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Power

New Nuclear Fuel Rods Endure 3,452F For 120-Day Test, Raising Hopes for Safer Reactors (interestingengineering.com) 79

Posted by EditorDavid from the going-nuclear dept.
Nuclear rods are traditionally clad in metal. But a U.S. energy company wants to develop a better, safer alternative that instead uses silicon carbide composites. Working with America's Energy Department, General Atomics Electromagnetic Systems just completed a 120-day irradiation testing period simulating the intense radiation and extreme temperatures (3,452F) of a pressurized water reactor in a real-world nuclear power plant.

And the tests "showed no significant mass change, indicating promising performance," the company said in a statement. "This indicates that the SiGA cladding is exceptionally resistant to the damaging effects of radiation." Long-time Slashdot reader fahrbot-bot shared this report from the Interesting Engineering blog: "This success is a key milestone on SiGA cladding's development path to enhance the safety of the existing U.S. fleet of light water reactors," added Scott Forney, president of GA-EMS. "It could also do the same for the future generation of advanced nuclear power systems." This advanced material offers significant advantages over traditional metal cladding. It can withstand temperatures up to 1900 degreesC (3452 degreesF), far exceeding the limits of current materials. This enhanced heat resistance is crucial for improving safety margins in nuclear reactors. Moreover, the company claims that in case of any accident, SiGA cladding is designed to maintain its integrity at temperatures where traditional cladding might fail. This could prevent the release of radioactive materials and significantly improve overall reactor safety.

Furthermore, SiGA cladding offers performance benefits. It enables higher power operation and longer fuel lifetimes. This translates to increased efficiency and reduced costs for nuclear power plants...

The design, safety, and installation of new nuclear reactors have been a prime subject for research. Recently, France-based Newcleo applied to the United Kingdom's Department of Energy Security and Net Zero (DESNZ) to enter its lead-cooled small modular reactor for generating fission energy in the generic design assessment phase. Newcleo's SMR can operate at atmospheric pressure, and the company also states that no significant energy release occurs in cases of vessel failure. This also eliminates the need for high-pressure-resistant containment.
The article notes that General Atomics's collaboration with the U.S. Energy Department is "part of the Accident Tolerant Fuel Program, a national effort to improve the safety and performance of nuclear reactors."

New Nuclear Fuel Rods Endure 3,452F For 120-Day Test, Raising Hopes for Safer Reactors More | Reply

New Nuclear Fuel Rods Endure 3,452F For 120-Day Test, Raising Hopes for Safer Reactors

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  • But what about the rest of the containment vessel?

    • But what about the rest of the containment vessel?

      Different layer in layered safety model. Same solution may or may not apply.

    • Re:Rods survived 1900C (Score:5, Informative)

      by wakeboarder ( 2695839 ) on Friday December 06, 2024 @05:58PM (#64996825)

      You could have the reactor go near critical and the fuel would sit there in the rods and not melt together. Its when the fuel melts to the bottom of the rector that you have a real problem, lots of neutrons, lots of reactions and lots and lots of heat. If the fuel stays in the rod there is a better chance to shut the reactor down if you don't have coolant, thus reducing the requirements for backup safety features.

      • Re: (Score:3)

        by e3m4n ( 947977 )

        Uhh near critical? Sit down before you hurt yourself. We always operate at criticality. It literally means the number of thermal neutrons born from fission go on to be absorbed and create fission. This is steady state. critical means power loss and you need to adjust rod height so your moderator can regulate reactor power. Promt-critical would be bad because the fast-born neutrons would also create fission. A meltdown often occurs due to pressure allowing a steam bubble which keeps the moderator from remov

        • Re: (Score:1)

          by mysidia ( 191772 )

          Uhh near critical? Sit down before you hurt yourself. We always operate at criticality.

          The word critical means: extremely dangerous or serious. Having the temperature status of a system go "near critical" means the thing's on the verge of a catastrophic failure. This is different from the maths concept of a critical point, and the physics of reaching criticality within the context of a nuclear chain reaction.

          Nuclear reactors typically by design must reach criticality to function properly, or what w

          • Re: (Score:3)

            by quenda ( 644621 )

            The word critical means: extremely dangerous or serious.

            In the context of a nuclear reactor, it absofuckinglutely does not. You have not the slightest clue what you are talking about, so please read what GP said and learn.
            Bloody Dunning Kruger!

