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Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive everywhere it has been implemented. Nat

Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive everywhere it has been implemented. Natural uranium isn't very expensive and separating the plutonium from spent fuel doesn't save much on waste disposal costs either. The US canceled a new MOX plant just 7 years ago due to cost and schedule problems: https://world-nuclear-news.org/Articles/US-MOX-facility-contract-terminated https://world-nuclear-news.org/Articles/US-MOX-facility-cont... Work started on the MOX Fuel Fabrication Facility (MFFF) in 2007, with a 2016 start-up envisaged. Although based on France's Melox MOX facility, the US project has presented many first-of-a-kind challenges and in 2012 the US Government Accountability Office suggested it would likely not start up before 2019 and cost at least USD7.7 billion, far above original estimate of USD4.9 billion. The most interesting "recycling" effort right now is the laser enrichment process of Silex/Global Laser Enrichment: https://www.wkms.org/energy/2025-07-02/company-developing-paducah-laser-uranium-enrichment-facility-hits-key-regulatory-milestone https://www.wkms.org/energy/2025-07-02/company-developing-pa... The company plans to re-enrich old depleted uranium tails from the obsolete gas diffusion enrichment process back up to natural uranium levels of 0.7% U-235. That uranium in turn would be processed by existing commercial centrifuge enrichment to upgrade it to power reactor fuel.

