Daniel and Kelly’s Extraordinary Universe - Why don't we have nuclear powered airplanes?

Episode Date: June 6, 2024

Daniel and Kelly talk about whether planes could be powered by nuclear reactors and whether that would be a bad idea, or a very bad idea.See omnystudio.com/listener for privacy information.

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Jorge and I created the show a few years ago, and the second season has just premiered. We're so excited to share this new batch of stories and adventures. Check it out on PBS Kids. Eleanor wonders why. Hey, Kelly, do your kids like to fly? Yeah, they do, particularly my oldest. They were a little bit scared at first, but I was explaining to them that like flying on a plane is probably safer than driving in a car, and I eventually convinced them it's safe and now

they just enjoy it. Hmm, you convince them it's safe, huh? Daniel, what does that mean? Flying is safe, but have you figured out a way to make it unsafe? I mean, current airplane technology is mostly pretty safe, but there are some pretty cool ideas out there. Okay, wait, safe and boring, as you described current planes, I feel like that's what you're going for.

That's what you want with planes. I guess so, but I bet your kids want a, ride at a new experimental crazy plane that involved nuclear power, don't they? I bet they won't because they're not going to hear about it, and I'm not letting you near my kids. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I'm a professor at UC Irvine, I want to bring the fun into Kelly's kids' lives. I'm Kelly Weider-Smith.

I'm adjunct at Rice University, and I think flying should be boring and safe. But what if we have crazy new ideas for how to get big, heavy stuff into the air? Dream a little, Kelly. You can try those out on your kids. That's not why I had kids. That's why other people had kids. I'm not sure you understand. and their motivations very well, Daniel.

That's probably true. And my goal here is not to explain people and their motivations, but the universe. So welcome to the podcast, Daniel and Jorge Explain the Universe, production of IHeartRadio, in which we do just that. We try to explain everything that's out there in the universe to you, the fundamental laws of reality,

the nature of space and time, and how we can use our understanding of that to bend reality to our will, to make it do cool stuff like fly tons and tons, of metal through the air, across the ocean, totally safely. Yes, safely. Cool and safe. Because cool is safe, kids.

But we're also interested in pushing the boundaries of what can be done. Every time we learn something new about the universe, we wonder, how can we use this to improve our lives? How can we use this to make life more exciting? What new kind of gizmo or what's it can this allow us to create that might change the very nature of what it's like to be a living human in this universe? I begrudgingly agree. And of course, the last century has given us lots of new insights into the nature of reality at the microscopic level.

Zooming in past atoms, we've discovered all sorts of new rules for how the universe works, rules that are counterintuitive that disagree with our classical intuition for how things operate. This new realm of quantum mechanics has opened up lots of crazy new opportunities and dangers for all sorts of humanity. Atomic weapons, atomic power, atomic devastation, and, of course, potential for nuclear winter. All sorts of consequences for doing physics. All kinds of reasons for my kids to not listen to your podcast. Do we talk about Project Plowshare at all? I can't remember.

What is Project Plowshare? Tell me. Project Plowshare was a U.S. project to try to use nuclear weapons for, like, cool good stuff. Like making bays by blowing up land so that you can have a little area where you can bring ships inside. close to land at some point. And we had a bunch of projects where we set off nuclear weapons for like funsies and building stuff that we thought might be nice. But of course, you know, being with the U.S. is history. We often did it in ways that were not amenable to the desires of the people who lived in that area. And eventually we stopped doing this, thankfully. But Russia or the

Soviet Union had a similar program. And if you look up Lake Cheygon, I think that's how you pronounce it. Chagin? I don't know. Anyway, they've got a lake and it's perfectly circular and that's because it was created by a nuclear weapon exploding and then some poor person had to swim across it to like convince everyone. No, it's safe. This is cool. This is cool. Wow, terraforming with nuclear weapons. That's just terrifying. But there was an era after the discovery of atomic power when people felt like this could change lots of different aspects of our lives. Our nuclear knowledge could wiggle its fingers into all sorts of aspects of everyday life. And of course, we know now that we have nuclear power plants and there are nuclear

powered ships and nuclear powered submarines. But today we want to explore another question, which is why nuclear power hasn't made inroads into the skies. And so on today's podcast, we'll be asking the question, Why don't we have nuclear powered airplanes? Well, should we see what the audience? Thanks. This is a fascinating question.

