Can molton salt reactors produce electricity safely?

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Speaker 1: Hey, or hey, are you a fan of molecular gastronomy. Molecular gastronomy is that like molecular astronomy, but you eat it exactly. They used chemistry to like transform the texture of your food into foams, so you might get like burrito bubbles for example. I'm not sure burritos need to give you more gas. Well, if you're not into spherical sandwiches, then I've got an idea for a new frontier and eating high energy physics gastronomy. What's that like proton pasta or bosonic burritos? Did you already invest in this startup? No? No, I'm thinking more about spices. What if you had a device that accelerated and heated up your spices and shot them out of a gun like the large any accelerator Exactly? Would you like a little molten salt on your proton pasta? I think you should get your money back, But I wonder what's for dessert. Hi, I'm more handmade cartoonists and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist and a professor you see Irvine, and I am actually a big fan of toasted spices when it was toasted spices like you pour spices on your toast raven. No, when you're cooking, you're supposed to warm up your spices, makes them volatile by toasting them in the pan, you know, it like brings them to life. Oh I see, I see, I see. Like if you don't put the spices at the end, you cook with the spices. Yeah, you gotta put the spices in the pan first so they warm up and become alive, and then you eat them. And then you eat them exactly interesting. Have you dug into the physics of that. I've taken a big bite out of it, But I wouldn't say I understood the science. I see. It's more of an experimental thing. I guess. Hands on so far, it's just exploratory. But I'm sure my wife, the biochemist, could explain to you why volatile molecules create better reactions in the news, why being volatiles tastier? Anyways, Welcome to our podcast, Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we spice up the universe by explaining all of it to you. We go out there and dig into black holes to understand what's going on on the inside. We take apart the core of neutron stars. We dig deep into the earth and into all the tiny particles that make it up in order to tease them apart and spice up your life with a little bit of understanding. That's right, because it is a pretty tasty universe, full of amazing flavors and colors and textures and deliciousness to discover, and we like to serve it to you in a three course meal. Here. I think there's an interesting and unexplored philosophy question there. You know, some people ask is it necessary for us to find the universe beautiful? But I don't know if anybody has ever explored the question of is it necessary for us to find the universe tasty? Could we have evolved in the universe that we just found kind of gross to eat? Well, I don't think it's necessary, but it's certainly nicer that things taste good and look nice. It would be kind of a bleak. I guess if everything didn't look nice or taste good. Yeah, what if we evolved in an ugly, bland universe? Boy, I'm sure glad we didn't. Or maybe we just lower our bar and start to appreciate the the ugliness of the universe. Maybe maybe that's what happened. Maybe there's another version of the universe where everything is more beautiful and more delicious interesting. So you think aliens would come to Earth and be like, boy, what a crappy place. Look at all this blue stuff and call the sky gets all red. That's disgusting. Yeah, there's another unexamined frontier. When aliens do come, they wouldn't just teach us about the universe. They might give us tips about how to cook, hopefully not how to cook us, hopefully not a direct lesson spices to serve to humanity, not new spices to serve with you. Finally, get up humans really sort of makes it more volatile, really activate activates their flavors. I don't think we want to learn about that dry aged Yeah, but anyways, it is a wonderful universe that we like to talk about, and we'll hopefully we'll be here for a long time to sort of appreciate how did walls and how it changes and how it gets more and more interesting and complex. And in order to stick around a long time, we need to power our lifestyle. We need to provide energy for our burners and for our oven so that we can continue to cook and bake delicious things to eat. As our society gets more and more complex, we have a larger and larger appetite for energy. Yeah, and so far in human history, we've basically resorted to one source of energy for most of you know, our existence, and that is to basically burn stuff. You know, take wood and set it on fire, or find oil and set it on fire. And it's kind of dirty and not as efficient as it could be. It's really shockingly inefficient. And the amount of energy you take out of coal when you burn it or when you burn wood is really a tiny, tiny fraction of the energy that's in there. It's like you find Bill gates wallet and you just take a single dollar out of there and then give it back to him. That would be would be shocking to you. That seems just like the right thing to be. No, clearly you should give Bill Gates his wallet back with all of his billions, but it's you know, maybe another analogy is like we're thirsty and we're standing next to a rushing river, but we're just like sucking droplets of water from the grass nearby. Yeah, because I guess we've only resorted to chemical means to extract energy out of matter, right, We only sort of release the energy that's trapped in the chemical bonds of materials. But it turns out that if you go deeper and smaller, you can release a whole bunch more energy. Yeah. At this sort of maximum efficiency would be to take particles and antiparticles and annihilate them into pure energy. If you had a huge source of antimatter, for examp couple, you could generate energy very, very efficiently. You turn a hundred of the energy stored in matter into energy. But of course antimatter not very plentiful, very expensive to make, and so not really a practical choice for energy production. You're not pro antimatter. I love antimatter. It's