What is Called Nuclear Waste is Mostly Unused Fuel for Molten Salt and Fast Reactors

Nextbigfuture has had many articles that try to educate people that what we call nuclear waste is unused fuel for different nuclear reactors. The waste is fuel that is mostly even numbered isotopes.

Unused fuel (aka nuclear waste) can be used as fuel in fast reactors like old fast reactors and molten salt nuclear reactors. Molten salt reactors are being developed in China and many by US companies.

96% of the mass of “nuclear waste” is the remaining uranium: most of the original 238U and a little 235U. Usually 235U would be less than 0.83% of the mass along with 0.4% 236U.

Uranium 238 can be fissioned in any nuclear reactor that generates fast neutrons.

About 20 fast neutron reactors (FNR) have already been operating, some since the 1950s, and some supplying electricity commercially. Over 400 reactor-years of operating experience has been accumulated. Fast reactors more deliberately use the uranium-238 as well as the fissile U-235 isotope used in most reactors. If they are designed to produce more plutonium than the uranium and plutonium they consume, they are called fast breeder reactors (FBRs). But many designs are net consumers of fissile material including plutonium.* Fast neutron reactors also can burn long-lived actinides which are recovered from used fuel out of ordinary reactors.

Uranium 235 is naturally fissile. Easily fissioned with low energy neutrons.

Uranium-235 fissions with low-energy thermal neutrons because the binding energy resulting from the absorption of a neutron is greater than the critical energy required for fission; therefore uranium-235 is a fissile material. Uranium-238 is a fissionable material but not a fissile material.

A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (100 TJ/kg), hence a speed of 14,000 km/s, or higher. They are named fast neutrons to distinguish them from lower-energy thermal neutrons, and high-energy neutrons produced in cosmic showers or accelerators.

64 thoughts on “What is Called Nuclear Waste is Mostly Unused Fuel for Molten Salt and Fast Reactors”

  1. For folks like scary it’s the inability to see the other unknowns such as why was there a Bronze age collapse
    Lemon trees in Joorsey might mean the
    wheat and corn and rice has collapsed
    And the sea people’s come and pick our
    It’s not just temps its plant and animal disease

  2. I proposed to the Nuclear blue ribben commisssion that the $30 billion spent fuel fund go to a fleet of molten salt and heavy water reactors run by the TVA
    Same sort of idea as yours

  3. Praise be to our kind, fair judicial masters. May their judgement be ever considered wise and impartial.

  4. Ok. but as I understand, Fast Neutron Reactors are too expensive to build and operate and will not ever be competitive unless uranium prices have a huge increase.

  5. The gods destroy people for excess hubris. Building reactors with sodium as coolant is excess hubris. Thorium MSR can breed fuel using thermal neutrons. No need for sodium.

  6. So, I’m not sure what you’re proposing, but the bit about CANDU fuel piqued my interest. So let’s see if I got this right: you’re saying that the optimal enrichment quantity in a CANDU fuel rod is (quite roughly, I suppose) 2 percent. And that, at the end, the fuel rod would be mostly depleted? Have I got that right?
    If I did then: does this rough estimation take into account plutonium-239 burnup?It’s fissile, and I know CANDUs produce quite a bit of that from U-238….
    Second question: I was under the impression that what stops normal fuel rods from burning longer is a combination of neutron poisons forming as fission products, and mechanical stress due to cracking. That would mean that the higher concentration of fuel compared to natural uranium would be offset by a higher rate of neutron poisons forming.
    Also, the point of a CANDU, if I recall, was to avoid enrichment. But that’s not a technical issue, though…

  7. I’m annoyed ‘cos I’m all into Gen IV fission…bu delivering the message in such an arrogant tone is exactly the way you get people to ignore or demonise you.
    If you wanna convince people, start by being nice to them. Yes, it’s annoying, especially when they be raving morons, but there’s seven billion of ’em and only a few of us… can’t afford to come out sounding arrogant or even boastful.

  8. In the Eocene, CO2 was 1000 ppm and sea level was 70 metres higher. Mean altitude of New Jersey is 75 metres. You’d get time to enjoy your lemons though, if the heat waves didn’t kill the tree.
    By the way, the climate scientists can’t get their climate models to show how the polar regions could be warm enough for palm trees and crocodiles, but the tropics weren’t outrageously hot. One theory is that massive ‘hypercanes’ could transport the heat polewards, but none of the theories seem to match the physical requirements of the models. https://www.dailykos.com/stories/2010/9/4/895900/-

  9. Sure I do. Moltex put their plutonium/sodium chloride in fuel rods ( steel, with sacrificial zirconium to keep it from corroding ) and run barren fluoride salts round that as the primary circuit. The fluoride salts have to be buffered to keep at least 1% of the zirconium as ZrF2, rather than ZrF4, which reduces chromium leaching from the steel to practically zero. The zirconium also acts as a getter for any oxygen in the system.

