How To Make A Nuclear Reactor Safe Enough For Children To Operate

[@dleddy14]

When I was 23ish (cerca 1989), Edward Teller visited Miami-Dade Community College, where my dad was the chair of the chemistry department, to give a talk to a small group of college staff, interested students, etc. The talk was in an otherwise empty room with foldy chairs for the attendees (I was one of them) and Teller. Teller, in his foldy chair at the front of the room facing the attendees, had a tall styrofoam cup of coffee on the floor in between his feet, and for the first ten minutes of the talk I kept thinking "man, he is going to kick over that cup of coffee". In about the eleventh minute, he interrupted his talk for a second and said "don't worry, I'm not going to kick over my cup of coffee."

[@tomburns70]

I know that you are talking about one of the most important men in History, but I bet very few knew he was a major figure in

[@tredogzs]

telepathic

[@Muonium1]

Most likely Teller was constantly acutely aware of where his foot was. Foot, singular, because of course he lost the right one in an incredibly gruesome accident when he jumped off a moving streetcar in 1928, fell, and it ran over his foot nearly severing it clean off. It had to be amputated and he was in pain for the rest of his life because of it. He wore a wooden one in its place and walked with a cane.

[@jaybee9269]

@@Muonium1 >> Aw, I didn’t know that. I am in pain as we type because I have one good leg.

[@dleddy14]

@@Muonium1 Wow I didn't know that.

[@AsbestosMuffins]

when you remember the guys designing this were doing so with paper, pens, and the field of nuclear physics being about 20 years old, its amazing they managed to accomplish so much

[@beeble2003]

And slide rules and adding machines. And probably some early computers. But never forget the slide rules. A skilled user of a slide rule isn't a whole lot slower than somebody using an electronic calculator.

[@PatrickKQ4HBD]

And don't forget a LOT less governmental regulation. We would have plenty of clean nuclear power if we were willing to accept just a smidge more risk.

[@rfichokeofdestiny]

@@PatrickKQ4HBD If common everyday items like cars and microwave ovens didn’t already exist, you couldn’t bring them to market today. Too expensive and too much legal risk. Imagine what amazing things we’re missing out on because of government regulation and a litigious society.

[@tomast9034]

yes...but..it took at least twice that long to build it.

[@beeble2003]

@@rfichokeofdestiny I think the fact that self-driving cars are becoming a thing clearly shows that society is not as cost- and risk-averse as you claim.

[@peterstickney7608]

In the early '60s, my father was doing a course of study at a research lab that had a TRIGA reactor (among others). One task that devolved to him, which he hated, was conducting tours - High School classes, Visiting DIgnitaries, and such. The highlight was to visit the TRIGA, which was dialed up to produce the expected Cherenkov Glow. On his first tour, Dad led the group in, looked into the pool, and said, loud enough fro everybody to hear, "Funny, it's never done _that_ before." He was taken off tour duty from that point on. While the fuel mix may still be Oxide, a lot of the TRIGA's features are built into the GEN III and GEN IV current reactor designs, which will fail safe in Loss of Cooling Accidents.

[@MEGAMIGA]

Nice one! XD

[@ian5576]

OMG, I am sooo going to use that line when giving my next tour!

[@MaxPower-11]

All these small, low-power research reactors are collectively known as swimming pool or open pool type reactors (with TRIGA being one such design). Many were built starting in the late-1950s through the 1970s at research institutions around the world. They generally operate at low power outputs, say 25MW or less, compared to typical nuclear power reactors which usually produce 700 to 2000MW thermal output. Besides research and non-destructive testing purposes, some are also used for the production of radiopharmaceuticals (isotopes used in PET scans, radiation therapy, and other nuclear medicine uses).

[@joshuahodge1181]

I love your name

[@jakobmax3299]

@@joshuahodge1181 I and Max power should marry, he gets my last name and when all the paper work is done we file for divorce. Voila Max Max

[@Blowfeld20k]

@@jakobmax3299 OK am onboard brother!! If you need an usher who won't take any shit, even from the sharpest elbowed relatives, gimme a shout cousin (wink) :D

[@spaceman081447]

@Max Power RE: "They generally operate at low power outputs, say 25MW or less, . . ." Reactors of that capacity would be perfect for start-ups of permanent manned installations on the Moon and Mars, and possibly for certain kinds of spaceship propulsion, as well.

[@daszieher]

​@@spaceman081447 one would not need to go into space for a good use. Look at, for instance, district heating or low power generation via Stirling engines.

[@berman00]

In my university in Argentina we have a small nuclear reactor for training, that was built by Siemens in the 70s to train the operators of the Atucha power plant. It still uses the original control panel and it is the coolest retro device I've ever seen, it has nixie tubes and a ton of analog instruments. The safety in this case comes from the fact that it produces very little power, half a watt maximum if I remember correctly, and it is surrounded by a massive lead wall. Another interesting fact is that in case of loss of power, the control rods are designed to spring UP mechanically, instead of falling down due to gravity like almost every reactor.

[@manatoa1]

Did you mean half a megawatt?

[@petrkubena]

@@manatoa1 Probably not, that would be insanely high for this purpose. Maybe half a kW. Ie in Prague there is a similar reactor intended for teaching nuclear engineers but with a configurable active zone and it has 100W heat output (500W peak).

[@n1352-m1i]

yet safetywise springing up is relying on the spring, not on the laws of physics (e.g. gravitation in reactors where moderating rods fall down)...

[@beeble2003]

@@n1352-m1i I think you've misunderstood. When people talk about the laws of physics making the reactor safe, they mean that it doesn't depend on a mechanical system but, rather, on the intrisic physical properties of the materials used. Moving control rods around is a mechanical system, regardless of whether it's done by springs or gravity. Or, to look at it the other way around, Hooke's law is just as much of a law of physics as Newton's law of gravitation.

[@thekinginyellow1744]

@@n1352-m1i Springs obey the laws of physics too!

[@davidelang]

I'd love to see more videos covering the small scale and inherently safe reactor designs from the last 20-30 years. there are a number of designs that are fail-safe in that they rely on neutrino mirrors and either moving the mirror or moving the fuel, so if power fails, the reaction will stop. I remember reading an article a decade or more back about pebble reactors (embed a chip of fuel in a pool-ball sized ceramic ball and then move them through the reactor with only a small number able to be in the focus at a time) There is far too little information about safe reactor designs and far too much fear of nuclear reactors being pushed.

[@gizmophoto3577]

I believe you mean mechanisms to reflect neutrons, not neutrinos.

[@davidelang]

@@gizmophoto3577 correct, thanks for catching that.

[@swizzlegrower]

Is that what they call pebble bed reactor?has it ever been proved..

[@gizmophoto3577]

@@swizzlegrower it’s my understanding pebble bed reactors don’t rely on movable neutron reflectors, though there could be designs I’m unaware of. Fixed reflectors can be found in many different reactor designs.

[@davidelang]

@@swizzlegrower I believe this is one of the things called a pebble bed reactor, I believe that there is another design also called a pebble-bed that is very different. In what I'm talking about, instead of a movable reflector, they instead move the 'fuel balls' through the focus of the reflector and each ball contains a small enough amount of fuel that if power is lost, the fuel in the focus will heat up more, but will be depleted fairly quickly, while the fuel outside the focus will not react significantly. The fuel balls are also extremely hard to extract the fuel from, so they could be manufactured with higher-grade fuel than would be desirable to have being shipped around in traditional-style fuel rods (again, going from memory from an article I read quite a few years ago)

[@CarlJacobsen]

Hey Scott, love your channel. The “I” in TRIGA is short, it’s pronounced more like “tree-guh”. Source: my dad worked at General Atomics. I heard about this reactor numerous times, growing up. One random story. They have a long pole they use, to manipulate things in the pool remotely (which may or may not have a length of line on the end, I don’t recall) - they called it the “fission pole” because it’s a bit like a fishing pole, and they’re using it with/over a body of water. Engineer puns.

[@francom6230]

Grammatically, a vowel before and after a consonant the first is pronounced hard... thankfully, language has much fungibiity

[@Milesco]

It seems to me that this whole "treega" vs. "try-ga" conflict could lead to conFUSION.

[@Myuutsuu85]

How in the world would you ever pronounce something that us written TRIGA as "tree-guh"? This sounds so wrong on so many levels.

[@Milesco]

@@Myuutsuu85 How do you pronounce the "i" in Nina, Mina, or Katrina? Or the name of the capital of Latvia?

[@TwoWholeWorms]

@@Milesco Niner, Miner, and Katriner. o.o

[@InvestmentJoy]

Bothers me to no end we can make low/no risk reactors with very minor waste and no one builds them.

[@SuperAronGamerMNO]

I had a debate with someone about nuclear power. I explained everything I knew about safe reactors, and the fact that we need nuclear power. After all of that, she had nothing left to say against me, but still refused to believe that nuclear power is a good option.

