I have to say, I really do like the CANDU reactor design. Up until now, I've mostly read about RBMKs and PWRs, but this is increasingly piquing my curiosity. To me, it resembles an RBMK, but then put on its side, without the graphite, sporting a proper containment building and done really, really well in terms of safety etc..
I'm not convinced on the safety aspect as the more complex a system is, the more likely of mechanical malfunctions requiring human intervention. And it's this human intervention that is likely to cause safety issues.
Hanford B Reactor used a much simpler and better method.... get a bloke to push out the spent rods with a long broom handle and have them fall out the back into a bucket of water! Then have another bloke put new rods in all while smoking Woodbines!
Anonymous Anonymous that’s not why the reactors caught fire, it caught fire because of 1) its cooling system; 2) the way they over used the reactor, a graphite pile, it accumulated to much energy; 3) they decided to overheat it in order to release the energy it accumulated. 4) they made things worse by turning on air when the fire started rather than cooling the pile with water.
The RBMK-1000 is a close copy of Hanford B, with most of the safety systems removed. The scary thing about Hanford B (where we discovered xenon poisoning) is that when the power mysteriously fell after a normal startup, our operators pulled the control rods *all the way out* in a misguided attempt to get it going again. (Fortunately the rods were put back in before any part of the core reacted and we got away with it, but boy was that ever dumb.)
@Gareth Johnstone You clearly aren't even smart enough to operate a bucket under any circumstances if you think uranium gets "white hot" in a nuclear "meltdown" so I don't think you have to worry about ever being anywhere near a nuclear reactor. Or even a bucket unless it still has the lid on it so you can't hurt yourself with it.
@@josephastier7421 I think "my" Hanford B reactor as a U.S. citizen and "your" Hanford B reactor must be two different reactors and two different designs used for entirely different purposes and with entirely different operators since my Hanford B reactor and its operators were never involved in any such "dumb" situation. Nor is my Hanford B reactor equipped with "control rods" period. So where is your Hanford B reactor and where can I learn more about it? Are you a nuclear engineer or otherwise educated on the subject of and/or personally experienced with "nuclear reactors" or anything else related to "atomic energy"? If so hopefully after sharing your resume' and/or curriculum vitae to establish your bona fides as a "nuc" but obviously not a "nuclear physicist" given you wouldn't be here WATCHING videos like this and critiquing whoever "got lucky" at your Hanford B reactor with a final grade of "really dumb" if you were and seem inclined toward "plain English"; maybe you can post a brief "bio" for your Hanford B reactor and its nuts and bolts in layman's terms, a short and sweet compare & contrast explanation of the few "common" reactor types, what "atomic energy" and "nuclear power" really are in basic junior high science class-level terms, how those reactors convert "atomic energy" into "nuclear power" or rather BEGIN that "conversion" from energy to "power" by releasing "atomic energy" in the fuel and converting it into "electrical energy" which "sparks" the "conversion" of additional fuel into "heat energy" which is as far as "nuclear reactors" can go converting "atomic energy" into "nuclear power" since energy must be "converted" into "force" when "potential energy" is "converted" into "kinetic energy" and the motion of "sub-atomic particles" the human eye cannot see is "concentrated" and "converted" into physical "power" we can feel as thermal "heat" or an electrical "shock" or as mechanical "motion". Then maybe you can explain what a "meltdown" is, how "control rods" are used in part to "prevent" a "meltdown" and how when they FAIL in a reactor the only way to "prevent" a "meltdown" is to insert "SAFETY RODS" which of course unlike "injecting" a liquid nuclear reaction "poison" into the "core" of a "CANDU" heavy-water reactor where even that "safety system" can fail to prevent a "meltdown" if the "control rods" are not "pulled out all the way" removing their "decay heat" from the "core" and reducing the "pressure" inside the "core" so the "poison" injection can occur soon and quickly and completely enough to "kill" the reactions occurring between the "fuel" and the "coolant" and "boiling" the coolant leading to a "loss of coolant" accident and "runaway" thermal reaction in the core, the result is a "meltdown" once the "core" becomes hot enough to oxidize (burn) in the open "air" that replaces the lost coolant boiled away when "control rods" doing "double duty" as "control rods" during "normal operation" and "safety rods" in an "emergency" in a "CANDU" reactor for some reason FAIL AT THE LATTER "DUTY" WHEN "GOING ALL IN" WITH ALREADY OVERHEATED AND INEFFECTIVE "CONTROL RODS" ONLY ADDS "FIRE TO THE FUEL" SO TO SPEAK AND PUTS MORE HEAT AND PRESSURE AND "MASS" IN THE CORE DISPLACING, DEFLECTING, DIVERTING AND "DESTROYING" COOLANT AND FURTHER DELAYING THAT "POISON INJECTION" IF NOT PREVENTING IT ENTIRELY. You can finish up your layman's lesson on Basic Nuclear Power 101 by walking us through your "Hanford B" reactor, it's "type", it's "control" and "safety" systems, how it's