wonderful. I wish we had so much more of it, so we could study it and do all sorts of things with it, and we could fuel all of our desires and charge up all of our bones with it. But it costs more energy to make antimatter than you get out of the antimatter afterwards, so it's not efficient for commercial industries for example. Right, Well, I think what you're saying is that if we could somehow take pure matter and transform it into pure energy, there would be a huge amount of energy, even just like a drop of water or even a tiny little raisin. A single raisin has more energy stored in it than a nuclear bomb. It's an incredible amount of energy that's all around us. It's just bound up. It's just tightly contained in the atoms and the molecules that we are surrounded with. We haven't been great at figuring out how to tap into that energy, right because I guess the energy inside of a raisin likes to stay there, right, Like a raisin I didn't want to give up its energy, or it doesn't want to turn into energy like it would take a lot of energy just to unlock that energy. Raisins are not like particles. They don't just decay, right, They just hang out. You take a raisin and you leave it in space, you come back a billion years later, you'll still have a raisin most likely. So raisins are stable elements of the universe exactly. This is energy locked into a certain configuration. To release it, you have to somehow pride apart. One way to do that is to collide with an anti raisin, But without anti raisins floating around, it's harder to crack open that raisin. Right, Well, I guess you could eat the raisin and somehow convert that to energy. Maybe you could, but humans are not very efficient at extracting energy from stuff. You know, most of the stuff in the raisin just passes right through you, and the energy stored in its matter you don't even touch. Humans do like a chemical rearrangement of some of the bonds in the raisin extract a tiny, tiny little sliver of that energy, which is why the matrix doesn't make any sense. You know, humans and sources of energy. I mean, come on, that's the part that doesn't make sense. That's the part that drives me crazy. That's the physics of it right there. You're like, you're so inefficient computers and they have to power a hyper realistic simulated world. There's no way they're doing that with human batteries. They should have used raisins. Maybe, yes, yes, exactly. Raisins are more efficient, So chemical means have a limit. So over the years, humans have tried other things, right, more intricate physical ways to do things, and that includes fusion. Yeah, we have looked up into the sky and seeing a fusion reactor at work. Right, Most of the energy that it is here on Earth originally came here Rhea the sun, the rays from the Sun, which are in the end the output of a fusion reactor at the heart of the star pushing high juging together to form helium. It's much more efficient than chemical burning, although much less efficient still than matter antimatter production. Interesting, and there's also fission, right, I mean, we've sort of done both in terms of at least nuclear weapons fusion and fission, but in terms of making energy power plants, we've only really used fission plans, right, that's right. Fusion has a lot of advantages. It's much more efficient, it doesn't produce any waste. You can use water essentially as fuel. But we haven't really managed to make it work yet. There are a lot of efforts in that direction, people working on it. We have a couple of episodes on how to make fusion power possible. But fusion is one of these technologies that always seems to be about twenty five years off, whereas fission splitting atoms in half and extracting the energy when a heavy atom breaks up. That is something we have working that is part of the electrons that you are probably using come from fission power plants. Yeah, if you're in Europe, most likely you're the energy you're using to listen to this podcast came from a fission power plant. And you're in the U. S. There's a pretty high likelihood also, right, Yeah, it's a significant fraction depending on the country. In France, for example, they have a very large fraction of their energy comes from nuclear power plants. Yeah, and it's been around for maybe like sixty years, right, a long time, like this is old technology now, Yeah, the first power plants were developed in the fifties, not long after we cracked open the atom and developed the weapons technology in the forties. So it's been around for a long long time. Of course, there are significant drawbacks to vision reactors, yeah, and so people are always looking for a new kind of fission plants that could maybe be safer and cleaner. And one such idea is the one we're going to talk about today, which is this idea of molten salt reactors. Exactly. They stole it from my heated spice accelerator. Maybe you should have filed the pattern sooner, Daniel, and so let's talk about that. So to be on the podcast, we'll be tackling the question can molten salt reactors solve our energy problems? Now, Daniel have to say, I'm not familiar with molten salt. Is that the same as Morton salt. That's a brand, right, that's a brand exactly. No, molten means liquid like super hot, you know, like molten lead. Heat up lead and it goes from being a solid to being a liquid and it's all glowy. That's molten. So in this case, molten salt refers to taking salts and melting them down. Oh, I see, So it's like melted salt, Like if you heat up salt, it'll melt into a liquid. M hmm exactly. And we're not just talking about like table salt. But there's a whole set of compounds and elements that chemists call salts, and any of those can be used. And so the idea is to use these for a fission nuclear power reactor to make them better. Yeah, there are these really interesting designs for nuclear power plants that use molten salts, which sounds you know, salty and dangerous and crazy, but it could actually be much safer than traditional nuclear power plants. So this is kind of a new idea, and so it's usual. We were wondering how many people out there had heard of melting salt for fission power. So