[@glennpearson9348]

I would assume fuel rods are the limiting component, but it may just be permitting for their construction and operation that is onerous.

[@InvestmentJoy]

@@SuperAronGamerMNO billions have been spent to condition people against nuclear. People operate on this pretense that all technology has improved extravagantly since the 60s, except for nuclear, and only nuclear. If they were to release a car today with the efficiency, emissions, and safety of an average car from the 70s there'd be outrage, yet the same people assume that a reactor from the early 70s is as good as it gets. It's the definition of insanity

[@InvestmentJoy]

@@glennpearson9348 it's permitting. You spend as much on planning and permitting to comply with legal requirements as the reactor itself. Meanwhile turkey, India and China are building giant, mega polluting coal plants and no one seems to notice.

[@glennpearson9348]

@@SuperAronGamerMNO It's hard to forget accidents like Three-Mile Island, Chernobyl, and Fukushima. You can explain it all you like, but some people aren't going to buy it. It's no different than people deciding not to fly because they saw a news story at some point about an airplane crashing and killing hundreds of people. Broadly speaking, humans have a very poor perception of risk factor analysis. We have these things called emotions that get in the way.

[@TheMichelFamily]

Scott, Loved the reactor video! My long-time friend, Dr. Keaton Keller, worked on the Manhattan Project. He taught me about the TRIGA and the aforementioned "Blue light" you spoke about in the video, Cherenkov radiation. (photons exceeding the speed of light, or trying to). The one thing you will find interesting that has NEVER been written about or published. Keaton and several coworkers "Took part in a nuclear chain reaction." They had a stack of enriched uranium bricks (sub-critical mass). The men had a live Geiger counter running on speaker. Tick..... Tick ... The group of men went up and put their hands on the pile, and the carbon in their bodies reflected the neutrons back into the pile, and the Geiger counter went crazy fast. When it did, they all backed off, and the pile went subcritical. Dr. Keller told me no one ever wrote about this, he thinks, because they knew it was a young men's foolish curiosity that could have been deadly.

[@RCAvhstape]

Sounds like the Demon Core nonsense that earned two cocky young men horrible deaths.

[@Muonium1]

I don't much doubt that this actually happened. After all, the moderating power of Harry Daghalin's own body was recognized as a factor in his own fatal criticality excursion misadventure. But it would have been the hydrogen in water and fat in the bodies of the men which was doing the moderating, rather than the carbon, of which there is only a few hundred moles in the average body, compared to the few thousand of hydrogen, and additionally the neutron scattering cross section for water is an order of magnitude greater than pure carbon.

[@TJ13062010]

I think he meant the carbon atoms and not pure carbon as in graphite or coal. As you said yourself: water and fat. Fat consists of hydrogen and carbon atoms (and a few oxygen atoms) only.

[@koka3243]

Cherenkov radiation is photons emitted (at exactly the speed of light in the liquid, since photons are quanta of light) by electrons moving at speeds greater than the speed of light in the liquid. The electrons are by-products of nuclear decay and have energy comparable to other products such as neutrons, but being 2000 times lighter than a neutron means they need to travel very fast in order to attain that energy, and thus easily exceed the speed of sound in the liquid.

[@insu_na]

@@koka3243 typo in the last sentence. good explanation tho!

[@tommythetoe]

That reactor design is amazing. I looked up the papers on it. Even with full power for extended time followed by a pulse followed by losing all the water you still do not get a melt down. the fuel rods stay intact. Thank you for this video

[@raul0ca]

Fuel rods are special. Designed by Iranian scientist working at General Atomics. Dude does not get enough credit

[@Bob_Adkins]

Maybe someday, but presently most people believe reactors all fail. Unless we overcome that dogma, our utility bills will become unaffordable to average people who will cut trees to stay warm.

[@S1nwar]

9:58 i did my physics diploma at the TRIGA in Mainz. we had a process that cools neutrons to "ultracold" temperatures meaning they wouldnt penetrate matter anymore so we could direct them through a metal pipe, trap them in a container and then let them flow out it into a detector like a liquid.

[@hammerth1421]

Neutron optics are black magic to me.

[@Muonium1]

@@hammerth1421 We do some neutron optics in the laser inertial confinement fusion world. Wild shit. It's basically just an arrangement of large bricks and slabs of polyethylene with a hole bored through the center that's some meters away from the target chamber and with a detector in the basement some several meters further away still pointed down the hole toward the target chamber. It's able to produce 14 MeV neutron images of the imploded fuel capsule cores with 10 micron resolution. I can't wrap my head around it.

[@petevenuti7355]

@@Muonium1 what's used for a camera sensor? Conventional Geiger counters don't even register neutrons, so it'd be interesting to see how that works!

[@Muonium1]

@@petevenuti7355 haha, I kid you not it's using oxygen saturated liquid xylene (💣💥!) doped with diphenyloxazole (PPO), and 1,4-bis (2-methylstyryl)-benzene (bis-MSB) as a scintillator coupled to a micro channel plate detector. See the paper "High-Resolution Neutron Imaging of Laser-Imploded DT Targets" for an older version using plastic scintillators.

[@S1nwar]

@@petevenuti7355 a typical neutron detector has a layer of boron which has a high chance of interaction with neutrons. after absorbing a neutron the boron will then decay into lithium + an alpha particle that can be detected by counting tube. our version was called a CASCADE detector.

[@fzbob2473]

Nice video, and excellent explanation. I studied Nuclear Engineering at Berkeley in the '80's and reactor lab was a major highlight. Our TRIGA reactor was deep under the vollyball court next to Etcheverry Hall. Very few students knew they were walking over the top of a nuclear reactor on the way to class! We all looked forward to seeing the reactor pulse. My recollection is that it was like a flashbulb going off. Back then there was a rubber duck floating around in the reactor pool. One time we were down in the lab and got a call from upstairs asking if we had felt the earthquake. None of us felt a thing, but apparently it was a pretty good quake - it made the nightly news and was felt all over the Bay Area. I recently met the demolition contractor who removed the reactor lab when it was decommissioned to make way for a new building. He said that concrete was by far the hardest, toughest, most stubborn concrete he had ever encountered. By the way, everyone called it TRIGA with a soft I....

[@MarkusNemesis]

Impressive 12 hour turn around from filming to publishing. Well done!

[@scottmanley]

I also went on a 5 miles hike and had lunch in the meantime

[@chrissinclair4442]

@@scottmanley dad brag while you Scott post. He does it all.

[@revenevan11]

@@scottmanley Scott you are something else 😆👍 I wish I could be half that productive, but I'll get there again one day!!!😅😁

[@joansparky4439]

@@scottmanley ah, good you're OK. I guess you heard about that fatal GA plane collision in Watsonville by now - involving a trainee pilot doing touch&go's and some twin engine hot rod coming in for landing?

[@alexhemsath6235]

Another reason why commercial nuclear power reactors might not be interested in a fuel designed to prevent prompt criticality accidents is that with the exception of Chernobyl (which is quite an outlier, thankfully), ensuring that the reactor shuts down and ceases any ongoing nuclear chain reactions (I.e. criticality) is rarely the problem. It’s the decay heat (which these research reactors are a lot less concerned with due to their small size).

[@RedPuma90]

Which precisely was the problem in Fukushima. Shutting down the reactors worked totally fine, but you still need to cool the fuel rods for days due to the decay heat, otherwise they'll melt. Which wasn't possible because they didn't have any (backup)power. In the worst case, the molten fuel lumps together and goes promptly critical, aka it will have a runaway chain reaction and basically becomes a nuclear bomb. But there are other problems outside of the actual reactor: The spent fuel rod pond needs cooling as well. When all water evaporates the rods can actually ignite themselves and then you end up with a situation worse than chornobyl, because theres typically more fuel in the pond than in the reactor itself.

[@rfichokeofdestiny]

@@RedPuma90 If the molten rods went prompt critical, my understanding is that they would physically disintegrate pretty quickly, ending the runaway reaction. If that’s true, it’s not exactly a “nuclear bomb” in the way most would think of it. It’s not going to vaporize everything within 20 miles or anything. It would just scatter the fissile material around the immediate vicinity.

[@alexhemsath6235]

@@RedPuma90 Nuclear bombs can't happen on accident. I suggest watching Professor Matthew Bunn's lectures here on KZbin to help understand why, but basically as soon as a critical mass occurs and a prompt nuclear chain reaction starts, the material will heat and expand and soon will stop being a critical mass because it becomes less dense. You can only get a significant energy yield if you "assemble" the critical mass in such a way to keep the material together long enough, and that can't happen by accident in a commercial nuclear power reactor (also, the enrichment level of the fuel, typically 5% or less, is nowhere near high enough).