supposed to operate and be operated "smart" from "startup" to "shutdown" to remain "safe" and prevent "meltdowns", what "smart" operators do in an "emergency" when something(s) and or someone(s) went wrong and/or "dumb" and how your Hanford B and it's "dumb" operators got into that "emergency" shutdown/hot "restart" situation and why pulling the "control rods all the way out" was "dumb" and they "lucky" and how the "rest of the story" went/goes, how you came to be such an expert on your Hanford B reactor, what happened, who was operating it, what happened and what they did and why they were "dumb but lucky" and most importantly of all why and how you decided they were dumb but lucky when obviously your Hanford B not only didn't have a "meltdown" it apparently didn't even have an incident or accident or close call "serious" enough to make your Hanford B even "famous" or "well-known" or maybe even "known" PERIOD by the "media" much less "infamous" since although there is plenty of info online about my Hanford B reactor, which again must be a whole different animal than yours since it not only has/had a perfect safety record but a whole different design, purpose and "process" by which it achieved it's "purpose" and it sure didn't and still doesn't have "control rods" and since it has 2000+ separate "cores" and all of them "controlled" separately and was "making fuel" instead of "using fuel" and the "cores" had to have "nuclear power" put into them to get "atomic energy" out and preventing "meltdowns" was sort of like keeping an aluminum saucepan from "melting down" on the burner of a gas stove while making mac and cheese in it. It can't happen until you boil away all the water, burn away all the macaroni and then figure out a way to get heat into the bottom of an aluminum saucepan faster than it can get out through that big "hole" in that's left when the "coolant" and "moderator" are boiled away and burned up. Aluminum can and does "burn" at temps lower than "gas" burns at, but if you want to "melt down" an aluminum container using a "stove", it had better be a wooodstove and you"d better put the stove "around" it instead of "under" it. Maybe your Hanford B folks should have talked to my Hanford B folks, huh? Or maybe you should go back to school for a different "career" or something. Because I don't think you're much of a "nuc" and pretending otherwise could be very dumb. How's your "luck" generally?
I understand that a unique characteristic of Candu reactors is that their fuel does not contain elements that can be used for a nuke. However, they CAN be used to burn plutonium from nukes as they are decommissioned. They also can burn a lot of spent fuels from other reactors. Making these reactors attractive as part of the reprocessing loop. Reducing global spent fuel stocks.
That's why you don't operate outside the design parameters (or way outside as in the case of Chernobyl). RBMKs are great at making plutonium for a renewable nuclear fuel cycle, but the things are beastly at 4500MW of raw thermal power.
@adekk9 The fuel channels of the RBMK were light water cooled. As you probably know, light water is not that good of a moderator compared to heavy water and graphite, because of a somewhat high neutron absorption cross-section. RBMKs were graphite moderated, so that is why they have such a positive void coefficient. In other words, power goes up and so does the temperature. The water becomes less dense it absorbs less neutrons and power further increases.
The CANDU also has a positive void coefficient, but fuel geometry is critical in this design: if the fuel channels overheat, gravity causes them to sag out of alignment, stopping the chain reaction.
@@laura-ann.0726 The CANDU proves that having a positive void coefficient doesn't automatically mean an unsafe reactor. Not only that, the CANDU can, as a last-ditch resort dump its heavy water moderator and replace it with plain water so the core cooling can continue, but the chain reaction cannot. That's something completely impossible with solid graphite blocks. And the CANDU has two independent, blisteringly fast shutdown systems. Something the poor RBMK would love to have, but never got. Before the Chernobyl accident, its single shutdown system took a skeletal 18 to 21 seconds(!) to fully insert all the control rods into the core. At that point you might as well put jelly in your pocket because you're going to be toast. By the time the control rods can make any difference, your reactor will have put itself into orbit. Which is what Unit 4 quite literally did that night.
@@swokatsamsiyu3590- Everything I've read about the CANDU makes it seem like the best overall reactor design for a commercial power plant, at least up to now. Producing the deuterium oxide is expensive, but then, so is enriching uranium for a light water reactor. But I think that where the CANDU absolutely outshines every other solid-fuel reactor design, is on-line refueling and total availability. No shut down needed to just swap out spent fuel bundles. One question I have though, is how do the refueling machines maintain a water-tight seal to the fuel channels? Spent fuel has to be kept under water continuously because of the decay heat, so the inside of the fuel handling machines must be full of water too. The fuel channels are horizontal, so how do you prevent reactor coolant water from leaking out onto the floor at the interface between the reactor fuel channel and the refueling machines?