Daniel went out there into the internet to ask the question, how do you think a molten salt reactor works? And thank you again to all of our cadre of volunteers who answer crazy physics questions without the opportunity to look anything up. If that sounds fun to you and you'd like to hear your voice on a future podcast, please don't be shy. Email us at Questions at Daniel and Jorge dot com for instructions about how to participate. So think about it for a second. What would you use melted salt for? Here's what people had to say. I honestly have no idea. If I had to guess, I would say that it uses some kind of molten salt mixture as a fuel source. I don't know if that's even possible. After I'm done answering this question, I'm definitely gonna look it up. Though the word reactor makes me think of power generation, but then molten sodium. The first thing that comes to mind is the reaction between sodium and water and how violent it is. So maybe it's a reactor that can harness the power of the reaction between sodium and water. Somehow. A molten salt reactor is a reactor that uses molten salt, and maybe something to do with the salts ions to help facilitate reactions. Well, I know that salts typically don't get molten. They have to be very very hot to become molten. Something to do with their conductivity probably. I'm not sure how that would work, but I expect it as something to do with the electrical conductivity of salts when they are in a liquid rather than a solid state. All Right, some pretty pretty cool answers here. A lot of people it seemed like it seemed like they're chemists. Yeah, people thinking about salt maybe as fuel, you know, But none of these are actually even close at all to the right answer. How we use molden salt inside a reactor. And that's not a criticism because to me, the whole design of a molten salt reactor is kind of bonkers. I never would have guessed either it melts your mind or at least the salt in your mind. Yeah, exactly. I prefer the molten pepper reactors. I prefer the melted oreganos because you know, I like my Italian energy compressed cinnamon reactors. I mean, that's the way I'm gonna go. It happens if you take like cinnamon and chocolate and you fuse them together inside a reactor, you get some new superspice. Interesting. I think you need to start a new like think tank where it's just spices used for making energy. Well, I think before I think about it. I just want to build an accelerator so you can shoot like cinnamon and chocolate particles at each other and just see what happens. I mean, I'm an experimentalist, not a theorist after all. You see, you just want to make like anti cinnamon maybe or dark cinnamon. What is anti cinnamon? Is that something you can add to your food to make it taste less like cinnamon? I don't know. It's intriguing though, right, Like what is anti chocolate taste? Like? Oh man, it doesn't sound very good, but I am curious. Or like anti salt, and speaking of salty situations, I want to give a special birthday shout out to one Salty listener, Happy birthday to Ben. His girlfriend Natasha tells us that Ben is something of a salt afficionado, so happy salty Birthday, Ben. All Right, this is an interesting idea to use, Maybe melted salt. I guess that's Stadia right, to melt salt because if you heat up so I've never tried heating up salt, does it actually melt into a liquid? Yeah? A lot of salts if you heat them up hot enough and we're talking like four fifty c, they'll melt into a transparent liquid. Can you said, like salt on fire? Wow, that's something I want to type into Google, but I don't want my university to have seen me type that into Google. Silt, What do you mean? He said, salt and fire. I think that's the kind that's going to get you on the t s A watch list, Like trying to think you're thinking of, like can I make a bomb at a salt? Yeah, that's the next thing to google, right exactly, salt bombs? Bombs? Is that sort of like a bath bomb? You know, like a salt bomb? Your I think that's that's what I was thinking. I think those exist already bad salt bombs are, Yeah, and then you can make a reactor. You can convert yourself from a dirty person into a clean person. Using a bath salt, you can make clean energy, or at least a clean you. I wouldn't recommend dipping your toes into four fifty molten salt, no matter how much you want to get into the bath. Yeah, it sounds like a bad idea, but this is all sort of leading towards making maybe nuclear power more efficient, more clean, and more clean. And so maybe we should start with that. Let's start maybe recapping how a nuclear reactor works, like the kind that we in our countries right now. You have to understand why molten salt is an attractive idea. You have to understand what it is doing in the reactor and what it's replacing. A lot of current fission reactors use water as an important element of it. Essentially, molten salt will be replacing the water. But you might not be familiar with the role of water in fission, like why would you even need water? So, yeah, we should probably break down exactly how fission operates. Yeah, and so fishing is like splitting the nucleus of an atom, and then when you do that, energy gets released. And so if you do that in the right way, you can just get energy from stuff. Yeah, I think it's really quite interesting that for light elements hydrogen, helium, et cetera, if you squeeze them together, you release energy, whereas for heavy elements everything above iron, if you break them in half you release energy. The reason for that is a bunch of really interesting nuclear physics details, which, as usual, we have planned for a future episode. But the point is that when you do fishing, you need to use heavy elements. Things like uranium or plutonium are good for fishing because when they break up, they produced neutrons which can then create more fission and they produce some energy. And so the way a fission reaction works is you have like a bunch of uranium, It splits up, shoots off more neutrons, which hits more uranium, which split them up, which shoot off more neutrons. And if you get enough uranium together, then it's going to self