[@stephanbrunker]

@@RedPuma90 As the others said ... no. There were a lot of criticality accidents in history, even with the core of a bomb (the so called "Demon Core"). Such an accident is surely not healthy for anyone in direct line of sight, but you get more or less only the same kind of flash like in the TRIGA reactor. Because of the chain reaction, most of the energy is generated in the last generations of the reaction and so the problem is not to get it critical (which is easy) but keep it critical long enough (which is hard). They tried two times to build a bomb with Uranium Hydrate fuel, but both were fizzles which didn't even destroy the mast they were put on.

[@RedPuma90]

@@stephanbrunker yeah I might be wrong with the fact that criticality will cause the thing to explode. But prompt criticality of a molten core is still a possibility and a really nasty scenario.

[@hackneo64]

Here in Oak Ridge, Tennessee they are starting a pilot plant for the production of fuel for reactors from the company called UltraSafe and its pretty exciting we may see these little micro reactors come into real use.

[@krakhedd]

ORNL is the birthplace of MSRs, a design several of us favor (I dropped a comment and it's getting a few likes and sympathetic comments)

[@vinak963]

Oh well, I'm the type of guy who will never settle down Where pretty girls are, well you know that I'm around I kiss 'em and I love 'em cause to me they're all the same I hug 'em and I squeeze 'em; they don't even know my name

[@jefferybarnes7817]

@@vinak963 you need to lay off the Vodka for a while

[@dertythegrower]

Bad idea. Turkey Point in Florida is smarter, and it is leaking now.. into the bay and your ocean.. get real kids.

[@dertythegrower]

Fix Turkey Point leaks.. they are covering that up... until then, calm down and get an education, son.

[@ArchersGearheadGarage]

Thanks for mentioning the SLOWPOKE reactor! I work at the NRU Research reactor 200ft from where the original slowpoke was built

[@FarrellMcGovern]

There used to be a SLOWPOKE reactor here in Ottawa (Canada's Captial, for those who don't know) at Tunney's Pasture, just slightly west of the downtown core where the Parliament Buildings are. It is a site where a number of Canada's Government agencies like Stats Can were/are located. Built in 1970, the SLOWPOKE-2 reactor was in full operation after it reached critical mass in 1971 until 1984 when it was then moved to another test site located in Kanata, later decommissioned in 1992.

[@sixft7in]

Interesting. I never knew about the TRIGA reactor's ability to pulse startup and shutdown. I wonder about the design choices that make that possible. --Former US Navy nuclear reactor operator

[@revenevan11]

Cool stuff and thank you for your service! I'd be knterested to hear if you have any cool (non-classified) reactor stories, or even just interesting facts or things that surprised you when you first became an operator.

[@railgap]

It's all about the fuel. It's very expensive fuel. ;)

[@kamakaziozzie3038]

@@railgap how expensive is Carbon in our atmosphere? It’s all about priorities

[@jdilksjr]

@@kamakaziozzie3038 Carbon as CO2 is a plant food and not a thermostat for the planet. We need more of it.

[@SubVet84]

I was wondering the same thing... Submarine or Target (Aircraft Carrier)? I wasn't a nuke, but learned everything I could. I've just always been fascinated by both nuclear power and submarines. I had originally thought of being a nuke on a sub, but thankfully my recruiter was a submariner, and he warned me against it. So I chose Sonar! Anyway, back to the topic. I understand that this is "safe" but I couldn't see the Navy ever allowing a procedure that ejects the rod to create a pulse. I don't know anything about zirconium-hydride fuel, but I'm assuming that's what gives them the negative temp coefficient?

[@flymypg]

It's pronounced Trig-uh, with "trig" pronounced like "trigger". I worked on two awesome projects associated with this reactor, though oddly enough neither occurred while I was employed at General Atomics. The first was from the 1990s while I was working at a defense contractor on an Air Force project called SNRS, the Stationary Neutron Radiography System, where we punched holes in the side of a Triga reactor to create collimated high-intensity neutron beams which were directed to a real-time neutron imager that was viewed by a sensitive and fast CCD camera. I built the imaging system for the neutron video, performing many image processing steps to finally provide a calibrated image to the radiographer operating the imaging and robotics system. This system exposed military aircraft metal composite skin segments to the neutron beam to search for hydrogen in the form of dihydrogen monoxide and metal hydrides, where the hydrogen would scatter neutrons causing an easily detectable change in the neutron image. I have several great stories about SNRS development, including how we obtained neutron test beams from an unmodified reactor that sprayed neutrons all over the reactor enclosure, causing us to carefully design our test runs to stay within our neutron exposure limits. The system is still working today! The second project was several years later when I was a consultant hired to isolate and remedying a bizarre glitch in the Triga reactor power sensor, an extraordinarily wide-range neutron detector that very accurately covered over 10 decades of neutron levels. More importantly, the instrument provided the first and second derivatives of the reactor power level (why is another fun story). These derivatives were needed to detect an anomalous power transient soon enough for the mechanical SCRAM system to react in time to do a safe and controlled emergency shutdown quickly enough to prevent a hazardous power transient (hazardous to local operators and staff, rather than to the reactor itself). This may be the canonical system for real-time embedded design. The problem was that the glitch was causing unnecessary and apparently unpredictable reactor shutdowns. This was my first "software forensics case". I created a simulator for the neutron sensor, validated it against operational data, wrapped it with a Monte Carlo simulation of neutron flux, then ran the instrument software under emulation. I mimicked each one of the operating scenarios that had triggered the glitch, and was soon able to isolate and independently replicate the flaws in the algorithms used. Remedying those flaws took a while longer, as multiple candidate algorithms had to be developed and tested against each other as well as the original code, and done not only under the known scenarios, but also under a very large number of "fuzzed" scenarios to ensure algorithm stability and robustness. I really wanted to publish the two reports I wrote (one each for investigation and repair), but my NDA prevented it. The Triga was ALWAYS a fun system to work with.

[@Erkle64]

No no, clearly it's the one acronym where the letters are pronounced like the words they come from. Which would make it try-jah. Because the G in general is soft.

[@flymypg]

@@Erkle64 I worked with some of the physicists and engineers who created, evolved and maintained both the product line and our local reactor. They pronounced it as I described. There is NO higher authority in this matter than the originators themselves.

[@dan_in_sd]

@@flymypg Worked at GA in the 90s. I walked the halls of the main buildings in Torrey Pines (an area north of La Jolla, CA). Trig-uh is what the Scientists used. "Trig" as in the beginning of trigger and just an "uh" sound after that. TRIGA

[@Erkle64]

@@flymypg Yeah, I was trying to agree with you by sarcasticly applying Scott's reasoning for the I.

[@flymypg]

@@Erkle64 *whoosh* I need to slow down! Sorry to have missed the sarcasm on my first reading.

[@tjzambonischwartz]

There's a TRIGA operating about an hour north of me at the USGS facility at the Denver Federal Center. They offer tours, and I plan on checking it out eventually. Always wanted to see an operating TRIGA.

[@mcb187]

Live in the springs. Gonna have to look into that. I’ve always wanted to tour a nuclear power station, but they don’t offer tours for… very obvious reasons. This might be the next best thing.

[@johanneskurz7122]

We have a TRIGA 2 at my university. It's quite eerily how calm it all is. It's also possible to pulse it to 1000x its nominal power for a second. But then your (for some reason) not allowed to watch it in person :D

[@sampfalcon5128]

Hey Scott! My grandfather is a professor of nuclear engineering, and I remember when I was very young, he took us to see the research reactor at Ohio State. (It’s called OSURR, and it’s a Bulk Shielding Reactor) That blue glow is something you never forget, it’s emanating from the water itself and it’s just so unique. While we were there, my older brother had a science fair coming up, so he brought an orange. They used the “fission pole” to drop it down as close to the core as possible. I believe the experiment eventually ended up being “does absolutely blasting an orange with radiation increase how long it’s preserved?” The answer was yes, but not a ton. It goes to show research reactors are literally safe enough for children!

[@sparky6086]

Edward Teller was the main model for Dr Strangelove is the movie by that name. Although he wasn't a Nazi, he hated the Soviet Union & came across uncomfortably enthusiastic about his creation, the H-Bomb.

[@ora6925]

I worked on the TRIGA reactor at the Technical University in Vienna, Austria! To this day cherenkov blue is my favourite color.

[@NomenNescio99]

A nuclear reactor should be operated by a man and a dog. The man's job is to feed the dog. The dog's job is to bite the man if he tries to push any buttons.

[@Arational]

A Boy and his Dog

[@NomenNescio99]

@@Arational Yeah, I should have written it like that. But I shamelessly copied this joke from one of the first chapters in the book "How to drive a nuclear reactor", highly recommend reading!

[@kunjukunjunil1481]

😆😆

[@Verrisin]

just more fear mongering ...