@@laura-ann.0726 This reactor design has it all; safety, robustness, a long service life, and it can run on various fuels including the waste from other reactors. And you can do a full refurbishment of its core components. The CANDU has high upfront costs, but it starts earning its keep from the moment it is up and running due to its long availability in-between maintenance/refuelling outages. A CANDU reactor actually holds the world record for the longest, safe continuous run; a whopping 1106 days. This was achieved by Darlington Unit 1. Since my specialty is the RBMK, I know a lot more about those than the CANDU. However, one of the feats both reactors share is the on-power refuelling. RBMK's refuelling machine has a special adapter head that provides an airtight/watertight seal with the channel to be refuelled. And each of the individual channels has valves that can control the waterflow through that specific channel. I think we can safely assume the CANDU system does something similar. The RBMK refuelling machine has a special water-cooled storage magazine for the spent fuel assemblies. The CANDU system has that as well. It is specifically mentioned in this video, as is the provision for a watertight seal between the refuelling machine and the channel interface. There are various ways with which this can be achieved; special couplings, gaskets, plugs etc. I do know that when a leak is detected, the machine will refuse to unclamp from the channel until things are resolved. Fifty+ years of safe CANDU operations prove it can, and has been done.
+Big Boss Kind of like what mark said but way more complex than that lol but simplifying it... The refuelling machine has a higher pressure that the pressure tubes so that when they plugs are removed the water from the streams doesn't leak out into the fuelling machines but instead is contained by a higher pressure wall. This causes pressure within the tubes to act as it the plug was still installed.
Once the fuelling machine is clamped on to the end fitting it becomes a part of the reactor pressure boundary. The snout of the fuelling machine firmly clamps onto the end fitting to create and maintain this seal.
As a separate discussion, why is it that nuclear fuel can be handled by the crew and appears as non-radioactive and safe to be handled via humans with no major protections, prior to insertion into the reactor?
Non enriched fuel is considered stable prior to being placed in the reactor. Once it’s placed in there, the chain reaction begins at which point it cannot be “stopped” only controlled.
Slick system! Hard to believe that the cost of a high precision system like that can, and its lifetime maintenance, be less expensive than outage refueling. More complexity usually means more headaches. No outages, what all of those poor road techs going to do!?
Gentilly 1 in Quebec was a prototype / proof of concept. It ran for 7 years, but only had 180 on-power days in that time. Gentilly 2 went online in 1982, has had an excellent service record, and is expected to run until 2040.
If I knew what I said... then wouldnt it be a given that I know that as well?. Just ran out of space for these coz CZcams decided that 500 characters is gonna be enough for more educated comments.
@-ACHTUNG you're kind of right with that. but at the same time very wrong. When you actually calculate the true power very comparing fission vs fusion you have to put it in the same units scale! For example you can't compare 2 litre 300 horse engine vs a 5 litre 500 horse power engine and say that the 5 litre engine produces more true power. because litre for litre the smaller engine produces 150 per litre while the 5 litre only produce 100 per litre. So when you scale the fission vs fusion...fusion always produces more power!
Yes, but probably not as much. As I was watching the animation of the rods getting loaded...I kept thinking to myself, "This is an engineer's nightmare because it is so complicated. What happens if one of the rods gets stuck during the automation process? Is the reactor now worthless?" I would be interested to know if they have a backup plan for such an event...or if their planning is only based on a "best case scenario". In any event, we need nuclear very badly, if not for energy...then
Exactly what I was thinking. I do see a worker injury, or death do to automation issues and unforeseen situations seeking immediate resolution due to fear of downtime.
@FlightSimTutorials Actually, a Single Fission of Uranium-235 yields more more than 10 times more energy as the Fusion of two Hydrogen Nuclei. Uranium Fission would yield about 200 MeV's while a Fusion of Hydrogen would yield less than 20 MeV's.
Atomic Energy Plant Atomic clock. Can be powered and energized by a solar energy clock but doesn't use sun power but only by laser light which is absorbed in clock's solar panel cells or photo voltaic cells which absorb laser light converts it to electricity and sends it to it's Atomic Core clock.The reason to use this. Not smart to have any electrical wires any were around atomic things;not fire safe, compared to laser beam which is safe even if cut.Or if under water a laser can still be used.
