It’s been a while, lots of work in the lab plus coming down with the flu the past few weeks was a lot. I’m back at it tho 💪🏼 and a huge thanks for sticking around and for the awesome support for the channel. 🤗 Also I am super happy and grateful for all the love you’ve been showing for the clothing line as we’re nearly sold out. 👕 Let me know what is your favourite reactor type and why as well as what else you’d like to see next. ☢️👩🏽‍🔬

The first three fuel assemblies with MOX fuel (mixed oxide fuel), which contains not only plutonium but also other transuranic elements: americium-241 and neptunium-237, have passed acceptance. The assemblies will be loaded into the BN-800 reactor at Beloyarsk NPP in the spring of 2024 and will be subjected to pilot operation for three micro-campaigns (approximately one and a half years).

Thanks for this video! Fantastic info! Yes, please do a separate video on fuel concepts. 😊

In November 2023, the fast neutron power unit BN-800 at Beloyarsk NPP with MOX fuel (a mixture of uranium and plutonium dioxides) was brought to 100% capacity of more than 800 MW.

I like the high temperature gas cooled reactor because of the potential to produce hydrogen. Please do a follow up video on TRISO particle fuel concept. Thanks for the learning experience!

When I was in the navy nuclear power i remember some of our discussions on HTGR but that was 15 - 20 years ago. Mostly we talked about the idea of ball fuel pellets and being able to remove pellets and determine if it still useful or if it is exhausted.. if it was still useful it got put back in if it was exhausted it would be replaced. I loved the idea of it but would wonder what has changed over the years. Honestly I would love more detailed videos of each type. I think I would be more interested in the reactors that could come online first more than the ones who are 10+ years out. I agree using Supercritical in the name of a reactor is a bad choice and i doubt if anyone who knew a lot of how reactors worked and the terminology was involved in the naming. well my favorite is the Thorium reactors types I have heard many interesting stories of them.

Tesm MSR molten chloride fast reactor. Burns anything fissionsble, could add technological channels for making isotopes and line the thermal region outside the core zone with plumbing that you could pump LiBeF3 through to make tritium or DUF6 to make extremely pure plutonium in the form of nearly pure 239 as the fluoride salt. The only drawback is that the iodine must be quickly removed as it will make the salt mix extremely corrosive.

Please do a video on the TRISO fuel. I helped run experiments at the Advanced Test Reactor and the Idaho National Laboratory. I was too busy working on the control system to learn about the fuel we were testing and maybe testing in the future. Love your videos - I got a BSNE in 1982 and your videos help me keep knowledgeable.

This is brilliant, thank you! With the exception of your channel, it's so difficult to find accurate information on reactor technology. And not being a nuclear physicist myself, I could never understand the technical literature myself. So I sincerely appreciate the effort you put into educating the public. I think everyone should watch your videos! For all the talk about 'clean energy' one hears nowadays (mostly from people who are clueless, such as politicians), I see very few people ever willing to discuss the potential of nuclear energy. This strikes me as ignorant (at best). In any case, please keep doing what you do, cheers!

Can you make a video on how a Liquid Metal cooled reactor starts up from cold and how it shuts down? Getting the “cooling” material liquid thru all the pipes at startup must be complex.

Nice vid, congrats! A small correction: around 6:05you say that material development for MSRs is challenging since fluoride/chloride salts are highly corrosive. On contrary, nuclear reactor engineering veteran Ed Pheil plans to use code verified materials exclusively for his Molten Chloride Salt Fast Reactor. He states that stainless steel is OK with chloride salts, actually water is more corrosive at elevated temperatures. Additionally, MSRs are not necessarily operate with thermal, or epithermal neutron spectrum only. Using chloride salts one gets quite a hard spectrum of neutrons, similar to SFRs. Anyway, the video is very informative and I wish success your channel lot of success!

Great video! Yes, let's hear more about triso fuel.

The Russian Submarines used the lead bismuth reactors for a while, so we have some experience. It seems they were not idea for submarines as they need to use steam when in dock to keep everything molten, it’s seems this would be more manageable in a fixed reactor

Appreciate this short nice summary. However, rather than animated subtitles, simple static reactor schemes shown full-screen would contribute more to understanding.