deepsun 1y ago
Also, nuclear waste is a very small problem, compared to other wastes. Yes, it stays active for 10k+ years, but it's actually not that expensive to store them at specialized storages forever. Because it's a very small amount on a grand scale. In comparison, managing steel production waste is way more expensive.
- potato3732842 1y ago
  10k years isn't that long. Some concentrated chemical stuff with heavy metals or mercury or whatever in it will be toxic forever.
  - cycomanic 1y ago
    The nuclear waste even without the radiation is going to be toxic. Anything with even trace amount of plutonium left (which has a half life time > 200,000 years), will be toxic (much more than e.g. mercury).
    - mlyle 1y ago
      Eh, I don't think I agree. Let's talk about the long-lived isotopes: Pu-239 and Pu-242. Significant inhaled Pu-239 has a fair risk of causing cancer even after a long time. However mercury is volatile and it's a lot easier to end up inhaling fumes. And mercury is absorbed well through ingestion and Pu isn't, and most of the risk after ingestion would be chemical, not radiological. From that standpoint, it's looking a lot better than other heavy metals.
      - lazide 1y ago
        Huh? The reason we don’t have more solid non-radiological toxicity data on Plutonium (compared to other toxic heavy metals) is because any amount significant enough to count kills people radiologically super quick. That doesn’t mean it’s non-toxic if we ignore the radiological effects.
        mlyle 1y ago
        We know: * Plutonium is not well absorbed by ingestion compared to other heavy metals and know ballpark ingestion toxicities * We also know that pretty much all the plutonium except the long-lived isotopes are gone on a timescale of tens of thousands of years-- leaving behind mostly uranium isotopes. * There's no real reason to believe this mixture of uranium and a small fraction of long-lived plutonium isotopes is significantly worse than ingesting uranium. It might be worse to inhale fine dust, though. * Mercury is way worse than uranium because it is so readily absorbed.
        lazide 1y ago
        Elemental mercury is not absorbed at all. You’re probably thinking of methyl mercury and various mercury salts (which, by the way, are not very common). We have nearly zero experience with weathered or bio modified plutonium. And the experience we do have with plutonium compounds, is limited by the fact people die awfully fast when they’re anywhere near them. Absence of evidence is not evidence of absence. Especially not when the evidence is absent because we can’t get there because everyone dies first from the more obvious bad things happening.
- throw0101d 1y ago
  > Yes, it stays active for 10k+ years, but it's actually not that expensive to store them at specialized storages forever. Because it's a very small amount on a grand scale. For some definition of "active". The first 6-10 years are quite dangerous, which is why stuff is in cooling pools. After about 200-300 years the most dangerous type of radiation (gamma) has mostly burned stopped, and you're left with alpha and beta, which can be stopped with tinfoil and even paper. I've heard the remark that after ~300 years the main way for nuclear waste to cause bad health effects is if you eat it or grind it up and snort it.
  - deepsun 1y ago
    Sorry, but you're wrong. I took some radiation safety classes, and the main point I got from that is that "it depends". For example, alpha- and beta-radiation are often more dangerous than gamma, because gamma is easier to detect and measure. People often focus on "radiation" part forgetting the "contamination" part. You can literally walk into the Chernobyl reactor active zone today for up to 2 minutes. But you cannot produce any food in soils around it for thousand years. And there's dozens of dangerous isotopes, each one accumulating and affecting human tissues differently. Public generally only knows about Geiger counter. Yes, it will scream if everything is FUBAR, but it's useless for estimating safety of a food product.
    - throw0101d 1y ago
      So nuclear waste is stored in casks: * https://www.nwmo.ca/canadas-used-nuclear-fuel/how-is-it-stored-today https://www.nwmo.ca/canadas-used-nuclear-fuel/how-is-it-stor... * https://en.wikipedia.org/wiki/Nuclear_flask https://en.wikipedia.org/wiki/Nuclear_flask Are you telling me it's unsafe? Someone better tell Madison Hill: * https://www.newsweek.com/pregnant-woman-poses-nuclear-waste-prove-point-about-radiation-idaho-1809500 https://www.newsweek.com/pregnant-woman-poses-nuclear-waste-... * https://twitter.com/MadiHilly/status/1550148385931513856 https://twitter.com/MadiHilly/status/1550148385931513856 * https://twitter.com/MadiHilly/status/1671491294831493120 https://twitter.com/MadiHilly/status/1671491294831493120 Or Paris Ortiz-Wines: * https://twitter.com/ParisOrtizWines/status/1195184970613936129 https://twitter.com/ParisOrtizWines/status/11951849706139361... (The context here is not walking down some road and getting bombarded with particles: but about the storage of industrial material and the risks it involves. Yes, stuff gets shot out at >300 years: but it's not just lying around randomly.)
- cameldrv 1y ago
  The strange part psychologically is that saying it lasts 10,000 years somehow seems worse and more unmanageable than say cadmium or arsenic which last forever.
  - deleted 1y ago
    [deleted]
  - natmaka 1y ago
    Other threats cannot compensate: defects and turpitudes of some (for example of certain waste of chemistry) do not form attenuating circumstance for others (nuclear waste). An accused defends himself badly by declaring to the judge "I am not the only culprit of homicide!".
- benlivengood 1y ago
  We can't even agree to keep under 2°C warming in 100 years, so I am also confused about why people are worried about waste that lasts 10K years. My guess is that they actually worry it will be leaked during their lifetime, whereas they know X° warming is beyond their lifetime.
whycome 1y ago
It’s a constant heat producer. Can’t we use it just for that? Store it somewhere and transfer the heat with traditional liquid cooling/heat exchanger methods? Store it up in the permafrost regions. Heat greenhouses.
- kevin_thibedeau 1y ago
  The Soviets did this with RTGs for remote on site power production. They're now abandoned and dangerous sources of nuclear material for those with evil intent.
