No, this Isn't How Plutonium is Made - Nuclear Engineer Reacts

Added: 2026-05-12

[00:00:00]while the resulting plutonium 238 shows purple or magenta tone.

[00:00:04]>> Okay. Now, today we're going to be looking at a video called How Plutonium is Made by X Product. And according to this, it looks like they use really long Nickelodeon green slime chambers. Let's see what this is all about.

[00:00:19]>> Imagine a stainless steel container no larger than a soda can filled with plutonium 238 oxide.

[00:00:26]This material can generate enough energy to propel a spacecraft to the >> Yes, it can. That one soda can can make a sci-fi space station. Oh, this is off to a great start.

[00:00:38]>> Outer reaches of the solar system.

[00:00:41]>> Yes. And be careful not to shake that soda can. All right. So, plutonium 238 does not propel anything directly by itself. It provides heat which is converted to electricity in what's known as a radioisotope thermmoelect electric generator or RTG. So it's more like a battery than a rocket engine. But how can something so small hold so much power? To find out we go to the Oakidge.

[00:01:07]>> Okay. Holding power is at least a better analogy. It's more of a cuz it effectively acts more like a battery than you know a thruster. At least what most people think of the things. Bridge National Laboratory to discover the fascinating process of producing plutonium 238, the fuel that takes humanity to the stars.

[00:01:26]>> Uh yeah. So just to be clear, it's not a commonly used ingredient in rocket fuel or anything like that. So when he says the fuel that takes humanity to the stars, well, it's mainly used on long range probes and unmanned vessels.

[00:01:45]It's just not energy dense enough in terms of how much energy is released to generate enough thrust to get humans to go to the moon or Mars or whatever.

[00:01:58]So, it's it's a very useful uh space exploration tool for what it's designed for, but it's not he's framing it like it's the only fuel source or something, which just isn't at all true.

[00:02:15]The story of plutonium begins in 1941 when >> love the AI voice and the dramatic music.

[00:02:21]>> Glenn Seabborg and his team at the University of California, Berkeley discovered this synthetic element by bombarding uranium 238 with neutrons in a cyclron.

[00:02:32]>> So a cyclron is not a neutron source. I mean they bombarded uranium with duteron. So dutyium hydrogen 2 that is to say a nucleus consisting of a proton and a neutron that ends up producing neptunium which decayed into. So cyclron is not a neutron source in the same way that you have say a startup neutron source in a nuclear power plant. Shortly after, during the Second World War, the Manhattan Project used the File >> uh project.

[00:03:06]This is good, isn't it?

[00:03:08]>> Plutonium 239 to develop the Fat Man bomb detonated over Nagasaki on August 9th, 1945.

[00:03:16]This explosion released an energy equivalent to 21 kilotons of TNT.

[00:03:21]>> Okay, they got that part right.

[00:03:23]>> As if an entire city had exploded in an instant.

[00:03:27]Okay.

[00:03:29]No. Um, it's a city. It wasn't a big fuel depot or something that was entirely volatile and nuclear explosion.

[00:03:40]So, they have various means of causing destruction. There's the there's the initial fireball, which happens in a fraction of a second. There's the blast that does the majority of the damage.

[00:03:50]Then there's the thermal radiation, the thermal pulse, which sets things on fire. But destruction is also going to depend on the urban layout. So the point is the entire city didn't doesn't explode.

[00:04:06]It didn't create cause some sort of chain reaction event within the city itself. The chain reaction happens within the weapon and is long done, long gone. All the nuclear reactions already took place long before you even see the fireball. So it's it doesn't result in the entire city exploding. It devastates it, sure, but yeah, it's not like you're chaining explosives together, >> marking a before and after in human history. Thanks to its ability to sustain chain reactions, plutonium 239 became a key element during the cold war with facil.

[00:04:48]>> Okay, they're showing the Hanford >> facilities like Hanford producing tons of this material. But our focus is on a different isotope, plutonium 238. Unlike >> I'm thinking there's this thing is aggregating a few different languages here or something. I don't claim to know how AI tools work. like 239. It is useless for weapons because it releases a large amount of heat and alpha radiation.