And so as usual, we went out into our list of volunteers to see what people thought about having a nuclear reactor on board an airplane. If you'd like to participate in this segment of the podcast, please don't be shy. Write to me to Questions at Danielanhorpe.com. We will set you up with random physics questions in your inbox every week. Everybody's welcome. So before you hear these answers, think to yourself, how do you feel about having a nuclear reactor on board your airplane. Here's what people had to say. Well, we are too far from having electric powered planes, but if we use water and

heating them up with nuclear reactor and use it as a propellant, then it could be, but that would require enormous amount of water to restore. So it's not very likely, but maybe in the future. I'd say no, because they're quite heavy, I think. And I think they need to be cooled down quite a lot because I know in nuclear submarines, they use the seawater to cool down the reactor. So I don't know. Water's heavy. And unless it was a very, very big airplane with nobody on board and nothing on board other than a nuclear reactor, I'd say no. Well, I wouldn't fly on it. I mean, a nuclear reactor is typically just a heat engine, steam engine or just creating heat like on the Mars rovers. So to have enough energy to continuously power an airplane would need

it to be enormous, and then I don't think you could put it on the airplane. So probably not, but since you're asking, maybe? Let's see. The biggest airplanes can carry about 400 or 500 tons. So I would say if you could make one that's light enough, I would say yes. They put them in submarines, so yes. I thought these answers were really good. To be honest, heavy wasn't the main concern that I had in mind when you sent the title of this episode to me, my thought was I wouldn't want to ride that close to a nuclear reactor, but then I thought, oh, well, they do it on submarines is probably okay. So then after deciding that that concern wasn't a big one, I thought, well, probably I don't want nuclear material flying over my head when sometimes airplanes don't

come down in the safest ways. You wouldn't want them to drop their nuclear material and spread it across Earth. But so the most common thing that the audience said was that is this too heavy to work on planes? Were they on the right track? That's definitely an issue and it's actually all entangled because one of the reasons that submarines can be saved is that they have lots of shielding because they don't have to worry about weight.

And so these questions of safety and shielding are all connected. Excellent. Good job audience. So my first thought here is that Plains seem to be doing just fine. But of course, it would be really nice if planes were using cleaner energy sources. And nuclear power is a good energy source if you're trying to cut down on greenhouse gases. So let's talk about the pros first.

I assume that's one of the pros. So why else might you want nuclear powered aircraft? The whole idea for nuclear power aircraft comes out of World War II. Of course, that's when nuclear power was invented. And maybe the primary motivation was to make airplanes that could fly for longer without needing to refuel. In World War II, a lot of our strategic decisions were based on needing to refuel. You had these bombers and you wanted to drop bombs on enemy territory. And those bombers needed gas.

And that limited how far they could fly. And in many missions, the bombers came back with just like fumes. It really limited the reach of these bombers. And so people were thinking, could we develop airplanes that ran on nuclear power that could fly? for much, much longer because nuclear fuel is so much denser. So, for example, submarines can operate for a very, very long time without refueling. Same with nuclear-powered aircraft carriers. These things can sometimes go decades without refueling.

Except the humans who ride them would need to refuel by sleeping at night. But I guess you could have a number of pilots circulate or, you know, taking turns that you could keep going. But like those bombers, aren't the figure something like, like one and four didn't return on each run, think of the amount of nuclear material that would be falling to earth with these bombers as they got shot down. But, all right, we're probably going to talk about that

in the con section, I'm guessing. So, but you know me, I always get hung up on the cons. Okay, so let's talk about more pros. That's definitely an issue. But if your goal is to have airplanes that could fly all over the world and drop bombs on any target without needing to refuel

or without needing to worry about like tricky areas, refueling maneuvers, which make you in the refueling plane very vulnerable to enemy aircraft or without needing to like buy territory in foreign countries for refueling bases. Did you know, for example, the United States tried to buy Greenland from Denmark, even before Trump offered. They wanted refueling bases in Greenland and they offered a hundred million dollars in gold to Denmark for Greenland. And Denmark said, no thanks.

We'll keep Greenland. And we did this so that we could refuel there. That was our main purpose. Yeah, Greenland is very strategic location between the U.S. and the Soviet Union. Absolutely. Yeah. Did we try Iceland next, maybe for less money?

And then Iceland was offended. They're like, what? Not as value is Greenland? Are you guys crazy? Yeah. Hence the Cold War, very chilly. But the idea was basically try to get airplanes that could fly longer, right?