            • Re: (Score:2)

              by mysidia ( 191772 )

              In the context of a nuclear reactor, it absofuckinglutely does not.

              Oh it absolutely fucking does. Learn to admit when you are wrong.

              That is all, thank you.

      • Re: (Score:2)

        by taustin ( 171655 )

        It's also a lot easier to pull the rods out to a distance the stops the chain reaction if they're still in solid form, and not dripping into a puddle.

        • It's also a lot easier to pull the rods out to a distance the stops the chain reaction if they're still in solid form, and not dripping into a puddle.

          Fuel rods are stationary, control rods get pulled to control the reaction.

      • What happens when rods at these temperatures get hit with cold water if, heaven forbid, there is an accident?

    • Re: (Score:2)

      by e3m4n ( 947977 )

      Peak Centerline Temp is not normally anywhere near that high. And moderator temp is just 480F at 2000psi.

      • One thought I had is that while they're posing it as a "safer" rod for current reactors, it was probably developed for use in GenIII reactors that use non-water moderators.

        Current reactors are stuck at only around 30% efficiency because of carnot limitations - they just aren't hot enough. If we are able to dial up the temperature enough, we could hit 50%, which has all sorts of benefits. For example, cutting cooling needs in half.

        Currently: 3GWt reactor creates 1GWe, needing 2GW of cooling.
        High temperatur

        • Re: (Score:2)

          by MrKaos ( 858439 )

          One thought I had is that while they're posing it as a "safer" rod for current reactors, it was probably developed for use in GenIII reactors that use non-water moderators.

          Current reactors are stuck at only around 30% efficiency because of carnot limitations - they just aren't hot enough.

          Complementary to this development I recall some years ago experiments with nano-particles to increase the cooling capacity [springer.com] of the primary cooling loop of nuclear reactor [tandfonline.com]. To be brief/specific the nano-fluids increase the heat conductivity and carrying capacity of the water used for the primary cooling loop of reactors allowing them to run hotter or safer, depending on the desired outcome for the plant, for example enhanced fuel rods.

          These kinds of "material retrofits" to nuclear power plants are quite

    • Another thing I haven't seen mentioned: Heat doesn't have to be even in a reactor. The reactor vessel could be cooler than the rods themselves, as the rods are where the reaction is happening, and if you get enough heat for the cooling water to flash to steam despite the pressure, temperature can spike much, much higher without the cooling.

      Keeping the rods intact gives a better chance to get the reaction rate under control, get the control and shutdown rods in, emergency boron dump, and such and have it w

    • But what about the rest of the containment vessel?

      The temperature declines as roughly the square of the distance from the heat source.

      The outside of an electric oven is much cooler than the heating element.

      Many reactor components are made of zirconium since it has a very small neutron cross-section and melts at 1,855C/3,371F.

    • Re: (Score:3)

      by gweihir ( 88907 )

      It does not matter anyways. A runaway core has no reason to stop heating up at 1900C. It will simply go a bit higher and still melt. May even do more damage there, as the melting is usually what stops the heating up. Melting later means there is more thermal energy in the core when it melts, so ...

  • Well that's kind of nice. (Score:4, Insightful)

    by MachineShedFred ( 621896 ) on Friday December 06, 2024 @06:59PM (#64996945) Journal

    It would definitely be a step in the right direction, safety wise, if we had fuel rod cladding that could continue to contain the fuel even in a runaway no-coolant situation. Fuel melt would be contained within the rod, and only if the rods were physically ruptured or damaged in some way would you end up with a "corium" elephant's foot [wikipedia.org] somewhere in your facility that is still radioactive enough to deliver a lethal radiation dose in a matter of minutes 40 years later.

    Seems like a very good development, especially if they are useable in current reactor fleets. Hopefully they don't make nuclear power even more expensive than it currently is.

    • I mean, it will help a little, but chemical bond energies (and therefore the maximum temperatures any material can endure without melting, and therefore how much heat energy it can absorb) have no chance, none, zero, of competing with the amount of heat being released by latent radioactive decay in a just-shutdown reactor.

      Radioactive decay heat output in a just-SCRAMmed reactor is nearly 7% of full power. Without some form of coolant circulation to take that heat out, the fuel will have no difficulty get

    • Re: (Score:2)

      by tragedy ( 27079 )

      If the material can withstand the temperature of runaway fuel, then shouldn't the floor of the reactor vessel be made out of it too? Shaped into a surface something like a pancake griddle so that the fuel pools into lots of little pools far enough from each other that it doesn't form into one big critical blob, just in case it still manages to leak somehow? Obviously that would be pretty hard to retrofit in an existing reactor and I guess these specially clad rods can be used in those, but maybe in new reac

    • Fuel rods are typically encased in Inconel, a proprietary stainless steel alloy.

