting itself to enrichment up to a level of 20% of U-235 (the more-active isotope, as opposed to U-238); more recently, however (and supposedly following an increase in Israeli sabotage and bombings), it announced it would enrich to a level of 60%, and the IAEA has confirmed this is indeed taking place. As of this month, Iran claims to have enriched 25 Kg to this level.

Ali Akbar Salehi, the head of the nuclear program, says in an interview that the 60%-enriched material is not intended for use as reactor fuel, but rather:

We do not want to use 60% enriched uranium as fuel for the Tehran reactor. We want to produce U3O8 (uranium oxide, or yellowcake) targets, which needs uranium with 60% purity. Thus, we produce targets, using 60% uranium.

...

These targets will be placed in the Tehran reactor. After being exposed to atomic radiation for some time, a substance called molybdenum is produced, which we must separate to remove the molybdenum. This molybdenum is the raw material for the manufacture and production of many radiopharmaceuticals.

Is this a legit claim? That is, can Iran meaningfully benefit from such a process, or is it merely an excuse for enriching to a higher percentage? Also, are there (other) civilian uses of 60%-enriched Uranium, which would be relevant in Iran?

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    Would be a better Q on an engineering stack.
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 13:28
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    @Fizz: I am willing to bet you they would say the same thing about asking it here...
    – einpoklum
    Commented Nov 5, 2021 at 13:34
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    Asking whether X% enriched uranium is used for radiopharmaceuticals doesn't seem like a question about politics. You could ask if this is an official Iran policy and what the background is, or maybe ask if other governments have similar policies for their use of enriched uranium, but just "is this technical process realistic" isn't a political question.
    – Giter
    Commented Nov 5, 2021 at 17:21
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    @einpoklum: Your edit didn't really change the question, you're still just asking if manufacturing radiopharmaceuticals is a realistic use case for the enriched uranium. Maybe you could ask "is 60% enriched uranium used to manufacture radiopharmaceuticals" over on Skeptics, though the claim may be a bit too vague.
    – Giter
    Commented Nov 5, 2021 at 20:26
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    Voted to reopen. Claiming that 60% uranium has some legit uses - besides building a bomb - is a good strategy to elicit sympathy for Iran's continued enrichment. This is a highly political subject, neither an Engineering nor strictly a Skeptics-limited concern. Whether or not it's true, either pertaining to pharmaceuticals or other reasons should be of interest here. At the same time... how much of the stuff is "needed" and how does that compare to the quantities Iran intends to produce?
    – Italian Philosopher
    Commented Nov 6, 2021 at 18:13

3 Answers 3

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Contra to Joe's answer, as far as I can tell, by 2019 the US had just managed to select some (domestic) companies to try LEU-based methods:

Mo-99 is used in hospitals to produce the technetium-99m employed in around 80% of nuclear imaging procedures. Produced in research reactors, Mo-99 has a half-life of only 66 hours and cannot be stockpiled, and security of supply is a key concern. Most of the world's supply currently comes from just four reactors in Belgium, the Netherlands, Russia and South Africa, and recent years have illustrated how unexpected shutdowns at any of those reactors can quickly lead to shortages. Furthermore, most Mo-99 is currently produced from HEU targets, which are seen as a potential nuclear proliferation risk.

Further, even these attempts are due to US legislation (American Medical Isotopes Production Act (AMIPA) of 2012).

So, while it may be possible to do produce Mo99 sans HEU, this apparently hasn't happened in substantial quantities, i.e. it's the road less traveled.

At least as recently as 2016, the USA was also a regular exporter of HEU (93.35% enriched) for this purpose, e.g. to France. According to a (fairly dated) 2012 article, the US was hoping to end such exports after 2020. There's also news that in 2020 Belgium managed to produce its first batch of Mo-99 for export to the US, without using HEU. According to that piece "This marks the beginning of transition to LEU targets in Mo-99 production in Europe. Right now, most of Mo-99 is produced in HEU targets, with the material supplied by the United States."

US HEU export to Europe for this purpose had continued through 2019, albeit a smaller quantity 4-5 Kg vs 7-8 Kg a few years before.

Some sites in Russia (operational at least since 2011) use a MEU process with 36% enriched uranium for Mo-99 production.

In general, if you have a reactor built/designed for >20% enriched Uranium, it seems pretty expensive to convert it to LEU as the saga of Germany's FRM-II showed. (Apparently they've finally managed that at FRM-II using a "special U-Mo fuel", which uses U at 19.75% enrichment, so as to meet the LEU limit, but tests with this are just beginning in 2022, it seems. The U-Mo tech is being tested more broadly for such conversions.)

Also worth noting that "the Tehran reactor" is a bit ambiguous. The older TRR initially supplied by the US with HEU was converted to run on 20%-enriched LEU that was supplied by Argentina... but that fuel seems to have ran out. There's another "IR-40" reactor under construction nearby Tehran at Arak, which seem intended to replace the TRR. IR-40 was has been changed while being built, but it's not exactly clear to me what its fate/status is now.