[@Carewolf]

What do you do then the dog has eaten the man, and is still hungry?

[@sakaraist]

This was absolutely a fantastic introductory explanation. I know its not your usual video type but I'd love to see more like it.

[@rougenaxela]

12:00 Regarding the barriers to being used in conventional power reactors, I find it kind of appalling that the required research and development into _various_ safer reactor designs for power generation hasn't happened faster. It seems like the sort of thing that could have a massive return on investment if you look at a long enough time scale. It feels like at least from roughly 1980 to 2010 things were entirely stagnant, a whole generation worth of potential progress on that front was lost.

[@NightLexic]

You can thank the Oil & Gas industry for that... also the "short term profits for short term gains" mentality

[@gretathunderer5596]

The NRC holds most of the blame for that. The NRC requires any modifications to go through the entire approval process again, as if building a brand new reactor; for each individual reactor in question. If you have two facilities with identical reactors, each facility would have to submit their own documentation and go through their own approval process to the cost of millions of dollars and years of time. It simply costs too much, given the very high risk the NRC will simply deny the request.

[@petevenuti7355]

And the tree huggers, discouraging nuclear options, till many woke up and realized they shot off their own foot with co2...

[@Globovoyeur]

The 1989 book The Demise of Nuclear Energy? by Morone and Woodhouse examines why this didn't happen. Basically, their answer is that the AEC rushed to commercialize the first proven designs, which were based on Navy reactors. Other countries did better. The UK had a set of High-Temperature Gas-Cooled reactors (I think there were 8) that ran for a good long time. The US had just one: Fort Saint Vrain, in Colorado. It was deemed a technical but not a commercial success because water kept getting in and causing it to shut down. Eventually it was replaced with a plant fueled by natural gas. Colorado has no nuclear power plants today.

[@jamesdriscoll_tmp1515]

Insurance was a problem as well.

[@retireeelectronics2649]

At the beginning of the video I thought you were talking about the Slowpoke Reactor. Happy you mentioned it later, was able to do a tour of the Whiteshell facility in Manitoba back in the 80's, neat.

[@samsonsoturian6013]

One super safe reactor was used to power a radar station in Greenland. The only problem was the immaturity of soldiers, as apparently the sergeant in charge yanked out the control rod just to scare/haze a recruit.

[@bergonius]

Ah, good old nuclear meltdown prank. So funny!

[@piercebros]

What the actual fuck?!

[@samsonsoturian6013]

​@@bergonius Best guess is he only meant to pull it out a few inches which would have been safe, but we don't know for sure because they're dead and reactor had to be disassembled.

[@michiganlineman357]

@@samsonsoturian6013 most based joke ever...

[@pricklesthecactus6183]

Could you share the source?

[@PlanetFrosty]

I’m always radiated by your content! I almost glow in the dark now after watching your many programs!

[@NeverTalkToCops1]

Name on patent: Theodore Brewster Taylor. Theodore "Ted" Taylor was hailed by Freeman Dyson as the smartest unknown person, ever. Taylor designed atomic bombs. One of his designs, a fission only device, had a yield of 500 Kilotons. That high a yield is usually only accomplished by a device using a combination fission/fusion processes, wherein a fission bomb is used as the trigger for the fusion fuel.

[@gizmophoto3577]

If memory serves, Taylor was described in John McPhee’s book The Curve of Binding Energy.

[@missano3856]

@@gizmophoto3577 I've been meaning to read that book.

[@PetraKann]

Designing atomic bombs can also be seen as evil and not very smart at all

[@RCAvhstape]

Taylor was mentioned in George Dyson's book Project Orion (George is the son of Freeman). Taylor worked on the nuclear pulse-propulsion program and was interviewed on the subject, search for it on youtube. He also famously used a parabolic reflector to light his cigarette with a nuclear bomb.

[@Jkauppa]

patents are for cry-babies

[@jamessnook8449]

Scott that was an excellent description of a TRIGA reactor. I operated the original TRIGA Mk 1 reactor in San Diego for three years back in the 90's. I pulsed the Mk 1 and a Mk 5 reactor (in the same facility) many times. We would take the reactor critical at a low power (a few hundred watts) and then fire one or more of the control rods out of the core with a pneumatic cylinder. We had experiments where we would inject enough reactivity into the core that the prompt supercritical event would shake the building. If you were standing over the the reactor pit you would see what the beginning of a nuclear explosion would look like. Also, TRIGA is pronounced like trigger.

[@danielkaczynski9702]

Yet another techno nerd cool video from you Scott! I would argue that nuclear is intimately connected to astronautics. Are the first pioneers on Mars expected to burn wood? Without nuclear power, we will be starved for energy for long duration space missions. It seems to me that nuclear power is a must have for space flight beyond the Earth - Moon system.

[@htomerif]

Yeah, so one of the reasons this can't readily be applied to power reactors is because uranium hydride breaks down at 500C and puts out hydrogen gas. Zirconium hydride (so far as I can tell) decomposes at about 800C. Uranium dioxide doesn't melt until about 2800C. The fuel temperature of rods in power reactors just gets way too high to use uranium hydride even during standard operations. If you ever had a failure to cool the reactor or keep spent rod cooling ponds cooled, uranium zirconium hydride would melt into a critical mass far, far easier than uranium dioxide. I don't think that's a reasonable obstacle to overcome.

[@krakhedd]

MSRs are a great idea for commercial energy production with a walk-away safe design that's low cost and easy to build

[@CarFreeSegnitz]

I’m a MSR fan for: Proliferation resistant. It’s hard to extract bomb materials. Waste burning. High-level radioactive wastes from traditional reactors can be mixed into the molten salt fuel to extract still more energy from them AND reduce dangerous levels of storage from 100,000+ years to roughly 400 years. Not perfect but vastly better. Known technology known since the 1950s but abandoned because it didn’t easily produce bomb material. Not much more research required. and, of course, like all other nuclear options, no GHG emissions.

[@krakhedd]

@@CarFreeSegnitz one more really great reason for ya: short half-life medical isotypes including alpha particles which doctors can place inside a carrier and deliver directly to cancer cells instead of general chemo & radiation

[@a-fl-man640]

seems like they are the answer to me.

[@gizmophoto3577]

MSRs are promising technologies, but there is considerable work to be done before they are deployed. For example, appropriate structural materials for a challenging combination of high temperatures, complicated chemistry, and very high radiation need to be developed, qualified, and available through a reliable supply chain. It’s doable, but there’s more to be done than many people realize.

[@YellowRambler]

The ultimate benefit of a MSR only happen with Thorium, such as remote installations for manufacturing or countries you might feel uncomfortable using uranium. Burning off the other 99% of uranium fuel in the waist of a inefficient Cold War relic reactors is also a good thing.

[@myownboss1]

I am actually a nurse, but am also a big nuclear energy geek! I’m older now and live too far away from the last active reactor in California, but would have loved to work at one. The Chernobyl series from HBO blew my mind and I loved it (I was a sophomore in high school when that occurred but didn’t appreciate the seriousness until years later…) anyway, great stuff Mr. Manley!

[@yetinother]

I like this branching out on a still space related subject

[@rayceeya8659]

Yeah I got into this years ago. One of my favorites is the pebble bed design. Germany has been experimenting with them. They intentionally initiated a "meltdown", but the reactor didn't melt down. It self regulated. The graphite "skin" on the pebbles became less efficient as a reformer as heat rose. There are ways to design reactors that are meltdown proof.

[@alexanderstone9463]

Wasn’t there a problem with excessive medium and low level waste produced by pebble bed reactors though? I mean, I guess you could probably work around that. The Germans didn’t like having to deal with it, but then again they’re Germans, so they’re not really inclined to like nuclear power in the first place.

[@kuhascoat]

Released 12 seconds ago! Wow! So glad to see another nuclear themed video! :)

[@clavo3352]

Always good valuable lessons from Scott Manley. I like it more when Scott is so familiar with the material that he is more conversational; and less, reading from a prompter. I shall fly safe!

[@Creolegumbo]

I truly enjoy not only the content but the way it’s presented. Been watching for years and so cool to watch SM progress. The “dad jokes” humanizes the material and keeps me from leaving bc I’m sooooo ignorant of all this scientific shit….ha. Thanks, Scott. Really appreciate your work. Keep it up!

[@ian5576]

I run experiments in a number of these TRIGA's, and even with the colorful pronunciation, this video is excellent.

[@vincentcleaver1925]

What I like best about molten salt reactors is exactly this, that thermal expansion damps out the chain reaction. With a freeze plug, if it still gets too hot or the electricity to the cooling circuit goes away the molten salt drains away and disperses. Even a spill of molten salt freezes in place and clean up is going to be straight forward

[@kg4boj]

That's what they said about the solar plant in nevada... and it then poisoned all its staff with nitric acid.... molten salt will kill you way faster than radiation as it turns out

[@darkgalaxy5548]

Super hot, corrosive radioactive salts circulating through meters of plumbing, valves, joints, pumps etc is a problematic design at best. Decay heat will keep salts liquid in the event of a spill. Freeze plugs design will divert salts to a secondary storage which will still need active or passive cooling also because of decay heat. Same as PWRs or BWRs.