This was very interesting to watch. You did a great job explaining everything. Would love if you made a video about TRISO fuel. I've read an article about it and it sounded very promising.

I always jump to watch a new video when you post them. I love the way you approach educating the general public on all things nuclear. Thank you!

Hope you are feeling better Dr. Charatsidou! Very good run down .

Elina, please talk more about which of them can operate as breeder reactors. Since breeders can use ore 100x more efficiently, they make nuclear energy inexhaustible. Generally fast reactors can breed , and some thorium types.

The main advantage of gen IV is low-pressure / high-temperature. Both bring the cost down of nuclear and high-temperature allows for high-grade industrial heat. The demand for industrial heat is 2x electricity alone.

Excellent survey, thank you. On the topic of Gas Cooled reactors, Peach Bottom Unit 1 was commercially operated from 1967 to 1974.

Very happy to hear from, I wouldn’t question your knowledge either way, Very helpful, thank you.

Hello Elina, Big fan of the channel along with all kinds of science explainers. Top tier work making science understandable for all us lay people. If I ask a question for a shorts reply. About a month ago I was at what I think Europeans call a "car boot sale." And one of the people there was selling a VERY old (1950s maybe) radiation detector. It wasn't a Geiger counter at all. It was an acrylic (maybe?) cylinder roughly the size of an ice hockey puck. Inside of it was an empty cylindrical chamber with several small red balls in it. There were instructions stamped on the bottom brass plate: "Shake container lightly until some balls float. if balls do not float or if previously floating balls drop, seek fallout shelter." I have never even heard of a radiation detector like that. Is that a real radiation detector? And how accurate (if at all would it be)? *The detector was also stamped with a TM for Nu-Klear and patent pending info

Great video, as always! Wish you did even more in the depth analysis of the SMR types you described here, as well as an analysis of the proposed fission and fusion reactor designs proposed by startups mentioned int the @age-of-miracles podcast.

Thanks Elina! As usual quite fascinating. Can you please also, at some point, talk a little bit about new prospects in fusion reactor research? Thanks!

Also , there was a prototype high temp gas cooled reactor in Fort Collins, CO 50 years ago, but it was shut down because the fuel became too expensive

Happy holidays Elina! Thank you for all the education 😊

Merry Christmas! 🎄

Yes please go into detail of the TRISO particles. When I first heard of these reactor types I was skeptical. I would like to understand them better.

Hey Elina. best wishes for the new year. stay happy and keep these great videos comming 🥂

Yes, yes continue explaining in detail please!

Wishing You good health! a very good video, I'd be happy to learn more about the TRISO fuel too

Thank you for this breakdown. It is very helpful, to understand were the technology is at.

Very encouraging, Thank You👍

Great explanations. Looking forward to 2024 and the ongoing resurgence in the interest in nuclear. Channels like yours are helping to bring no-nonsense info into the hands (and minds) of an increasingly growing and (we hope) influential number of people. Merry Christmas. Lots of cheer.

My reactor wish list: - Uses most of the energy in the fuel, leaving relatively low level waste. - Passive safety - Ideally general safety, not just meltdowns - some designs look like they have a fire risk with coolants like Sodium - Uranium and thorium (not necessarily in the same reactor, but I'd like to see the energy system using both) - Zero water - you can put one in the desert and air cool it with no external water input, and thus no environmental impact on waterways and no shutdowns because climate change or overuse dried out the river - Ideally high temperature operation, for thermodynamic efficiency and for use in chemical processes like 0C jet fuel synthesis. - Ideally not a lot of expensive fuel pre processing such as enrichment - Would be nice if it could burn down high level nuclear waste, perhaps added to the fuel mix, though special purpose reactors would suffice for this niche task. So is the above list even achievable?

Hi Elina, Are you going to do a video on the Triso Particle Fuel? That sounds interesting, I'd like to hear more about it.