[00:05:13]>> Okay, so plutonium 238 does have high decay heat plus high spontaneous vision rate. So that is to say a neutron background will occur in the presence of plutonium 238. So it does make weapon design with him extremely impractical.

[00:05:30]Technically not impossible, but yeah, for all intents and purposes, you don't want it if you're designing weapons. You want plutonium 239. Plutonium 239 is more energetic. It releases more energy from fision. You even see that in nuclear power plants because nuclear power plants use lowenriched uranium 235. So it has a lot of uranium 238.

[00:05:51]Well, that uranium 238 can still absorb neutrons. Turn into uranium 239. A couple of beta decays later, well, you get plutonium 239. And you just fision it as part of a normal nuclear fuel cycle. Now, it's more energetic relative to uranium 235, but we're not talking bomb levels in a nuclear plant. It just means the reactions respond a little bit faster towards the end of core life as a greater percentage of it becomes plutonium based rather than uranium based. So, it's actually a good thing because it makes the reactor a bit more fuel efficient when this since this process occurs. But in nuclear power plants, you're talking slow, methodical, controlled reaction, very stable for 18 to 24 months at a time, >> making it unsuitable for explosive fishision. However, these same characteristics >> sci-fi space station >> make it the perfect energy source for space exploration. In the 1950s, NASA discovered that plutonium 238's decay generates constant heat.

[00:06:54]>> Now, they say this orange bit is true. I mean, that's you're you're seeing decay heat from plutonium 238, but they always like to include the green stuff in the thumbnails, which I think is hilarious.

[00:07:05]>> For decades, ideal for missions in the darker regions of the solar system where sunlight is not enough.

[00:07:12]>> Yeah. So, plutonium 238 has a halflife of about 85 87 years. And it has very predictable heat output cuz that's one thing about RTGs or really anything with stable amounts of heat. It's just very predictable. So something at a low power level but sustained. So you can also use plutonium 238 in remote Antarctic monitoring stations for instance. Things that you really don't want to send someone out to replace and they could just sit there for decades. So, not just spacecraft, but also remote monitoring.

[00:07:50]So, things that don't necessarily take a whole lot of energy to use, cuz once a spacecraft is in space, you don't really need the intense rocket propulsion anymore because you've already sent it on a course. It's not really needed for a course correction anymore because I mean plutonium 238 again is not going to generate massive amounts of uh energy that can be converted into thrust or things like that but it's mainly for instrumentation sensors that sort of thing. I mean you could theoretically do it but it would just it would take a lot of stuff. We're talking something that's on the order of watts of energy, not kilowatts, megawatts, gigawatts that you see when you think of in nuclear power plants on Earth, >> such as the orbits of Jupiter or Saturn.

[00:08:38]In 1961, the first radioisotope thermmoelectric generator using plutonium 238 powered the transit 4 satellite.

[00:08:48]Since then, iconic missions like Apollo 11, Voyager 1 and 2, Cassini, and the Curiosity rover have relied on this element to operate in the darkness of deep space.

[00:09:00]>> So again, he's saying using plutonium 238 um showing images of rockets and stuff.

[00:09:08]It's not powering that like in the context of Apollo 11. No, no, no. It did not power the propulsion system of the lunar lander and Apollo 11 plutonium 238 powered heaters just to keep instruments warm enough to function on the moon.

[00:09:25]Not as sexy as rockets, so I get the reason of showing rockets, but it's just a bit of a bit of a disconnect there.

[00:09:32]>> A typical generator with only 4.8 8 kg of plutonium 238 can produce about 110 W of electricity. Enough to keep scientific instruments running for 15 years or more. Okay, that part they got right. I'm actually uh I don't know, maybe my my expectations with some of this have dropped a bit, but I was thinking they were going to say it produces about a couple of kilowatts, but it produces a couple of kilowatts thermal and its electrical output is only about 100 or so. So yeah, very low efficiency, but that is the real engineering tradeoff here. Something that you don't need to replace. It's very inefficient, but it's steady and it will get its job done. Compare that to a nuclear power plant or anything operating really in a steam cycle that you're talking numbers in the 30 to 40% range. Really, really closer to 30. 40% you're looking at the ideal uh carno heat engine there. But yeah, these um RTGs are not built for efficiency.

