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Triso particles have safety features that may power a new generation of reactors
- sparker72678 6y agoIs this the same thing as “pebble bed” reactors I read about many years ago?
- DiabloD3 6y agoI literally came here to say the same thing. It reads like someone is just trying to remarket the concept to people in their 50s and up to accept nuclear power as their one true God.
- verandaguy 6y agoYes, this is about pebble bed reactors. From the article: The Xe-100 is a small pebble-bed reactor that is designed to produce just 75 megawatts of power. I should add that I'm thrilled steps are being made to make these a reality.
- api 6y agoSeems like the pebbles are much smaller in these. I recall one very mundane but difficult issue with previous pebble bed reactors was pebbles jamming and other mechanical problems with the fuel. These seem like they'd flow like that weird pseudo-sand stuff in kids toys.
- pjscott 6y agoThese very small fuel particles are embedded in larger graphite structures with whatever geometry is convenient for handling. (Pebble bed pebbles are one such possibility, and PBRs have been made which use TRISO-based fuel pebbles.)
- tersers 6y agoI also believe it's true of liquid fluoride thorium reactors: https://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor#Safety https://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reacto... I remember watching a documentary on nuclear power in the US and how the thorium reactor was the focus of a lot of research in the 70s, but I can't remember for sure.
- pjscott 6y agoTo clarify: molten fueled reactors (like LFTRs) trivially can't have their fuel accidentally melt, because their fuel is already molten. (And there are some nice options for dumping their fuel into a subcritical passively-cooled configuration in case of an emergency.) This is different from TRISO fuel, which isn't supposed to be molten in normal operation but which structurally limits the spread of fuel and fission products at high temperatures.
- acidburnNSA 6y agoThey can melt. They all do during fuel synthesis. They're pre-melted.
- acidburnNSA 6y agoNo. LFTRs have fluid fuel. There are some solid-fueled clean molten salt cooled reactors that are called Fluoride salt cooled high-temperature reactors (FHRs).
- Gibbon1 6y agoI read a detailed report of the one in Germany. Thing totally sucked. Two big problems the indestructible alumina pebbles cracked and contaminated the reactor. Second was inhomogeneous burn rates. I think I remember some pellets got stuck when they decommissioned the reactor.
- corty 6y agoTHTR-300 https://de.wikipedia.org/wiki/Kernkraftwerk_THTR-300 https://de.wikipedia.org/wiki/Kernkraftwerk_THTR-300 . Not alumina pebbles, graphite pebbles with enclosed BISO particles (predecessor to TRISO from the original article). Whole containment is contaminated with graphite dust, very high beta radiation levels. They had problems with broken graphite pebbles all over the reactor because the pebbles were brittle, often got jammed and had to be unjammed by force. They even produced a radiation release to possibly "blow out" graphite dust from the gas pipes that had collected there.
- jabl 6y agoYes, and no. Most(?) pebble bed reactors have used triso style fuel (there was a similar earlier fuel type called biso, don't know if any reactors using it were ever built), but triso fuel can be used in other reactor types as well. And yes, triso is pretty cool tech. Like the article says, it can withstand exceptional temperatures without any fission products escaping.
- Xcelerate 6y ago> Most nuclear reactors today operate well below 1,000 degrees Fahrenheit I have a background in chemical engineering and still had no clue that nuclear reactors operate at the temperature of a pizza oven. That's wild.
- klodolph 6y agoWhat’s amazing to me is that the kind of graphite used in nuclear reactors doesn’t burn until it’s white hot, somewhere around 1650°C.
- corty 6y agoThat is not a property of the graphite, its a property of the atmosphere (CO₂, He) or lack thereof (H₂O, molten salts) around the graphite. The Chernobyl core started burning as soon as external atmosphere hit the graphite after an explosion.
- klodolph 6y agoActually, it is a property of graphite. You may be surprised. http://nucleargreen.blogspot.com/2011/03/does-nuclear-grade-graphite-burn.html http://nucleargreen.blogspot.com/2011/03/does-nuclear-grade-...
- sbierwagen 6y agoGraphite doesn't burn well, but it does erode away in a stream of hot oxygen or CO2. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660019918.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/196600... The CO2-based Advanced Gas-cooled Reactor runs at 650C to keep core lifespan reasonable. https://en.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor https://en.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor
- Obi_Juan_Kenobi 6y agoUsing liquid water as your moderator really constrains how hot you can go.
- pjscott 6y agoBecause the article isn't clear: no, this isn't about pebble bed reactors. This is about a type of fuel where a little bit of uranium has been encased in a number of protective layers, such that the fuel will remain safely contained in its tiny packaging even at very high temperatures. You take a bunch of these poppy-seed-sized things and embed them in graphite rods or pellets, which both keeps them in place and acts as a moderator for the reaction. These can then be used in a variety of reactors, including (but not limited to) pebble bed reactors.