[@foobarrel9046]

If it gets too hot, the molten salt expands, reducing the reaction rate, so it automatically cools down again without any human or mechanical intervention required. This physics-driven negative feedback is a separate passive-safety feature from the freeze-plug, which, as you correctly point out, drains & deactivates the reactor in case of a complete electrical power failure (the Fukushima scenario).

[@darkgalaxy5548]

@@foobarrel9046 You haven't addressed decay heat

[@brodude7194]

@@darkgalaxy5548 Unfortunately you're terribly wrong -- the hoter the salt, the less reactivity. A core meltdown is simply not possible with this design. If the core is usable after such an event is another question, but it doesn't leak radioactive material to the outside.

[@michaeldunne338]

Nice segment on an intriguing bit of nuclear technology - the Triga. I also liked the reference to SNAP10a.

[@thedabblingwarlock]

I would love to see the TRIGA reactor concept revived and explored, not because I'm a madman wanting nuclear devastation, but because I believe that we will have to use nuclear power if we want to reduce our dependence on carbon based energy, and I'm all for anything that reduces the US's dependence on foreign powers. We will also need safe reactors for power beyond Mars and the Asteroid Belt. Also, I 100% agree with Scott's pronunciation of TRIGA, because I use the same reasoning to say that it's GIF with a hard G, not GIF with a soft G. After all, we say graphics with a hard G don't we? :P

[@joesterling4299]

How do you pronounce the acronym "WHO"--"who" or "oo-hoe"? It stands for "World Health Organization," so shouldn't it be pronounced "oo-hoe"? Acronyms are pronounced as the words they form, not based on what the initials stand for. And the 'g' is *generally* pronounced softly before an 'e' or an 'i'. There are exceptions like "get" and "give," but that just exposes the extremely lax English pronunciation rules. In Spanish, for example, the 'g' *always* has the soft 'h' sound before an 'e' or 'i' (hard before other vowels). Not that I care very much, but I prefer the "jiff" pronunciation of GIF.

[@rfichokeofdestiny]

@@joesterling4299 I guess you’d say “wuh-hoe.” 😏

[@rfichokeofdestiny]

The fact that you felt the need to qualify your desire shows how effective the anti-nuclear propaganda has been. Granted, it mostly arose out of the Cold War, so I partly understand. But it demonstrates how binary and reflexive most people are in their thinking. Nuclear = Cold War = killing everybody in the world. Therefore, anything nuclear is pure evil. The previous generation took it in the opposite direction in an equally silly fashion: nuclear = scientific progress = the future of mankind. Therefore anything nuclear is the answer to life’s problems. Nuclear trains. Nuclear cars. Drinking thorium for health. The sky’s the limit! Danger? There’s no danger! It’s Science!

[@sashimanu]

TRIGA-class nuclear reactors are not meant for commercial power generation - only for research, testing, teaching and small scale radioisotope production.

[@DrWhom]

since it is a play on how we pronounce the word trigger, there really can be no debate

[@johnwang9914]

I'm glad you mentioned the Canadian SLOWPOKE reactor. The low numbers of the SLOWPOKE reactors built is attributed to the Chinese building clones of it and selling them internationally at a much lower price. The purpose of the SLOWPOKE was to neutron bombard samples in a sample chamber to produce radioactive isotopes for research. It was proposed to use SLOWPOKE reactors to provide district heating for remote northern communities and even to power a 8 man civilian research submarine called the Sagan through sterling engines (it was to be called the n-Sagan if nuclear powered, they built the hull but a taxation dispute between Canada and France killed the project). There was also reports at the Royal Military College about retrofitting the old Oberon class submarimes with the SLOWPOKE reactor with sterling engines to be able to recharge batteries while submerged but I believe those were student papers (note there were also papers proposing using RTG's to do the same albeit more slowly).

[@barryinkpen6026]

You are a "gold mine" of information Scott; thank you!

[@commerce-usa]

Scott, your dad jokes are the bomb. 🤣 Thank you for doing this video. 👍

[@baomao7243]

Glad you got your pun past the moderator.

[@brianlaney7596]

Thank you for the well researched explanation. I worked at General Atomics back in the day. It was pronounced like ‘TREE GA’ by everyone there. Just for the record, it was Dr William Whittemore behind the ingenious design of the fuel. I had never heard of Teller being involved but that was before my time. I think it would be difficult to use the UZrH fuel to a power reactor at scale. It was designed specifically for generating high flux neutron pulses, not so much for steady state operation at high temperatures as would be required for large scale power production. The hydrogen would diffuse out. The blue light is from Cherenkov radiation.

[@sterlingoodson1135]

Little do people know a bunch of 19year olds straight out of high school run all the nuclear reactors for the navy.

[@markbike5288]

Not quite straight out of highschool, There is Power School, navsea navy milHome NNPTC powerschool Academics proceed at a rapid pace with high academic standards enforced in all subjects. Students typically spend 40-45 hours per week in the classroom with an additional 10 to 35 hours per week of study outside of lecture hours. As far as I can tell, it is like a condensed Bachelor (B.S) level training, specific to Naval Power. So some other engineering topics get left out, but it is pretty high-level where it goes. Lots of ex-Navy nukes in commercial power plants. A-school (electrical systems) is also part of the curriculum.

[@sterlingoodson1135]

@@markbike5288 currently in nuclear powerschool, can 100% say you are not wrong, just crazy seeing some of the people here lol.

[@dannywilliamson3340]

@@markbike5288 Veteran of the "Forty-one for Freedom," and retired from the commerical industry. What a road.

[@Ikbeneengeit]

Scott Manly: your earlier nuclear series are my favourite KZbin videos ever. I love your nuclear physics even more than the space vids!

[@dwayne7356]

I found that the greatest danger of operating nuclear reactors is management. - Retired licensed BWR 3840 MWth reactor operator.

[@GraemePayne1967Marine]

Yes! Coming from a Quality Assurance perpective, the root cause of MANY problems is failure of TOP MANAGEMENT!

[@jacoblojewski8729]

Great descriptions! I love that you went into enough detail to even mention that weapons grade uranium reactors can't practically operate with a prompt negative temperature coefficient. That's not really an issue for civilian reactors, but military reactors usually use weapons grade uranium. For those wondering why: longevity. Weapons grade uranium can last decades, non weapons grade fuel needs to be replaced every few years.

[@jackfanning7952]

What should we, no, excuse me, you do with the nuclear waste for the next million years? Who pays for it?

[@johncooper5124]

Elitists view cheap power granted to the public the same as handing a "machine gun to an idiot child."

[@DrWhom]

you manage to get a lot of confused half-truths in one short sentence

[@tedgood1224]

As a licensed operator on a TRIGA reactor I can say that this is definitely one of the better explanations of how neutron upscattering from the hydrogen in the fuel causes the negative temperature coefficient.

[@trshbrnr1]

I submit that the LFTR reactor developed in ORNL and currently being brought online in China is the ideal and safest reactor possible.

[@jimgraham6722]

Thanks Scott. My recollection is some of these operate in downtown school buildings.

[@deanlawson6880]

Very Interesting Scott!! Thanks for this!! I wonder exactly what kind of reactors NASA is investigating for the Nuclear Thermal reactor driven propulsion they are currently looking at for trips to Solar System destinations. Lots of good options available for this. IMHO that's the only real practical way we're going to be able to get to Mars and other solar-system destinations with crew on board. We can't be sending ships with crew out there for months and months and have to keep the crew happy and healthy and breathing and hydrated and fed over long periods of time, that just becomes completely impractical. Days or even weeks we might be able to do, but months is just not even realistic.

[@csdn4483]

Scott, as someone that did my studies on a TRIGA and was an actual student operator for the University of Arizona (now decommissioned), the pronunciation that was used is like trigger, so treh'GUH. Also of note, the TRIGA at the University of Arizona was the first one that went to a University and initially was installed as a TRIGA mark 1, but was later upgraded to a TRIGA mark 3 some years later. As such, being one the oldest TRIGAs, it had a relatively lower power compared to others without our highest steady state power being 100kW thermal. The UofA's TRIGA is no more as it was decommissioned in the late 2000s/early 2010s.

[@DonJoyce]

When discussing safe nuclear reactors, we often forget the lowly septic tank: the need for regular injection of fuel rods, commonly found moderator fluids, and eerie brown glow are all key design features of this safe technology that even kids can use.