[00:10:37]They're built for let them do their thing and forget about them.

[00:10:41]>> Like a small engine that never stops >> in a way of speaking. Sure. Though there's no moving parts here. That's one of the reasons why you can say something like that. I mean, it's just the thermmoelectric effect, the the Cvec effect. basically have a hot brick wired to a voltage generator. Very simple.

[00:11:01]>> But how is this material which sustains our planet's space exploration actually made?

[00:11:08]>> I love this space station here. I I don't even know what it what it's from as I'm sure it's just generic AI generated space station.

[00:11:16]>> Production begins with Neptunium 237, an actonide derived from nuclear reactor waste. The same >> Mhm. nuclear capture chains >> type of waste that in the 1940s and50s fueled the production of plutonium 239 for weapons. This material arrives at the Oakidge National Laboratory in Tennessee as a 30% nitric acid solution with a dark green color like a concentrated spinach juice. Okay, so he this is where he gets the green stuff.

[00:11:47]So the color descriptions aren't necessarily reliable. Meanactide solutions can vary just by chemical properties, not nuclear properties.

[00:11:57]Based on its oxidation state, based on the lighting in the room, this is not particularly relevant here. So, it's like, uh-oh, it came in as a light green nitric acid solution. That that that by itself doesn't really tell you anything.

[00:12:16]The first step is to transform this solution into a solid in a sealed chamber. The solution is pumped through a stainless steel rotary kil 2 m long.

[00:12:25]>> There he's showing a trigger pulse reactor. Has nothing to do with what he's talking about. That's Oh man.

[00:12:36]>> Inside a glove box with lead walls 5 cm thick to protect workers from alpha and beta radiation. Operating at 800° C, the kiln evaporates the acid in a controlled process lasting about 6 hours, leaving a fine neptunium oxide powder with a >> Okay, so we're talking about um chemical processing while you're showing people moving fuel in a small test reactor. I mean, the audio is right using a kiln, denitration, calcination. Sure.

[00:13:09]a sandy texture and a slight metallic sheen similar to the sand on a volcanic beach. This powder is mixed with aluminum powder in a precise ratio of 80% neptunium oxide to 20% aluminum which >> I guess I mean aluminum acts as a matrix for the radiation and the exact composition could vary based on the program. This 8020 rule isn't a hard and fast thing. At least not that I'm aware of. For all I know, he just used the paro principle and just applied a generic 80/20 rule that works about 80% of the time.

[00:13:45]>> Acts as a binder to facilitate pressing.

[00:13:48]The mixture is transferred to an automatic pellet press, a high-tech machine that works with the precision of a chef shaping perfect cookies. Before >> again, he's showing uh refueling operations for all this. That's it's not really it's not related. This is chemical engineering and fabrication is what he's describing.

[00:14:07]>> Pressing the mold made from hardened steel is cleaned with automated brushes and lubricated with a graphite-based compound to prevent the powder from sticking. The powder is poured into a titanium funnel. I love this inspirational music. Ram applies a pressure of 2,000 kg per square cm, forming cylinders 2.5 cm long and 1 cm in diameter, each weighing 7 g. These pellets must be uniform to with >> I don't know these numbers. Um I mean sure there's precision manufacturing going on here but >> stand the extreme conditions of irradiation with a standard as strict as assembling components in a Swiss watch.

[00:14:51]I I don't think we're talking Swiss watch stuff here. I So, it's about uniform neutron exposure and thermal behavior in a reactor. It's not whereas the whole Swiss watch thing at least. I just think of the aesthetics and the whole I don't know. I maybe that comparison does hold merit. It's just not the first thing I think of.

[00:15:12]>> Each pellet underos thorough quality control in a sealed chamber. Four precision lasers measure the diameter in two different points with a tolerance of 5 microns. While a vacuum device equipped with optical sensors verifies the length. Atomic emission spectrometers analyze the chemical composition to detect impurities such as carbon, iron or magnesium, which could alter the nuclear.