  - meepmorp 1y ago
    Ok, but couldn't we just do the part where we somehow extract usable energy from nuclear waste without the subsequent abandonment?
    - crote 1y ago
      The Soviet Union wasn't exactly intending to fall apart, and yet it did. If you look at the current state of US politics, it should be pretty obvious that we can't even count on the richest and most advanced countries to remain stable for even a couple of decades: your "no abandoning nuclear sources" policy can be completely gone in the blink of an eye. When it comes to something as dangerous as nuclear material you should hope for the best but plan for the worst. Using latent heat might be a neat idea in a best-case scenario, but quickly turns into an absolute nightmare in a worst-case scenario.
- toomuchtodo 1y ago
  I had considered submitting a YC application for a startup that would do this, take waste radioactive material and turn it into uniform physical pellets or cubes for district heating via vitrification, but it seemed like between the capital costs and regulatory hurdles, it's just really, really hard to make commercial economics work. At least with electrical generation with nuclear, you can get some buy in from people willing to tie up billions of dollars for decades even with a high risk of failure, or get someone with deep pockets like big tech to sign a power purchase agreement for existing nuclear capacity. If the waste has to sit somewhere generating heat, might as well get some value from it. (global district heating TAM is only ~$200B, idea sprung from xkcd spent fuel pool what if: https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/)
credit_guy 1y ago
Many of the proposed new designs use higher enriched uranium, with up to 20% U-235. I expect that if they could work with 5% they would, but they can't. So from here I conclude that their waste might contain a much higher level of U-235 than the current PWRs, for example 3-5%. This would make it good for burning in a PWR, but of course, you need to first clean it up, and that requires processing.
- deleted 1y ago
  [deleted]
CGMthrowaway 1y ago
> Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive everywhere it has been implemented. All it takes to change that is a federal subsidy supporting the industry. The same was said about wind & solar until it wasn't (due to tax credits). Now that the credits are going away with BBB, the cost of every new utility-scale development just went up ~30% and many, many projects will be killed.
- toomuchtodo 1y ago
  Wind and solar are still competitive without the credits, and while it'd be great to keep the credits to get off of fossil fuels faster, they are no longer needed. https://pv-magazine-usa.com/2025/07/01/solar-cost-of-electricity-beats-lowest-cost-fossil-fuel-even-without-tax-credits/ https://pv-magazine-usa.com/2025/07/01/solar-cost-of-electri... > Lazard’s analysis of levelized cost of electricity across fuel types finds that new-build utility-scale solar, even without subsidy, is less costly than new build natural gas, and competes with already-operating gas plants. > Despite the blow that tax credit repeal would deal to renewable energy project values, analysis from Lazard finds that solar and wind energy projects have a lower levelized cost of electricity (LCOE) than nearly all fossil fuel projects – even without subsidy. (Lazard is the investment banking gold standard wrt clean energy cost modeling: https://www.lazard.com/research-insights/levelized-cost-of-energyplus-lcoeplus/ https://www.lazard.com/research-insights/levelized-cost-of-e...)
  - CGMthrowaway 1y ago
    As someone in solar I can tell you unless you are O&O/IPP it is not profitable to build without credits, no matter what an investment bank says
  - quickthrowman 1y ago
    Does Lazard make money from putting together financing and investment for solar and wind projects? If the answer is yes, that is precisely what I would expect them to say, given their incentives.
- 1y ago
numpad0 1y ago
> Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive Isn't this, though certainly not intentionally, just reiterating that lawful high tech labor fundamentally has no place in modern globalized economy? [Manufacturing iPhone] from [externally sourced parts] into [complete phones] has been economically unattractive everywhere, too.
natmaka 1y ago
> The US canceled a new MOX plant For nations devoid of uranium reserves and not absolutely sure to always be able to secure uranium supply (i.e. not a superpower) recycling is an interesting way. Case in point: France.
FilosofumRex 1y ago
Does anyone know of a good engineering level reference on Silex/GLE or general/commercial scale laser based separation. Most search results just show descriptive write ups.
- philipkglass 1y ago
  I think that the Wikipedia article is about as good as it gets, because the process details are classified: In June 2001, the U.S. Department of Energy classified "certain privately generated information concerning an innovative isotope separation process for enriching uranium". Under the Atomic Energy Act, all information not specifically declassified is classified as Restricted Data, whether it is privately or publicly held. This is in marked distinction to the national security classification executive order, which states that classification can only be assigned to information "owned by, produced by or for, or is under the control of the United States Government". This is the only known case of the Atomic Energy Act being used in such a manner. https://en.wikipedia.org/wiki/Separation_of_isotopes_by_laser_excitation https://en.wikipedia.org/wiki/Separation_of_isotopes_by_lase... The United States developed the somewhat related AVLIS process to industrial readiness for the Special Isotope Separation project to produce high-grade weapons plutonium from old reactor fuel. However, it was ready just in time for the end of the Cold War, so it got shut down in 1990. https://inis.iaea.org/records/r6yew-5nk17 https://inis.iaea.org/records/r6yew-5nk17 Construction and operation of a Special Isotope Separation (SIS) project using the Atomic Vapor Laser Isotope Separation (AVLIS) process technology at the Idaho National Engineering Laboratory (INEL) near Idaho Falls, Idaho are proposed. The SIS project would process fuel-grade plutonium administered by the Department of Energy (DOE) into weapon-grade plutonium using AVLIS and supporting chemical processes.