@@nerissacrawford8017 No kidding. The graphite moderated reactor concept is very good and the Chernobyl type RBMK-1000 is just a not so successful modification of the idea. It's predecessor AM-1 has been very successful reactor and the modiffied MKER is also promising: en.wikipedia.org/wiki/MKER
He said "molten salt" (at least in the post I saw). He never said "sodium". Flouride is a salt, as well! And there is such a thing as a "molten salt reactor" design. It would use Flouride as a liquified fuel. The only main technological hurdle to that right now...is developing a way to avoid the potential corrosion because flouride is corrosive. The non-technical hurdles...are ASTRONOMICAL! I see this is an old post. Perhaps you have heard "The Good News" since then about molten salt and
Yep. But Uranium-235 is hundreds of times more massive, and that's why its fission is less energy dense and specific than fusion reactions involving light elements. More importantly, fusion involves more reactions per unit volume/mass which means more neutron radiation. Neutrons are the lifeblood of any fission or fusion fuel cycle and can perpetuate the production of excess fissile/fusile fuel.
definitely for medicine (but we I say we DO need nuclear for energy, as well). But, we also need to get away from Gen1 and Gen2 ASAP and change the nuclear landscape. We really need liquid fuels, be that molten salts...or some liquified uranium/ thorium method not thought of, yet........
The best energy sources in the world are no good if the operators fail during an emergency. The Fukushima-Daiichi and Three mile Island incident's are prime example's of operator error.
All the more reason to use Integral Fast Reactors and Molten Salt Reactors. Use the IFRs to breed the fuel needed to start-up and run the MSRs, and the fuel for those IFRs is the spent fuel from older light water reactors. And while you're at it, instead of using the IFRs to produce electricity, use their heat to run desalination plants. Enjoy the benefits of less waste, and plenty of clean electricity produced by MSRs and IFRs that are physically incapable of melting down.
Thorium. If your haven't, I suggest you do some research into it. It sounds pretty promising...if the one technical hurdle (and the many political hurdles) can be overcome. The only financial hurdle is tied into the many political ones...worldwide (China, U.A.E., and India excluded), people don't want to invest in ANY nuclear development when they don't know what the regulatory environment is going to be in ten years....................
vehicle. Also, if I purchased photovoltaic shingles, that will probably mean someone else is unable to do so for their own home...because the materials to manufacture them are not, unlike the sun from which they absorb the energy, unlimited. (It should be said that "rare earths" really aren't rare...but if we tried to scale up to the kind of renewables infrastructure some advocate for...THEY WOULD BE! And, I also know that the sun is, over billions of years, limited, but for our sake, it isnt
(But, here is a carrot from the renewables people.... If we begin to fuel nuclear reactors with a Thorium cycle, Thorium obtained from waste from the mining of rare earths for the very renewables you all seem to love so much...then perhaps the price of renewables will decrease because what was once a hazardous waste material obtained from "rare earths" mining...has now become a valuable, marketable, or at least one that can be given away, commodity.)
The horizontal reactor lay-out seems pretty unique.
For power reactors, yes. However, the first large scale production reactors at Hanford were similar in layout, although much, much larger.
It's great or allows them to avoid shut downs for refueling.
By far CANDU is the best reactor ever conceived! it can run on any fuel from thorium to reprocessed long lived waste!
David Vermillion water-cooled reactors are ancient
David Vermillion got it own problems like the possitive void coefficiency and Cant breed plutonium
If at this moment there is a best reactor should be the Bn800
The later is not a negative. Since you can sold those reactor a said contry and your're sure they wont make nuclear weapons out of it.
good ancient reactors,in Romania we have 2 of these and they works wonderfully.....
This is one area where Canada is definitely leading the world.
I have to say, I really do like the CANDU reactor design. Up until now, I've mostly read about RBMKs and PWRs, but this is increasingly piquing my curiosity. To me, it resembles an RBMK, but then put on its side, without the graphite, sporting a proper containment building and done really, really well in terms of safety etc..
I'm not convinced on the safety aspect as the more complex a system is, the more likely of mechanical malfunctions requiring human intervention. And it's this human intervention that is likely to cause safety issues.
@@mrdan2898
If 50+ years of safe, reliable CANDU operations do not convince you, I don't know what will.
@@mrdan2898 we been using them in canada without much issue since the 60's, aswell as other countries around the world
Hanford B Reactor used a much simpler and better method.... get a bloke to push out the spent rods with a long broom handle and have them fall out the back into a bucket of water! Then have another bloke put new rods in all while smoking Woodbines!
Anonymous Anonymous that’s not why the reactors caught fire, it caught fire because of 1) its cooling system; 2) the way they over used the reactor, a graphite pile, it accumulated to much energy; 3) they decided to overheat it in order to release the energy it accumulated. 4) they made things worse by turning on air when the fire started rather than cooling the pile with water.
Graphite moderator reactors have gone out of style.
The RBMK-1000 is a close copy of Hanford B, with most of the safety systems removed. The scary thing about Hanford B (where we discovered xenon poisoning) is that when the power mysteriously fell after a normal startup, our operators pulled the control rods *all the way out* in a misguided attempt to get it going again. (Fortunately the rods were put back in before any part of the core reacted and we got away with it, but boy was that ever dumb.)