And the concept there, the physics underneath it, is that nuclear fuel is so much. much more dense. Like if you think about how much energy is stored in uranium versus how much energy is stored in like diesel, it's really just enormous. Like diesel and gas has more energy than coal or more energy than like, you know, animal fat or whatever, but just by a few factors. Uranium has 76 million megajoules of energy per kilo of uranium, whereas gas has 46 megajoules. So the energy density in uranium is a million times that of diesel. Oh my gosh, that's incredible.

Okay, so this is an amazing power source. Tell us about subs and why it works so well in submarines. Yeah, this is something that works very, very well for submarines. And the newest generation of submarines, they never need to refuel. Like they think these subs will last for like 50 years and the fuel will also last for 50 years. You'd like just build the sub. You build the fuel in and you never. refuel it because it's so energy dense it's amazing that's incredible so they have these miniaturized

reactors and they're powered by uranium and you know there's fission that happens there and the fission releases heat that heats water which produces steam which turns a turbine which then directly turns the ship's propeller often in land-based nuclear power the turbine then spins a generator which makes the electricity you put it on the grid but there's no need here to generate electricity you can just directly have that turbine spin the ship's propeller. And the cool thing is this is much quieter than diesel engine. There's no pistons, for example. And so if you're trying to run quiet underwater,

that having a nuclear-powered submarine that never needs to come up to refuel is quite the advantage from a military point of view. That is pretty incredible. Is the U.S. the only country that has these? I'm going to guess that the Soviet Union also came up with this. And so Russia has it too. Absolutely. The Soviets have them.

and we've had them for decades. They're not the Soviets anymore. The Soviets had them. The Russians now have them, of course. But this is something which is decades old. It was 1960 when we had the first submerged circumnavigation of the globe. Like the first time a submarine went around the globe without surfacing. That's just like a decade and a half after the whole invention of nuclear power.

Wow. That's incredible. Yeah. And a few decades later, we had more. nuclear reactors in ships than there were on land producing electric power. So like the military has really been into this idea for a long time because they're like not refueling and they're like the quietness of these reactors and frankly probably because they don't also care as much about the potential disasters and the ecological impact. And why is that? Is it because the bottom of

the ocean is sort of desolate and it doesn't even if a sub crashes, most of the material stays in one spot so the you know devastation and the problems are sort of limited or yeah why do why would you not care about the ecological well I don't want to speak to the motivations of the military person but you know you're developing weapons anyway that are causing huge destruction right your goal is destruction so like gentleness about the territory I mean I guess it must always be second or third concern but you're also right that like a submarine that crashes underwater water water is a pretty good shield from radio And so unless that uranium then leaks out and like spreads into ocean currents, the actual radiation from the crash site is pretty limited to that location because water is an excellent

shield. Okay. That's good. All right. So we use a lot of these underwater. I happen to also know that they're very helpful in space. So where have they been used in space? They've been used underwater.

They're also used on the surface. The U.S. Navy 11 carriers are all nuclear powered. Some of these things have two. some of them have eight separate reactor units. So like maritime nuclear power, very well established. But you're right, we also use nuclear power in space. Some of the rovers that we have sent to other planets use nuclear power.

They don't have nuclear reactors in the same way that these subs do in the sense that they have controlled vision reactions. Instead, they use another kind of nuclear power where there's uncontrolled decay that essentially leads to heating, sort of more like a nuclear battery. These use plutonium and they work for like 10. 10 to 15 years, providing a gentle source of heat, which is then converted into the electricity to run some of these rovers like curiosity and perseverance. So we definitely have nuclear-powered craft underwater on the surface and in space.

Well, we also have little nuclear reactors in some satellites. We don't do it so regularly anymore. The U.S. had Snap 10A, which we sent up, and it did okay for a little while. Then it failed, and we boosted it to a graveyard orbit. so that that didn't go super well for us. And I think maybe it's leaking a little nuclear material. Whoops. And then the Soviets actually sent up something like 33 nuclear powered satellites.

And they used these because they wanted to go kind of lower for like surveillance purposes. And they were low enough that they were starting to hit like atmosphere particles. So solar panels would have slowed them down. So the nuclear reactors allowed them to go for a long time without the solar panels, which would slow them down. And that went okay most of the time They didn't always spread nuclear material Across Canada So that's good

There's just that one time You get one freebie right I mean I'm sure Canada's cool with that one time There's a lot of Canada And like a lot of it's not being used For other stuff maybe Wow you're pretty cavalier about safety When it's not your kids involved Kelly

You know Canadians have kids also You understand how that works? I am so sorry, Canadians. I was joking, and I shouldn't have. I shouldn't have done it. All right. So we've talked about the various places that we find nuclear reactors. Let's take a break and, you know, shield our houses against the radioactive material that might come falling down on us at some point in the future.