- oxymoron 6y agoThe confusing part about the article was that it initially stated that they were very small, and then went on to speak about billiard ball size. Does that mean that the protective coating is very thick, or that there’s a range of sizes for the actual uranium mass? I remember reading in one of Feyman’s biographies about how he visited an early fuel plant, and was horrified to see them storing what amounted to a near a critical mass in barrels, in long rows. we’ve come some way since.
- pjscott 6y agoThe TRISO fuel particles are very small -- about a millimeter or so in diameter. The "billiard ball sized" fuel pebbles designed for the Xe-100 reactor are graphite balls with a bunch of TRISO fuel particles embedded in them.
- VBprogrammer 6y agoI went through a phase of reading about nuclear power and in particular the nuclear accidents. It feels like we kinda got to the Comet¹ stage of Nuclear power and gave up. We still learn lessons from each accident, for example Fukushima has resulted in Passive auto recombiners being installed which convert hydrogen back to water. It also added provisions for using mobile generation and cooling (fire trucks). I certainly don't have the answer but to how we can make nuclear power fool proof but I do feel like we should still be asking the question. [1] https://en.m.wikipedia.org/wiki/De_Havilland_Comet https://en.m.wikipedia.org/wiki/De_Havilland_Comet
- Xylakant 6y ago> We still learn lessons from each accident, for example Fukushima has resulted in Passive auto recombiners being installed which convert hydrogen back to water. Seems we are on a global level not very much learning from incidents. These are common (mandatory?) in Germany and colloquially named “Töpfer-Kerze” after the minister who had them installed: https://de.m.wikipedia.org/wiki/Reaktorsicherheit#T%C3%B6pfer-Kerze https://de.m.wikipedia.org/wiki/Reaktorsicherheit#T%C3%B6pfe... Klaus Töpfer was responsible for nuclear security from 1987-1994. This would have been the time to learn.
- corty 6y agoUse of passive auto recombiners (PARs) started over 30 years ago on a large scale and has been state of the art for more than two decades now: https://inis.iaea.org/collection/NCLCollectionStore/_Public/33/020/33020098.pdf https://inis.iaea.org/collection/NCLCollectionStore/_Public/... However, many operators didn't want to spend the money, which is why Fukushima didn't have a PAR at the time of the accident. The problem with Fukushima is that I fear we do not learn from accidents. Otherwise, Fukushima wouldn't even have been in operation at the time of the accident as it is an old reactor model well past its design life. The location was, as we have known before the accident, poorly chosen. Safety measures, such as PARs, seawalls and properly redundant power supplies were skipped or badly implemented due to the cost involved. All this was known before the accident, however neither the operator nor the national oversight took any action before it was too late.
- imtringued 6y ago
- pdonis 6y agoThe article is conflating two very different kinds of "meltdown". A meltdown during actual reactor operation is the kind the article is talking about in the first paragraph, and the kind that the type of reactor discussed in the article is designed to make impossible, according to the rest of the article. But the meltdown at Fukushima was caused by lack of decay heat removal after shutdown, which is different from what could or could not happen during actual reactor operation. So there are two kinds of "prevent meltdown" that are required, not one. The article does not talk at all about how, or whether, the type of reactor it discusses would prevent a meltdown of the second kind, the kind that happened at Fukushima.
- VBprogrammer 6y agoThey are designed to be operated at much higher temperatures because the use gas as a coolant where they can effectively use natural convection to remove decay heat.
- corty 6y agoYes and no. Not all gas-cooled reactors can work completely through convection cooling without melting, some do need fans even to just remove decay heat. Also, reactors containing graphite (as many pebble-bed reactors will) do need a oxygen-free atmosphere, otherwise the graphite will ignite. So only convection of the proper uncontaminated protective atmosphere will work.
- pjscott 6y agoThe article is (confusingly, and a bit confusedly) discussing a type of fuel, not a reactor design. The type of fuel in question can withstand very high temperatures, whether from fission or from decay products, without letting the fuel out of its little protective shells.
- joncrane 6y agoSo apparently Fukishima's power failed and the generators were damaged by the tsumami. Why can't nuclear reactors at least have the option to power themselves?
- peachy_no_pie 6y agoCan anyone speak to the implications for this type of Triso fuel and radioactive waste? Is there less radioactive waste once it is spent or how similar is it to other types of nuclear fuel in that regard?
- pjscott 6y agoIt should produce amounts of waste similar to other once-through uranium fuel cycles, e.g. most reactors in use today.
- jabl 6y agoIt ought to be safer since the fission products are encased in the protective and non-corroding triso structure. That being said, used LWR fuel rods are also enclosed in protective cylinders (see eg the designs for the Finnish Onkalo storage site). Both safe enough per current best knowledge. If one wants to do some fancier recycling and reprocessing rather than once through, I understand this is relatively undeveloped.