[00:15:36]>> That's important.

[00:15:37]>> Approved >> mainly cuz they could just either get in the way, potentially attenuate, potentially scatter. Anything with nuclear physics, you're looking at probabilities and odds of interaction.

[00:15:46]That includes nuclear power plants, but that also includes any sort of material fabrication using a reactor.

[00:15:52]>> Moved pellets are placed on a transfer device called a boat, a stainless steel tray that carries them.

[00:16:05]I don't know why I found that so funny.

[00:16:06]It's like, maybe I'm going to work now.

[00:16:08]I'm using a transfer device called a car.

[00:16:12]It's just so I I I don't know what to say about that.

[00:16:16]>> To the next stage, like a train transporting valuable cargo to its destination. A single boat contains >> and they're all showing like refueling stuff and they showed a bit of an underground repository. And >> enough material for one target to be irdiated. The pellets are inserted into aerospace grade aluminum tubes.

[00:16:35]>> That's dry cast storage right there.

[00:16:38]Okay. 30 cm long and 2 cm in diameter, sealed hermetically by laser welding to withstand temperatures of up to 1,000° C and extreme pressures. Each of the >> I mean, so there's some relevance here.

[00:16:53]Okay, there there is welding shown on when you weld the uh cast when it's closed after you've offloaded the reactor from or not the from the reactor, you offload fuel from the spent fuel pool that has sat in there for years to where it's decayed low enough that you put it in the dry cast. It's not really relevant to what he's talking about, but I guess it's like, hey, cool nuclear related welding.

[00:17:20]Awesome. These tubes known as targets holds between 20 and 30 pellets stacked with great precision by robots that use smart cameras to avoid errors. Then at the high flux isotope reactor in Oakidge, these tubes are exposed to an intense stream of neutrons for several days. This expos Okay, so the important part is neptunium 237 to plutonium 238 via neutron exposure. That's the core physics in where it comes from.

[00:17:50]Neptunian 237 neutronian 238 beta decay plutonium 238 neutron capture plus decay mentioned several days of a radiation production you're looking more at weeks to months I mean I guess you could argue that's several days but a week's not enough typically >> exposure transforms part of the original material neptunium 237 into plutonium 238 the result each tube produces about 4 g of plutonium ium oxide which >> maybe I mean it's going to be configuration dependent here >> is the material used as an energy source however this process is not clean it also generates radioactive waste such as cesium 137 and strontium 90 >> no it does not fision products plutonium 238 production is primarily neutron capture not fision so it's possible you could get some cuz again there's the whole spontaneous vision thing that is less likely from your external source but not the main pathway and the amount you get compared to say in any nuclear power plant is going to be not very much even taken into account percentage-wise just because it's a completely different not only are you dealing with smaller quantities but you're dealing with a very different uh mechanism of what nuclear reaction is taking place here >> the same isotopes that once made it extremely difficult to purify plutonium 230 39 for the first nuclear bombs in the 1940s.

[00:19:23]The facilities >> in trace amounts maybe >> are protected by reinforced concrete walls 1.5 m thick designed to withstand magnitude seven earthquakes or direct impacts like a bunker guarding a treasure. Radiation, temperature, and pressure sensors monitor the reactor core in real time with automatic systems that can shut down the reaction in less than 1 second if an anomaly is detected.

[00:19:48]Okay, so that's a reactor trip various reactor protection system. I mean, you would still have these things in a nonpower reactor, a fabrication reactor that they would rapidly insert their control rods, reduce reactivity rapidly.

[00:20:02]Could you do it in less than a second?

[00:20:03]Well, a typical nuclear power plant, it's more like twoish, but this one's smaller. And really it's kind of how fast are the rods falling to hit and shut down the reactor in less than 1 second maybe but if not certainly less than three. During irradiation the neptunium emits a dark green glow while the resulting plutonium 238 shows purple or magenta tone.