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Effect Podcast Network, the iHeartRadio app, Apple Podcast, or wherever you go to find your podcast. And we're back. All right. So we've talked about the various ways nuclear power has been used in things like submarines and satellites and rovers and, of course, nuclear power plants. Let's talk about some engine concepts for how you might be able to make this stuff work in an airplane.

Yeah, it's really fun to think about how you might actually power an airplane using a nuclear reactor because the basic concept that works underwater is to have it directly spin a propeller. But those propellers can spin fairly slowly and still power the ship. But on airplanes, of course, we have jet engines. And so people have explored lots of different ways to make a nuclear powered aircraft. But the leading idea, I think, is a nuclear jet engine. Oh, sounds epic.

Yeah. So to review the way a jet engine works in general is essentially your burning fuel, jet fuel, essentially some fossil fuel to heat the air. And that expands through a turbine into a propelling nozzle to provide thrust. So the goal of the fuel, the reason you need fuel, the reason we have jet fuel in airplanes is to heat a bunch of air, which then expands and that expansion gives you thrust. So the core idea of a nuclear power jet engine is just to replace the source of fuel. heat. And so because fission produces heat, right, produces these energetic particles, people thought, well, let's just use fission to directly heat the air instead of having the diesel fuel do that job. And then it's was the, the air is just whatever air is surrounding the airplane in the sky? Or are you like putting some gas in there that gets heated? No, that's one of the cool things about a jet airplane

is that as it's flying through the air, it's pulling air in, compressing it and then expanding it with the heat. And that's how the whole jet engine runs. That's why jets don't work so well at low speeds because they require this influx of air into the compressor. Okay. And so then would fission be able to heat it up even more, like better than the other methods? You could go even faster or the point is just that it can heat for longer because it burns slowly? Yeah. The idea is just that it can heat for longer, that the fuel is much more dense. And that's also an attractive feature of nuclear power jets because you'd like to be able to lower your weight in the air, right? when a 747 takes off for a cross-country trip,

it's carrying enormous amounts of fuel. Some of that fuel is just in order to provide the thrust to carry the rest of the fuel. It's like the whole rocket equation problem in miniature. And so if you could figure out a way to make your fuel less, then you can lighten the whole weight of the aircraft and then need less fuel. Yeah.

So, okay, so at the beginning of the show, the listeners said that they thought the problem was weight, but it sounds like you were saying that's not the problem. Actually, this could be a less heavy way to fly. Weight is definitely an issue. And we're going to talk about like the shielding and the reactor itself being quite heavy. But in terms of the fuel, there is a win. And so we're going to keep track of the weight accounting in terms of the fuel volume and weight, nuclear power wins.

When it comes to the actual equipment involved, you're going to see it's an overall loss. But, you know, there's something in the win category there. And so people have actually, and so people have actually built these things. They have prototypes. You can go to the Idaho National Lab. They have a couple of these set up that you can actually see. They built them in the 50s

and they tested them and there's sort of two different models there. One is a direct air cycle where the air comes in from the compressor, goes directly into the nuclear core. That air gets heated up by the nuclear power plant

and then emitted. That's very powerful, but the problem is the air that comes out also kind of radioactive. That's a problem. And so if you're like flying regularly back and forth across your own country and you're spewing radiation and that's you know bad so they developed a second

model an indirect air cycle where you basically have two different loops you have the air that comes in and then it gets heated by something which has been heated by the nuclear reactor so for example the nuclear reactor doesn't directly heat the air it might heat like liquid metal in pipes or very high pressure water which is then getting radioactive but it's not getting sprayed out the back of the jet engine instead it's just heating up the air so you're sort of shielding the air from the radioactivity by having this indirect loop of liquid metal or high pressure water. That sounds more complex but better. Yeah, exactly. You're not killing your own people, but now you have to have this extra machinery and you have to hope that your high pressure

liquid metal doesn't explode. You have to monitor that. So it becomes more complicated, which is the downside of it. But the basic idea works. Like in principle, you can have a nuclear powered jet engine. I don't think I would want that flying over my home. What are some of our other options? So instead of having a jet engine, you could also have a nuclear-powered thermal rocket. So a chemical rocket, the thing that like the Saturn 5 used to get off the surface of the earth, you have some chemical reaction which creates expansion and gives you propellants, basically momentum out the back.