@Gareth Johnstone You clearly aren't even smart enough to operate a bucket under any circumstances if you think uranium gets "white hot" in a nuclear "meltdown" so I don't think you have to worry about ever being anywhere near a nuclear reactor. Or even a bucket unless it still has the lid on it so you can't hurt yourself with it.
@@josephastier7421 I think "my" Hanford B reactor as a U.S. citizen and "your" Hanford B reactor must be two different reactors and two different designs used for entirely different purposes and with entirely different operators since my Hanford B reactor and its operators were never involved in any such "dumb" situation. Nor is my Hanford B reactor equipped with "control rods" period. So where is your Hanford B reactor and where can I learn more about it?
Are you a nuclear engineer or otherwise educated on the subject of and/or personally experienced with "nuclear reactors" or anything else related to "atomic energy"?
If so hopefully after sharing your resume' and/or curriculum vitae to establish your bona fides as a "nuc" but obviously not a "nuclear physicist" given you wouldn't be here WATCHING videos like this and critiquing whoever "got lucky" at your Hanford B reactor with a final grade of "really dumb" if you were and seem inclined toward "plain English"; maybe you can post a brief "bio" for your Hanford B reactor and its nuts and bolts in layman's terms, a short and sweet compare & contrast explanation of the few "common" reactor types, what "atomic energy" and "nuclear power" really are in basic junior high science class-level terms, how those reactors convert "atomic energy" into "nuclear power" or rather BEGIN that "conversion" from energy to "power" by releasing "atomic energy" in the fuel and converting it into "electrical energy" which "sparks" the "conversion" of additional fuel into "heat energy" which is as far as "nuclear reactors" can go converting "atomic energy" into "nuclear power" since energy must be "converted" into "force" when "potential energy" is "converted" into "kinetic energy" and the motion of "sub-atomic particles" the human eye cannot see is "concentrated" and "converted" into physical "power" we can feel as thermal "heat" or an electrical "shock" or as mechanical "motion".
Then maybe you can explain what a "meltdown" is, how "control rods" are used in part to "prevent" a "meltdown" and how when they FAIL in a reactor the only way to "prevent" a "meltdown" is to insert "SAFETY RODS" which of course unlike "injecting" a liquid nuclear reaction "poison" into the "core" of a "CANDU" heavy-water reactor where even that "safety system" can fail to prevent a "meltdown" if the "control rods" are not "pulled out all the way" removing their "decay heat" from the "core" and reducing the "pressure" inside the "core" so the "poison" injection can occur soon and quickly and completely enough to "kill" the reactions occurring between the "fuel" and the "coolant" and "boiling" the coolant leading to a "loss of coolant" accident and "runaway" thermal reaction in the core, the result is a "meltdown" once the "core" becomes hot enough to oxidize (burn) in the open "air" that replaces the lost coolant boiled away when "control rods" doing "double duty" as "control rods" during "normal operation" and "safety rods" in an "emergency" in a "CANDU" reactor for some reason FAIL AT THE LATTER "DUTY" WHEN "GOING ALL IN" WITH ALREADY OVERHEATED AND INEFFECTIVE "CONTROL RODS" ONLY ADDS "FIRE TO THE FUEL" SO TO SPEAK AND PUTS MORE HEAT AND PRESSURE AND "MASS" IN THE CORE DISPLACING, DEFLECTING, DIVERTING AND "DESTROYING" COOLANT AND FURTHER DELAYING THAT "POISON INJECTION" IF NOT PREVENTING IT ENTIRELY.
You can finish up your layman's lesson on Basic Nuclear Power 101 by walking us through your "Hanford B" reactor, it's "type", it's "control" and "safety" systems, how it's supposed to operate and be operated "smart" from "startup" to "shutdown" to remain "safe" and prevent "meltdowns", what "smart" operators do in an "emergency" when something(s) and or someone(s) went wrong and/or "dumb" and how your Hanford B and it's "dumb" operators got into that "emergency" shutdown/hot "restart" situation and why pulling the "control rods all the way out" was "dumb" and they "lucky" and how the "rest of the story" went/goes, how you came to be such an expert on your Hanford B reactor, what happened, who was operating it, what happened and what they did and why they were "dumb but lucky" and most importantly of all why and how you decided they were dumb but lucky when obviously your Hanford B not only didn't have a "meltdown" it apparently didn't even have an incident
or accident or close call "serious" enough to make your Hanford B even "famous" or "well-known" or maybe even "known" PERIOD by the "media" much less "infamous" since although there is plenty of info online about my Hanford B reactor, which again must be a whole different animal than yours since it not only has/had a perfect safety record but a whole different design, purpose and "process" by which it achieved it's "purpose" and it sure didn't and still doesn't have "control rods" and since it has 2000+ separate "cores" and all of them "controlled" separately and was "making fuel" instead of "using fuel" and the "cores" had to have "nuclear power" put into them to get "atomic energy" out and preventing "meltdowns" was sort of like keeping an aluminum saucepan from "melting down" on the burner of a gas stove while making mac and cheese in it. It can't happen until you boil away all the water, burn away all the macaroni and then figure out a way to get heat into the bottom of an aluminum saucepan faster than it can get out through that big "hole" in that's left when the "coolant" and "moderator" are boiled away and burned up.
