Nuclear Physicist Explains - What are CANDU Reactors?
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- čas přidán 4. 02. 2023
- Nuclear Physicist EXPLAINS - What are CANDU Reactors?
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In this video, I explain CANDU Reactors from the perspective of a nuclear physicist. I go through CANDU Reactors and what they are and compare them to current Light water reactors.
Hope you like the video Nuclear Physicist EXPLAINS - What are CANDU Reactors? Don't forget to like, subscribe, and share with friends and family. - Věda a technologie
I have a special connection with CANDU reactors as this was the reactor type that got me fascinated about nuclear energy and almost a decade later, here I am! ☢️👩🏽🔬
I hope you’ve enjoyed this video! Let me know what your favourite reactor type is!⚛️
i believe Canada offered this technology to india in the 70s
I like a good fusion reactor.
@@LinuxLuddite Yep. India, Pakistan, China, Romania, and a few other places.
Hi Elina.
Engineer from Canada here. I worked with CanDU reactors in nuclear safety for 15 years.
I really like your channel and how you're making technical knowledge of nuclear reactors accessible to the world. Well done.
You mentioned that Canada has an abundance of natural uranium and heavy water, which is why the CanDU reactor is particularly suitable to Canada. My understanding of how the CanDUs came to be here is somewhat different.
Heavy water (D2O) isn't really a natural resource at all. It's a trace component of all water on Earth. Canada had a specialized part in the Manhatten project where it isolated heavy water by the energy intensive process electrolysis. After the war, there was heavy water on hand and a policy of non-pursuit of atomic weapons. Consequently, Canada began researching and developing reactors that could use heavy water for its neutron efficiency to permit sustained critical reactor operation minimal enrichment of fuel (eventually no enrichment). Several development reactors were built with light water coolant and heavy water moderator. As we got better as conserving coolant, precious heavy water was used as the coolant as well. I think the void coefficient on those light water cooled/heavy water moderated reactors must have been wild!
So there you have it: Canada took the CanDU route to leverage its existing D2O asset and to distance itself from atomic weaponry while developing a nuclear power and isotope production technology.
As the CanDU fleet scaled up, there was a need for more heavy water and mass production plants employing a chemical equilibrium reaction were built. After some decades of operation, the industry had become so efficient at conserving heavy water that the supply on hand is expected to last for generations. Much D2O is now on loan to a neutrino observatory deep underground. Those D2O plants were demolished, and we no longer produce any.
You are quite correct that our domestic stock of expertise has been essential to continued operation of CanDUs. The seed for the workforce was planted as a war measure. The generations of people who have since dedicated their careers to those machines have made them highly beneficial in the long run, but that workforce doesn't develop suddenly just because a country decides to spend money. Having attended to those reactors myself, I've gained an affinity though I can see how other nations might be discouraged by all the novel moving parts.
I learned a lot about the CANDU reactor type indeed however it would be interesting to see how it compares to gas cooled reactors as well.
I worked my US navy career in the nuke program .... learned what I know about CANDU on my own as a hobby. I think it's another example of Canada doin' it right. The Calandria system is amazingly safe and the control systems are simple and effective. I've been a fan of Canada ever since the Avro Arrow was developed. I'm probably not gonna be changing my mind any time soon.
I was a sad day when the Arrow was cancelled but you guys in the US benefitted when the engineers and technicians left that project and played a HUGE role in the US space program.
@@Snowdog070 there is a 60% scale flying replica avro arrow being built and designed in Calgary Alberta at the avro museum
@@Kraigthecanadian At the Springbank airport.
@@threeparots1 oh yes that's the airport name but its in Calgary and most who know anything about Alberta likely knows where Calgary is
Sometimes, we CANDU things right in Canada.
It is worthwhile noting that a CANDU is a Calandria vessel (not pressure vessel), where there are multiple horizontal fuel channels consisting of a pressure tube to contain the fuel 'bundles' and Calandria tubes which separate the fuel channels from the moderator. This is how it is able to be re-fuelled online because you only have to open a single fuel channel to do so. Back when Canada designed the CANDU there was no capability for Canada to construct large pressure vessels like what other countries were using such as the PWR. I also want to correct you in that South Korea does have an operating CANDU at the Wolseong Nuclear Power plant.
I was able to see Wolseong #3 up close a number of years ago. IIRC they closed the tours at the Pickering NPP. No problem, I flew halfway across the world and saw one anyways ;)
I think the USA has lost the ability to make large pressure vessels. When we decided to replace the reactor heads we had to buy them from Japan because they could not be made in the USA. There is no foundry that can produce something that large in the US. If you don't use it, you lose it.
hmm... multiple channels, that phrase sounds vaguely familiar ;-)
I'll have to see an illustration.
@@davidhomer78 You nailed it sir/madam! I think JSW is the only one left .... I thought there was a place in Europe that forged them in the '70s but can't remember who ... or where.
As a Canadian I knew about Candu reactors only in the sense that I knew they existed. Thank you for explaining in such detail how they work and how they compare to LWRs.
Check out Osama's channel. He's a Canadian nuclear engineer and has a lot of CANDU content. www.youtube.com/@OsamaBaig
I was able to take a tour of one in Wolseong, ROK. It was interesting to see the 60s Canadian manual for it on display there, among a sea of Hangul :D. They were building two LWR (probably built by now lol) and the guide explained that the remaining spent uranium from the LWR will be finished off in the PHWR. It was a pretty sweet tour, you had to sign up for it to win it, and my gf at the time kept entering my name till she got us in.