[@Kevin_Street]

Thank you for another really interesting video! TRIGA is a very intriguing approach to the problem of moderating nuclear reactions.

[@htmagic]

Scott, a molten salt reactor using thorium is even safer. If the reactor overheats, a fusible plugs melts and the molten salt core drops into a holding vessel below, stopping the reaction instantly. Thorium couldn't be used for weapons, so uranium was favored for military reasons.

[@gizmophoto3577]

Th-232 breeds Th-233 which can be used in weapons. Also, the freeze plug concept is applicable to uranium fueled MSRs, as well.

[@missano3856]

The US and the USSR definitely tested U233 bombs and India probably has but it's kind of a pointless stunt.

[@ScreamingDoom]

@@gizmophoto3577 This is incorrect. Th-232 breeds into U-233; there is no such thorium isotope 233 as far as I know. A thorium reactor IS a uranium reactor, it's just that the amount of uranium in it at any particular time is tiny and it continually creates more of it. U-233 can be used in weapons, sure, but it's a lot more difficult, produces atomic weapons that degrade quicker and are easier to detect, and thorium reactors don't produce enough U-233 fast enough for it to be worth it.

[@gizmophoto3577]

@@ScreamingDoom you are correct. I wrote that when I was tired late last night. Th-232 absorbs a neutron to become Th-233, which quickly decays to fissionable U-233 (I don’t remember the half life). Apologies for the error.

[@lastoptionavailable]

My old school's TRIGA was able drop the enrichment from highly enriched to low enrichment fuel with only a relatively small amount of reactivity loss by increasing the density of the uranium. People rarely think that the increase of the fuel's density would effect the production of neutrons, just as much as the change in enrichment.

[@Stubbies2003]

Well of course it would affect it. The denser the fuel the better a chance that one reaction can trigger another. Which is all about what nuclear reactors is about is maintaining and managing criticality.

[@Ben-ry1py]

Living in times when one country can throw the world into relative chaos I've been wishing humans would get their head out of their butts and built a lot more safe nuclear power plants. Thanks for making this video Scott. I've heard that thorium reactors could be much smaller and safer than the weapons grade stuff most reactors use. I only know enough to wish for it to be though.

[@krakhedd]

Thorium-fueled Molten Salt Reactors. MSRs can also burn other fuels (U, various waste isotopes from "conventional" nuclear reactors), Th is just the perfect intersection of cost, safety, availability, energy security

[@icaleinns6233]

The ONLY reactors that use weapons grade stuff belong to the U.S. Navy. Commercial reactors use U-235 that is only enriched by ~4%.

[@gizmophoto3577]

Unless you’re talking about military reactors, most reactors do not use weapons-grade fuel. Light water reactor enrichments are on the order of 4% U-235, vs. somewhere I think on the order of 90% for weapons. As for thorium, lots of claims have been made, with very little follow through. From examination of NRC’s website, no thorium MSR designer is engaged in discussions to prepare for licensing, for example. Such designs may well be desirable, but they have a lot of work to do to get ready. I worked on MSRs at NRC until 2019 and I can tell you exactly how many times I heard from anyone advocating a thorium design - zero. Things may have progressed from that point, but there isn’t a lot going on in that realm according NRC’s website, though other MSR designers are engaging with the regulator.

[@CHIEF_420]

🎓

[@General12th]

Nuclear power is pretty darn good, but it suffers from the problem that it takes a long time to plan and build. That means higher investment costs, longer ROIs, and a greater delay between when the project starts and when carbon-free electricity starts rolling in. The best time to invest in nuclear was yesterday. I'd love to see more nuclear stations come online while we continue to switch to renewables across the board.

[@GraemePayne1967Marine]

Thank You very much for talking about this! I have, of course, been aware of the good and evil aspects of nuclear energy for almost all of my life. (Born in the UK in 1949, living in USA since 1961.) Even though I lived under the cloud of "Mutually Assured Destruction" (or deterrence) I have always been in favor of using nuclear energy for non-military purposes. I remember a few of my favourite science-fiction writers sometimes using "pocket reactors" (nuclear was implied) in their plot lines. But I was not aware that was an actual possibility until seeing your presentation here. I believe much of the US public opinion about nuclear energy is still shaped by the end of WW-II, the years of atmospheric nuclear weapons testing, the Three Mile Island (TMI) incident, and the Chernobyl fiasco. Most do not know (or don't believe, or don't care) that the TMI hearings showed that the TOTAL release from TMI was much less than the average DAILY dose in the US Capitol Building room used for the hearings. Even with the current push on science and engineering education, most of the public appears to be either uneducated about - or willfuly ignorant of - the basic facts about how safe nuclear energy really is, and how low-cost it can really be. For example, I used to work in a US Navy shipyard that serviced nuclear powered submarines. Frequent testing at the radiological facility always showed that the river water coming INTO the building had higher radioactivity levels than the water goiung OUT OF the building and being released back into the river. Of course, the river water orginated in moutains having minerals that naturally contained radium, uranium, thorium and so on - but some fools thought that was "safer" because is was "natural". My wife used to work for a company that reprocessed used nuclear power fuel rods - removing the fission products that reduce efficiency, and refeshing with fresh uranium pellets. They started building a new production plant, but eventually shut down because the NRC wanted to apply the same seismic and other safety standards to the old building (which was going to be shut down) as were required for the new one. Insanity. Thus nuclear power in the US is so expensive because the fuel must always be made from newly-mined uranium, instad of reprocessed fuel at economical cost savings. (Yet another advantage nuclear has over fossil fuels: you cannot reprocess burned coal or petroleum to make new fuel!

[@pliskenmovie]

Just like the FAA is the biggest impediment to aviation advancement, so to, the NRC and DOE is to advancements in nuclear energy. Nobody is willing to foot the bill and take the time to get a new design 'certified', so we plod along with designs from the 1950s because they're able to be used w/o the extra cost and endless review cycles of something new and "scary".

[@jimsmith7212]

I think public acceptance is a bigger factor. No permits were attempted in the U.S. because of public backlash, so why invest? After 3 Mile Island and Chernobyl, nuclear power was anathema. Many large nuclear reactor designs had structural or design faults that could be catastrophic. Global warming and better designs have changed public opinion lately though, including mine.

[@richardbaird1452]

There are some Gen IV's going through the process now with in service estimates within this decade. Natrium in the US and Moltex in Canada are two examples.

[@bryancollins4059]

This is a wonderful segment! You are an amazing science communicator, and I have hoped to see you do an entire series on Gen4 nuclear and it's place in powering modern society. I'm a Molten salt (fast or thermal) enthusiast, as thorium decay chains lead to LARGE (relative) amounts of Pu-238 for RTGs. I would love, and I think many people would, a deep dive curtesy of the "Astronogamer"!

[@chemistryofquestionablequa6252]

Hopefully one day these will be widespread and common. Nuclear power is the solution to the fossil fuel problem.

[@Arational]

There is not a huge supply of Uranium for reactors but Thorium is much more plentiful.

[@chemistryofquestionablequa6252]

@@Arational there is absolutely enough uranium for each state or province to create their own energy. The u.s., Russia and Canada have big deposits that aren't being mined for the most part right now. Isn't thorium less abundant on earth than uranium?

[@missano3856]

@@chemistryofquestionablequa6252 Thorium is more abundant but it's a moot point, there is adequate uranium especially if you use fast/ breeder reactors. Thorium has a kind of bizarrely passionate fan base tho.

[@chemistryofquestionablequa6252]

@@missano3856 I've noticed that some people are awfully enamored with thorium. I expect it's not nearly as good for a reactor fuel as they think it is. I've seen a lot of pie in the sky: "safe power with no waste, the government is suppressing it" kind of talk online for years.

[@susanyoung6579]

Gold is more abundant than uranium on Earth. It contains a lot of energy but it only goes so far.

[@joshattheroot]

Blooming love these videos Scott. Add someone who is interested in science but not particularly science educated, you make the more complex/deeper science subjects accessible. Keep it up mate! 👍

[@escomag]

I've always questioned Teller's use of the bomb to cure slums, poverty, and homelessness.

[@EFCasual]

California needs to run a test program to gather data.

[@DrWhom]

Teller was such a card!

[@Technoguyfication]

I’m literally using one of these reactors right now as I watch the video. Amazing machines.

[@loberd09]

My college has/had one of these nuclear reactors. I remember nuclear engineering majors telling me about how they’d joust with control rods…after they got in trouble for jousting with fuel rods.

[@jfan4reva]

I was going to say something about calling college students "children" in the title, but then this....

[@loberd09]

@@jfan4reva haha. I think they probably were ones for demonstrations.

[@alanh8664]

At PSU, we had a TRIGA. When I was going there for Nuclear Engr, we often did that for the students.

