See full video here: ruclips.net/video/T_jcbhE0u-8/видео.html *Note - Modern nuclear reactors can never really explode like a nuclear bomb because the nuclear fuel is not compact enough to cause an uncontrollable chain reaction. The reactor at Chernobyl exploded but this was not a nuclear explosion.
I used to think nuclear energy was its own thing, like Godzilla's atomic breath. Imagine my disappointment when I found out that nuclear energy is just boiled water making turbine go brrrrr.
There are other ways to get energy from nuclear reactors. But for commercial reactors some sort of fluid is generally used to transfer heat to a turbine.
One thing to note from this explanation. The primary loop water, which goes through the reactor, never goes through the steam turbines. There is a heat exchanger to the secondary loop, which carries the energy to the steam turbines. If you ran the primary loop through the steam turbines, the turbines would become so radioactive that you could never service them. Therefore, the primary loop and secondary loop water never touch. This was over-simplified in this video.
That's true for PWRs. The type shown in the video is a BWR, which has only a single loop (activation products do get into the turbine at BWRs, but their dosimetry programs prevent major issues there).
its not just control rods at most plants. at the plant i work at we use boron in the water to absorb neutrons and thats the primary way to control the reaction. Think if we had to insert the control rods from the top a lot of the fuel would be unevenly used therefore the boron allows for a more even use of the fuel as it is in equal concentration through the reactor coolant water
@@dornog70 there’s a lot of things that go into maintaining plant status. We’re talking about reactivity and that’s controlled through boron. There’s also 31000 valves 😂
@@dornog70The turbines run on actual steam, but that steam is created with additional steps to avoid steam in the reactor itself (which generally is part of a major accident) .
I really like Arvin's presentation style. "How is the chain reaction controlled ...?" "Now how do control rods do that?" Asking questions like that prepares the viewer to receive the next bundle of facts. And it never sounds like he is READING the script; the delivery is always as if he were just talking naturally. Excellent.
@@ThomasConoveryou're comparing apples and oranges dude. Atomic bombs CAN make a crap ton of radioactive materials if the are ground burst. This is from nuetron activation of the earthen materials.
@@kayakMike1000 🤣🤣🤣 you obviously have allowed your doctor to X-ray scan your brain a few hundred times too much. I’m not disagreeing to your statement tho, but your statement was completely irrelevant to my comment whatsoever. 👍😊
@@ThomasConoverChernobyl was a gas explosion, too much steam, xenón-135 and hydrogen caused the seal to explode due to the high preassure and go up and down and when hydrogen meets oxigen it becomes volatile and thats was the big explosion.
I think this is an pwr style reactor, it used pressurized water in the reactor as a moderator, that water is in a closed loop that goes through a heat exchanger that heats water in a secondary loop which creates the steam that spins the turbine which creates the power.
The water isn't boiled in the reactor. It reaches an EXTREMELY high temperature with water kept at high pressure to avoid the creation of steam. Steam is created from a loop within the reactor that brings the high pressure heated water through a pipe into a steam generator tank, where water surrounding the high temp water piping gets coverted into steam.
A reactor cannot become a bomb because the enrichment of U 235 is far too low at less than 5%. Super criticality would lead to a meltdown. Control depends on the design but criticality is usually maintained through extent of insertion of control rods and/coolant chemistry in the case of water moderated reactors.
@anthonymonge7815 I am a nuclear scientist, working in Uk nuclear power industry for 35 years. Commercial reactors have a maximum of 5% U 235. Our AGRs have an average 3.8% while the water reactors have 4.5%. Only submarine reactors have high enrichments of more than 70 % because of high neutron leakage from their tiny reactors.
Control Rods are used to shut down a reactor not really controlling it. Reactor power is controlled by varying the concentration of boron in the cooling water.
Using Boron in the cooling (water) is one way but originally the control rods were partially lowered into an operating reactor to moderate the neutron velocity, which in turn slowed the reaction. Boron in the reactor fluid does the same thing but can be more precisely controlled and doesn’t leave hot spots like the old method did.
@@richb2229 Using rods to control reactor power is how the US military does it. Commercial reactors operate with all rods completely withdrawn. 10 years military nuc plus 22 years commercial nuc here. All on PWR operations dept.
Military reactor power is controlled by the rods but commercial reactors are controlled by boron concentration. A military reactor uses highly concentrated U235 which is essentially bomb grade. Commercial reactors use very low concentrations which can't produce a nuclear bomb. 10 years military and 23 years commercial nuclear plant operations here.
In the Russian reactor the neutrons are absorbed by cooling water which lead to the disaster because air pockets were forming in the water tubes leading to an out of control temperature rise.
Facts. This is why nothing can ever progress anymore. Too many uneducated brainwashed fudds who refuse to do a sliver of research think their opinions should matter on a subject they've been made to be scared about.
@@DrDeuteronnuclear mechanical engineer, from what I've seen, you're right it mostly comes down to the application. The fizikz of the reactor are very intriguing, but I can see how it becomes a bit confusing, with all the daughter elements formed briefly and then forming something else almost instantaneously. It's alot of probability curves, esp in breeders in my understanding.