deepsun 1y ago

Also, nuclear waste is a very small problem, compared to other wastes. Yes, it stays active for 10k+ years, but it's actually not that expensive to store them at specialized storages forever. Because it's a very small amount on a grand scale. In comparison, managing steel production waste is way more expensive.

potato3732842 1y ago
10k years isn't that long. Some concentrated chemical stuff with heavy metals or mercury or whatever in it will be toxic forever.
- cycomanic 1y ago
  The nuclear waste even without the radiation is going to be toxic. Anything with even trace amount of plutonium left (which has a half life time > 200,000 years), will be toxic (much more than e.g. mercury).
  - mlyle 1y ago
    Eh, I don't think I agree. Let's talk about the long-lived isotopes: Pu-239 and Pu-242. Significant inhaled Pu-239 has a fair risk of causing cancer even after a long time. However mercury is volatile and it's a lot easier to end up inhaling fumes. And mercury is absorbed well through ingestion and Pu isn't, and most of the risk after ingestion would be chemical, not radiological. From that standpoint, it's looking a lot better than other heavy metals.
    - lazide 1y ago
      Huh? The reason we don’t have more solid non-radiological toxicity data on Plutonium (compared to other toxic heavy metals) is because any amount significant enough to count kills people radiologically super quick. That doesn’t mean it’s non-toxic if we ignore the radiological effects.
      - mlyle 1y ago
        We know: * Plutonium is not well absorbed by ingestion compared to other heavy metals and know ballpark ingestion toxicities * We also know that pretty much all the plutonium except the long-lived isotopes are gone on a timescale of tens of thousands of years-- leaving behind mostly uranium isotopes. * There's no real reason to believe this mixture of uranium and a small fraction of long-lived plutonium isotopes is significantly worse than ingesting uranium. It might be worse to inhale fine dust, though. * Mercury is way worse than uranium because it is so readily absorbed.
        lazide 1y ago
        Elemental mercury is not absorbed at all. You’re probably thinking of methyl mercury and various mercury salts (which, by the way, are not very common). We have nearly zero experience with weathered or bio modified plutonium. And the experience we do have with plutonium compounds, is limited by the fact people die awfully fast when they’re anywhere near them. Absence of evidence is not evidence of absence. Especially not when the evidence is absent because we can’t get there because everyone dies first from the more obvious bad things happening.
throw0101d 1y ago
> Yes, it stays active for 10k+ years, but it's actually not that expensive to store them at specialized storages forever. Because it's a very small amount on a grand scale. For some definition of "active". The first 6-10 years are quite dangerous, which is why stuff is in cooling pools. After about 200-300 years the most dangerous type of radiation (gamma) has mostly burned stopped, and you're left with alpha and beta, which can be stopped with tinfoil and even paper. I've heard the remark that after ~300 years the main way for nuclear waste to cause bad health effects is if you eat it or grind it up and snort it.
- deepsun 1y ago
  Sorry, but you're wrong. I took some radiation safety classes, and the main point I got from that is that "it depends". For example, alpha- and beta-radiation are often more dangerous than gamma, because gamma is easier to detect and measure. People often focus on "radiation" part forgetting the "contamination" part. You can literally walk into the Chernobyl reactor active zone today for up to 2 minutes. But you cannot produce any food in soils around it for thousand years. And there's dozens of dangerous isotopes, each one accumulating and affecting human tissues differently. Public generally only knows about Geiger counter. Yes, it will scream if everything is FUBAR, but it's useless for estimating safety of a food product.
  - throw0101d 1y ago
    So nuclear waste is stored in casks: * https://www.nwmo.ca/canadas-used-nuclear-fuel/how-is-it-stored-today https://www.nwmo.ca/canadas-used-nuclear-fuel/how-is-it-stor... * https://en.wikipedia.org/wiki/Nuclear_flask https://en.wikipedia.org/wiki/Nuclear_flask Are you telling me it's unsafe? Someone better tell Madison Hill: * https://www.newsweek.com/pregnant-woman-poses-nuclear-waste-prove-point-about-radiation-idaho-1809500 https://www.newsweek.com/pregnant-woman-poses-nuclear-waste-... * https://twitter.com/MadiHilly/status/1550148385931513856 https://twitter.com/MadiHilly/status/1550148385931513856 * https://twitter.com/MadiHilly/status/1671491294831493120 https://twitter.com/MadiHilly/status/1671491294831493120 Or Paris Ortiz-Wines: * https://twitter.com/ParisOrtizWines/status/1195184970613936129 https://twitter.com/ParisOrtizWines/status/11951849706139361... (The context here is not walking down some road and getting bombarded with particles: but about the storage of industrial material and the risks it involves. Yes, stuff gets shot out at >300 years: but it's not just lying around randomly.)
cameldrv 1y ago
The strange part psychologically is that saying it lasts 10,000 years somehow seems worse and more unmanageable than say cadmium or arsenic which last forever.
- deleted 1y ago
  [deleted]
- natmaka 1y ago
  Other threats cannot compensate: defects and turpitudes of some (for example of certain waste of chemistry) do not form attenuating circumstance for others (nuclear waste). An accused defends himself badly by declaring to the judge "I am not the only culprit of homicide!".
benlivengood 1y ago
We can't even agree to keep under 2°C warming in 100 years, so I am also confused about why people are worried about waste that lasts 10K years. My guess is that they actually worry it will be leaked during their lifetime, whereas they know X° warming is beyond their lifetime.