sustain, it's going to keep going, it's going to cause like a chain reaction. Right, that's the idea. I mean, that's kind of how an efficient bomb works, is that if you put enough of it together, you break one atom one nucleus, and that breaks other nuclei and then then you have a runaway explosion. That's a bomb. But for a reactor you do the same thing, but you do it in a I guess more controlled way. Yeah, naturally occurring uranium will just spontaneously decay, and that doesn't always start a chain reaction, although we did have a fun episode about a dense depositive uranium underground in Africa which did create a natural, self sustaining reaction. But in general, naturally occurring uranium can't set off a chain reaction. Those neutrons just go into whatever other material. But you get uranium that's dense enough and you have it pure enough, then it can reach critical mass and so it sustains itself. And as you said, if you have the right kind of fuel, it can create a runaway explosion or very rapid release of energy. That's a bomb. You can slow it down and moderate it a little bit so that for example, every neutron creates one more uranium that split, which creates one more and rather than growing exponentially, it'll just keep going at the same level, producing some heat. Right, because each time the atom splits, it releases sort of like other particles or you know, like light or heat in some way that you then capture through another means exactly. Usually you capture that in like water, which then you boil into steam and you can feed it through some turbine and that generates electricity. So that's the basic idea, but it turns out to be a little bit more complicated in a crucial way because there's different kinds of uranium, and the different kinds of uranium some of them are really good to use in fission and some of them are not very good to use in fission. You got to get the right blend and you've got to get the neutrons going at just the right speed. So there are a couple of details there. Yeah, and there have been a couple of problems in history in making these things work. And so let's get into all of those details and all of that history. But first let's take a quick break. All right, we're talking about melting salt to make fission power more efficient. Now, is this sort of a new idea, Daniel, or something you just came up with this morning, or has this been around for a while. Now? This is fascinating history because it's an idea that has been around for a while, and it was explored early on, but then was put aside because it didn't have enough weapons applications. It wasn't good for developing fuel for nuclear weapons, so it's basically ignored. And now that's actually an advantage and so it's being looked at again, right, interesting, and it might make our food tastier somehow. Exactly don't you want your kid to have molten salt sprayers so they can shoot their own eggs with molten salt? I want my kist sweet food that's not glowing perfectly. But you said there are some details here about fishing that are important to understand, and they sort of have to do with the fact that basically to do fishing and to make fission reactors, you need uranium. Now, I guess maybe step me through here, like why do we need uranium? Like, you know, everyone has probably heard of uranium for movies or TV shows because they know it's related to making nuclear energy, But like why uranium? Why not the next material over? Or why not iron or why not you know, chlorine? Well, you can do fishing with lots of different kinds of stuff, and we'll talk a little bit later in the program about alternative fuels. You can use plutonium, you can use thorium, you can use all sorts of different heavy elements. Uranium has been used traditionally because it satisfies a lot of the requirements, like it is fizzile, meaning if you hit it with a neutron, it will split in half and produce more neutrons. And also because it's abundant, like there's a lot of uranium around. There's more uranium than plutonium, for example, which is almost non existent in the Earth's core. Interesting, so it's like, and is there a reason why it's more abundant. It's really interesting and deep question actually about just like why various elements exist in the universe in their various proportions. Typically there's a trend that, like the heavier elements, there's less of them because it's harder to make them you need like collisions of neutron stars. And also the heavier ones are less stable. So uranium is a bit of a sweet spot there in terms of being heavy enough to be fizzile, but also long lived enough to still be around in the Earth's core. I see maybe there were other kinds of material, physical materials, but they just naturally split by themselves over time, and so they're not that material anymore. Yeah, And some of the heavier ones there's just harder to make because the heavier they are, the more neutrons you need to get together in the core of a neutron star to make them. So there are just less of them. And so uranium is around, and it's I guess there's enough of it around right now that we use it for nuclear reactors and so like, what's the process of using uranium for fission? So uranium comes in two flavors in the Earth's core is uranium two thirty five and uranium two thirty eight, and there are the same element. They have the same number of protons. Both of them have ninety two protons in the nucleus, but uranium two thirty eight has three more neutrons. So that doesn't change, you know, what element you are, doesn't change the number of electrons. It just changes how many neutrons are in the core. So it's a different isotope. But uranium two thirty five and two thirty eight are really quite different. Uranium two thirty five is great for fusion, it splits nicely, it produces more neutrons. It's excellent. But most of the uranium we find in the Earth is uranium two thirty eight, the one that's not good for fission. In fact, it's like more than nine nine of the naturally occurring uranium. And I guess for those of us who don't remember high school chemistry, that the two thirty five and the two thirty eight means, it's like