Aluminum can and does "burn" at temps lower than "gas" burns at, but if you want to "melt down" an aluminum container using a "stove", it had better be a wooodstove and you"d better put the stove "around" it instead of "under" it.
Maybe your Hanford B folks should have talked to my Hanford B folks, huh?
Or maybe you should go back to school for a different "career" or something. Because I don't think you're much of a "nuc" and pretending otherwise could be very dumb.
How's your "luck" generally?
👍I really do like the CANDU reactor design.
I understand that a unique characteristic of Candu reactors is that their fuel does not contain elements that can be used for a nuke.
However, they CAN be used to burn plutonium from nukes as they are decommissioned. They also can burn a lot of spent fuels from other reactors.
Making these reactors attractive as part of the reprocessing loop. Reducing global spent fuel stocks.
The candu reactor CAN produce plutonium because:
1) use natural uranium
2) can change the fuel without shutdown.
Looks to be a very efficient fueling system. I'm curious, what is the average generation cost per kw using the AECL 1000?
@TAz69x
do you think its more awesome than an PWR reactor?
Now, the record for the longest run is held by Heysham 2 unit 8
rebroken again by canada, darlington nuclear plant, online for 1106 continuous days
That's why you don't operate outside the design parameters (or way outside as in the case of Chernobyl). RBMKs are great at making plutonium for a renewable nuclear fuel cycle, but the things are beastly at 4500MW of raw thermal power.
@adekk9 The fuel channels of the RBMK were light water cooled. As you probably know, light water is not that good of a moderator compared to heavy water and graphite, because of a somewhat high neutron absorption cross-section. RBMKs were graphite moderated, so that is why they have such a positive void coefficient. In other words, power goes up and so does the temperature. The water becomes less dense it absorbs less neutrons and power further increases.
The CANDU also has a positive void coefficient, but fuel geometry is critical in this design: if the fuel channels overheat, gravity causes them to sag out of alignment, stopping the chain reaction.
@@laura-ann.0726
The CANDU proves that having a positive void coefficient doesn't automatically mean an unsafe reactor. Not only that, the CANDU can, as a last-ditch resort dump its heavy water moderator and replace it with plain water so the core cooling can continue, but the chain reaction cannot. That's something completely impossible with solid graphite blocks. And the CANDU has two independent, blisteringly fast shutdown systems. Something the poor RBMK would love to have, but never got. Before the Chernobyl accident, its single shutdown system took a skeletal 18 to 21 seconds(!) to fully insert all the control rods into the core. At that point you might as well put jelly in your pocket because you're going to be toast. By the time the control rods can make any difference, your reactor will have put itself into orbit. Which is what Unit 4 quite literally did that night.
@@swokatsamsiyu3590- Everything I've read about the CANDU makes it seem like the best overall reactor design for a commercial power plant, at least up to now. Producing the deuterium oxide is expensive, but then, so is enriching uranium for a light water reactor. But I think that where the CANDU absolutely outshines every other solid-fuel reactor design, is on-line refueling and total availability. No shut down needed to just swap out spent fuel bundles. One question I have though, is how do the refueling machines maintain a water-tight seal to the fuel channels? Spent fuel has to be kept under water continuously because of the decay heat, so the inside of the fuel handling machines must be full of water too. The fuel channels are horizontal, so how do you prevent reactor coolant water from leaking out onto the floor at the interface between the reactor fuel channel and the refueling machines?
@@laura-ann.0726
This reactor design has it all; safety, robustness, a long service life, and it can run on various fuels including the waste from other reactors. And you can do a full refurbishment of its core components.
The CANDU has high upfront costs, but it starts earning its keep from the moment it is up and running due to its long availability in-between maintenance/refuelling outages. A CANDU reactor actually holds the world record for the longest, safe continuous run; a whopping 1106 days. This was achieved by Darlington Unit 1.