  • Awesome, but (Score:5, Insightful)

    by hdyoung ( 5182939 ) on Friday December 06, 2024 @07:48PM (#64997077)
    The first priority is to address the waste issue. Storing the waste for “all the centuries” at hundreds of above-ground sites across the country is jawwwwww-droppingly stupid. I consider myself pro-nuclear, but we shouldn’t even be considering new nuclear reactors until we work up the will to address the waste. It’s not a tech issue - it’ s a matter of will.

    And the LAST people we want dealing with nuclear tech is the silicon valley crowd. I don’t want to hear about Zuckerberg’s plans for modular nuclear reactors. Absolutely the wrong guy for dealing with that. Those SV bros are amazing when the product cycle lasts 9 months, the worst physical consequence for a major f&*k-up is “oh no, airlines have to cancel some flights for a day or two”, the problem is fixed by slamming out a software patch, and zero liability or responsibility is taken.

    A big nuclear mistake is basically forever. A patch of the planet becomes a no-go zone for ten thousand years, and an entire continent sees an uptick in cancer rates. CS, business and marketing bros are really, really good at what they do, but nuclear needs to be led by the hard physical scientists and engineers. And, while I’m ranting, why the f&ck are we considering nuclear for AI? It’s turning out to be the MOST expensive power, not the cheapest. Solar farms are dirt, dirt oh-so-dirt cheap nowadays and getting cheaper by the moment, and it’s not like AI needs to run 24-7 or anything. Solar-fed AI seems like an obvious slamdunk to me.

    • Itâ(TM)s not a tech issue - itâ(TM) s a matter of will.

      Doing nuclear right is incompatible with capitalism as we practice it almost anywhere. As you say, we essentially have the technology (we can do vitrification for example, but it's very expensive) but we refuse to use it. And ironically, even though you have nuclear power, the cost of energy remains a large part of why it's not feasible.

      while Iâ(TM)m ranting, why the f&ck are we considering nuclear for AI? Itâ(TM)s turning out to be the MOST expensive power, not the cheapest. Solar farms are dirt, dirt oh-so-dirt cheap nowadays and getting cheaper by the moment, and itâ(TM)s not like AI needs to run 24-7 or anything. Solar-fed AI seems like an obvious slamdunk to me.

      We should put the AI in space, where it can get solar power much more efficiently. The more latency the application can tolerate, the higher the satellites you use should be

      • Solar+AI-in-space is clearly possible but still in the sci-fi regime. On the other hand, nowadays it’s dirt cheap to throw up a bunch of solar panels on junk land (of which there is a lot). The hardest part is probably getting the local government to approve the cable that runs to the AI center. The rest is standard construction work.

        • Solar+AI-in-space is clearly possible but still in the sci-fi regime.

          I think the only big problem besides launch cost is upgrades. You wouldn't want to do it yet. The hardware is still developing pretty quickly.

          On the other hand, nowadays itâ(TM)s dirt cheap to throw up a bunch of solar panels on junk land (of which there is a lot). The hardest part is probably getting the local government to approve the cable that runs to the AI center. The rest is standard construction work.

          It seems like they ought to do more and smaller installations to increase the odds of having units near the user which are currently insolated. That's a lot of permitting.

    • Re: (Score:2)

      by Creepy ( 93888 )

      The real problem is fast fission, which the US was developing in 1994, and was killed off by Democrats because of issues such as nuclear waste. Of course, fast fission breeds up nuclear waste to plutonium and burns it as fuel, so... yeah, politicians are stupid and do no research or listen to scientists, but hey, the people elected anti-science president Donald Trump, so you guys are all in the right, heil Trumpler.

      *grumble* idiots in politics.

  • Someone tell my why we can't heat up garbage to 3000 degrees in a large silicon carbide container and let the elements settle out over a week or so, reclaiming pure elements for sale? Before you say "pressure", the gasses can be collected and separated in similar ways.
  • Nuclear is far safer than burning coal, natural gas or other fossil fuels. Making it safer still won't change the minds of Green Peace and their like. They will still fight and make it impossible to build plants in an economical way. Green Peace saved the coal industry in the 70s they will do everything in their power to keep it alive now.