Thank you for this video

This is a great overview of the Gen IV reactor systems! It's very exciting to see more public information about these exciting developments! Just a few side notes... The chloride salt reactors can operate completely in the fast spectrum, nearly as hard as the GFR. The VHTR can only operate in thermal spectrum due to the use of graphite as the thermal inertia. One of the biggest challenges to the LFR is the corrosivity and erosivity of its coolant. I'd love a video deep diving into the MSR, because there are SO many variants from thermal to fast, breeder and burner, thorium to plutonium... Check out the GIF MSR Taxonomy video for a detailed overview!

Very interesting, Thank You.

For SFR you missed Phenix and Superphenix who worked in France but were killed for political reasons, but research continued with the ASTRID project mainly stopped now but most engineers moved to SMR projects who're using the knowledge.

Great video, thank you for sharing, please make a video about TRISO fuel!

THANK YOU for talking about this. Please tell what the most economically viable solution for the near future will be.

Fantastic video!

As a layperson, I understand some of the content in your videos, but that gives me the inspiration to make an effort to educate myself about the subject, so I can better understand what you are discussing in your videos.

nice overview, thanks, would be interested in your review of the design, benefits, constraints, risks, economics of traveling wave reactors

The Hermes demo reactor at the site of the old K-25 facility here in Oak Ridge will be using TRISO fuel (also being produced in Oak Ridge) in a molten fluoride salt cooled system. Also X-Energy is developing a HTGR using TRISO here in Oak Ridge. I'm personally more a fan or molten-chloride fast reactor (MCFR) or other MSR reactors, since they don't require the fuel manufacturing step, and seem better suited to using up existing waste stockpiles. This could be especially helpful with decommissioning nuclear powered ships.

Great video, really intetesting & informative. Would be great to see individual studies of each type. Would also be interested on your opinion of fusion reactors, I've got an (un-scientific) feeling they will never actually work.

Elina, you are absolutely amazing! Intelligence AND beauty in one incredible human being! On top of everything else, I love your accent! I could listen to you talk all day! Your voice is very soothing to me! I absolutely adore you! Just one question is eating at me. How do you pronounce your last name?!?! ❤️🌹

SCWR sounds like a steam explosion waiting to happen.

Happy Holidays

Wow thank you very much for this content! It is always very interesting to learn more about these different reactors, I wanted to ask about which ones had the capacity to be able to operate in smaller scales? From my understanding it seems like maybe the Swedish Lead reactors are the best solution for that, but I’m not sure what do you think? Also I would love to learn more about the triso fuels, they seem interesting, which one is your favorite type of reactor and why?

SOS Namaste 🙏 Elina Charatsidou🙏 It is my humble request to you please make some videos on Off-site safety & security. What do organizations and governments do to achive the off-site safety and security ? How can they aware & prepere the local residents about it ? What should local residents do at the time of radiological emergency caused by any accident ? What should be the SOP and fundamental or essential infrastructure training, drill for local residents to stay safe in any nuclear disaster ? Please it will your great kindness.💐🙂🙏

def need a dedicated triso video!

I'd love to see a video on what exactly radioactive contamination is. Is it the presence of radioactive particles that are transferred from one place to the next to the next? It is one radioactive atom or molecule causing another atom or molecule to become radioactive through interaction? Is it something else? How can some things be cleaned and not others?

Each of these reactor concepts would be worth a separate video. Also, the current breed of SMRs that seem to be adopted in, eg, Poland - they seem all to be of either "classical"pressurized light water kind or boiling water, using thermalized neutrons and enriched uranium fuel - so, pretty conventional. Also, I believe that Japan plans on building some kind of high temperature reactors they would utilize for hydrogen production, something they seem to be enamored with. A video on that topic would be nice, too. BTW, are those deadly looking talons/claws removable? Retractable, perhaps? 😀 (I don't imagine gloves like them...) Happy holidays and thank you!

The US is also developing SFR, GE-Hitachi’s S-PRISM. They have a partnership with Terrrapower to build a reactor in Kemmerer WY. The intermediate loop has been replaced with molten salt allowing the reactor to be separated entirely from the load isolating the nuclear island (this was my dissertation research). Furthermore the SFR was designed (metal fuel) for entirely closed fuel cycle with complete consumption of the minor actinides. This is known as the Integral Fast Reactor. Pyrometallurgical processing is very interesting in its own right. Regarding the molten salt reactors if there is anything that thorium can do, uranium can do better. There is nothing that makes this reactor type inherently thorium based reactors.