  10. According to the renewable accounting rules, big hydro isn’t renewable, but small hydro ( or maybe ‘run of the river hydro’) is.

  11. I hate bubbles. I’ve had literally months spent trying to get rid of tiny bubbles.
    Stupid little round floaty things.

  12. You just agreed with me…although you don’t know the difference between fluoride and chloride salts. Only fluoride salts are viable in the primary loop for a molten salt reactor.

  13. Your references for stainless steel corrosion are for higher temperatures, which, though desirable, are not necessary. The Moltex, Thorcon and Terrestrial designs all propose temperatures of around 550 C, and changing out the rods containing the fuel (Moltex), or the whole primary circuit ( the Ts ) every few years. ‘347SS and 321SS had very little oxidation for 400 and 500 °C, indicative of a protective corrosion scale and low corrosion kinetics.’ ‘Current commercial CSP plants use molten nitrate salt mixtures as the heat transfer fluid and the thermal energy storage (TES) media while operating with multiple hours of energy capacity and at temperatures lower than 565 °C.’ Also, the tests you cite were sparging with oxygen, which is excluded in all the MSRs.
    From Thorcon’s executive summary -‘But after the MSRE, ORNL did a series of experiments with stainless steel and fluorides salts. Some of these tests ran for 45,000 hours (5 plus years). The tests showed that, provided the salt was free of impurities and maintained in a reducing condition, the effective SUS316 corrosion rate was about 0.025 mm/year. In other words, an extra 1 mm thickess is worth about 40 years.’

  14. Hands up who would prefer if the program was building giant rockets to send waste into the sun?

    At least we’d get a giant rocket development program out of it.

  15. It’s always annoying when people assume you’ve seen some new TV show, movie or pop singer and use it as a metaphor or something so that you don’t know what they’re talking about without going off and wasting hours to catch up on the latest pop culture.
    Even worse when they don’t identify what pop culture they are referencing, assuming that everyone knows who they mean when they say “Marty McFly” or whoever.

  16. It’s important to remember that the cost of building and running a 1970 Chevelle SS was actually much, much lower than the cost of building and running a Prius. At least if you were trying to do it in 1970.

  17. The reason you wanna burn the wastes is to not give them something to point at when they ask about the wastes. They COULD be better at handling them, but why? It serves well enough for everyone in power. So… a burner would FORCE them to stop seeing it as wastes, while showing that the nuclear industry isn’t the model T of the energy business.
    People tend not to be as callous as yourself about these things. Don’t turn into a c**t, like that moustache dude in Chernobyl (yeah, you know who I’m talking about; the one who just could give no sh**s, as if there was no one around but him; textbook psychology that one)

  18. “couldn’t care less if they have to dike New York or if the Indonesians need to move up hill”
    Well, you could at least TRY to give a s**t about your fellow man… it’s not like he’s out to get you.
    He might be, though, when he moves in to your backyard due to changing climate 😛

  19. Don’t know where you got that composition but I think there is some plutonium in there, which is necessary for the startup of fast reactor … I believe.

  20. Absolutely correct. Now if a judge had ruled that a MOX plant be built then by god it would have been made to happen.

  21. Overkill. It is a bunch of underground tanks. They don’t even know that any of the tanks are leaking. And they could just pour stuff in the tanks to solidify it…like paint is disposed of.
    The only way their disposal method could squander more money is to build rockets and launch them into the sun.

    I think it is another pay through the nose for your presumed sins thing. They don’t want it to be cheap. A sort of deterrence to doing it again.

  22. Didn’t the FED spend more than six billion dollars on the MOX plant that was cancelled before it ever made a fuel rod? that money would be pissed away

  23. O.K, let’s take bring all to our highly developed infrastructure of Molten Salt and Fast Reactors.

  24. The elyssium guy, ed phiel, spends his day trolling LinkedIn nuke stories with me. He seems to have a lot of free time, and an axe to grind, just like me.

  25. That’s not at all true. It has already been proven….that they don’t last long enough.

    316SS can’t even handle molten nitrate salts (with zero neutron flux) which are vastly more benign.

    And testing of molten chloride salts with stainless steel did not go well at all. 1/4+ inch a year is way too fast.


    316SS isn’t even recommended to be in seawater for years.

  26. MSRs are a bit of a case of “if we had some ham we could have some ham and eggs, if we had some eggs”.

    Build it and then we can talk about getting rid of the nuclear waste.

  27. 316SS works just fine for molten chloride salts. It still needs to be proven how long they can hold up at various flux levels and duration while containing those salts, but that’s what demonstration plants are for.

  28. There doesn’t exist a single metallurgical alloy known to stand up to molten chlorides for more than a handful of years (call it 5).