[@MakeMeThinkAgain]

There was a research reactor at UCLA when I was a kid, I wrote a paper on it with lots of photos when I was in junior high school. Sadly, I don't recall enough about it to know if it was this kind of reactor or not. Sounds strange now that they let a little kid climb around on a reactor back then, but then again I spent the first 12 years of my life downwind of the nuclear testing in Nevada. Not to mention all the lead in the air from leaded gasoline. It's a wonder any of us are still alive.

[@beeble2003]

UCLA's reactor was an ARGONAUT (ARGOnne Nuclear Assembly for University Training). Berkeley and UC Irvine had TRIGAs.

[@MakeMeThinkAgain]

@@beeble2003 Wow. Thanks.

[@rfichokeofdestiny]

But it also puts into perspective younger generations’ paranoid fragility over everything imaginable.

[@beeble2003]

@@rfichokeofdestiny Which, in turn, puts into perspective older generations' assertion that everything used to be better, and young people today are just terrible.

[@a2e5]

@@rfichokeofdestiny People will always find out about new scary stuff, turning unknown risks into knowns. The ability to mentally process and model such risks and probabilities unfortunately does not grow as fast.

[@avs332000ify]

Awesome IntoTheAM shirt, I love their space inspired t-shirts. Love your videos as well!

[@sparky6086]

When I was a young man, there was a nuclear reactor across the street from me, in the middle of the city. It had a sinister looking geodesic dome. It belonged to the local engineering school.

[@GeekboyNC]

Takes me back to 1974 when we packaged bits of Racoon liver from the lower Cape Fear river basin into little plastic vials and zapped them in the NC State University reactor. We analyzed the bits using Neutron Activation Analysis to determine the amount of mercury and subsequently how much mercury was in the fish the racoons consumed. That was one of the more exciting and fun parts of my undergraduate chemistry education.

[@DragonsAndDragons777]

It's a shame nuclear power is so disliked, it is rather cool

[@NewJak14]

Such great work Scott!! Thank you for this :)

[@ANonymous-mo6xp]

You want to really solve climate change, you need to build and deploy safe nuclear reactors.

[@cornishman99]

Love this. I visited the Triga reactor at ICI Billingham in the 1980s, and the Cerenkov glow was wonderful to see. By the way, UKAEA Winfrith had an I inherently safe reactor called Dragon. Shaped like a funnel, you fed new fuel pellets in the top.

[@s.m.1354]

The problem with LWR is the waste, due to excessive amounts of other breed materials than Pu-241, with long decay periods. A better way is like the Candu reactors using PSHWR(Pressurized steam heavy water reactor) because only fast neutrons will influence the material, breeding Pu-241 in the process. Because heavy water acts as the coolant and moderator, depressurizing would also not sustain the fission reaction. However in case of meltdown there are many safety features. In my point of view the Americans with all their waste and light water reactors are being not efficient and could learn a lot from the Canadians.

[@GwynRosaire]

Great job explaining the nuclear theory! There's a good KZbin video from the Texas A&M Nuclear Science Center TRIGA reactor pulse.

[@_EVANERV_]

The most current designs use water as both moderator and coolant. So if the fission process ran away and causes the coolant water the boil off, then the moderators is also gone. With the moderator gone, fission is no longer possible this will shut down the reactor.

[@K_Hansen]

navy uses this type

[@_EVANERV_]

Although this method only works for lower concentration u235. Anything above 20% enrichment will likely not work.

[@_EVANERV_]

@@K_Hansen Actually the naval reactors currently in use all utilize 90%+ enriched uranium. Which means it is far too concentrated to technically need a moderator; although they still use moderators to increase efficiency. I believe the naval reactors use beryllium as moderator. Beryllium's melting and boiling points are way too high for this "safe" method. This is also one of the reasons why US Navy is researching into using 20% enriched fuel for future naval reactor designs.

[@derekp2674]

@@_EVANERV_ I believe some Russian naval propulsion reactors have used similar low enriched uranium fuels.

[@_EVANERV_]

@@derekp2674 if true, that is indeed very interesting. Could you provide me with the reactor or sub type that used lower enrichment level uranium? I would very much like to know.

[@davidvik1451]

Makes me wonder, why the the USA scrapped the Integral Fast Reactor research? This reactor design used "metallic" fuels that I understand is self regulating for reasons similar to what you have described. In April 1986 EBR2 at the Idaho Research Facility performed tests where they twice shut off the coolant flow and the reactor successfully shut itself down without any damage. The problem was that Chernobyl happened the next day and news reports of the test if printed at all were relegated to the back page. The Fast Flux Test Facility at Hanford, WA also demonstrated the inherent safety of the design. Love your productions, I always find something new each time I view.

[@deathgun3110]

I think it was because of cost overruns in the research and the building cost per reactor, I think they were 2-3x more expensive than pressurized ones.

[@solotron7390]

A handheld solid-state nuclear reactor capable of continuously generating electrical power would be quite useful.

[@AsbestosMuffins]

anything nuclear would probably not be great for your hand lol

[@petevenuti7355]

IC's with built in betavoltaics , possible I guess, but if you're thinking about running your phone like that, there won't be enough power to light up the screen or use WiFi... Maybe something like an sms pager with e-ink screen that after the betavoltaics charge a supercap for an hour it updates the screen and gets new messages.

[@SyntheticFuture]

I love how there's nuclear reactors and centrifugal particle accelerators being run by students. We have a cyclotron in our city being run by the university. Got the chance to see it and it was quite cool but also a bit weird to see that tech being so... Well... Accessible.

[@AKjohndoe]

The patented Manley Dad Joke 🤣

[@brianlance]

We have a TRIGA here at UC Irvine that was famously used to analyze bullet fragments from the JFK assassination. Got to tour it several years ago and it was pretty neat to see the blue glow at the bottom of the pool in person.

[@Freshwaterboy]

When the choice is nuclear energy or no internet or smartphones, or air conditioning or TV, watch how quickly nuclear is accepted.

[@CarFreeSegnitz]

Watch how quickly people reject nuclear when you repeat the mantra “Three Mile Island, Chernobyl, Fukushima, nuclear waste”. I’m all for nuclear because we know full well the downsides of fossil fuel energy sources. Coal fire electricity distributes more radioactive elements than all nuclear accidents to date. Germany is having to rethink its anti-nuclear stance now that they know the dance-with-the-devil downside of Russian energy dependence.

[@Freshwaterboy]

@@CarFreeSegnitz 100% agree. I envision neighborhood sized reactors that are safe and effective and produce no waste and are incapable of meltdown. We need a new way to produce our electrons though. Even fusion will run steam powered generators. It's all because we need to produce heat.

[@BabyMakR]

PBRs are, I think, the safest options. The hotter the pebbles get, the slower the fission happens. If, for some reason, designed weak points in the structure holding the pebbles melt and the pebbles fall into an anulus where no 2 pebbles are close enough to feed neutrons to each other. And, if you want, you can fill the chamber the pebbles are stored with water to quench them. The normal operation of the design uses no water, just any nonreactive gas, usually helium, though, in a pinch you could raid the local pub and swipe a couple bottles of beer gas to achieve the same result. They can use waste from current nuclear plants as fuel, in the process, transmuting the longest lived products into shorter half-life elements, eliminating the need for mining new fuel or planning sequestration of old waste products. If the cooling fluid (gas) stops, the pebbles expand, reducing interaction between the individual flecks of fuel in the graphite ball, to the point that they will self regulate. The power plant scales load by increasing cooling to the core to cool the pebbles, making them contract, making the fuel particles closer together and making more reactions. If the cooling fails, they heat up and expand making the particles get further apart, slowing the reaction. There is nothing to leak as long as non-reactive gas is used.

[@joedarkness808]

it's a a shame that the research in safer reactor designs isn't getting the funding it needs, I have no doubt that if it could be used for weapons they wouldn't have any funding issues, One of the reason that MSR got funding that it was going to be used in ARE (Aircraft Reactor Experiments) for powering bombers

[@swokatsamsiyu3590]

Thank you for this most interesting video! Have seen some of the videos with the TRIGA doing a startup with the accompanying blue flash and always wondered how they work and came into existence. I have to say, they're awesome little reactors! Would pay my last savings to be able to visit one some day.

[@christopherg2347]

"The inventors of "foolproof" designs, underestimate the ingenuity of the fools." - old saying. And of course, it still does not solve where to put that highly toxic and slightly radioactive waste.

[@ImieNazwiskoOK]

Afaik big portion can be stored until it becomes safe. The worst parts of it(aside from being tiny portion of already not that much), there may be some new ways for it. Instead of using deep mines using similar equipment to oil drilling to drill even deeper so it's effectively out of system.

[@jackfanning7952]

Admiral Rickover, father of the U.S. nuclear navy, said, "in every foolproof plan, eventually the fools will overcome the proof." We have 75 years of watching that come true.