Please Elina elaborate on the different types of fuel pellets. I'd love to know.

Wonderful. I've been waiting for a this one for a while. TRISO fuel with helium coolant seems to be the safest way to go but I like MSR idea also, in spite of the the corrosivity because they can use thorium as well as uranium. And yes we did run some Th fuel in the Oak Ridge MSR no matter what the government says. I know because I analyzed the samples from the cleanup. Thorium has the added advantage of being 100% burnable whereas only a tiny percentage of uranium can be a fissioned.

A unique and interesting design is the Moltex SSR which is a cross between an MSR and SFR. It uses fuel pins like the SFR but filled with molten salt fuel and so they can use natural convection to keep the fuel mixed and transfer heat to a surrounding inert salt so you can get the benefits of MSR without having to pump super radioactive fuel around a circuit. I think its a really clever design and could be the dark horse of gen 4.

Thanks very well explained at least at my level of understanding, take care. Also yes any videos on reactors or progress on designs, I've believed for a very long time this is the fuel for the future, we must make sure the designers are in control NOT the politicians or 'bean counters'.

I'm starting to realize that separating these designs into categories of "reactor types" like this may not be very useful anymore. For example a sodium cooled fast reactor and lead cooled fast reactor don't really have that many differences but warrant a different category apparently. In the meantime Molten Salt reactors were a single category even though something like the Heavy water moderated Thorium cycle container sized reactor from Copenhagen atomics is VASTLY different from Molten Chloride Fast Reactor developed by Elysium Industries (although maybe now bought by TerraPower from what it looks like)

🎯 Key Takeaways for quick navigation: 01:48 🌊 *Sodium Cooled Fast Reactors (SFRs):* - Operate on a fast neutron spectrum. - Use sodium as a coolant for higher temperatures, efficiency, and fuel utilization. - Russia (BN600, BN800) and China (CFR) are actively developing SFR technology. - Challenges include potential material reactions due to sodium. 04:48 🔥 *Molten Salt Reactors (MSRs):* - Operate on a thermal neutron spectrum using molten salt as fuel. - Advantages include online refueling, potential waste reduction, and suitability for thorium. - Limited operational experience; actively developed by the US, Canada, and China. - Challenges involve materials development for the corrosive environment. 07:56 ☢️ *Lead Cooled Fast Reactors (LFRs):* - Operate in a fast neutron spectrum with lead as a coolant. - Provide inherent safety with a negative void coefficient. - Developed by Russia, European countries, and Sweden. - Challenges include material development for corrosive and erosive lead. 10:54 🌀 *High Temperature Gas Cooled Reactors (HTGRs):* - Operate in both fast and thermal neutron spectra using helium as a coolant. - Potential for high-temperature applications like hydrogen production. - Limited operational experience; mainly developed by China. - Challenges involve developing a new trio particle fuel. 12:45 💧 *Supercritical Water Cooled Reactors (SCWRs):* - Operate with supercritical water as a coolant, offering simplified design. - Potential for higher thermal efficiency. - Early stage of development by China and Canada. - Challenges include high-temperature and high-pressure conditions. 13:54 🎈 *Gas Cooled Fast Reactors (GFRs):* - Operate on a fast neutron spectrum with helium as a coolant. - Offer efficient heat transfer and potential for high-temperature applications. - Limited operational experience; primarily developed in France. - Challenges include early-stage development and material compatibility. Made with HARPA AI