whycome 1y ago

It’s a constant heat producer. Can’t we use it just for that? Store it somewhere and transfer the heat with traditional liquid cooling/heat exchanger methods? Store it up in the permafrost regions. Heat greenhouses.

kevin_thibedeau 1y ago
The Soviets did this with RTGs for remote on site power production. They're now abandoned and dangerous sources of nuclear material for those with evil intent.
- meepmorp 1y ago
  Ok, but couldn't we just do the part where we somehow extract usable energy from nuclear waste without the subsequent abandonment?
  - crote 1y ago
    The Soviet Union wasn't exactly intending to fall apart, and yet it did. If you look at the current state of US politics, it should be pretty obvious that we can't even count on the richest and most advanced countries to remain stable for even a couple of decades: your "no abandoning nuclear sources" policy can be completely gone in the blink of an eye. When it comes to something as dangerous as nuclear material you should hope for the best but plan for the worst. Using latent heat might be a neat idea in a best-case scenario, but quickly turns into an absolute nightmare in a worst-case scenario.
toomuchtodo 1y ago
I had considered submitting a YC application for a startup that would do this, take waste radioactive material and turn it into uniform physical pellets or cubes for district heating via vitrification, but it seemed like between the capital costs and regulatory hurdles, it's just really, really hard to make commercial economics work. At least with electrical generation with nuclear, you can get some buy in from people willing to tie up billions of dollars for decades even with a high risk of failure, or get someone with deep pockets like big tech to sign a power purchase agreement for existing nuclear capacity. If the waste has to sit somewhere generating heat, might as well get some value from it. (global district heating TAM is only ~$200B, idea sprung from xkcd spent fuel pool what if: https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/)

credit_guy 1y ago

Many of the proposed new designs use higher enriched uranium, with up to 20% U-235. I expect that if they could work with 5% they would, but they can't. So from here I conclude that their waste might contain a much higher level of U-235 than the current PWRs, for example 3-5%. This would make it good for burning in a PWR, but of course, you need to first clean it up, and that requires processing.