Same here too as canadian, It's quite satisfying to finally know the basics behind this enigmatic candu reactor and the hype really worths it :) Thanks for this fabulous video!! knowledge acquired
@@MrStarmat You could have just went to a foreign national's museum showcasing the tech like I did, 10 years ago :P
It is also worth noting that this technology makes Canada the largest producer of medical istopes in the world. The fact that one of the facilities had to shut down for maintenance actually created a global shortage of this material.
I grew up in a town right next to a CANDU site with 8 reactors and had family and friends who worked there. To me, the most interesting thing about CANDUs is that their design enables passive failure modes. Natural Uranium doesn't have enough neutrons to sustain a reaction by itself, hence why the heavy water is required. This also means that if the supply of heavy water is cutoff, or if light water is introduced, the reaction will stop. This allows the design to use safety features that don't require active intervention or power, preventing situations like Fukushima. Based on the comments I had from people who work there, the workers have to spend much more time just keeping the reaction going instead of working to keep the reactor from going boom.
Thank you for pointing this out as it was missed in the Video and is one of the ket structural safety advantages of CANDU.
Where did you grow up? My grandfather’s farm was in Underwood.
@@michaelbradley6175
Kincardine, but my mom grew up in Underwood.
Natural Uranium can sustain a chain reaction, but only in the presence of heavy water.
the heavy water just does the moderating not the cooling. cooling happens by light water circulating through the core hence CANDU reactors have a positive void coefficient if light water coolant is lost. in that case the heavy water is more easy to manage than graphite though as it won't catch on fire.
One key point of CANDU which was not addressed is tritium production. Tritium is essential for fusion research and while it is theoretically possible fusion can become self sustaining with tritium blankets it is another very difficult engineering problem (because fusion didn't have enough of those already). The CANDU reactor is how the world will get tritium for initial research and is essential to potentially cracking viable fusion.
Perhaps it will have value for initial research but the production rate is too low to be meaningful as a fuel supply. Half life is around ten years so we can't even keep it in a bottle waiting for a fusion reactor.
@@adamgavey1028 Viable fusion will need a C rate of ~10 and tritium neutrality. In an ideal world if we are 30 years from viable fusion we will need tritium produced to start reactors and perform research. More Candu reactors are key to this and perhaps short lived Candu SMRs with a ~10 year life may be a good way to generate it. Candu SMRs are in development. Without something we will never achieve fusion due to being supply constrained (in addition to the many incredible engineering challenges).
Very good point, and I would add It is an identified concern that the scheduled decommissioning of these CANDU reactors presents a limitation for future fusion research. It is surprising to me that so little effort has been focused on validating that breeding tritium from lithium is actually viable for fusion power generation.
@@ccibinel Agreed, Li6 blankets for breeding Tritium seems to be one of the only viable options. Fusion has a long long road to hoe.
@@Pnote2000 Actually, one of the key mission ITER is to test tritium breeding. To me, it seems like one of the easier problems to solve in fusion. I think you also need the 14 MEV neutrons from fusion to test in real conditions so it is very dificult to test without a large fusion machine.
I got my engineering degree in Canada specializing in nuclear power many decades ago, and learned a fair bit about CANDU reactors back then. I have to say that you did a great job explaining the technology, both pros and cons. No fake news here :).
Hi Elina! Great presentation of the Candu reactor! I had the pleasure to work for a CANDU operator (then Ontario Hydro) and the designer ( Atomic Energy of Canada). One slight correction. South Korea does operate Candu...these are the Wolsung 1 and 2 NPP as well as they bought designs of our MapleX research reactor. Regardless, this was a great summary of the technology. One interesting bit of history - when the Soviet Union fell, and the former Soviet republics were reducing their nuclear weapons number, Canada's CANDU reactors were used to consume the fuel from the nuclear warheads, as you mention, the use of heavy water allows for the use of multiple fuel types.
Hello, Elina and greetings from Romania 🙂I have driven past Cernavoda NPP a lot of times but I did not know we were the only CANDU reactor operators in Europe.😃
Interesting that Ceausescu’s communist regime chose Canadian designs and not soviet ones.
But I think its ’ because Ceausescu was paranoid about not being dependent on foreign countries, and since Romania has its own heavy water production facility and natural uranium reserves, it would have made sense.
I am from Cernavoda and people in the city are still waiting for Units 3 and 4 to be built many years after Unit 2 was put in operation. (let's not talk about Unit5)
The politicians seem to just run down the clock until the first two units close and then back to burning coal it is I guess. :(
I mean, we have 11 hydro power plants already built 98% and we just aren't using them. Goddamn expensive imported electricity seems to be very tasty.
Hah I was in Romania 3 years ago and I did not know this! I would have gladly taken a tour (if they do them) when I was there.
@@cezarcatalin1406 I am from Arad. Not only that, but from what I have heard, we have natural uranium deposits but we import uranium because our processing plants are shut down. Lovely country to live in :)
@@alexandrufrateanu
I mean, you can be sure that if the socialists wouldn’t’ve built most of the current housing and infrastructure Romania relies upon nowadays, all the neoliberals after 1990 would’ve never even attempted it themselves. They can’t even build roads right (compare Transfăgărășan with Transalpina or “Transrarău” and let’s not forget the Brașov-Orăștie highway that crumbled in 3 months) and even when it comes to maintaining the old infrastructure they constantly fail (the “repair” job done at Unirii passage in Bucharest where vans constantly get stuck and the surface road started slumping into the concrete construction below).