    And nuclear waste is not a problem. As long as you aren't stupid about it you can bury it almost anywhere and it won't contaminate the environment excessively. W

    • It was not. The problem is the water is used as a moderator and if it boils too much the radioactivty goes wild which leads to run away reactions.

      Sodium based reactors do not have this problem and is a more efficient (as the water in a legacy reactor never touches the generators and instead goes to a radiator with a 2nd body of water which touch the generator) and when it overheats cools itself as cenvtion currents takes away the radioactivity.

      Bill Gates is investing in some of these. You do not have to wor

  • Sodium based reactors (Score:3)

    by Billly Gates ( 198444 ) on Friday December 06, 2024 @11:10PM (#64997351) Journal

    Bioling water is so 19th century based on steam from burning coal. Liquid sodium on the other hand actually cools itself when it overheats due to the change in convenction currents inside the reactor. It is also more efficient in transfering heat as the radioactive water in a legacy system never touches the generator. It only goes through a radiator with another tank of water which actually touches the generators.

  • Silicon Carbide 'Pebble' beds were tried. Ask someone and they say no metallic leakage. Ask another, and they will say leakage, those sneaky radiation particles - seemingly Houdini like did the impossible passed through the carbide and escaped into the water. That seems fixable with a heat exchanger - but the French nuclear plants found cracked in welded pipework. Uranium loves to fool engineers/scientists. One recalls a DOE sodium reactor were something leaked out, making the liquid sticky enough to glue

    • Re: (Score:2)

      by Tailhook ( 98486 )

      Silicon Carbide 'Pebble' beds were tried.

      It is being used now. The new Shidaowan HTR-PM pebble bed reactor in commercial operation today uses silicon carbine cladding.

      • Depending on the thickness, the radiation leakage may be acceptable. However this does not explain something that should be impossible at the atomic level, even in perfect pebbles without microcracks or gross impurities. A source also said if you toss radioactive waste in say a 2km deep pit, bits will migrate to each other and perhaps become critical some day. But is some water or underground stream wet the pit bottom, bad indeed.

  • So? (Score:2)

    by gweihir ( 88907 )

    An insufficiently cooled core will go higher than that and still melt. This does not make reactors "safer". It might make them slightly less horrendous expensive to run.

  • I'm happy China has started up the first commercial Thorium reactor in the world. Though small, it is a good proof of concept that can be expanded on if ultimately successful. It's default behaviour will shut itself down on almost any catastrophic failure. And the waste is not as reactive and the half lives are much less. I'd rather do away with Uranium and Plutonium reactors altogether. If that happens, I suppose this could be good for a transition phase.
    • A thorium reactor is still a uranium reactor. Thorium has no fissile isotopes, it is there to breed a fissile uranium isotope that will go on to fission and produce most of the reactor power.
      • You're right, thorium reactors have exactly the same design and safety issues as a uranium fueled reactor. Oh wait, they don't. They have completely different designs and way less safety issues (relative to uranium reactors almost none). You are an obtuse asshat only intent on misconstruing a comment in order that you can feel that you look superior in some way. You don't. You still look like an asshat.
        • "Asshat" ðY£ when you say "thorium reactors" I guess you are referring to molten salt reactor designs where the thorium (and yes, also definitely uranium) is dissolved in the liquid molten salt. For sure there are some safety advantages w that. But as always, there are some very serious tradeoffs as well. This is why none have been built for more than 50 years and very few have ever been built. Now china has built one so it will be interesting to see what is the operating experience once that com
  • Ceramics like SiC can withstand higher temperatures than metals without melting, but they are brittle, and thus can be harder to work with and might be more subject to cracking. So when switching to a ceramic cladding from a metal cladding this is a major tradeoff that engineers have to consider. Perhaps you gain some margin for an accident scenario, but the cladding might be harder to manufacture, and thus cost more, and it might introduce other problems like cracking. Also SiC probably absorbs more neutro
  • The press release from General Atomics [ga.com] says, "unfueled nuclear fuel rods using the company’s SiGA fuel cladding successfully survived a 120-day irradiation testing period ... to validate the robustness and integrity of the SiGA cladding after exposure to high neutron flux in a pressurized water reactor environment." And "This material provides greater stability and safety at temperatures up to 1900 C". It never says the rods were actually tested at 1900C.

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