Of the six proposed fourth-generation nuclear reactor types, the Molten Salt Reactor (MSR) is the only type with high fuel efficiency, no danger of explosion, and does not generate substantial amounts of plutonium. The fissile uranium-233 produced by the MSR is difficult to use for weapons because of the presence of highly radioactive uranium-232. While other Small Modular Reactors (SMRs) can serve as a short-term solution, MSRs are considered a more promising mid-term solution due to their potential to address these issues more comprehensively. Hopefully, we will have fusion by the time we run out of uranium and thorium. With the molten salt reactor, 7.5 million tons of uranium will be exhausted in a thousand years at an annual consumption of 7500 tons. Using thorium will extend it by a couple of thousand years. The differences between Light Water Reactors (LWR) and Thorium Molten Salt Reactors (TMSR) are significant in fuel utilization and waste production. LWRs use approximately 0.5-1% of uranium fuel, leading to the generation of long-lived radioactive waste due to inefficient energy conversion and the use of enriched uranium. In contrast, TMSRs can achieve fuel efficiency of up to 98%. This is achieved by converting fertile thorium-232 into fissile uranium-233, substantially reducing waste production and more manageable radioactive waste. Uranium Molten Salt Reactors (UMSR) will produce more plutonium but are just as effective as TMSRs. 940 kg of natural thorium in a Molten Salt Reactor (MSR) can generate 1 gigawatt (GW) of electricity for one year. In comparison, generating the same amount of energy in a Light Water Reactor (LWR) would require mining 210 tons of uranium. In an MSR, the storage requirement for 83 percent of the spent fuel is 10 years, and 300 years for the remaining 17 percent, whereas in an LWR, 24.44 tons of spent fuel need reprocessing and storage for 200,000 years. MSRs can utilize the spent fuel from LWRs. A coal power station will need to burn 3.5 million tons of coal and emit 10 million tons of carbon dioxide to produce the same amount of energy for one year. That amount of coal contains 3 to 14 tons of uranium, 3 to 14 tons of thorium, and an average of 84 tons of arsenic. MSRs can adjust power output to match electricity demand, thanks to the inherent and automatic load-following capability provided by the fluid nature of the molten salt coolant. A key safety feature of MSR is that it automatically adjusts to prevent overheating. This is achieved through a "negative thermal reactivity coefficient," which means that as the temperature rises, the reactor's reactivity decreases, preventing a runaway chain reaction. Additionally, the MSR has a "negative void reactivity coefficient," ensuring that the reactivity decreases if there is a loss of coolant or boiling, preventing potential overheating. These safety measures help keep the reactor stable and safe under various conditions. Looking ahead to 2040, China plans to deploy Molten Salt Reactors (MSRs) for desalination of seawater, district heating or cooling, hydrogen production, powering of ships equipped with thermoacoustic Stirling generators, and power plants with supercritical carbon dioxide turbines within its borders and globally. In the Earth's crust, thorium is nearly four times more abundant than uranium. Every atom of natural thorium can be harnessed, unlike natural uranium, where only 1 out of every 139 atoms can be used. China produces thorium as a byproduct of its rare earth processing. Similar to the trends observed with solar and wind technologies, MSR costs are anticipated to decrease with the scaling up of production and the development of robust supply chains.

Love the designs that shut down on their own ....seems so much safer ... takes the scary meltdown off the table!

My favourite would be the gas-cooled fast reactor, but anyone of them would be better than what we have now as an alternative to light water reactors, burning fossil fuels or relying on intermittent power

Have you done a video about the problems of scaling up from prototype reactor to full size reactor? The UK built a prototype AGR and the simplified version of event is that the prototype was quite easy to build and worked really well so several full size power stations were ordered and they turned out to be enormously more difficult (and expensive) to build than expected and had all sorts of unexpected operational hitches when they were being commissioned. This did a lot to ruin the reputation of nuclear power in the UK. How can we be certain that a promising small scale reactor won't scale up really badly and become known as a bit of a white elephant? (it was the mention of on-load refuelling that reminded me of this - the AGRs were supposed to be capable of on-load refuelling but afaik it's never been done on a full size AGR power reactor.)

Yes silicon carbine layer videos please. Also using helium is super cool ---- it's basically radiation proof and can get super hot --- except it is also a very small atom and will leak through most metals so containment is an issue at those temperatures. (Would be interesting if doping a metal lattice with helium could make it stronger, um ...)