This is the way a rocket engine works. Well, you could imagine a nuclear-powered version of that, where the heat comes from the nuclear reaction and that flies off some propellants and those propellants are then pumped through the core to heat up something. So it's sort of similar to the jet engine concept. You're using the nuclear reactor to heat something

and then that is expanding and flying out the back, but we call this a thermal rocket instead of a jet engine because you also don't have the compression cycle. Is this what Project Orion was all about? Project Orion was actually blowing up nuclear bombs behind it. So it's sort of similar. It's sort of similar and much more awesome and impossible, but. Awesome if you're like not living on the planet where they're trying it out, maybe.

Yeah, awesome. All right. If you see it, you're like, oh my gosh, wow. So this is a more delicate approach. Yeah, exactly. The third approach is to think about actually generating electrical power and then using that electrical power to run like an electrical engine. So you sort of separate the two components. You have the nuclear plant on board.

It's running, it's producing steam, that's turning a turbine, that's running a generator, that's producing electrical power, then you're feeding the electrical power to like a turboprop engine. So the engine and the power generation are separate. So do you have a sense for out of these three methods, which one is like the best? So they differ in complexity, they differ in pollution or, you know, how bad they are for the environment below. they probably differ in how much power they produce for a given amount of nuclear material.

Is there like a favorite amongst people who are excited about these ideas? I think the jet engine is definitely the leading idea. People like jets, jets can go really fast. They work really well on airplanes. People have actually built prototypes of this and proven that it can work. So the jet engine is definitely the leading concept. All right. So we've talked about the different ways to make this work.

We've talked about the pros, you know, why you would want. wants to use nuclear power for an airplane. But we all know that Kelly's the wet blanket around here. So I'm excited for us to move on to the cons. What are the reasons why this idea that sounds bad to me is bad? So many reasons. Let's start with the practical ones. And that's the issue of weight, right?

So reactors can be big and they can be cumbersome. This has been mostly solved. People have made miniature versions of reactors like to put on a submarine. or to put several of them independent reactors onto a big aircraft carrier. So you can make the reactor fairly miniature. Physicists are really good at figuring that kind of stuff out. What's very hard to miniaturize, though, is the shielding.

Like on a boat, a submarine, or an aircraft carrier, you can have lots of layers of steel, not a big deal, right? But on an airplane that really costs you. And so it's possible to miniaturize the reactor itself and reduce the weight there, but the shielding is always going to be an issue. You want to put a lot of heavy atoms between you and the source of radiation. And a lot of heavy atoms are always just going to be heavy.

So you had said that, what was it? Like gas was something like 50 megajoules per kilogram and uranium was almost like 80,000. So even with that massive increase in the amount of power that you get, that that doesn't do enough to even nearly offset the shielding. Is that the message here? Yeah, exactly. You either need a lot of shielding or you need to not worry about your crew. And it was actually a time when people talked about only having crew that were like past childbearing age or had a terminal disease anyway. People seriously talked about this kind of stuff. Like the documents from the Cold War are crazy. You're going to die anyway. Fly on our plane. You always wanted to be a pilot, right Craig? And basically every step you take to make these things more safe makes them impractical because now they're too heavy.

So not just the shielding, but also the cooling systems, right? You want to generate this heat, but you also don't want to overheat the rest of the airplane. And you want to have devices in place to protect yourself against meltdowns and all sorts of other issues. And so all these cooling systems and safety systems and all that shielding just gets heavy. And I think perhaps the biggest dagger in this idea to me is that if something goes wrong and you crash, you spread nuclear material across a large area, probably, which is a problem. Yes, poisoning the earth bad, for sure. And it's definitely something people think about also when we go into space with nuclear power. Like every time we launch a rover with a blob of plutonium in it, we worry, like, is this going to be the time it blows up in the atmosphere and then spreads that plutonium on. our planet, it's a risk every time they do it. And so they worry about it. But those are pretty

rare launches. Oh, you mean, is this going to be the second time? Yes, exactly. The next time. The next time. Yes. But if you're talking about regularly flying bombers or even commercial airplanes around the world with nuclear power, then you're constantly taking that risk. And, you know, crashes happen and they kill people and you don't want to then compound the dangers and the consequences by also poisoning the planet. when especially if these planes are being used as like weapons of war or surveillance things and you know other countries might specifically be trying to shoot them down that seems bad yeah although maybe a country won't shoot down your spy plane if they know that they're going to be like contaminating their land with radioactive waste so oh you forgot that in the pro section Daniel it's like the poison pill but you know realistically and maybe sadly if you ask me like why aren't there nuclear powered airplanes right now I don't think that's the reason. I think the reason we don't have nuclear-powered airplanes are not because they aren't safe or they would kill your crew. I think that people would make those compromises if they thought

it was good for our military or our strategic situation. The reason I think is actually just strategic that nuclear-powered bombers are no longer the quiver we thought we needed in our arsenal. Is that because satellites are so good? We can just spy from there? Or, yeah, why? I think the reason is that you don't need nuclear bombers. You don't really need bombers anymore. I mean, we have ICBMs. We can deliver nuclear weapons from the planes of Montana without putting any humans in the air. And we have nuclear-powered submarines which can sneak around the oceans and send nuclear weapons to anywhere on Earth very quietly.