How can you say Ceausescu was paranoid for not being dependant on foreign countries? This is a good thing and he did well. Should we put him down for everything?
Another thing to mention is the the production of Cobalt-60, CANDU reactors have produced to majority ever used! Also the Bruce site is now producing other rare radioactive elements!
I grew up in Inverhuron, right next to Bruce...there is a very informative visitors centre there for anyone really intersted in CANDU reactors😃
And now Darlington will be producing Molybdenum-99!
Whats the use o cobalt-60?
@@joaquimbarbosa896 Treating cancer, and sterilizing food mostly
@@canaanval modern medical equipment does not use decaying sources any more, but linear accelerators to produce gamma rays as needed.
In terms of safety, you didn't mention that every CANDU station has a building attached to the reactor building that is under vacuum and has water sprayers. In case of a LOCA (loss of coolant accident) it sucks up and condenses any radioactive steam. This is one of the safety barriers to releasing radioactive material to the environment.
The Cernavoda NPP does not have a pressure relief building. Not every CANDU station has that building. 😁
I think that the only ones with a vacuum building are the sites in Ontario having 4 or more reactors sharing a vacuum building. The single unit in New Brunswick does not have one.
You are correct.
This is not new. Russian VVER 1200 and VVER TOI use SAOZ (САОЗ) tanks to fill the reactor with borated water, which is simpler in principle, because everything is contained in a containment along with the reactor.
Fantastic presentation of the CANDU reactor which I had no idea that existed. You northerners have consistently invented/created ingenious products. Chalk this one up as another winner as well! Thanks for the lesson.
Thank you for the videos, I used to be very ignorant and anti nuclear but your videos have changed my mind.
Thanks a lot for the comment ! I appreciate it and I’m glad the videos were informative enough that gave you all the necessary info to make your own decision on the topic!☢️👩🏽🔬
@Richard, You hit the nail on the head. Global eduction is perhaps the biggest hurdle holding back nuclear energy. It's awesome to see that you had a curiosity to acquire knowledge and facts about nuclear, and that it changed your opinion on it. 👍
7:28 Didn't India produce its weapons grade plutonium from heavy water reactors?Doesn't online refueling make it a bit easier to remove fuel after low burnup?
7:41 Correction:D20 has lower thermal neutron absorption cross section compared to H20
indeed, that was a fail from Elina.
Online refueling is indeed a good way to make weapons grade Pu in a "water reactor",while generating electricity no problem. In a PWR you can also do it, but why would you? Just use HEU.
Yes that was a jarring misstatement for me too. The whole "D2O is a better moderator" line is a bit of a furphy, it's not the moderation but the lower absorption rate which allows a CANDU to have a neutron economy able to support unenriched uranium as a fuel.
@@sjholmesbrown Exactly. And historically that was the reason why Werner Heisenberg in Germany decided to use Heavy water for the experiments, since regular water didn't fit the bill. In terms of moderation light water is better, since the proton has the same mass as the neutron while the deuteron has twice the mass.
I was hoping someone brought this up. I hope more countries buy CANDU reactors, but we should be realistic about proliferation
The German Wikipedia article on CANDU reactors actually mentions that this reactor type is especially suitable to generate plutonium:
"* die Bauweise als Druckröhrenreaktor. Sie erleichtert technisch den Bau solcher Reaktoren und erlaubt zugleich eine relativ einfache Gewinnung von Waffenplutonium, da im laufenden Betrieb Brennstoff zugegeben und entnommen werden kann."
->
"* the construction principle utilizing preasured reactor pipes. It makes building such reactors more easy technically, at the same time it allows for a realtively simple creation of weapon grade plutonium as nuclear fuel elements can be added and removed at any time while the reactor can be kept running"
I grew (Winnipeg - had a tour of the CANDU simulator in Pinawa, MB) up believing that the 2 biggest safety features (esp in light of 3 Mile & Chernobyl) is the heavy water moderator lends to non-weaponizable materials (as you noted) but also because if a runaway condition should happen, dumping the coolant/moderator/water actually stops the reaction - it fails safe.
Yes dumping the moderator would stop the reaction but poison injection where a neutron absorber is injected into the moderator acts much faster and is what is used.
Also, since heavy water is necessary for the reactor to work, any overheating of the fuel will boil the water, removing the moderator and stopping the chain reaction.
Plutonium is actually produced, but for the weapons-grade stuff you'd need to irradiate each fuel assembly for a suspiciously short time which would produce very little electricity. The whole world would immediately notice your weapons program and stop selling you uranium.
Refueling a nuclear reactor while in operation, now I feel silly as an IT professional for calling "hot swap" what we do to server's components
You can hot swap floppy drives in any computer (that even has them still) FYI... Maybe not really "hot" as they only use the power when reading or writing to disk, but you can certainly swap them with the computer fully booted.
As a Canadian, I appreciate your candor and integrity. We are collectively proud of the CANDU reactor.