[00:20:28]>> Okay. No, there's no visible glow under normal conditions. I mean are what are you doing? Are you shining it with UV light or something? That doesn't count.

[00:20:36]any glob nuclear systems you're going to have like the Cheronov blue in water and that's mainly driven by the in water part of it as in particles moving faster than light in water color changes are not process indicators here and come on >> through leaded glass windows this change in color is a visual sign that the process is advancing correctly >> no it's not >> after irradiation the targets are intensely radioactive with gamma radiation levels of up to 1,000 rads per hour.

[00:21:09]>> Oh, come on. Red is absorbed dose. I mean, yes, it's a real unit, energy per unit mass, but it's not typically what's reported for operational exposure.

[00:21:19]You're going to put it in REM or severs cuz that takes into account the effects on the human body. You can tell this is just and I moved to hot cells, shielded enclosures with lead glass 1.2 2 m thick and liquid mineral oil as a barrier against neutrons like a strainer separating unwanted ingredients in a recipe.

[00:21:42]>> Okay, so yeah, hydrogenous material basically anything with water, concrete is good at shielding from neutrons. One of many reasons why reactor containment structures use concrete and why water is very effective at reducing ghost.

[00:21:59]Robotic arms controlled by hydraulic systems with millimeter precision cut the aluminum ends off the targets using automated diamond saws. Between 20 and 30 targets are placed in a stainless steel tank known as a dissolver equipped with corrosion resistant piping. The chemical process begins by dissolving the aluminum with 10% sodium hydroxide.

[00:22:22]A procedure that >> we're just showing like remote operations here. Yeah.

[00:22:28]Uh, I feel like I feel like I'm watching something that like what's the opposite of picturein picture when you're just showing like an unrelated video and you're there's a bit just a bit of an out of sync element with what they're talking about and what they're showing.

[00:22:45]>> Takes 4 hours and leaves the neptunium and plutonium oxides intact. Then concentrated nitric acid is applied to dissolve the actctonides separating them from the fish products. The solution passes through ion exchange resin columns which >> again mentioning fision products. I mean uh >> selectively trap plutonium 238 with 95% efficiency while >> I mean that's plausible but I I don't know what to believe anymore. The neptunium and wastes such as iodine 131 are discarded like a coffee filter that retains the grounds but lets the liquid pass through. The plutonium precipitates as a bright purple powder with a >> okay so plutonium compounds can vary in color and the whole statement again of hey just when it changed to this color that means you know it's good. That's not the case. It's not a reliable or meaningful indicator. And that I think there is a misconception here that nuclear processes are like chemical processes. When you look for like a change in in color or skate or some sort of other chemical process like if it's a liquid if it gets all you know cloudy or something then a precipitation event took place. That's not really relevant to a nuclear reaction, at least in as far as did this create plutonium 238 or get it to the desired level of enrichment or what have you. Cuz I saw this I've seen this misconception with enriching uranium as well, like implying that uranium 235 and uranium 238 are chemically different when they're not.

[00:24:26]They're chemically identical. They're just their nuclei are different. And that's just has to do with the difference between chemical processes versus nuclear processes.

[00:24:36]>> The radioactivity of 17 curies per gram and is washed with >> Okay. All right. That's something else they got right. That's pretty solid for plutonium 238. And that's that that's a very high number for specific activity.

[00:24:50]A cury is a big unit. It's 37 billion disintegrations per second. Most radiation sources are typically given as micro curies or nano curies in terms of activity. So that you have 17 full-on curies. Yeah. And that's essentially to how plutonium 238 operates and that's why it makes so much heat >> with oxylic acid solutions to remove trace impurities. The plutonium oxide is pressed once again into pellets with 90% purity.

[00:25:21]>> Oh, and then some mining. And then we cut to different types of uh assembly fabrication. All right.

[00:25:28]>> 400° C for 8 hours in sealed furnaces with an inert atmosphere to increase its density. These pellets 1 cm in diameter are encapsulated in stainless steel containers designed to withstand extreme heat and radiation for decades. A container with 150 g of plutonium 238 generates 84 W of thermal power. Enough.