    So there’s got to be some advances in metallurgical technology before a molten chloride reactor will even be feasible.

    So it is a “perfect” paper reactor. I’ve seen a lot of those.

    Considering there has been little advances on that front from the 2011 paper below, we should have that metallurgical technology around about “never”.

    “However, the corrosion processes for chlorine are more complex than those for fluorine. Consequently the knowledge base for structural materials tolerant of chloride-based salts is not as mature as that for fluoride-based salts. A confident structural material selection cannot yet be performed for a chloride salt-based FS-MSR.”

    You want to know the advance they made? “A confident structural material selection cannot yet be performed for a chloride salt-based FS-MSR.” is now “There is no material that can yet work for a chloride salt-based FS-MSR.”


  29. There is real nuclear waste.

    $242 billion to clean up mostly the Hanford site is actually nuclear waste. It’s waste from stupidity (EDIT: and ignorance) in the 50s from the nuclear weapons program, though, and not commercial nuclear’s fault whatsoever.

    As for pretending spent nuclear fuel has value, I don’t see anybody buying it up. That is the very definition of garbage aka waste.


  30. “Our nuclear fuel cycle is like a 1970 Chevelle SS 454 instead of like a Prius. Why? Because it’s easy, and we’re ‘Mericans.”

    Don’t forget to mention that we shouldn’t kid ourselves and acknowledge that the odds on making a fuel reprocessing plant in the USA are zero. In terms of regulations, lawsuits, protests, congressional (in)action… it won’t happen.

    I’ve wondered if we could just contract with a country like France. Ship them our waste, pay them $$$ and get fuel back.

  31. to get the most megawatts out of the installation rather than to use the fuel economically. If there were pressure to use fuel economically without all the hassle of reprocessing (hassle often greatly underplayed by proponents), then this would be the way to do it. Lower heat rate. Less water in the reactor. Higher conversion ratio (closer to breeding while still burning). It’s been done before. It is just more economical to run them at as high of heat rate as the system will allow and throw away the fuel and throw away the tails. Our nuclear fuel cycle is like a 1970 Chevelle SS 454 instead of like a Prius. Why? Because it’s easy, and we’re ‘Mericans.

  32. continued…

    According to many experts reprocessing used fuel and “closing the fuel cycle” is crucial to maintaining long term fuel supply and banishing the specter of transuranic waste into nonexistence. Knowing the technical aspects of the fuel cycle from mine to reactor to cask, I am bored by the emphasis placed on eliminating transuranic waste. It makes no difference to me. Looking at the table above, it is pretty clear to me that by evolving our reactors to work with 2 w/o enrichment we triple the mileage of the existing supply. Note that the RBMK was designed to use ~2 w/o feed, not to save uranium, but because enrichment was expensive at the time. 

    There is a mechanical lifetime to a fuel rod. If using UO2 in zirconium alloy cladding, that lifetime is 1460 days at 20 kW/m. The CANDU fuel approaches less than 30% of this limit before discharge and LWR fuel approaches about 80% of this limit. Using 2 w/o enrichment in the CANDU seems likely to match the mechanical lifetime to fuel depletion so that the fuel is 1) enriched to the minimum 2) burned to the maximum allowed by material properties. That is the very definition of fuel economy. This minimizes waste, enrichment, tails, does not require advanced technology, etc., etc.. I’m not saying that we should use CANDU everywhere. What I am saying is that our core designs should get closer to the Shippingport experiment. In reality, the fuel is cheap and the cost of operations is high, so it is important


  33. Uranium naturally has 0.7 w/o 235U; depleted uranium ‘tails’ typically has 0.25 w/o 235U. According to Wiki, a separative work unit (SWU) = 55 kW-h (centrifuge), and the wholesale cost of power is about $40/MW-h. Neglecting some very significant fabrication/processing costs, we have:

    w/o Tails(tons) SWU(MW-h) Elec_cost
    1% 0.7 18 $734
    2% 2.9 107 $4295
    5% 9.6 441 $17651
    10% 20.7 1048 $41930
    15% 31.8 1674 $66977
    20% 42.9 2309 $92379

    Seems market price for SWU is almost an order of magnitude higher than cost of power per Google… anyway check me, so, we throw away 9.6 tons of ‘tails’ making 1 ton of standard 5 w/o 235U fuel. Since it currently costs > $12,000 per ton U to convert U3O8 to UF6, the tails remain in UF6 form and are stored in large kegs. There are megatons of UF6 sitting in kegs.

    Any ‘burner’ reactor needing more than 5% enrichment is a step backwards in the big picture of uranium utilization (Kairos, eVinci). Next time you read “20% enriched”, remember “43 tons of tails”. Note that the paper reactor only needs this enrichment because it geometrically too small (eVinci) and/or too dilute (whatever MSR), or the core structure is built of parasitic materials like steel (eVinci). LightBridge fits in here somewhere; it needs 10 ± 2 w/o 235U, but is not made out of paper.