I grew up not far from the Bruce Nuclear Power Station and now live not far from the Darlington Nuclear Power Station. Knowing the advantages of the CANDU, I always wondered why it wasn't more popular.
the higher upfront cost and not being able to
Make plutonium efficiently is two reasons why it’s not more popular
Can't make bomb byproducts. Hippie Canadians :P
Because it has few advantages. Basically, this is the cost of heavy water. Considering that France and Russia are massively enriching uranium for reactors, enriched fuel for light water quickly pays for itself. And also its complex design, like the RBMK reactor, only CANDU is also under pressure, which causes a lot of problems with pressure pipes.
@@nedward.7442 Heavy water is easier and cheaper than refining petroleum. The problem is that it is unconsumed, once you've made it you don't need to make more, and therefore has a small niche market.
Enriched Uranium is consumed faster and is simpler to make a bomb with, hence a larger market. It is also less safe. All the nuclear disasters have been from enriched uranium facilities.
@@allanlank
1) What does oil have to do with it? How is heavy water production cheaper than recycling? This is a completely stupid comparison: a product that is consumed by the whole world, and a product that is needed only in narrow circles of production.
2) The bomb requires a uranium enrichment plant and the purchase of lithium 6, this will be such a large-scale production that everyone will notice it. Moreover, the main disasters did not occur due to enriched uranium at all, but mainly due to the incorrect design of the reactor and the carelessness of the workers (Chernobyl Nuclear Power Plant and Fukushima).
How long has it been since your enriched uranium burns out faster? In reality, it’s just the opposite: the higher the enrichment, the longer the life of one company.
Thanks so much for this video, as a Canadian I knew of the CANDU and roughly how it works but I didn't knew all the details as to why we had them or why they weren't popular elsewhere.
Thank you for your comment ☢️👩🏽🔬 I am glad you found the video informative
Having such a different design can mean safety regulations are not appropriate or hard to apply. For example, most reactors have a negative void coefficient, meaning the fission rate falls when coolant is removed, but CANDU reactors have a slight positive coefficient. This is actually a very minor issue, especially when so many other factors and active safety systems have an effect, but regulations assuming a negative coefficient will disqualify a CANDU without an effort to change the regulations (which some people might regard as weakening them under corporate pressure).
He Elina!!! I just found your channel and have binging your content. I’ve always been fascinated in nuclear physics and reactor design despite being an arm chair physicist but your content has helped me be a much a more informed civilian and for that I say that you!
Hey Elina, nice to see a video just before bed. Bedtime learning. Love this channel!
As a Canadian I appreciate your CANDU attitude!
Perhaps an over-simplification, but my understanding is that CANDU trades off capital/start-up cost for operating cost. In other words, per MW, it's more expensive to build and bring on-line, but less expensive to operate for all the reasons identified (fuel cost/availability and on-line refueling, deuterium cost (more-or-less one-time?), etc..
I liked the entire video, it was full of information without making assumptions, and also talked fairly about both the pros and cons, costs, time to build, as well as the advantages such as online refueling. The video covered everything perfectly.
Great video but you got some parts wrong. Heavy water is indeed a better moderator, but the reason is that it absorbs LESS neutrons, leaving MORE neutrons to be absorbed by the uranium which results in a better neutron economy.
This, and online refueling, is also the reason that MORE plutonium is being produced in a CANDU which is not a problem but creates higher demands for non-proliferation measures.
Excellent job! I learned something new. Thank you! I shared this on Twitter.
Thank you. Great description of these units. I learned a lot.
Thank you very much Elina.
Good description of these units. I learned a great deal.
Thanks for dropping this nucle- I mean knowledge bomb on us. Very interesting subject
Theres also a new CANDU style Small Modular Reactor being developed in Canada atm, and its the only SMR in development afaik that can use unenriched uranium. Four of our provinces are working to advance our SMR industry, and Saskatchewan, which exports lots of uranium but currently doesnt use any itself, plans to start using SMRs by 2030
I'm not aware of any actual work being done on the CSMR. Do you have a reference other than the marketing materials? I know we're working on MOLTEX, ARC and BWRX licensing, but am not aware of any CSMR work actually being done.
Smrs are like free beer tomorrow signs at the local bar. Anything that runs a pressurized water system will require containment
As the primary expense currently nukes must be big for economy of scale. Thorium Liquid salt and low pressure primary loops will make smrs a reality. Till then it's all flying car advertising...
What a great explanation, thank you!
Great video explanation! Thank you very much!
They're fantastic. Natural unenriched uranium fuel? Better usage of fuel? Ability to be reloaded while operational? Stellar safety record & easier to manage wastes? All good.
Thank you for your excellent presentations. As I'm 68 years old, you can imagine how out of date my technical education is, but your explanations make things understandable.
props for still learning 👍
The CANDU reactor is about as old as you are, if not older. IIRC the first CANDU reactors had very little if any computer controls (I mean yeah they used TTL, but not full on computers).
At 7:48 heavy water has the ability to slow down (not absorb) neutrons better than regular water (i.e. it is better moderator). Heavy water will make Tritium the odd time it absorbs a neutron; light water absorbs far more neutrons than heavy water.
Nice explanation video.
Thanks Elina for the clear cost/benefit explanation. As a student in UT, we were told there was a small Candu reactor under the physics building. I always wonder why it wasn't more popular...now I know. You made my day!
If you're talking about the reactor at The University of Utah, it's actually a TRIGA reactor (much lower power and used primarily for research) and its on the engineering campus.