the sum of the number of protons and neutrons in the nucleus. Right, Like said, it has ninety two protons and three neutrons. If you add those up, that gives you the two thirty five, And so uranium to thirty eight has just three more neutrons in it exactly, And uranium two thirty five is the one that is really good for fission. Wait, why is two thirty five better? Like what is adding those just three neutrons to the nucleus due to the whole thing, it makes it more or less stable. So uranium two thirty five is a little bit less stable. If you hit it with a neutron, it's more likely to split up than uranium two thirty eight, And that has to do with like how the neutrons are arranged. Remember we talked once about super heavy elements and how the protons and the neutrons inside the atom arranged into these shells sort of the same way electrons do in their orbits. And if you have the right number, then they're much more stable. It's like completing an arch, like a Roman arch. If you have all the pieces, it's much more stable than if you're missing one or two. So uranium two thirty eight is harder to split than uranium two thirty five, right, which is weird because it just had three more neutrons, which are you know, neutral, but I guess they also sort of contribute to the general stickiness of the nucleus, right, like through the gluons and quirks. Yeah, neutrons are neutrals. They don't have electromagnetic forces, but they do have the strong force because they're made of quarks, and it's a strong force that holds the nucleus together. So the fact that neutrons are neutral doesn't mean they don't play a role in the strong force. They totally participate just as much as protons. Both of them have three quarks, and so just adding those three makes a huge difference, and so that's why we prefer uranium to thirty five. But it's like the minority in the uranium we find it's the minority. And also uranium two thirty five likes a very particular kind of neutron. It likes slow moving neutrons. That's moving neutrons are much less likely to cause uranium two thirty five to split. So the problem with naturally existing uranium, as we find it, is that there isn't enough uranium two thirty five, and when it splits, it produces neutrons that are sort of have too much energy. They're going too fast to be effective to split more uranium two thirty five, right, So it's rarer. So we that's why people could talk about enriching uranium. Right, it's like you're sort of sifting through the uranium and you're separating the two thirty five with the exactly. So to solve these two problems, to like get more uranium two thirty five and to fix the neutron speed, we have two solutions. One is enrich it, and so we use centrifuges and all sorts of other technologies to get uranium two thirty five to be a larger percentage so that there's enough in there to do the fission. And then we do things to slow down the neutrons that are produced so that they are much better at causing fission. And that's where the water comes in. In traditional reactors, we bathe these uranium rods in water, which is really good at slowing down neutrons, so they go from the fast speed to the slow speed where they're much better at causing fission. Right, So you make like a bar of this enriched uranium, and if you just leave it there, it's gonna decay, right, It's gonna glow, it's gonna give up heat. And so the idea is that you sort of put a bunch of these bars sort of together, and like the neutrons from one bar then cause the atoms from the next bar to split up, and then that one releases more stuff and that then causes the atoms and the other bars to split up, and that's how you get the chain reaction exactly. And the water plays a crucial role between the bars there and slowing down the neutrons, because slower neutrons are much more likely to cause fission. You need to enrich the YouTube thirty five component, and you need to slow down those neutrons. And so that's called a light water thermal reactor. Thermal there just means the neutrons are slow and water means the thing you're using to moderate the neutrons and also to provide coolant for the whole thing and to suck off the heat to create electricity is water. So that's the traditional structure of a fission reactor. Right. You just take a bunch of rods of enriched uranium and you dip them in water, basically, right. But it's interesting, I think too, because the way they control the reaction is they control how much do you dip the rods in water? Right? Exactly? If you overmoderated, for example, then you'll slow down the reaction. You'll slow all those neutrons down so that they can't even provide fission anymore. Right, And so what is it called light water thermal reactor? Oh? As opposed to heavy water. Sometimes they use like deuterium water and that has different Properties' is like a thousand different varieties of these reactors. And this is the one that uses like normal water, the kind of water that we can drink. I see, all right, So then you dip the rods and water. That's how you get a reactor. But there are problems with that, right. There are a bunch of problems with these reactors. Number one is that you're only really burning the uranium two thirty five, which is a tiny fraction of your fuel. So the uranium two it's in there, you're just sort of wasting it like it could maybe be turned into fission, but you don't use it. And so uranium depleted uranium is uranium where you've burned the uranium two thirty five, just like leaving most of the uranium gone, sort of like you know, you try to burn a camp fire and you only burn the pine needles on the tree. You burn like the real core of the tree. So most of the energy is wasted. It's not even used. Wow, and then that becomes nuclear waste, right because this stuff is still like breaking down shooting off dangerous particles. And that's why it's radioactive exactly that you two thirty eight doesn't burn, it doesn't participate in fission, but all the neutrons that are flying around will convert it into really dangerous stuff like plutonium and all sorts of other stuff, and that stuff has half lives of like tens of thousands of years. So