Since my specialty is the RBMK, I know a lot more about those than the CANDU. However, one of the feats both reactors share is the on-power refuelling. RBMK's refuelling machine has a special adapter head that provides an airtight/watertight seal with the channel to be refuelled. And each of the individual channels has valves that can control the waterflow through that specific channel. I think we can safely assume the CANDU system does something similar. The RBMK refuelling machine has a special water-cooled storage magazine for the spent fuel assemblies. The CANDU system has that as well. It is specifically mentioned in this video, as is the provision for a watertight seal between the refuelling machine and the channel interface. There are various ways with which this can be achieved; special couplings, gaskets, plugs etc. I do know that when a leak is detected, the machine will refuse to unclamp from the channel until things are resolved. Fifty+ years of safe CANDU operations prove it can, and has been done.
So, when the plugs are remove, how is the 9 MPa pressure contained?
+Big Boss Kind of like what mark said but way more complex than that lol but simplifying it...
The refuelling machine has a higher pressure that the pressure tubes so that when they plugs are removed the water from the streams doesn't leak out into the fuelling machines but instead is contained by a higher pressure wall. This causes pressure within the tubes to act as it the plug was still installed.
+Bones9696 Ah ha. Yes, that makes sense. Thank you :)
Once the fuelling machine is clamped on to the end fitting it becomes a part of the reactor pressure boundary. The snout of the fuelling machine firmly clamps onto the end fitting to create and maintain this seal.
that guy is a boss
@amfmful Do you know anything about Nuclear Reactors?
The quality of this video is thus:
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My word that is some feat of engineering.
Nice work friend (buddy/guy) lol
Mate, dude, man, herr, gringo...
@@johno9507 It's Canadian, so I had to reference South Park
complex but very interesting
As a separate discussion, why is it that nuclear fuel can be handled by the crew and appears as non-radioactive and safe to be handled via humans with no major protections, prior to insertion into the reactor?
Non enriched fuel is considered stable prior to being placed in the reactor. Once it’s placed in there, the chain reaction begins at which point it cannot be “stopped” only controlled.
Ah yes, of course this is relevant in 2021. Thanks YT algorithm
Slick system! Hard to believe that the cost of a high precision system like that can, and its lifetime maintenance, be less expensive than outage refueling. More complexity usually means more headaches.
No outages, what all of those poor road techs going to do!?
@antony1103
I hope they are built at some places
AP-1000 for the win!
I wonder how difficult it is to maintain this. Seems overly complicated
They have refurbished multiple of these reactors with pressure tube replacement.
is it safe to examining the fuel bundle with hands?
Yes, completely safe.
@@paulanderson79 spent* fuel bundle ?
@@AronqwapArshath Spent fuel bundles are not safe to touch for a long time
@@HiyuMarten I know that and that's why I was making sure which one he/she was talking about and then answer to the question ,thanks anyways 😅🤗
doesn'T that spend fuel still generate megawatts of power amazing that this can be done safely
Gentilly 1 in Quebec was a prototype / proof of concept. It ran for 7 years, but only had 180 on-power days in that time. Gentilly 2 went online in 1982, has had an excellent service record, and is expected to run until 2040.
Except y'all shut down the whole thing! Tabarnak!
If I knew what I said... then wouldnt it be a given that I know that as well?. Just ran out of space for these coz CZcams decided that 500 characters is gonna be enough for more educated comments.
Rendered on a potato.
+leerman22 Video is from 2008. So 8 years ago (7 from your comment). Technology moves fast, and CGI does not age well.
+Nikola Tasev That may have also be a reference to GlaDOS in the game Portal 2, hard to say.
It's actually crazy how much things have changed... it's also crazy to believe that 2008 was one year shy of a decade ago.
Bringing up your conception story is not relevant
@-ACHTUNG you're kind of right with that. but at the same time very wrong. When you actually calculate the true power very comparing fission vs fusion you have to put it in the same units scale! For example you can't compare 2 litre 300 horse engine vs a 5 litre 500 horse power engine and say that the 5 litre engine produces more true power. because litre for litre the smaller engine produces 150 per litre while the 5 litre only produce 100 per litre. So when you scale the fission vs fusion...fusion always produces more power!
You are the dumbest person on CZcams.
Yes, but probably not as much. As I was watching the animation of the rods getting loaded...I kept thinking to myself, "This is an engineer's nightmare because it is so complicated. What happens if one of the rods gets stuck during the automation process? Is the reactor now worthless?" I would be interested to know if they have a backup plan for such an event...or if their planning is only based on a "best case scenario". In any event, we need nuclear very badly, if not for energy...then
Exactly what I was thinking. I do see a worker injury, or death do to automation issues and unforeseen situations seeking immediate resolution due to fear of downtime.
This is flipped RBMK with water moderator :D
heavy water moderator*
@FlightSimTutorials Actually, a Single Fission of Uranium-235 yields more more than 10 times more energy as the Fusion of two Hydrogen Nuclei.