@@tedgood1224 , It's probably like you said for research but in Canada. :-)
@@test40323 It was actually a SLOWPOKE reactor, another type of research reactor, and is currently shutdown. Edit: you can have a look at the wikipedia article for SLOWPOKE reactors.
@@harryhall4001 , ah...you are right. My memory failed me. Thanks for the correction.
I think UT is the Universtiy of Toronto.
Basically, we need a ''Manhattan Project'' for the most viable, modular reactor that can be mass produced and cost effective. That will be my favorite reactor.
In India we use CANDU reactors since 1970s. The reactors are quite safe and inspired our own version of heavy water reactor the IPHWR. Currently we use IPHWR-700 version
"Inspired" lol, such a cute way to say xerox copy of / logical evolution of the original cirus into a large scale colandria based phwr
Hi Elina. I just discovered Sabina Hossenfelder’s channel and wondered if you had her as a professor in Sweden. If you are unfamiliar with her, she has a great science news channel and often covers nuclear energy topics. She was talking about heavy water reactors and as I had just watched this video everything made sense to me - hooray!
As usual, I am learning so much from your channel! And of course, Slava Ukraini 🇺🇦
One of the main reasons that Canada developed this technology was also because it did not produce weapons-grade nuclear fuel! This is also why it is not popular with many large countries that see themseleves as nuclear powers or want to be nuclear powers. I.e. UK, France, Russia and other former parts of the Soviet Union, Pakistan, India and China. For the most part Canada is very careful with whom they share the technology so as to control nuclear proliferation. Sadly, this is not the case for companies from some other countries.
Most people tend to overlook Canada's role in the development of nuclear energy. Canada has been involved in this areas of research from before WW2 and its scientists and industry were well involved in the Manhattan project. This lead to the development of the Chalk River research complex and the further development of the CANDU reactor in Canada. It should also be noted that Canada is also a major producer of medical isotopes using smaller reactors that are often installed on university campuses. I personally used one such small reactor at Dalhousie University in Halifax, N.S in 1981; however, I don't know if it is still operational.
Nifty, I find myself wanting more details and deeper dives into the things you talk about.
There are books about this stuff, or take a tour of an NPP if you can.
Romania is building two additional CANDU units at Cernavoda. It is expected that they come online around 2030.
Thank you very much for that. I started on B&W and finished on Westinghouse with a little GE and CE thrown in at the end.
Thank you 😊
I never bothered to do a even a internet search for CANDU and still I knew about many other reactor types. Just knew that they existed. Thanks! I want this channel to exist.
Thank you Elian, great presentation. Anything that can educate the general public on the advantages of nuclear power is greatly needed today in view of our global warming challenges . Nuclear power is needed now more than ever to meet those challenges and to encourage countries that nuclear is a safe choice. Keep up the good work!
My uncle was a top engineer in the Ontario, Canada, nuclear power industry for ~40 years. He recently died at 93. His longevity is, in part, testament to the safety of Canadian reactors.
I seemed to understand which I thought was good. Thank you.
Great video! more videos on reactor types please. Even on more specific ones, like the one france built in finland
this is so cool!! very interesting stuff. As a canadian, i hope that we use more of this technology to reduce our emissions :)
Great explanation. Thankyou. :)
Ohh good job thank you very much for your useful information.
Glad it was helpful!☢️👩🏽🔬
Everyone needs a friendly nuclear physicist, especially when she delivers such clear discussion of an extremely complicated issue. Thank you.
Well explained thank you. Summarized: The Candu reactor is a type of pressurized heavy water reactor that uses natural uranium as fuel and heavy water as both coolant and moderator. The Candu reactor has a high safety record, as it can shut down automatically in case of a loss of coolant or power, and it has a negative void coefficient, meaning that the fission rate decreases when the coolant density decreases. The Candu reactor is also efficient, as it can achieve a high burnup of fuel and can use a variety of fuels, U238 and such as thorium or plutonium. However, the Candu reactor is also expensive, as it requires a large amount of heavy water, which is costly to produce and maintain, and it has a low power density, meaning that it needs a large reactor core to produce the same amount of power as other reactors. Size and heavy water production costs are the main issues for this kind of reactor.
Compared to the Molton reactor (next-generation technology)
The molten salt reactor is a type of liquid fuel reactor that uses a mixture of molten salts as both coolant and fuel. The molten salt reactor has several safety features, such as a freeze plug that can drain the fuel into a safe storage tank in case of an emergency, and a low operating pressure, which reduces the risk of explosions or leaks. It can be built in small sizes. The molten salt reactor is also efficient, as it can operate at high temperatures, which increases the thermodynamic efficiency of the power cycle, and it can breed more fuel from thorium or uranium-238, which are abundant resources. However, the molten salt reactor is also costly, as it requires complex materials and technologies that can withstand the corrosive and radioactive nature of the molten salts, and it has a high proliferation risk, meaning that it can produce weapons-grade material that can be diverted for illicit purposes. Young technology, corrosive issues, and preparation of the salts are the main issues of this reactor.
What kind of reactors do atomic-driven aircraft carriers use. They use uranium and need to be refueled only once in 30 years and are relatively small?
Thank you for this video, with you I found information that I need
My favorite reactor: БН-800
Thank you for teaching us so much about nuclear energy. CANDU is my favorite because it can keep running when refueling.