@@Not_Sure_2505 the good news is decay rates (half lives) add just like resistors (capacitors)... so that math is well known. When I say "physics" I mean things like daughter 1/2 lives and reaction differential cross-sections vs. energy (esp. n + U235 -> X + Nn) and stuff like that. Also those meta-stable intermediate nuclei that gamma decay. That has all been measured and tabulated long ago. It's a massive body of work. e.g. the national nuclear data center at Brookhaven (one of the few labs I've never been to): nndc (dot) bnl (dot) gov (slash) nudat3
@@Not_Sure_2505I still can’t fathom nuclear. The people saying it’s primitive and it’s just a steam engine are just dumb imo. it’s so much more than a steam engine. We have a big plant in Ohio. David- bessy. Spelling could be wrong.
Edit: This may no longer be correct. OP: For those wondering, the neutron-absorbing material is usually cadmium, indeed as in nickel cadmium rechargeable batteries (it’s what we had before NiMH, and they were heavy).
you forgot the water ( moderator ) they slow down the moving neutrons so that it won't achieve nuclear fission that fast and also it cools down the reactor so it won't create to much heat
The nuclear reaction is not controlled by control rods. The nuclear reaction is stopped by the control rods. There is a moderator in the reactor coolant, usually boric acid, where the concentration controls the nuclear reaction. If not and control rods were inserted halfway the fuel would be used not evenly over the fuel element so that would not work.
This seems specific to a single design . Multiple designs exist in the original nuclear countries . Some accept the uneven use of rods, some use solid moderator blocks, some vary the number of rods inserted etc. etc.
The water that makes contacts with the rods don't get turned into steam. It runs the heated water in a loop to heat secondary water which then turns into steam and turns the turbines. That steam gets returned as water to the 2nd loop and the cycle continues. The water that heats via the fuel rods is radioactive it wouldn't come in contact with anything else.
Along with control rods, other methods of limiting the rate of reactions are commonly used. Substances like boric acid are typically used as a type of "liquid control rod," or a nuclear poison. It functions essentially the same as the control rods except for the fact it's in solution, and thus as another person mentioned, has a more even effect on slowing a reaction. Also, the uranium in nuclear reactors is not weapons grade. That is, it isn't refined enough to cause a nuclear explosion when prompt critical.
@@ArvinAsh To begin with, commercial nuclear power plants lack the highly concentrated Uranium-235 necessary to cause a nuclear explosion, as was described and graphically shown.
slightly misleading things: -Rods inserting from the top despite being a boiling water reactor -"Steam Generator" is really not a steam generator because of the missing cold leg. -Steam turbine has incorrect design -Deaerator Missing (if im wrong, please tell me)
I worked at the SONGS (San Onofre Nuclear Generating Station) for a couple of refueling cycles. In that system high pressure superheated water heated a secondary source for steam generators. That secondary source was further cooled through a third set of pipes that went out to the ocean. The dampening rods had a fail safe default to close using gravity if there was a catastrophic system failure or loss of power. In other words the dampening rods were raised to start the reaction and if a total shutdown was required they just dropped. It worked really well until California bureaucrats got involved.
You have 2 separated systems to produce the steam. 1 has the radio active water (or molten sodium), then it goes to a heat exchanger that heats regular water (non radioactive). In your explanation, the cooling towers would be emitting high levels of radiation. Then there's no way a nuclear power plant can turn into a nuclear bomb. The fuel cells will melt, but they will not have a explosion to compress the uranium. You can get a hydrogen explosion (Fukushima), but that's from super heating the water and the Hydrogen separated.
The water acts as both as whybto get energy out of the system woth steam but also a moderator slowing down the neutrons to increase the probability of collision. As the water turns to steam, it becomes a worse moderator, which makes the fission events less likely, helping to regulate the reaction.
This the basic explanation of a BWR (Boiling water reactor). In a PWR (Pressurized water reactor) the water stays inside the reactor vessel, and is kept under pressure as the name suggests. The water then exchanges its heat through an exchanger and then steam is created. Now the RBMK (Infamous for the Chernobyl disaster) Has instead of just a vessel full of water, has steam channels. It works similar to a BWR, but has channels and is very old.
Water in the primary vessel is not turned to steam, it is super heated, and uses a heat exchanger to transfer heat to non irradiated water to produce steam. The cavitations of boiling would allow heat spikes similar to Chernobyl.
this is an old method. today the chainreaction ist mostly controlled by adding bor-acid to the water. btw the material in the controlrods is also most likely bor. further more a reactor that reached criticality is self sutainable and has its balance at the criticality point (0.995 - 1.005)
"become an atomic bomb" The rbmks were the only reactors that would blow up; this is because of bad design choices. All other reactors do not blow up but rather melt. The uncontrolled fission of the fuel causes it to melt, not explode. For instance, in Fukushima, the BWR reactors experienced fuel damage by melting (aka a meltdown). The explosions on the plant were hydrogen explosions completely separate from the reactors.
One obvious detail is 90% of reactors have a secondary heat transfer system & heat from reactor doesn't directly drive turbine, this isolates radiation.