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  • How do you square this with the table on the Wikipedia Te-99 page, which lists some of the main manufacturers as using LEU?
    – einpoklum
    Commented Nov 5, 2021 at 20:20
  • @einpoklum: of the "Large-scale producers" only the South Africa one is LEU/LEU; the other four are listed as using HEU either as fuel, target, or both, as of right now en.wikipedia.org/w/… (the page hasn't been changed since Oct 10.)
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 20:25
  • South Africa + Australia (also LEU/LEU) might have 30% of the market together, but I'm not too sure of the reliability of the latter figure[s]; they were "Rosatom estimate[s]".
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 20:30
  • Unfortunately, up-to-date reliable figures cost $$$$ dataintelo.com/report/global-molybdenum-99-mo-99-sales-market
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 20:40
  • And I'm a bit skeptical South Africa has such high market share since their processing plant was shut down for a full year Nov '17- Nov '18 world-nuclear-news.org/Articles/… Generally that tends to lose customers in fields like medical, where supply reliability is not to be trifled with ...
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 20:59
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As @Joe also points out, Radioactive Molybdenum is really produced with highly-enriched uranium and is a key material in producing radio-isotopes for medical imaging, via Technetium-99.

As the Wikipedia article regarding Technetium-99 indicates, there are 4 active large-scale producers of Technetium-99: Belgium, South Africa, The Netherlands, and France. Iran, often being under strict sanctions by the US, its allies and other world states, has often/always not been able to buy Technetium-99 from these suppliers (Note: Additional information about this would be useful; in particular why Iran couldn't by Tc-99 from South Africa). Instead, Iran was using a now 50-year-old research reactor in Tehran to produce Tc-99, possibly with LEU or maybe with HALEU; and when there was no fuel for it, Iran was having difficulties, or couldn't, secure sufficient Tc-99 for its medical needs.

Assuming (and I have not verified this) that there are benefits - in terms of any of the engineering simplicity, cost, safety, or output-weight-for-input-weight - to using 60% HEU, it would make sense for Iran to wish to use such a process in its Tc-99 production.

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    ⁹⁹^mTc decaying into ⁹⁹Tc plus the γ-ray used for medical purposes has a half life of only 6 h. Fast delivery is thus important, and even a possibility that includes export restriction burocracy may take so long that hardy anything arrives. Even the ⁹⁹Mo it is produced from has a half life of < 3d, so again, if the export procedure causes a delay of 2 weeks, there's only 3 % of the purchased material left.
    – cbeleites
    Commented Nov 5, 2021 at 18:14
  • @cbeleitesunhappywithSX: Well, if you believe in homeopathy maybe that's a good thing :-P
    – einpoklum
    Commented Nov 7, 2021 at 22:32
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Radioactive molybdenum is really produced with highly-enriched uranium and is really used in medical applications...

The short answer is that molybdenum-99 is used to make technetium-99m, which is the most commonly used medical isotope in the world. It's used in medical imaging (e.g. MRI).

There are five reactors around the world that use highly enriched uranium (20% U-235 or more).

... but...

There are at least three reactors that make molybdenum-99 that do not use highly enriched uranium, and the cost is just about the same.

So they don't actually "need" 60% enriched uranium for this at all.

There is also nothing particularly special about the 60% enrichment, other than it would be produced as an intermediate step in a hypothetical multi step process to make 90% enriched uranium.

In other words, Ali Akbar Saleh is probably saying something that is entirely true but completely avoids the actual significance of these facts.

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    1. MRI uses magnetic fields, I don't think it would need radioactive isotopes. Perhaps you mean PET, SPECT or CT? 2. "There are at least 3 reactors" - none of them in Iran, and Iran is under a heavy sanctions regime which IIRC prevents them for importing even medicinal supplies. I doubt they would be able to purchase radio-isotopes. And if they could, that would have both a high monetary price and a diplomatic one.
    – einpoklum
    Commented Nov 5, 2021 at 12:27
  • My point was not that they could purchase molybdenum-99. My point was that, if their purpose was to create a domestic molybdenum-99 industry with a reactor, it does not require any HEU.
    – Joe
    Commented Nov 5, 2021 at 13:34
  • Well, you could make the same argument abot the Osiris and BR2 reactoers, which use HEU. That is, perhaps it's not necessary, but apparently it's convenient under some circumstances.
    – einpoklum
    Commented Nov 5, 2021 at 13:36
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    It's probably less economical to do it without HEU or it would have been done that way a long time ago and without 2010 US legislation that put pressure in that direction. proquest.com/openview/4e166196ba8718dc0c83172395c86b29/… Which source precisely says the costs are the same? I can't find the claim in the Wikipedia page you linked.
    – 264 champagne bottles on ice
    Commented Nov 5, 2021 at 13:44
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    The link Fizz has provided points that alternative sources to HEU for Mb99 are only being investigated due to Obama's administration will of depriving Iran of an alibi for its enrichment program. It also points that only tiny amounts of Mb99 are being obtained in these experimental reactors, and it is yet to be seen if they will become a practical source of Mb99 or not - and if they will, we'll see if it's economically viable, specially for poorer countries. So far, this option is just like nuclear fussion: desirable but non-existant.
    – Rekesoft
    Commented Nov 5, 2021 at 14:01

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