Thanks for the comment ! Indeed this is a very cool feature ☢️👩🏽🔬
The main reason CANDU reactors were not more widely deployed is most countries wanted Plutonium for weapons. Decades later those countries have an installed base and experience in operating LWRs (or AGR in the UK) and there's a lot of inertia to change.
Watching this one day before exam
Great explanation
Tq
That was very informative. You covered all the bases, I think. The security features are about the only thing I knew something about. Decades ago when a third world country wanted a reactor, people worried they'd use it for weapons grade material. Having the CANDU option removed some of those worries. e.g. someone like Saddam Hussein was never going to be interested in a CANDU reactor. It wouldn't explain all of his enrichment facilities.
CANDU reactors are terrible for proliferation as they avoid the whole enrichment step -- fuel it with unenriched uranium and it makes plutonium that you can separate chemically with no costly enrichment equipment. It also makes tritium just in case you feel like going thermonuclear.
Hi Elina. Beautiful video. Personally I don't think that there is a better technology, but CANDU and LWR (in particular EPR) are both very reliable technologies that should actually work together, in particular with the DUPIC cycle for spent LWR fuel.
It's probably because I've been up for too many hours, drinking bad coffee, but for a moment there I read the title as mentioning "Candiru Reactors" and instantly winced in pain at the scream in my head.
Correction. Heavy water absorbs LESS neutrons because it already contains more neutrons. However, it moderates WORSE than light water because deuterium is heavier and you have the best moderation with a particle as heavy as the neutron: a proton!
While these videos dont make as much views as tiktok dances, without them the world would be much dummer. Thx for making these. Rarely a professional in a field decides to make content for the tik tok crowd, but boy we need it.
Thank you so much for your kind comment! ☢️👩🏽🔬 I am glad and excited to have such platform to inform and educate the public 😊
tiktok is a platform for the spreading of mental retardation and insane ideas that will get you killed - don't watch that brain-cancer inducing platform, nothing good is there.
Interesting for sure. I don't know enough to make an educated choice. I wish you could do a video on reactors used in ships and submarines. Thanks
A friend who worked in the Pickering plant said he had another use for heavy water. According to him even a small addition to a significant amount of regular water changes the surface tension of the water. Mosquido young, the wigglers hang from the surface of ponds to breath and if the surface tension changes they can't stay up and drown. Another question I have is how much replacement heavy water is required to top up operating reactors. I have seen quite small and relatively inexpensive systems that produce heavy water.
Candu reactors are in fact perfect for proliferation - it is the perfect design to produce plutonium continously, since single rods can be exchanged during operation. It does produce less plutonium than a light water reactor, but it does produce sufficient amounts for weapons use. And since it does not require uranium enrichment, which is complicated (plutonium separation is much easier) it especially appeals to developing countries, which want to hold the door open for the production of weapons grade plutonium.
Very cool presentation! One thing I would add is that CANDU reactors are much more expensive than other reactors (BWR/PWR) mainly due to the huge dimensions of the calandria. Aside complexity and cost of materials, this also requires a very large containment building. So initial cost could be much larger.
a few other points. candu reactors have lower power density than light water so typically generate less power for a given size. and the tubes that enclose the fuel rods are a special zirconium alloy that only last 15 -20 years at which point the reactor needs the tubes replaced. that costs about a billion $. so that is planned for when constructing.
Unit 3 and 4 at Bruce A are using the same pressure tubes it was built with when they first came on line in 1977/78. They are prone to creep and have had to be 'shifted' at least a couple of times on Unit 3 (Unit 4 can float on both ends so not as big a concern) to compensate, but they do go longer than 20 years, at least the newer alloy that isn't as prone to delayed hydride cracking (the problem with the old tubes on Unit 1/2). Unit 3/4 were down for about 5 years of that total operational time during the infamous layup period before Bruce Power was formed and brought them back to life. So, other than maintenance outages, those pressure tubes have performed for at least 33 years or so of high power operation. If the tubes are not being replaced already, they will be soon, as they were several years ago on Unit 1 and 2. I retired from Bruce A a few years ago as an Operator, at the last in the Control Room as an ANO. Good job and a great overall reactor/turbine design.
@@frederickcwinterburn1837, Bruce plans to re-tube all the others. Unit 6 is nearly done and set to return to service this year and will be followed by 3 and then 4. Not sure about scheduling for the rest. Expected lifetime of the new tubes is 30-35 years.
I'm interested in the PBR reactors. The passive safety features especially. The fact that there is no fluid, that any non-reactive gas can be used in an emergency and that even in a loss of cooling, the 'pebbles' expand, moving the fuel particles further apart, self regulating the reaction without a human having to do anything to stop an accident.
I only live 15mins from one of the primary labs for there development actually meant one of the primary physicist worked on the candu project completing by chance i sampling her well hours deep in the middle of nowhere. i also work on occasions on projects for themwith work its all pretty interesting and neat to see how it all works the infrastructure thats required to support and to ensure safety nevermind the level of security and how seriously they take safety. I think this a great explanation of them i will be using it as a reference in the future when im explaining it to people.
There is an old '60's TV show, Voyage to The Bottom of The Sea with a nuclear powered sub. Some of the scenes involving the reactor I think you would get a kick out of lol.
I was reactor repair in the Navy, subs and aircraft carriers. One of the things I liked was sitting on the reactor while doing repairs, feeling its warmth. Shut down, of course.