deleted 1y ago
[deleted]

CGMthrowaway 1y ago

> Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive everywhere it has been implemented. All it takes to change that is a federal subsidy supporting the industry. The same was said about wind & solar until it wasn't (due to tax credits). Now that the credits are going away with BBB, the cost of every new utility-scale development just went up ~30% and many, many projects will be killed.

toomuchtodo 1y ago
Wind and solar are still competitive without the credits, and while it'd be great to keep the credits to get off of fossil fuels faster, they are no longer needed. https://pv-magazine-usa.com/2025/07/01/solar-cost-of-electricity-beats-lowest-cost-fossil-fuel-even-without-tax-credits/ https://pv-magazine-usa.com/2025/07/01/solar-cost-of-electri... > Lazard’s analysis of levelized cost of electricity across fuel types finds that new-build utility-scale solar, even without subsidy, is less costly than new build natural gas, and competes with already-operating gas plants. > Despite the blow that tax credit repeal would deal to renewable energy project values, analysis from Lazard finds that solar and wind energy projects have a lower levelized cost of electricity (LCOE) than nearly all fossil fuel projects – even without subsidy. (Lazard is the investment banking gold standard wrt clean energy cost modeling: https://www.lazard.com/research-insights/levelized-cost-of-energyplus-lcoeplus/ https://www.lazard.com/research-insights/levelized-cost-of-e...)
- CGMthrowaway 1y ago
  As someone in solar I can tell you unless you are O&O/IPP it is not profitable to build without credits, no matter what an investment bank says
- quickthrowman 1y ago
  Does Lazard make money from putting together financing and investment for solar and wind projects? If the answer is yes, that is precisely what I would expect them to say, given their incentives.
1y ago

numpad0 1y ago

> Recycling plutonium from spent power reactor fuel into mixed-oxide (MOX) nuclear fuel has been economically unattractive Isn't this, though certainly not intentionally, just reiterating that lawful high tech labor fundamentally has no place in modern globalized economy? [Manufacturing iPhone] from [externally sourced parts] into [complete phones] has been economically unattractive everywhere, too.

natmaka 1y ago

> The US canceled a new MOX plant For nations devoid of uranium reserves and not absolutely sure to always be able to secure uranium supply (i.e. not a superpower) recycling is an interesting way. Case in point: France.

FilosofumRex 1y ago

Does anyone know of a good engineering level reference on Silex/GLE or general/commercial scale laser based separation. Most search results just show descriptive write ups.

philipkglass 1y ago
I think that the Wikipedia article is about as good as it gets, because the process details are classified: In June 2001, the U.S. Department of Energy classified "certain privately generated information concerning an innovative isotope separation process for enriching uranium". Under the Atomic Energy Act, all information not specifically declassified is classified as Restricted Data, whether it is privately or publicly held. This is in marked distinction to the national security classification executive order, which states that classification can only be assigned to information "owned by, produced by or for, or is under the control of the United States Government". This is the only known case of the Atomic Energy Act being used in such a manner. https://en.wikipedia.org/wiki/Separation_of_isotopes_by_laser_excitation https://en.wikipedia.org/wiki/Separation_of_isotopes_by_lase... The United States developed the somewhat related AVLIS process to industrial readiness for the Special Isotope Separation project to produce high-grade weapons plutonium from old reactor fuel. However, it was ready just in time for the end of the Cold War, so it got shut down in 1990. https://inis.iaea.org/records/r6yew-5nk17 https://inis.iaea.org/records/r6yew-5nk17 Construction and operation of a Special Isotope Separation (SIS) project using the Atomic Vapor Laser Isotope Separation (AVLIS) process technology at the Idaho National Engineering Laboratory (INEL) near Idaho Falls, Idaho are proposed. The SIS project would process fuel-grade plutonium administered by the Department of Energy (DOE) into weapon-grade plutonium using AVLIS and supporting chemical processes.