So you don't really need nuclear-powered bombers to stay aloft for 24 hours anymore. We can already bomb people with impunity. Oh, yay. And I think that's probably the reason we don't have it. All these other concerns are reasonable and it makes it impractical and it makes it unsafe. But I think because it's not strategically valuable is probably why we don't actually have them. I guess we should all be glad that we have ICBMs instead. I suppose.

But of course, the U.S. spent billions and billions of dollars and more than a decade trying to build nuclear-powered airplanes and they actually flew airplanes with reactors. on board. Were these jet engine reactors like you were talking about? No, we've never actually flown an airplane that was powered by the reactor, but they did fly airplanes that had reactors on them. All right, let's take a break, and then you can tell us more about that. A foot washed up a shoe with some bones in it.

They had no idea who it was. Most everything was burned up pretty good from the fire, that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA right now in a backlog will be identified in our lifetime. A small lab in Texas is cracking the code on DNA. Using new scientific tools, they're finding clues in evidence so tiny you might just miss it. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha.

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and how breaking up with perfection can actually free us. Plus, if you're someone who gets anxious about flying, don't miss Session 418 with Dr. Angela Neil Barnett where we dive into managing flight anxiety. Listen to Therapy for Black Girls on the iHeart Radio app, Apple Podcasts, or wherever you get your podcast. Get fired up, y'all.

Season two of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people and an incomparable soccer icon Megan Rapino to the show and we had a blast. We talked about her recent 40th birthday celebrations co-hosting a podcast with her fiance Sue Bird, watching former teammates

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So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Presented by Capital One, founding partner of IHeart Women's Sports. The OGs of Uncensored Mother are back and badder than ever. I'm Erica. And I'm Mila.

And we're the host of the Good Mom's Bad Choices podcast, brought to you by the Black Effect Podcast Network every Wednesday. Historically, men talk too much. And women have quietly listened. And all that stops here. If you like witty women, then this is your tribes. With guests like Corinne Steffens. I've never seen so many women protect predatory men.

And then me too happened. And then everybody else wanted to get pissed off because the white said it was okay. Problem. My oldest daughter, her first day in ninth grade, and I called that. I asked how I was going. She was like, oh, dad, all they were doing was talking about your thing in class. I ruined my baby's first day of high school. And slumflower.

What turns me on is when a man sends me money. Like, I feel the moisture between my legs when a man sends me money. I'm like, oh my God, it's go time. You actually sent it? Listen to the Good Mom's Bad Choices podcast every Wednesday on the Black Effect Podcast Network. The IHeart Radio app, Apple Podcast, or wherever you go to find your podcast. Okay, so now we're back. So you said that a plane has flown with a nuclear reactor on it.

Was that plane just transporting the reactor from one place to another? Or, yeah, why would you want to carry nuclear material with you on a plane? You don't pack nuclear material every time you take a flight, Kelly? Not yet, but if it was strategically valuable, maybe I would. Yes, you might. Now, this was like the first step in the U.S.'s exploratory project to build nuclear power aircraft. They thought, well, first, let's try to fly an airplane with a reactor on board, study the shielding issues, the safety issues. Can we actually get this thing working and operating in the environment of an airplane before we actually try to connect the reactor to the engines?

So in the 50s, they had this project using a modified B-36 bomber with a working nuclear reactor on board. So you have your standard jet engines flying this airplane, but in the center you have a miniaturized reactor designed specifically for flight. Wow. Okay. And so, so that this comports with your, even if it's hard, we'd do it if it were strategic because this was, what decade were they trying this? This is in the 50s. I'm going to assume that in the 50s they had enough shielding. Is that true? Or were they able to do this because they, you know, forewent shielding for this experiment? Well, both, actually. They put a lot. of shielding. So this is like an 18-ton reactor producing one megawatt. And they had it in this special version of the aircraft where the humans would live in this little pod, this like special cockpit that was super shielded. You have 12 tons of lead and rubber that the humans would get in

and the rest of the airplane would just be like totally irradiated. And this little pod has like windows in it that were like 12 inches thick and pockets of water to protect them. But still there was a lot of radiation, even though they were shielded, it was well above anything you would consider safe for the pilots. Oh, yikes. And if you ever need to do any work on the body of the plane, any technician who's working on it is going to be getting irradiated, right? Yeah, exactly.