most of the stuff in your fuel doesn't contribute in a useful way and then turns into like poison which will kill people and ruin the environment for like you know, thousands and thousands of years. Wow. Not good. Definitely not good. Yeah, And it's also a little bit you know, risky too, because if you don't control the the reaction well enough, you can have a big meltdown. Yeah. One problem with water is that it boils at a pretty low temperature, right a hundred C, and so you need to keep it at a very high pressure in order to keep it liquid because it has to be liquid to play this role to flow through your reactor and to pull off the energy and to be a moderator. And so a lot of these reactors operated extremely high temperatures, like a hundred atmospheres, which is you know, dangerous, and it means that these things are big and bulky. They have to have like thick, thick layers of steel to contain them, and it takes work to maintain this, you know, to keep this thing flowing and to keep it under pressure. And for it all to be safe, and you can also have accidents which have happened in the past, right, notably like Kushima and Chernobyl. Those were sort of like failures in controlling the fission reaction exactly, And all those failures are linked to the water. You know, in Chernobyl that water boiled because it got too hot. In Fukushima, the water pumps were knocked out by the tsunami. In Three Mile Island and earlier disaster, the water hatch was jammed and so the water didn't flow. And so like this water, it can work. And you know, more modern reactors have more and more layers of safety, but it's complicated. It's interesting from an engineering point of view. I think that as we learned to do fission reactors with water, the time it takes to build and get one of these things up and running gets longer, not shorter, right, because we're learning how to do it safely. We're just like adding layers and layers of precaution as we developed new reactors, right, because I guess you know, when they built Fukushima, they were probably didn't think, like, hey, what if there's an earthquake in the middle of the ocean and that causes a giant tsunami wave that then hits our water pumps. Right, Like, you have to think of everything, and that's really hard. Why didn't they think of that though? Like who builds a nuclear power plant near an earthquake line or near the ocean? You know, it doesn't make any sense to me. You're expecting this thing to be there for decades and decades, Like she's put it far away from everything that could potentially cause it any damage. But I guess there's always something unexpected. I guess, you know, even if you put it in the middle of the mountain, then something else is going to happen, right, There's always something I expected. That's true. Yeah, And you know that's the danger here. We're dealing with very high pressure, very high temperature environment and it needs to maintain that or it's going to melt on and cause a disaster. And so it's a bit fragile, and I think that's one main concern of these water reactors. All right, Well, um, let's talk about then, how to make things better, how to make them cleaner and safer. It seems like water is kind of a problem here because water boils too easily maybe, And so you have you have to be very careful with it because if it evaporates, then you don't have anything controlling the reaction. Yeah, and that's why people think about using molten salt. Right. You take fluoride, for example, and you heat it up to four hundred and fifty c it melts into a transparent liquid. It looks like water, right, It flows. It's clear, sort of weird to think about it, but that's what happens. That's the chemistry of it. And so you can use molten salt in your reactor instead of water. And the advantage is that this thing stays liquid at much higher temperatures, that doesn't boil, right, and so so you don't need really high pressure. You can keep it like one atmosphere and you can still do the same job that water does for you. So you're talking about like a salt that uses four rain and then melting it and then using that like bathing the uranium rods in that liquid. Yeah. And here when we say salt again, we're talking about in a chemical definition of what as salt is, right, the same way that like astronomers consider everything heavier than helium to be a metal chemists have a specific definition of salt, and so fluoride is one example. And so yeah, you melt it, and then you can use this to cool your reactor, to pull the energy out of it. And you don't even have to wrap your rods in it. You can dissolve the fuel itself into the salt. So you just have this like mixture of molten salt with your fuel flowing around your reactor. Whoa, so you you mix the fuel into the this salt that's at the four and fifty degrees celsius? Is that the idea? So you have this boiling hot stew of radioactive uranium and salt, and and then how do you get the energy out? Or like what happens to does it just stay hot forever? Does it start to heat up if you leave it alone? What do you get? What are you gotta do? Well, you have the reactor and you pump some of this salt out into a heat exchanger, so then you can like you know, take the heat out and spin turbines, etcetera, etcetera. And there you know, you could transfer it to water or whatever you need to do. But there's lots of really cool options because it's much hotter because molten salt stays liquid at higher temperatures. It's much more efficient actually for energy generation, and it gives you other options like creating hydrogen fuel as like sort of chemical battery to store all this energy. So, yeah, you have this molten salt flowing around in your reactor and some of it gets pumped out into a heat exchanger so that you can pull the energy out. Well, it's intense because you pump it out, but it's radioactive to right, Yeah, it is radioactive. It still has your fuel in it, so fission is happening in it. And so I guess what happens if you just have a vat of this dissolved fuel. Does it eventually just heat up to like a million degrees or I guess it eventually would melt whatever container it's in. Well, you're