I must thank you for the information. It's rare do actually learn something new everyday. Although I do have 2 questions and sorry if this isn't exactly the criteria. What are your thoughts on thorium salt reactors and with your power grids are they just as antique as the ones in the USA? Thank you I'll dive into your channel a little bit later today.
Hey 👋. Just found your channel. As a proud Canadian, you could've saved a lot of talking by simply saying "Canada Rocks!!" 😂🤣😂🤣 You are very knowledgeable. Also, is that an Italian accent? Love it 😀
Very interesting
I had never heard of an CANDU Rx before, TY! my fav would be LWR as that is what we had on my submarine. It worked great we never had any issues.
You don't have to worry. The US would never rely on another country, even their friendly neighbour to the north for their nuclear energy technology.
I'm guessing the answer is "the solution to our energy and nuclear waste problems"? :D
Happy to see you cover those!
Had to design one of these for senior design over 8 months, we didn't have the best final product-positive void coefficient and it made a hell of a lot of weapons grade plutonium. Well, wasn't the best power reactor design but it'd work well near a nuclear weapons plant.
How did you model it? I'm assuming some kind of software?
You seem to be feeling better!
I went to middle and high school in Pinawa, MB, which had a slowpoke, but we learned tons about CANDU reactors every time we visited the plant as well.
Sounds like a school I’d like to do to ! In my school we learnt nuclear is lethal and we’re given the example of Chernobyl !
Damn we had Pickering NPP not TOO far away from us, they could have taken us there. What years were you in elementary school? I went in the late 80s, when there was still funding and interest (as well as pride) in this kind of stuff. FFS my middle school had a full on woodshop - gone now.
@@YourFriendlyNuclearPhysicist In Poland, they started Zarnowiec NPP, but I think Chernobyl had something to do with that project's stop.
You sould talk about the Shoreham NPP - Long Islanders are STILL paying for that mistake, literally.
@@YourFriendlyNuclearPhysicist Just came across your channel. I grew up 1.5 hours away from Bruce Nuclear, largest CANDU plant in the world (8xCANDU 6 ~6400MW). Our high school physics class went on a tour during construction of the last 4 reactors in the '80s and could walk around inside the containment. I have touched the face of a CANDU calandria...lol
Overall a good video, but a couple of questionable bits.
1) CANDU reactors don't have a pressurized "vessel". Instead the vessel (calandria) which contains the bulk of the moderator (D2O) is at atmospheric pressure and the individual horizontal tubes or fuel channels are pressurized. It is through these tubes containing the fuel bundles that the coolant (also D20) flows. Canada didn't have the ability to forge such large vessels and this is a design compromise that allows local production of reactors without that ability, plus it allows for online refueling as a bonus.
2) It is highly questionable to state CANDUs are more proliferation resistant. CANDUs actually produce more Pu than LWRs, but they also burn more. A typical LWR gets about 1/3 of it's energy from Pu Fission. A CANDU gets about 1/2 from Pu Fission. If the fueling cycle is followed, there is less Pu in spent CANDU fuel compared to LWR fuel (as % of mass). However and this is where the potential problem is, due to it's ability to online refuel, a nefarious operator can sneak fuel bundles in and out for short fuel residency times which is exactly what is needed for isotopically pure Pu-239 production. In fact, that's how the Hanford dedicated military production reactors worked (but with graphite moderator instead of D20). The reality is as you rightly exposed on your thorium video, if you have a reactor of any type, then you have a proliferation risk unless IAEA controls are strictly enforced.
You should do a review of the MOLTEX designs if you haven't already. That is likely to be what eventually replaces CANDU plants in Canada.
Overall great job...keep it up!
The original Candu reactors were built across the bay from our family cottage in Ontario. I eventually sold the cottage to Ontario Hydro, since they needed the forest acreage for greenbelt around the reactors. There were five reactors in total, and I was told that each of them has more power than Niagara Falls.
Everyone needs one!
Nicely explained. How are the Fukushima reactors different? Can you have a session on that please?
Enjoy your candid upbeat explanation.
Loving the candu attitude
Currently in college for Mech E, considering Nuclear thanks to you! The -11% job growth is concerning though :(
Love your vids.
Elina, I am not a nuclear physicist or engineer so correct me if I’m wrong but stating that CANDUs make less Neutrons and therefore less plutonium is incorrect. Indeed they make the same neutrons as light water reactors. However the overall neutron usage economy is much better which allows much less fissionable material ratio while still maintaining criticality. Since you can run on 0.3% vs 3-5% you essentially also burn away any bred actinides more efficiently down to the much lower percentage. I would guess that CANDUs basically produce just as much plutonium as any other reactor but they are far better at then burning that material away down to the lower percentage during the course of normal civil power generation profiles before the fuel elements are discharged out of the reactor.
Indeed, CANDUs share far more design commonality with Hanford weapons Plutonium production reactors. They use natural Uranium, can be refueled and defueled online, have a horizontal fuel profile and horizontal fuel tubes with individual fuel channels. Again the reason CANDUs Dont make weapons materials is because of the manner in which they are operated. They keep the fuel in the core far longer and achieve the higher burn up.
I would also guess that the perceived anti proliferation benefits from CANDUs are derived more from the fact that any nation using them can avoid the more key weapons technologies of enrichment and reprocessing while still having civil nuclear power facilities.
Again, correct me if I’m mistaken and missing something.