[@jackfanning7952]

@@ImieNazwiskoOK It is safe when 10-20 times the half-lives of the hundreds of radioactive isotopes is over. Unless it transmutes into another radioactive isotope or lead, which is still toxic. Drill a hole, put it in there...what happens when it leaks through fissures and contaminates the aquifers for half a continent? DOE dumped 63,000 gallons of water on top of Yucca Mountain to see how many years it would take for any of it to reach the center where the waste was to be stored. All of the water made it there in 3 months. How long did it take for radioactivity to explode out of the WIPP permanent storage facility for transuranic waste? $3 billion in clean-up so far and it is still a mess. Finland's permanent repository pipe dream at Okalo hit an unanticipated snag when they discovered the copper casks they planned to put the waste in were too susceptible to corrosion from water leaking in. Bentonite or other clays meant to encase the copper casks absorb water. Vitrification lasts for less than 100 years before it breaks down. Back to the drawing board. Maybe in another 100 years or so, the nukies will figure it out what to do with the hundreds of thousands of tons of high-level radioactive waste we currently have and the quantities still to come. Then maybe they will be able to figure out what to do with the billions of tons of low-level and intermediate-level radioactive waste...and who is going to pay for it. If we last that long. By the way, the indians want their land back after the mines left their mountains of acidic and radioactive tailings piles and million gallon sludge lagoons.

[@ImieNazwiskoOK]

@@jackfanning7952 Thing is if you drill deep enough(far below ground waters and such) there is effectively no chance of interfering with ground waters or even moving significantly. And also the containers would be quite strong (possible stronger than those fro transport, and they survived crashes of rocket powered testing trains and similar absurd tests). Yucca Mountain was totally different design so in this case it's pretty irrelevant. And I feel like you do not know that much about the nature of waste here. (don't get me started on what are the alternatives and their problems)

[@jackfanning7952]

@@ImieNazwiskoOK So simple, eh? Tell me. Where is it being done? By whom? If not, why not? Let me know when you find a contact. I have about 35 million gallons of high-level radioactive, corrosive sludge leaking into the ground water about 90 miles from my home. Been there since the 1960s. Let's start there, shall we. Then let's find a borehole for the 100,000 tons of high-level waste in open pools and casks at reactors within spitting distance of every major city in the U.S. The utilities might miss that $1 billion a year the taxpayers are paying them for the "temporary" storage but, hey, we all have to sacrifice if we want to boil water. No, I don't know much about the hundreds of radioactive isotopes or the actinides left from the fission reactions. I have a list of their scientific names, their half-lives and their types of radiation (alpha, beta, gamma, etc.), also some of the specific organs they attack, but little direct knowledge of each of them. Nukies don't know much about that stuff either and don't like to talk about it. Don't worry, be happy. The Science Writer for the New York Times, Mr, Lawrence, who also was the official historian for the Manhattan Project (that's odd, I didn't think journalists were supposed to work for the agencies they covered) wrote about 160 puff pieces about the 2200 test bombs and never mentioned even once anything about the radiation. The troops who marched out to observe the explosions weren't told either. You know, nuclear secrets. Might give scientific progress a bad name.

[@HuntingTarg]

It's very cool that you endeavored to properly understand the physics and engineering in order to make this video. It's not quite the sort of thing that I could use on the average schmo on the street, but it is still an explanation of how nucleonic power generators can be made inherently safe, contrary to media propaganda and (usually congruent) popular opinion. However, you flubbed two things; - Real Engineering has done a video on the potential practicality of nuclear rocket engines for interplanetary travel. Worth watching. - You discussed the thermal corrective properties of Uranium Hydride fuel, but you didn't discuss the 'Doppler broadening' effect, which causes neutrons to be scattered at a wider range of kinetic energies, and therefore there are fewer 'thermal' neutrons available to start reactions, which is the engineering feature that TRIGA reactors are designed around.

[@kenoliver8913]

There have been many reactor designs since that are "meltdown proof" (basically, the thing is physically incapable of getting hot enough to melt). Pebble beds, thorium, SMRs etc. Most work well at a physical level but turn out to not scale up to power plant size, or need constant refuelling (an inherently unsafe procedure moving lots of fuel around the country), or can't get hot enough to operate a supercritical steam turbine - in other words, they're very safe but uneconomic. Which is the story of nuclear power generally - it is such a complicated way to boil water that if its safe its expensive, and if its cheap it's not safe.

[@Karreth]

One of the main reasons safe nuclear power plants are so expensive is that there is virtually no economy of scale. Every reactor is a bespoke piece of equipment. If we decided to, we could probably launch an initiative that would build several such plants and thus greatly decrease the cost per unit, though it might take several nations cooperating. Sadly, due to public perception of nuclear power, I don't think it will happen.

[@Toefoo100]

Thorium is a fuel not a reactor

[@cdgonepotatoes4219]

@@Toefoo100 Semantics, of course they meant "thorium-fueled reactors"

[@derekp2674]

@@cdgonepotatoes4219 Thorium-232 is a 'fertile' material that can capture neutrons and form the fissile nuclide uranium-233.

[@ImieNazwiskoOK]

Statistically they are both, but then how much of safety (because you could pretty much always improve it). Thing is they make sense longer term and cost to start is big.

[@mfx1]

There was a training reactor operated in Greenwich called JASON which is pretty much central London for decades without the general public knowing it existed, thousands of people drove past it every day. I saw part of it's removal operation. That design wasn't inherently failsafe but it was very low power.

[@topeka088]

While I understand the proliferation concerns for HEU reactors on Earth, is that really going to be a problem in space? If a country can figure out how to get to my reactor on the Moon or Mars to steal my HEU, they probably already have their own and don't need mine.

[@davidelang]

I think the concern is that encouraging HEU reactors for space means that you need to grow the number of people who can build them to satisfy the demand. And either the expertise or components could then be redirected away from the intended space use to misuse here on earth

[@susanyoung6579]

@@davidelang exactly. It's about limiting enrichment and the tools necessary for it in the first place.

[@topeka088]

@@davidelang As long as there are naval reactors there will be HEU reactors. And having some federal weapons lab making HEU reactors isn't going to let any genie out of a bottle any more than it already is. At least for now. Who know how things will be once The Expanse becomes real.

[@davidelang]

@@topeka088 it's not about federal weapons labs making reactors, it's universities and corporations making them for science and commercial satellites. They aren't going to have their components built and secured by the military.

[@topeka088]

@@davidelang Of course not. I never said make ONLY HEU reactors for space. I'm specifically talking about reactors for powering large space applications, like colonies. Research and satellites clearly don't need the large power densities that HEU makes possible.

[@jacobsparry8525]

My grand father worked at Aerojet General Corp. on the Polaris SLBM dry fuel systems, BUT he also worked on Project NERVA which I discovered was a nuclear engine for spacecraft on long distance missions and when he was older he told me, or hinted at, a nuclear engine for atmospheric aircraft that they experimented with that he said was a failure. I am always amazed at the things they did in total ignorance of possible consequences. Though some of what they did worked out better. The Polaris Series of SLBM’s were a total success, but they soon quit playing with nuclear systems and rightfully so. Can you imagine them trying to put a small reactor on an aircraft.

[@pdqkevin]

The problem is we have political leaders and the voters who select them who base their decisions on the feelings they had when they watched movies. They watched Bambi and created the wild land management policies that have led to giant and lethal wild fires. They watched One Flew Over The Cuckoos Nest and created policies that have led to much of the homelessness crisis. And they watched China Syndrome and decided nuclear power is bad and instead we spent billions and billions of dollars on wind and solar which now causes shortages of electricity during times of peak demand.

[@bobtherat99]

LANL built a self-regulating reactor that ran at a set power level for over a year without human intervention. The design was basically a liquid fuel in an annular case. The bottom of the case was a reflector and the top was a poison. The fuel would heat up and expand. This shoved fuel up into the poison region where the fission rate dropped. The fuel cooled and flowed to the bottom by convection. This process would continue until homeostasis was achieved. The power output level was set by the ratio of the poison ring to the reflector ring. It self regulated to within a few watts for over a year. This included an experiment involving pulling out old fuel while pumping in fresh fuel. I found it while I was researching Phoebus-2A reactor.

[@3D_foos]

really interesting i wonder how it would compare to a liquid fluoride thorium reactor. in safety, efficiency, cost, etc.

[@Bradley_UA]

like comparing a childs bicycle to a sports car?

[@Drewmikola]

The flouride part is a pain as you have to refine lithium which creates weapons grade material (lithium 6 is a component of hydrogen bombs). Check out the chloride salt reactors concepts. Far simpler than running a flouride lithium beryllium molten salt solution (all of those components are quite nasty if they hit the atmosphere).

[@gizmophoto3577]

THE TRIGA concept cannot be easily adapted for power generation, so it isn’t a basis for comparison.