pulling the heat out of it, right, because you're using it as a reactor. And there's also sort of a safety valve which is at the bottom of this thing. They have a plug which is made out of another frozen salt, and so if the whole thing overheats, if it gets too hot, then it will melt this frozen plug and it'll just all sort of like drip out of the reactor and it'll cool down fast enough to become solid and then the reaction will stop. The reaction only happens when it's liquid. Oh, that's a good mechanism for safety. Like it, so if the salt solidifies, then that stops the reaction, like the reaction only works if the salt is melted. All right, Well, that's sort of one idea to make fission safer and cleaner. And so let's get into another one that it may or may not be related to the Avengers. But first let's take another quick break. All right, we're talking about making fission energy safer by maybe some new ideas to make the fission reactor process safer. And one of them we talked about was melting salt or a kind of salt as the sort of mediator between the field enrich uranium. And so that's a pretty good idea, right, it seems safer, it does exactly. It seems like a cool idea. Another version of that is using molten metals, like you can have liquid lead in your reactor instead of water, and it's actually maybe even safer than water because again it doesn't have to be at such high pressures, right, And that's good because I guess high pressure of things that are radioactive are kind of danger. Yeah, exactly. It's just less likely to blow if it's not a high pressure, all right, So melting salt is one way. Another way is to use something called thorium exactly. And I'm desperate to hear about your avenger's connection. Well, I'm just wondering if it's related to holkium in in iron manium. Well, I see thrium, right, How can I have missed that? No, Thorium is an element. It's something that exists in the Earth. It's actually more plentiful than uranium, and it's something that we produce as a byproduct already of rare earth mining. You know, when you're trying to get like cobalt or namibium or whatever you need for your new batteries. When you're doing the rare earth element mining, you already are just like digging through lots of thorium to get it. And so thorium is something we have a lot of, and it turns out to be an excellent fuel for nuclear reactors. Wait, what, so there's something else it's not uranium that could also be used for fission reactors. Is it like lighter or heavier or what's what's different about it? The cool thing abou thorium is that it can't actually do fission on its own, but when you hit it with a neutron, it turns into uranium two thirty three. So now another version of uranium. See it is kind of like the Hulk. It turns green and more volatile. Sounds like the Hulk. Yeah, and uranium two thirty three is not something that exists in the Earth crust in anything but trace amounts. But it's an slow fuel for FISHI and it's very fiscile, and it can operate with slow neutrons. If you just hit thorium with a neutron, it turns into uranium, which is then fuel. So the reactor can turn thorium into fuel four itself. Wait what like? Wait, so you take thorium, you somehow bombarded with neutrons, it becomes uranium two thirty three, and then when that splits, it splits back into thorium. Is that the idea? Now, when that splits, it splits into lighter stuff, releases energy and neutrons and those neutrons. It produces enough neutrons not just to split other uranium two thirty three atoms, but also to hit thorium and turn it into uranium two thirty three, So it like breeds its own fuel. Oh interesting, I see, Like the process of the fission reaction would actually make more fuel in the process if you put more thorium in it. Like it's not making stuff out of the blue. No, it's not just generating it. But if you pour thorium into the reactor, it will turn thorium into the fuel that it needs and then burn that fuel, turning more thorium into the fuel that it needs. So you need to keep adding thorium. But thorium by itself is very stable. It's not fizzle, so it's not like dangerous the way uranium, right, And it's also better because it's not it's not as wasteful, right or dangerous when it gets used exactly, it burns up a lot of the uranium, and it doesn't produce crazy dangerous things that last tens and thousands of years. I mean, it produces very dangerous byproducts. Sum one thirty seven is very very poisonous, but it has a half life of like fifty issue years, not ten thousand years. So you need to put this stuff in a barrel and wait a couple hundred years before anybody goes near it. But you don't need to wait fifty thousand years. Wow, this sounds great. Why don't we use that? Like, why are we still using uranium regular uranium? Let's switch to the avengers. Exactly, it's a much better idea, but historically it hasn't been pursued in the United States because it doesn't produce plutonium and other heavy elements, those things which are very dangerous and last forever. Those are also excellent for building nuclear weapons, and so the Department of Energy, for example, Yeah, they wanted to promote atomic power, but they also wanted to develop facilities which would generate fuel for nuclear weapons. And so burning uranium two thirty five was very inefficient. But the uranium two thirty eight that was there, some of it turned into plutonium, so you could make weapons grade fuel. Wait, what are you saying that most nuclear power plants are also secretly like weapons weapons and factories, not secretly. A lot of nuclear power plants can produce plutonium, and it's certainly an issue you need to also enrich it. Right, it doesn't come out with pure plutonium, but a lot of the uranium two thirty eight gets converted into very dangerous, long lived waste, and some of that waste is excellent fuel for weapons. Wow. So I guess maybe they saw it as like a two for like a bonus, Like, Hey, if we use this kind of fuel, this uranium two thirty five to thirty eight, then as a byproduct, we have kind of kind of a steady source of nuclear weapons exactly. And so if, on the other hand, you would like