Ah...seeing HTGR's rise again. When I got my degree in Nuclear Engineering in the 1980s I did an HTGR Design Project for my Reactor Design Class. Was largely based on what was going on at Fort St.Vrain in Colorado USA (long since decommissioned). Alas...that was so long ago...I don't recall much about it. Thanks for the always interesting videos. I left the Nuclear Industry back in the mid 1990s...but I always like to keep track of what the current topics are. You are MOST helpful for doing that.

Great info Elina. Can we talk about the coolant (sodium, lead/bismuth) and its state when it comes time to disassemble the reactor in 30 - 50 years time? I imagine the coolant is highly radioactive?

Yes, please teach us about Triso(sp?).

*Summary* - *0:00** Generation 4 Nuclear Reactors Overview* - 0:00 Discusses the transition from current reactors to Generation 4 types. - 0:17 Focuses on six proposed Generation 4 reactor types. - 0:27 Compares them based on differences from current light water reactors, pros and cons, countries developing them, and development stages. - *0:49** Sodium-Cooled Fast Reactors (SFRs)* - 0:53 Operate on a fast neutron spectrum, better at fusing uranium-238. - 1:31 Coolant is sodium instead of water, allowing higher operational temperatures and efficiency. - 1:46 Russia leads development with operating BN600 and BN800 reactors, and the upcoming BN1200. - 2:04 China also developing SFRs, including the CFR. - 2:46 Challenges: sodium's reaction with materials requires careful design. - *3:01** Molten Salt Reactors (MSRs)* - 3:07 Use molten salt as fuel, circulating in fluoride or chloride form. - 3:39 Allow online refueling and reduce downtime. - 4:07 Potential to reduce nuclear waste and use thorium as fuel. - 4:50 Inherent safety features and passive cooling. - 5:55 Material development challenges due to corrosive nature. - 5:21 Limited commercial operation experience. - 5:23 Countries like the US, Canada, and China are key developers. - *6:24** Lead-Cooled Fast Reactors (LFRs)* - 6:40 Use liquid lead or lead-bismuth as coolant. - 6:50 Offer efficient radiation shielding and high-density benefits for smaller reactor size. - 7:25 Higher temperature operation leads to efficient heat transfer. - 7:54 Inherent safety with negative void coefficient. - 8:35 Material challenges due to corrosive nature of lead. - 8:55 Limited commercial experience. - 7:32 Russia and European countries, including Sweden, are prominent developers. - *9:01** High-Temperature Gas-Cooled Reactors (HTGRs)* - 9:04 Operate on both fast and thermal neutron spectrums. - 9:22 Use helium gas as coolant, enabling high-temperature operations and hydrogen production. - 9:57 Utilize tristructural-isotropic (TRISO) particle fuel. - 9:49 China leading development with HTGR-10 and HTR-PM projects. - 11:01 Challenges include new fuel development and limited commercial experience. - *11:08** Super Critical Water-Cooled Reactors (SCWRs)* - 11:13 Early development stage. - 11:31 Super critical state refers to water being between liquid and gas. - 11:57 Simplified design compared to current light water reactors. - 12:24 Can operate in both fast and thermal spectrums. - 12:29 Higher temperature and pressure operations for better heat transfer and efficiency. - 12:00 China and Canada among the countries developing SCWRs. - 12:57 Very limited commercial experience. - *13:02** Gas-Cooled Fast Reactors (GFRs)* - 13:04 Operate on a fast neutron spectrum, mostly developed in France. - 13:07 At an early research stage, potentially employed in the 2040s. - 13:14 Use helium as coolant, similar to another reactor type, but combined with a fast neutron spectrum. - 13:27 Efficient heat transfer and high temperature applications, such as hydrogen production. - 13:43 Inherent safety due to inert and non-reactive helium. - 14:07 Disadvantages include no operational experience and being at an early development stage. - *14:15** General Overview of Generation 4 Reactors* - Understanding Generation 4 reactor types, neutron spectrum, coolant choices, development stages, and countries involved is essential. - 14:42 No perfect design; each has its own advantages and challenges. - 14:47 Different designs are chosen based on the ability to tackle specific challenges. - 15:02 Countries choose designs based on their capability to address challenges and specific applications. - 15:27 USA and Sweden, for instance, are focusing on multiple designs and lead-cooled designs respectively. - 15:34 Future developments, challenges, and potential design changes are anticipated in this evolving field. *Summary of top comments* (as of 2023-12-30 with 21150 views, 208 comments, 1.7k likes) - Requests for specific follow-up videos: - Separate video on fuel concepts, especially TRISO fuel. - Video detailing the start-up and shutdown process of Liquid Metal cooled reactors. - Video on the efficiency and design of various reactor types including pebble bed reactors. - Video on the potential of nuclear energy, fusion reactor research, and fission-fusion reactor designs by startups. - Video exploring radioactive contamination and its cleaning processes. - Video on helium cooling in reactors and its impact on materials. - Comments on specific reactor types and fuel: - Interest in high-temperature gas-cooled reactors for hydrogen production. - Discussion of the use of MOX fuel in BN-800 reactor and its composition. - Comments on the cost and complexity of manufacturing TRISO fuel. - Mention of Russian submarines using lead-bismuth reactors. - Discussions on the MSR molten chloride fast reactor and its potential. - Comments on thorium reactors and their efficiency. - General discussions and queries: - Questions about the corrosiveness of fluoride in MSR designs. - Curiosity about the materials used in reactor construction, especially steel and its reaction to radiation. - Discussions on the economic viability of different reactor types. - Interest in the potential of breeder reactors for efficient fuel use. - Mention of historical reactors like Fort St. Vrain HTGR and Peach Bottom Unit 1. - Queries about the relative efficiencies of different reactor designs. - Personal stories and experiences: - Sharing personal experiences and memories related to nuclear power and reactor technology. - Expressions of gratitude for the educational content and requests for more detailed explanations of reactor types. - Miscellaneous comments: - Wishes for the holiday season and new year. - General appreciation for the informative content and requests for more videos on nuclear technology. - Discussions about futuristic concepts like using nuclear arsenals for space projects. - Comments on the use of helium as a coolant and its properties. Disclaimer: I used chatgpt4 to summarize the transcript and the youtube comments section.