- acidburnNSA 6y agoTRISO fuel has some very interesting capabilities as noted in the article. It also has some challenges. Traditionally, the challenges are: * Very low power density requiring absolutely massive reactor vessels for a certain power level * Very expensive fuel fabrication ($10k/kg), hopefully can be brought down * Difficult to reprocess (this is probably fine until nuclear produces like 50% of the world's energy, at which we will begin to challenge the fuel resources) Also traditionally, these are high temperature gas-cooled reactors. A new twist is the molten-salt cooled (basically just melted salt, not fluid fuel like in full-on molten salt reactors) TRISO-fueled reactors. These are called FHRs.
- jabl 6y agoThe FHRs seem like a nice combination of the safety of Triso fuel and the higher power density and low pressure of MSRs. Wonder why they haven't been studied more..
- acidburnNSA 6y agoIt is a pretty new reactor idea, and has lots of benefits. It was popularized recently by MIT Professor (formerly of ORNL) Charles Forsberg. Here's a full presentation showing the case from 2012 [1]. [1] https://whatisnuclear.com/assets/FHR_Project_Presentation_January_2012a.pdf https://whatisnuclear.com/assets/FHR_Project_Presentation_Ja...
- pfdietz 6y agoTRISO sounds like another example of solving the wrong problem. Nuclear's big problem isn't safety, it's cost. TRISO will also make dealing with spent fuel more difficult, as the dry casks are going to have to be much larger.
- jessriedel 6y agoBut the high cost of nuclear power is probably due to the extraordinary (and perhaps very excessive) safety procedures, no? It's not like the raw material or basic principles are very expensive. So I presume the idea is to hope that having a more intrinsically safe fuel will allow those expensive safety procedures to be relaxed (although, given the sclerotic nature of nuclear regulation, probably not).
- nordsieck 6y agoOne thing that' slightly worrying: > But during the INL tests, Demkowicz demonstrated that triso could withstand reactor temperatures over 3,200 degrees Fahrenheit. > ... > Sell says. “It is physically impossible—as in, against the laws of physics—for triso to melt in a reactor,” 3200 F = 1760 C > The first phase lasted only several seconds, with temperatures locally exceeding 2,600 °C, when a zirconium-uranium-oxide melt formed from no more than 30% of the core.[1] It seems like it's yet to be demonstrated that Triso fuel can withstand the highest recorded temperature inside a nuclear reactor. I get that the physically impossible quote is probably partially puffery, but IMO puffery is not appropriate when it comes to nuclear reactors. ___ 1. https://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Chernobyl_accident https://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Chern...
- LatteLazy 6y agoAll the major incidents with nuclear power are despite dozens of safety systems, redundancies, clever designs etc. This is because nuclear power is tightly coupled and complex. Humans have never mastered such systems. We have them and we accept they fail sometimes (eg fires at conventional power plants: 200 plus years of engineering and they still happen). But with nuclear that isn't an option. This is why people are unconvinced by clever new fuels or "it's totally guaranteed this time" engineering. You can't fix a systems/human nature problem with new fuel cells.
- nine_k 6y agoFrance is choke-full of nuclear power plants. Can you remember a major nuclear power incident in last, say, 30 years? I think that reactor standardization really paid off there. They have few types, a wide operation experience, and apparently well thought-out procedures. This, of course, is hard to achieve without a massive rollout planned ahead.
- VBprogrammer 6y agoOne thing I like to remember is that there are still 10 RMBK reactors in operation. Fundamentally the same design as the reactor 4 at Chernobyl. In fact, one thing a lot of people don't realise, the 3 other reactors at Chernobyl were restarted and ran until 2000 (actually, reactor 2 shut down earlier because of a non-nuclear accident with its generator) when the EU paid to have them shutdown.
- LatteLazy 6y agoThe Chernobyl reactors were all perfectly safe. It was almost impossible for them to suffer a meltdown. That's the problem here: greed and incompetence and pride can't be fixed with better cooling systems. Today's perfect reactor is just as dangerous as the perfect reactor at Chernobyl once someone wants a bonus or needs to improve efficiency or doesn't want to admit he is confused and turn the thing off...
- 6y ago
- dukoid 6y agoWhat are the exact differences between this "new generation" of reactors and the failed AVR(1) and THTR-300(2) 1) https://en.wikipedia.org/wiki/AVR_reactor https://en.wikipedia.org/wiki/AVR_reactor 2) https://en.wikipedia.org/wiki/THTR-300 https://en.wikipedia.org/wiki/THTR-300
- empath75 6y agoCapitalism being what it is, it doesn’t matter how much this improves safety, newer plants will keep pushing for tighter and tighter safety tolerances chasing after efficiencies until this is just as risky as the current fuel.
- IXxXI 6y agoWhat ever happened to thorium based nuclear energy?