[00:25:52]Yep. Plutonium 238's about half watt per gram thermal >> to power the systems of a spacecraft like the Perseverance rover for one year.

[00:26:01]>> Okay. Yeah. Rovers don't those little rovers don't use a whole lot of power.

[00:26:07]>> Before these containers can be used, they undergo a series of rigorous tests in specialized laboratories. They are scanned with X-rays capable of detecting tiny cracks smaller than a human hair.

[00:26:19]>> Don't put them in a pulse reactor. Then high precision scales verify their weight with a margin of error of only half a millig. They are also subjected to vibration tests to simulate the forces of a space launch and chemical analyses are performed to ensure that the material's purity exceeds 99.

[00:26:38]>> The clips are on a loop >> 9.9%.

[00:26:41]>> Once they pass these tests, the containers are stored securely in reinforced concrete vaults at Oakidge.

[00:26:47]There special ventilation systems with HA filters capture any radioactive particles. From that location they are transported to the >> Okay, this is installation of dry cask in an underground repository. Cool but very different.

[00:27:04]>> Los Alamos National Laboratory where they are finally integrated into radioisotope thermmoelectric generators.

[00:27:10]>> So um sure we don't have to go to Los Alamos. They can go to Oakidge as well as other sites. And here we're just talking about the US, but okay.

[00:27:21]>> Known as RTGs, V RTG contains 4.8 kg of plutonium 238 and can generate enough energy to keep a spacecraft operational for more than 15 years.

[00:27:34]>> Not not this, not the rocket.

[00:27:38]This achievement stands in sharp contrast to the Cold War days when as much as 60 tons of plutonium 239 were produced annually for military use. Even at its peak, I don't know, more like the number I'm familiar with is like 100 tons total, not per year, like during the entire cold war. Today that same technology has been transformed to serve space exploration and other peaceful purposes showing the positive turn nuclear science has taken.

[00:28:13]Why is plutonium 238 the answer is its reliability? Unlike fossil fuels or solar panels, plutonium 238 provide >> Yeah, good luck using fossil fuels up in space.

[00:28:25]>> It's constant energy even in places where it is extremely cold or where sunlight never reaches. It can operate in extreme conditions such as the minus 150° C of space or the hostile atmosphere of Mars, powering cameras and scientific instruments for many years.

[00:28:44]In addition, its production reuses existing nuclear materials, generating very little radioactive waste, especi >> very little in terms of like weight, but it's still going to produce what's considered highle waste, the uh the transeuran waste. And it's very controlled and I don't mean to say it's excessive or anything but it just depends how you define it. So small quantity but large classification level in terms it does make high level waste that needs to be treated as such >> compared to the plutonium once used for making weapons.

[00:29:18]Safety is a priority throughout the entire process. The laboratories that handle it such as Oakidge are equipped with advanced systems that prevent any leaks or accidents. the demon core.

[00:29:29]>> Since the 1960s, more than 25 space missions have used this type of energy without incident thanks to highly resistant containers that protect the material.

[00:29:39]>> Talking about safety, show a picture of Demon Core, >> but its usefulness is not limited to space.

[00:29:44]>> So talking about no incidents, now they have survived launch failures and been engineered for containment. So the risk I would classify this as a mitigated risk, not absolute zero. You you really don't want to say risk of anything as absolute zero. That's uh it's just bad engineering.

[00:30:03]>> It has also been used to power scientific stations in extreme locations on Earth such as Antarctica or the ocean floor. The current challenge is that it is produced in small quantities and with new missions on the horizon such as those planned to explore the moons of Jupiter or Uranus. It will be necessary to increase production requiring coordination between scientists, engineers and governments and that is how plutonium is produced. Tell me what did you think of the process?

[00:30:34]>> Yeah. Um that that was an interesting one.

[00:30:39]All right. So, the hard part isn't the physics. It's very simple. Couple of basic nucle couple of basic nuclear reactions. One that effectively does itself for you. But it's the chemistry, material science, and reactor engineering required to make grams of the stuff at a time. This was a bit silly. Thanks so much for the recommendation, and thanks so much for watching. I'll see you next time.