Replacing helium might me expensive in the long run as it excapes through seams. This is a rare gas, and it's always in demand for cryogenic refridgeration.

Can you do a deeper dive on the GCFR, this one seems to have the best and safest operating parameters.

It seems to me that for current construction, the CANDU reactor is the best choice. It allows on-line refueling and will burn waste fuel; it has extensive commercial experience. For future research the MSR (either Thorium or Uranium) seems promising because of its ability to load follow. The MSR can heat a large pool of molten salt. At periods of high demand, the turbine can extract heat from the molten pool faster than the reactor's maximum capacity. After the peak passes, the reactor continues to function at maximum capacity until the pool has been reheated (see TerraPower). As I understand it, the technology or Thorium and Uranium are quite similar for a MSR. Being able to use the byproducts of rare earth metal mining (thorium) is an extra benefit to having multiple fuel types at different sites.

How does the GFR deal with a loss of coolant accident? Surely with helium as a coolant it must have a near-zero void coefficient so it must be actively SCRAM-ed but they still have to remove the residual heat somehow. Great video btw!

TRISO fuel is also one of the prime candidates for nuclear thermal propulsion for space applications.

Thank you, I appreciate the breakdown and definition on national pursuit. Which has the most potential for “least weight” category? Meaning likelihood for space flight operations (assuming that the other conditions are also suitable for this purpose)? Is that why helium gas, a finite and fundamentally difficult material to obtain, is being considered for several design options?

Such an improvement from long shutdowns to remove partly used fuel and replace with slightly more enriched fuel, to using the kidney to remove transuranics and actinides and add fuel, even other reactors' waste as fuel!

The scfr is fasenating. Sodium being a strong reducing agent should be very innert relative to any metals that comprise the reactor components, though another issue could arise where metals are instead soluble in the molten sodium.

Nice video.

Do you have commentary on the Nuke'Em high movies? I recently saw those.

The AGRs in the UK provide an interesting case study for higher thermal efficiency (since they run hotter than LWRs) and also the pros and cons of gas cooling. And they are a full production design with several decades of service life. The main problem is cracking of the graphite blocks in the reactor cores was always going to be life limiting.