The whole thing is going to be a disaster. And, you know, for this project, they only recruited pilots above childbearing age because they basically knew that they were killing these people. Oh, my goodness. You know, U.S., people above childbearing age are still valuable. Just throwing that out there. It's kind of amazing how they treated these things. Like, they knew that there were potential disasters, and they actually tried to plan for them.

Like, so this thing took flight in the 50s. They made 46 flights with this bomber. Wow. And every time they did, they also flew it with a special extra bomber that had specially trained paratroopers. That if this plane crashed, the paratroopers would jump out of the airplane, paratroop down to the crash site and seal it off. They were like nuclear-trained paratroopers to help trying to contain a disaster. Were they all also above childbearing age? Yes, and they all wore lead underwear.

Oh, good. Good plan. Although it's too late, I guess. But so when they were flying over the Southwest, were they specifically trying to fly over portions of the Southwest that are not populated? I mean, like those paratroopers aren't going to be helpful if it lands in Phoenix. You know, I hope so. I don't have any details to back that up, but I certainly hope they do.

But, you know, this thing was airborne over the Southwest, 46 times in the 50s. So they definitely took a risk. Did it ever crash? This one never did crash. But they tried to estimate what would happen if it did crash. They created some situations where they, like, put a fuel rod into a burning jet engine in Idaho. So they did these experiments. And this is pretty bad.

Those experiments ended up, like, releasing quite a bit of cesium-137. into the air above Idaho. Yeah, it was pretty bad. And they called this test Operation Weiner Roast because they used a bunch of live cattle at varying distances to help measure the effects of the radiation. Wow.

I mean, they clearly should have been using dachshunds, those little weiner dogs. So I was scoffing because that was really a missed opportunity. You have just pissed off a lot. of dog owners out there, Kelly. I'm sure I have. That's right. So this is like a real government program.

You know, they invested a lot of money into this program. Billions of dollars, decades of research to try to make this thing happen. And they got as far as flying airplanes around with nuclear reactors on board. That's, that's pretty far. Just to confirm, we've never flown anything that was actually powered by the nuclear power source, right? It's just been sort of carried along like a purse. Exactly. We got as far as airplanes with nuclear reactors on board and then on the ground nuclear powered jet engines that never flew. But we never put them together into an airplane

that was powered by a nuclear reactor. Okay. So there's always a Soviet equivalent to these sorts of things. So did the Soviet Union have a similar project? Of course they did. In the 50s, the Soviet Union had a project to fly one of their enormous TU20s. If you haven't seen a picture of one of these things, this is like a really incredibly huge bomber with this really elegant swept wing design. And they were working on a similar project. Details are a little bit sketchy. And part of the information is a little confusing because in the 50s, there was an article in Aviation Week that turns out to be having mostly filled with false information, claiming that the Soviets were already testing a nuclear airplane that was powered by nuclear power.

It turned out to be misinformation, but, you know, it kept the U.S. program going for a few more years. But the Soviets ended up coming to the same conclusion we did, which is that there's a huge radiation hazard to the crew, and the crash risks were significant, and so they abandoned the projects right around the same time we did. Presumably, they also had ICBMs and stuff, and so they had the same capabilities without the technology, just like we did, right? Or were they behind on ICBMs? No, that's exactly right. And so in the early 60s, both programs were abandoned because people realized that nuclear-powered submarines and ICBMs filled the strategic need in a much simpler way than nuclear-powered aircraft. All right. So does that mean that both Russia and the U.S., like no country on Earth right now was working on this program because we all have better ways to do this? Is that right? Yes and no. No country on Earth that we know of is trying to fly an atomic-powered aircraft with people on it.

But the Russians claim to be working on and have developed a nuclear-powered cruise missile. A cruise missile is basically like an unmanned aircraft. It can fly, it can loiter, it can turn. It's not just like ballistic. You're not just like throwing a bomb. It has like engines and it can steer, et cetera. And the idea of a nuclear-powered cruise missile is still kind of attractive because it would have basically unlimited range. This thing could take off.