Great video! Not too many people know about this third main type of reactor and how reliable, safe and durable they are. In fact they are the electrical backbone of Ontario, Canada's largest province and they are also currently looking at doubling their CANDU fleet (using the CANDU Monark 1000 design I believe) as well as investing in SMR's especially at the Bruce site. So I'd say the future of these ones is pretty secure domestically even if other nations don't build them, although they should, especially the USA which still in late 2023 is dependent on fuel from Russia from keep its fleet going... Meanwhile in Canada...
Daily dose of Friendly Nuclear Physics
This video is very interesting and informative Elina. If these reactors have this many advantages despite the requirement for heavy water, they look like a great way to deal with spent nuclear fuel without further increasing nuclear weapons proliferation concerns. They do not however burn up the fuel completely as the LFTR or Liquid Flouride Thorium Reactors do. The fact that enrichment of the Uranium should be a big plus for countries who just wants nuclear power without the headaches and expense of enriching Uranium. I hope Kirk Sorensen's efforts to promote LFTR's bears fruit here in the U.S. as well as the efforts to develop nuclear fusion reactors. That would be right of Star Trek, my favorite science fiction series. If I had to pick a favorite type of nuclear reactor, it would be the CANDU and LFTR reactors because they can use more than one kind of fuel, and in the case of LFTR's can be used to dispose of Plutonium-239 from decommission nuclear weapons. Megatons to megawatts is a win-win for everyone.
Beautiful words that never come true. I'm worried that never, given Vogtle's experience...
Thank you Elina, the same applies with thorium reactors that are very interesting for India for the presence of thorium mineral into the country, do you agree?
Indeed, although thorium reactors pose some serious proliferation issues as I explained in my thorium reactor video ☢️👩🏽🔬
Very proud of CANDU. I wish more of the Federation used CANDU since it is really the Ontario reactor. The longest record for continuous online operation for a CANDU is 895 days or 2.5 years. I think whats stopping them from going for longer records is the aging of the reactors and regular maintenance taking higher priority then bragging rights.
Greekings from Canukistan
😂
@@MitzvosGolem1 🤘☺️✌️
Thanks Elina, love your talks. You talked me into it, where do I buy one😀
I assume the heavy water is not pure deuterium but just a higher concentration deuterium, do you know? I thought production of deuterium was very complicated and extremally expensive.
Would love to see you do a video on pebble bed reactors at some point. The molten salt and helium cooled variants being built by Kairos and X-Energy are especially intriguing. ☢
I'm also a fan of MSRs but would like to see the NRC allow a liquid/molten salt fuel at least in some research/experimental reactors. We really need to be developing the next generation reactors now.
@@johnmason455 Concur!
I remember when some people from ORNL did a exhibition when I was in middle school. They brought among other things some of the uranium beads used for making the pebbles in this reactor. They were in a little glass bottle and as fate would have it when it was being passed around it got dropped, and lots of tiny uranium beads went all over the classroom. They swept most of them up, then we all got turns using the Geiger counter to hunt the rest. They made a game of it. We ended up finding all but 4 of them. Could only imagine what would happen nowadays 😅
@@christopherleubner6633
Uranium is laboratory radioactive, but very toxic.
@nedward.7442 in the form it was in, it was not an issue, the tiny beads were like mini jawbreakers that had a hard silicon carbide shell, a layer of graphite, and some a nice chewy uranium core. The beads were super tiny as well, about the same size as a pin head.
High pressure is worse than low pressure reactors for safety, because... you know, high pressure. If the pressure drops suddenly all your coolant is suddenly steam. The safest reactor would be low pressure, low temperature with a negative energy coefficient. But of course you want high temperatures for the best energy efficiency. The higher the difference between the hot and cold side of a system, the more energy you can extract out of that flow. And since the cold side is usually fixed to something near room temperature, like a river or cooling tower, the only way to increase that gap is to heat up the core.
Actually, India is building an indigenized CANDU derivative. They call it Indian Pressurized Heavy Water Reactor (IPHWR), with the current design being built at scale being 700MW. Design into a 1000MW unit is being done. And India is studying the use of Thorium-Plutonium MOX to fuel them. Along with MSRs.
In China and Korea, the CANDUs are using reprocessed uranium (0.9% U-235). More research isn't being done, because they are focusing on a LWR+FBR fuel cycle.
Favorite reactor types for me are CANDUs, RBMKs, MKER(an evolutionary version of the RBMK, and could have become a "discount CANDU" if further developed). And both molten chloride salt reactors, as well as pool-type sodium and lead cooled fast reactors.
All are for similar reasons. Very efficient use of nuclear fuel with Pu breeding, use of Thorium, reusing and processing LWR fuel , and addressing the issue of long lived transuranics.
The RBMK is an interesting reactor that unfortunately has been rushed into implementation, with several design problems. It's supposed to be able to run NU, but it is extremely unstable doing so, so it runs 1.5/2%LEU(There's 8 RBMKs still operating in Russia no problem). The MKER would solve the problem.
RBMK and MKER are already dead. They have the advantage that, with a certain design, they can also operate on natural uranium (the ADE-2 reactor, a producer of weapons-grade plutonium, could do this), burying CANDU. But their main big drawback is the impossibility of recycling, because... after the end of the life cycle, hundreds of tons of radioactive graphite and chlorine (a product of graphite processing) remain, so there is no other way out except bricking. it's under concrete.
Regarding the production of plutonium, fast reactors cope with this much better.