nuclear power without creating weapons fuel and without creating environment poisoning waste that last tens and thousands of years, you can do both at the same time by switching to thorium. Wow. Well, it seems like countries that you know don't have nuclear weapons, like does France have nuclear weapons? Like, why wouldn't they switch to thorium. Well, it's just not something that's been as developed. You know, we did some research in the fifties and sixties and developed these reactors, but uranium turned out to be kind of cheap and plentiful, and people didn't really care about the fact that you were wasting most of it, and it had these nuclear weapons benefits. So it's largely just sort of abandoned for decades and decades and just not really pursued. Oh I see, So now it's maybe more of like a historical inertia kind of like this is what we know what to do, This is what we know how to do it. We know how to make the safe. But thorium who knows, right, Like, who knows? We don't know enough of it. Nobody has done it enough to really kind of meet the same safety standards. Maybe is that? Could that be an obstacle? Yeah, it's a regulatory issues. You know, you're a company and you're deciding to invest one billion dollars into a nuclear power plant. What are you gonna do? You're gonna use the plans for one that where was recently approved that already sailed through the approval process and is working well, instead of like, yeah, we're going to work on development of some new technology. It requires the government to take the lead in terms of research and developing and making sure these things work. And so outside the United States, some governments are doing this. China, for example, recently completed a flora thorium reactor and they were supposed to turn it on at the end of one. I haven't heard if that thing has been turned on yet and works. But you know, a lot of other countries are looking into this. They can't find a thor's hammer to start the reaction or something. Every time you gotta reboot it. Exactly, you've gotta call thora um. And not just China, India. Also. India is home to twenty five percent of the world's thorium deposits, so it would be a great place to rely on this kind of energy, and so they're developing a the orium nuclear power program as well. Wow. Interesting, I guess it just takes a long time, right, I mean, you gotta you can't just like do this in a rush. You gotta do this, do this very carefully. You do. And there are some challenges to salt reactors that don't exist for water reactors. For example, molten salt is kind of corrosive. Like you have that in the inside of a chamber for a long time, it's going to eat away at the inside. So that was an obstacle a long time ago. But these days we have fancy new materials that can be basically hardened to the salt and so it's no longer really a challenge. So with the help of new technologies to overcome some of these technical challenges. There's lots of places that are looking into this. There's a company in Denmark actually called Copenhagen Atomics, and they have a strategy to build one of these thorium reactors and they want to make them into shipping containers. The whole thing is just totally self contained. You never have to open it up or do anything. You just turn it on. It runs for like fifty years, produces energy steadily for fifty years, and you can like them. You're like, oh, we need ten of those. All we need five of those. And to the self contained, what do you mean like they produce the waste, But it's the wayt stays inside, the waist stays inside, and you just like bury it for two hundred years and then it's done. So that's pretty cool idea. It's a company called Copenhagen Atomics. And for the record, you're not you haven't invested in this company heavy, You're not like Elon Musk trying to game the markets. No, but you should buy Daniel coin. Really, it's my new cryptocurrency, dan Coin, there you go, Exactly, it's going to fund all of my heated spices for your other the other arm of your subsidiary corporation, right, spicy dan exactly working on development of anti chocolate technology. All right, So those are two pretty interesting ideas using melted salt molten salt and also maybe switching up the fuel to do something that's maybe cleaner. And it sounds like people are working on it, and maybe we should too because it sounds like other countries are working on it. It's definitely pro missing technology. And if you think that nuclear power is an important part of a clean future, then definitely thorium is a better choice than uranium. It's a question, you know, whether or not even the waste produced by thorm reactors is worth the risks, but it's definitely all better than burning fossil fuels, right, and it's much better than hawkeye. Um. Yeah, maybe you should just take the avengers and grind them up into fuel. Well, they definitely make enough money to self sustained. It's its own reaction there, Yeah, exactly, will mint avenge coins at a ground up avengers? There you go, marvel Coin, marvel Coin, you might as well have their own economy, right, they're basically just printing money, all right, Well, this is kind of hopeful news to know that maybe they're people are working on cleaner and more efficient energies and to get humanity into the stars maybe and into the far future so we can learn more about the universe and discover more of it exactly. And it's always fascinating to learn about the history of these things and how like political choices that were made decades ago really changed the direction of research. And it's not always for a good reason, not always for reasons that we would agree with today, And so the things that people are working on currently are just sort of the things people have been working on, and they're often really promising directions that were overlooked for silly reasons. All right, Well, we hope you enjoyed that. Thanks for joining us, See you next time. Thanks for listening, and remember that Daniel and Jorge explained. The Universe is a production of I Heart Radio. For more podcast from my Heart Radio, visit the i Heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.