Hi Elina! Do you know about the Dual Fluid Reactor (DFR). Is this a promising idea? Or is it just MSR under a new name?

Thank you and Merry Christmas Dr. Elina. I realized a long time ago that nuclear-powered electricity generation was one of the most reliable and economical in the industry. Of course, in my opinion, hydroelectric power plants are the most reliable and economical way of generating electricity. As an engineer, I see the potential of the helium coolant reactor, which can also generate hydrogen. However, hydrogen will cause the metal to become brittle and fail. Carbon composite tanks could work, but carbon fibers are made from petroleum byproducts. Therefore, we would once again depend on fossil fuels.

At this point, based on my understanding, I prefer the MSR reactors.The ability to refuel on the fly is great, but I think the biggest benefits are the ability to consume our existing nuclear waste as fuel, and (again as far as I understand it) the waste is both significantly reduced in volume and its half-life. I think the cons of the corrosive nature of the liquid and the lack of commercial experience are both solvable.

Fuel in multilayer spheres that contain carbon are flammable. The problem only appears if the reactor casing is damaged. Combustion would be partial in the best case, stopping at the level of the silicon carbide layer.

HTGRs are indeed operating in the thermal spectrum. Not in the fast range at all! It uses the graphite of the various fuel form whether pebbles or prismatic blocks as neutron moderator.

Couple of missed advantages in some of these designs. Specifically in MSRs a couple of big ones. Molten salts chemically bond with most fission products. This increases safety through sequestration of materials that in current designs can be easily volatilized and dispersed. Also, in thorium MSRs you can achieve much of the advantages of fast spectrum reactors in a thermal spectrum due to the breeding ratios of the fuel cycle while eliminating some fast spectrum disadvantages. Particularly higher fuel requirements and enrichment requirements. A final missed advantage on MSRs is the passive safety offered of a liquid fuel and solid moderator configuration. During reactor temperature excursions or other safety critical conditions, a simple passive freeze plug can melt and gravitationally drain the fuel away from the moderator core ceasing fission and placing the fuel in a safe confinement location all without human intervention. Some of the advantages of these other reactors coincide with the above list as well. But IMHO the MSR concept captures virtually all of the best advantages of the generation 4 reactors with minimal downside. As well as being perhaps the second or third most tested concept in the list.

Does anyone know the relative efficiencies of any of these reactor designs? My memory tells me that a 1GW electric LWR is about 3GW thermal, but I've never come across the figures for SFRs or lead eutectic reactors. I'd love to see something about pebble bed reactors in a future video!

I greatly appreciate the comparisons. It can be difficult to remember the various types. One comment: I've repeatedly heard that floride is not corrosive! It becomes corrosive if there is moisture (H²O) in the mix, but pure molten salts are less corrosive than pure water.

Pleas , can we get some short video on each type, a bit more of detail?

Yes, let's explore the TRISO fuel!

Is the VHTR reactor some sort of Pebble Bed? Those have been around for decades, haven't they? Also, can fast neutron reactors be fuelled with current nuclear waste, reducing its life from 25000 years to a couple of centuries?

I am most interested in the Molten Salt types, they seem to have the benefits of: online refueling, neutron poison extraction, commercial and medically important isotope production, burning of existing nuclear waste, and Thorium fuel cycle.

Do any of the designs load follow well?

Please, do a video about Threads (1984).

How about small self contained reactors Power working at the small community level..video on that?

I don't like sodium cooled reactors because the coolant is potentially more dangerous than fuel. While we may not have much experience with sodium cooled fast reactors we have lots of experience with sodium cooled thermal reactors and they've had some frightening accidents.

Great! These nuggets of info may be trivial for you, but even for us non-nuclear engineers it's black magic. The MSR sounds very promising to me. Inherently safe, as gravity can always be relied on to flush the molten salt in case of overheating!

You are fantastic, but I needed to set the playback speed to 85%. And the showtime of the graphics should be 3 times longer. It is like a repititorium going through just seen material at double speed.