It could fly around the earth a couple of times. You could even like hang out for a while, like doing loops, you know, take the long path over in the North Pole or something. And so Russia claims to be working on this thing. It's called the SSCX-9. And in October 2023, Putin claimed that they tested it successfully, though a lot of people are pretty skeptical. Yeah, I mean, that guy always tells the truth. So slam dunk, we've got to believe it. Huh. Do you really need a cruise missile that can, like, circle the world four times?

Why not just, like, know where you're going to shoot it off and shoot it off from one spot using another fuel source and just get there right away? Yeah, a lot of these Russian modern weapons programs seem kind of bombastic and unnecessary. Like, he's also talking about his supersonic missiles. It's like, you know, do you really need supersonic missiles? Are there really advantage to that? I think a lot of this stuff might just be PR. I think Putin wants to advertise to the Russians that their military is cutting edge, that they have advantages over the West, et cetera, et cetera.

So analysts that I've read suggest that a lot of this is just for internal propaganda, not actually military strategy. I can believe that. All right. So let's bottom line this. Give me the summary, the take home points for the nuclear plane story. So a nuclear powered airplane is possible. Physics says you can do it. You put a reactor on board, we have the techniques, we've proven that you can build a nuclear-powered jet engine.

The problem is the way it becomes very impractical. If you want your crew to survive, then you've got to shield them from the nuclear reactor, and that's going to make your plane very, very heavy. In addition, the crash risks are significant. So it's possible, but dangerous and kind of impractical at this point, and not really necessary anymore because we have other weapons that fill the strategic, niche that originally motivated the idea of nuclear power aircraft. So really the only remaining reason to do it is like, ooh, it kind of sounds cool.

Also, if I'd gotten my kids all excited about flying on one of these nuclear-powered airplanes, you're telling me I'd have to let them down by saying, oh, Daniel got you excited about something that isn't really going to happen. It's not strategically helpful. Sorry, kid one and kid two. They'd be very disappointed. Yeah, exactly. So unless you're like a nuclear nerd who likes to think about nuclear power.

powering everything and new ways to do stuff and you want to have like a nuclear toaster on your kitchen. There's not really a good reason to even consider nuclear power airplanes. Is this a material science question? Like if we can find a much, much, much better shield that's light than suddenly this all becomes a better idea or does such a thing not exist? From the physics point of view, really shielding is just about having enough high Z atoms between you and the source. So it's hard to imagine how you're going to do that without a lot of high Z atoms, which are pretty heavy. So unless you come up with a new way to do nuclear power, which doesn't produce the same

kind of radiation, like, for example, if you had a mini fusion reactor, or a fusion reactors don't have the same kind of radioactive output. So a fusion powered airplane, that might be possible. But first we have to get fusion to work like on the ground before we can get it to work in the air. Well, that's a big ask. We've been saying we're pretty close for 50 years. But there are some pretty cool companies doing some cool work.

So hopefully we get that eventually. Yeah. And maybe eventually they'll develop fusion and then they'll miniaturize it. And maybe we'll have fusion powered airplanes because also the fuel for fusion is just hydrogen. And so it's not as dangerous. So a crashed fusion powered airplane wouldn't be any more dangerous than a crashed diesel powered airplane. Safe is cool. I like it.

All right. And so while it's fascinating to think about how. discoveries in physics can change our world, allowing us to create devastating weapons and also sources of clean energy, they don't always necessarily translate to changes in technology that affects our daily life. Sometimes the old ways are better. Yay! Thanks very much for joining us today, everybody, and thank you, Kelly, for taking this trip on a nuclear-powered podcast. Thank you for having me. It's been a blast as always. All right, tune in next time. For more science and curiosity, come find us on social media where we answer questions and post videos.

We're on Twitter, Discord, Insta, and now TikTok. Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. Culture eats strategy for breakfast, right? On a recent episode of Culture Raises Us, I was joined by Belisha Butterfield, media founder, political strategist, and tech powerhouse

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podcast. The U.S. Open is here and on my podcast, Good Game with Sarah Spain. I'm breaking down the players, the predictions, the pressure, and of course the honey deuses, the signature cocktail of the U.S. Open. The U.S. Open has gotten to be a very wonderfully experiential sporting event. To hear this and more, listen to Good Game with Sarah Spain, an IHeart Women's Sports production in partnership with Deep Blue Sports and Entertainment on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. Why are TSA rules so confusing?

You got a hood of you. I'll take it all! I'm Manny. I'm Noah. This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that. Why are you screaming? I can't expect what to do. Now, if the rule was the same, go off on me.

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