Uranium Fission would yield about 200 MeV's while a Fusion of Hydrogen would yield less than 20 MeV's.
2040-1982=58, NOT 40
Atomic Energy Plant Atomic clock. Can be powered and energized by a solar energy clock but doesn't use sun power but only by laser light which is absorbed in clock's solar panel cells or photo voltaic cells which absorb laser light converts it to electricity and sends it to it's Atomic Core clock.The reason to use this. Not smart to have any electrical wires any were around atomic things;not fire safe, compared to laser beam which is safe even if cut.Or if under water a laser can still be used.
40 years is not long
RBMK is better, it uses light water for cooling, and a graphite for neutron moderator. It also can be refueled without shutting down.
Origoangelohrol322 positive void coefficient FTW!
Like Chernobyl?
I think I found a nuke troll.
Are you fucking kidding me here?
@@nerissacrawford8017 No kidding. The graphite moderated reactor concept is very good and the Chernobyl type RBMK-1000 is just a not so successful modification of the idea. It's predecessor AM-1 has been very successful reactor and the modiffied MKER is also promising: en.wikipedia.org/wiki/MKER
This would be a lot simpler if it was just molten salt fueled.
He said "molten salt" (at least in the post I saw). He never said "sodium". Flouride is a salt, as well! And there is such a thing as a "molten salt reactor" design. It would use Flouride as a liquified fuel. The only main technological hurdle to that right now...is developing a way to avoid the potential corrosion because flouride is corrosive. The non-technical hurdles...are ASTRONOMICAL! I see this is an old post. Perhaps you have heard "The Good News" since then about molten salt and
@TAz69x
Just typical USA maded video.
You'd be wrong...since CANDU Reactors are Canadian.
Yep. But Uranium-235 is hundreds of times more massive, and that's why its fission is less energy dense and specific than fusion reactions involving light elements.
More importantly, fusion involves more reactions per unit volume/mass which means more neutron radiation. Neutrons are the lifeblood of any fission or fusion fuel cycle and can perpetuate the production of excess fissile/fusile fuel.
definitely for medicine (but we I say we DO need nuclear for energy, as well). But, we also need to get away from Gen1 and Gen2 ASAP and change the nuclear landscape. We really need liquid fuels, be that molten salts...or some liquified uranium/ thorium method not thought of, yet........
lol, im the 66,666th
ACR-1000 sounds safer than an ACR-1 nuclear reactors are a crazy way to heat water.
Why not direct all your love for this clean energy source to Japan and find a solution to this nightmare that's going on
The best energy sources in the world are no good if the operators fail during an emergency. The Fukushima-Daiichi and Three mile Island incident's are prime example's of operator error.
Maybe that's why we shouldn't have this poison with no cure on our planet
All the more reason to use Integral Fast Reactors and Molten Salt Reactors. Use the IFRs to breed the fuel needed to start-up and run the MSRs, and the fuel for those IFRs is the spent fuel from older light water reactors. And while you're at it, instead of using the IFRs to produce electricity, use their heat to run desalination plants. Enjoy the benefits of less waste, and plenty of clean electricity produced by MSRs and IFRs that are physically incapable of melting down.
agreed, but also consider japan had to battle with multiple major design flaws, And, A once in a million disaster, TMI was textbook operator failure.
@@ramon23598 This stuff comes from the ground in the first instance. Nuclear radiation is an entirely natural phenomenon.
Thorium. If your haven't, I suggest you do some research into it. It sounds pretty promising...if the one technical hurdle (and the many political hurdles) can be overcome. The only financial hurdle is tied into the many political ones...worldwide (China, U.A.E., and India excluded), people don't want to invest in ANY nuclear development when they don't know what the regulatory environment is going to be in ten years....................
"design" or reactor???????????????????????????????????????
vehicle. Also, if I purchased photovoltaic shingles, that will probably mean someone else is unable to do so for their own home...because the materials to manufacture them are not, unlike the sun from which they absorb the energy, unlimited. (It should be said that "rare earths" really aren't rare...but if we tried to scale up to the kind of renewables infrastructure some advocate for...THEY WOULD BE! And, I also know that the sun is, over billions of years, limited, but for our sake, it isnt
Safety does not come in "levels".
(But, here is a carrot from the renewables people.... If we begin to fuel nuclear reactors with a Thorium cycle, Thorium obtained from waste from the mining of rare earths for the very renewables you all seem to love so much...then perhaps the price of renewables will decrease because what was once a hazardous waste material obtained from "rare earths" mining...has now become a valuable, marketable, or at least one that can be given away, commodity.)
Not gonna lie this hardly sounds energy positive.