  34. I find the world Climatescammer they who are against every thing but cant give an argue.

    How many are Climatescemmer?

    We are in an 2.6 million year long ice age ande the interglacial before had 2,5 C warmer climate, so how can the power elit fool so many?

  35. I´m sorry What is your argument in technology and economy?

    If you cant giv me argument I guess you are a climate scammer that are against all that not give power to UN.

  36. It was cancelled by an anti-nuclear administration, when it was a year or two away from completion after thirty years of development.

    In any case, it doesn’t have anything to do with MSRs, being a totally different technology.

  37. That section is about reprocessing LWR fuel, so I don’t see that it has much to do with MSR viability, either fast or thermal. We don’t *have* to use LWR waste to fuel them.

  38. They have power that is produced at different rates. They get a lot more profit, if they can buy it cheap and sell it high. They may only have a few sources they can get real cheap. If they have to buy more, they have to pay more per GWh…sometimes much more. They may have to get some old stinker power plant warmed up that has been sitting collecting dust…and that can take days and is very expensive to get back up and running. What they charge is highly regulated, so they can’t just charge a $1/kWh and gouge you good. Getting you to use less means they can just buy cheap stuff and gouge you without you really noticing.
    And lately in some of the States in the US, they are required to buy a certain % of renewable. But they don’t have to build as much of it, if they can get people to use less power, as the relative % of renewable would go up if overall consumption was lower. A dam only makes so much power…and they prefer that. It is usually much cheaper than solar or wind.

  39. Scary, you may have commented on this before, but what are your thoughts on the General Atomics EM2 design?

  40. Generally I agree but between Now and our future of Elysium reactors there is much testing and much more certification.

    To fast track this we should set up a reactor on the far side of the moon. I’m not really kidding.

  41. Molten Chloride Fast Reactors (FS-MSR as you call it) are a “perfect” long-term design choice. I’d argue they’re better than LFTR, if only for the more mundane materials. But we still have a lot of first-of-a-kind experimental confirmation required around delayed neutrons, pumps, heat exchangers, reactor control and observation systems.

  42. Fast Breeder Reactors are totally unnecessary for now. The focus on breeding ratios in the past was both for weapons production and low estimates of our fissionable resources. The budget overruns were inconsequential, the IFR was cancelled b/c it was conflated with nuclear proliferation. We could quite easily build a sodium fast reactor with a negative breeding ratio and consume waste today, just like EBR-II. It’s one of the only non-LWR designs that’s operated commercially in the US already.

  43. Because it is easier to push their customers in to artificial scarcity than it is to build new power production.

    (Coming from a guy who replaced every bulb in my house with LEDs when they cost $15 each because they finally got the light hue right)

  44. Electric utilities are the only companies that advise customers to use less of their product. The company that sells the electricity advises the end users to install energy efficient devices in their homes… Electric utilities literally do community outreach encouraging energy conservation. Doesn’t fit the typical business model, to say the least.

  45. Because our hydraulic despots don’t want the hoi polloi getting uppity thanks to full energy security, and even less that they start believing they don’t need their betters’ wise rule on every facet of their lives.

  46. I have a fever-dream that one day a judge will rule that the Federal government must spend the money collected to deal with nuclear waste on a Gen IV reactor that burns nuclear waste. Obviously the judge will pick the appropriate fuel chemistry and appropriately sub contract development of a reprocessing plant.

    Because judges are very wise and kind magistrates.

  47. it is a bit of a stretch for me to deduce their inner motivations but being charitable I will propose that that they are in love with solar and wind power because it is ideologically good (in contrast to methane which is kind of evil and nuclear which is icky).

  48. I suppose because their actions are always to tell people that they need to use less energy and to make energy more expensive so that people will use less energy.

    I mean that is what politicians seem to do all the time.

  49. We had made an attempt at a fast breeder reactor in the USA. We totally failed. It overran its budget and in the end it was cancelled. Fast breeders and MSR won’t happen here for now. Maybe two decades from now if the political climate changes or nuclear power economy becomes much cheaper.

  50. Skip to section 3.4 of that ORNL pub, read it, then put the technology back on the shelf with that report because it is a pipe dream.

    I just looked up the etymology of ‘pipe dream’ and it is a late 1800s way of saying that you are smoking drvgs.

  51. Yes Brian You Can!

    The problem is that no politicians want cheap energy (maybe Donald Trump)?

    FS-MSR can be built much cheaper and simpler than the model ORnl gave the Blue ribbon commission.

    No ful rods closed Brayton and super critical CO2 for produktion of electricity and maybe heat pumps of wolfram to produce cheap hydrogen when the local electricity demand is fulfilled?


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