The superheated radioactive steam does not go to a turbine. It goes to a heat exchanger where it heats clean water for steam that goes to the turbines and all the heat exchangers throughout the ship/facility. It would be bad to spread radiation all throughout your work entire facility!
Everyone tries to oversimply what we call reactor kinetics. You described the reactor shutdown system. Control for the reactor is actually based on the number of neutrons that are born delayed. In other words, those born from the decay of fission fragments. After reaching what is known as the point of adding heat (POH), the reactor is kept slightly subcritical in the power range. This buys the contorl system and operators' time to see how pressure and thermal effects are feeding back into the overall neutron population. There are typically 6 factors in the reactor control equation. Operators monitor these effects with many instruments. Power range nuclear (radiation) instruments, temperature and pressure instruments, and in the case of a pressurized water reactor (PWR) pressurizer level in the primary system. However, the rate that heat is removed by the steam systems affects the temperature of the primary (reactor) cold return water, which also affects the operation of the reactor core. If electrical demand increases, steam output must also increase, and that causes reactor return temperature to decrease. Therefore, the differential temperature of the core is important in keeping the power level constant. A reactor is not simply a boiler. And, criticality is the measure of the time rate of change of neutron density in the core. Exactly critical is where the total number of neutrons born in one generation is exactly equal to the number of neutrons to be born in the very next instance in time. In response to decreasing temperature, an operator withdraws the control rods a little, exposing more fuel to neutron flux in the reactor core so that more heat is generated in the core to make up for the previous loss. The number of new neutrons generated takes the core slightly above critical to cause more fission events and heating the reactor materials, raising hot output temperatures to generate more steam and things balance back out at a new equilibrium. Nothing but physics and math. People should have been told a long time ago that these truths, while moderately complex, are not mysterious. They are, in fact, extremely well understood. If this 61 year old can remember how a reactor works after being away from the industry for over twenty years, certainly young, vibrant minds could be taught this reality. Don't over simplify the facts. Instead, tell it all the way things really are!
So if the control rods absob neutrons, they should increase the number of neutrons per atom, making the atoms unstable and therefore radiactive. Then the control rods will have a short lifespan, during which they will become less and less efficient at absorbing neutrons, I'm right @ArvinAsh?
A bit misleading. Control rod is not for stopping, but absorbing 1 out of 2 neutron, keeping the chain reaction linear. For stopping nuclear reactor, you have to take out the uranium. There is no other way. Even if you bury them by a solid block of "control rod", they just keep splitting, overheat, melting everything. In conclusion, control rod is not for stopping reactor, its for maintaining linear reaction.
Where do the neutrons that get absorbed by the control rod or slowed down by the moderator eventually go ? Because if they just stay in the reactor and accumulate in the control channel or moderator they would eventually hit atoms of uranium 235 and causing a reaction
Problem is, regulations. LWRs have already been in commercial operation for a long time with lots of OPEX data and regulatory scrutiny. Unfortunately, but also fortunately, the regulations take a long time to go through, but it makes sure things all work correctly.
Using a nuclear reactor to heat water as the main coolant working fluid is quite ingenious and not primitive. Water is excellent at this task. Water has high heat retention and it blocks some of the radiation. It can be pumped so that the energy from the core becomes portable and can be transferred to somewhere else, usually to another loop of water that becomes steam to run an electrical turbine. Turbines are important because the AC electricity used in our distribution infrastructure is most easily generated by a rotating armature in a magnetic field.
Where are the triple redundancy rods? Can we not get a 3 sided reactor with multiple incertion points? Can we not include an emergency manual separate incertion rod? Considering the alternative this seems reasonable
In most PWRs the control is through the boric acid concentration in the coolant water. The control rods are reserved for shutdowns and emergencies. just sayin ...
I have a doubt ✋, If atoms are splitting appart again and again so that means the rods will degrade Right? And the water will be contaminated with radioactive waste and fission products right? And these things have to be changed over and over ? And again fission produces so heat per atom fission so these plutonium and uranium rods will take couple of time to degrade?
To start atomic weapons need 90% U-235, power plants have 3 to 5% fuel. Secondly a weapon needs amazing amount of pressure and heat in instateneous combustion... This is caused by exploding uranium with explosive charges to compress and heat the isotope...
The control rods do not stop the reactor from becoming a bomb. Reactor fuel rods are too far apart and then do not move so the fuel cannot become super critical and explode. They can over heat and the rods will melt forming a puddle of extremely hot radio active fuel that can spread radiation if exposed to water that explodes into steam. But it cannot explode by nuclear fission.
But a running reactor is at temperature so the fuel rods are still hot, even though the control rods have been dropped into the core and the nuclear reaction has ceased . The fuel rods are still very hot and need to be cooled for a very long time after the nuclear reaction has stopped. This is why we have meltdowns as in Japan !
If the rods can't be lowered, use a basic heat fuse to open a big bottom hatch and drop the whole mess into a pool of control rod chunks. No threat of China Syndrome. Not that I actually know what I'm talking about, of course - take with a grain of molten salt.
and to think, all this high end tech. is coupled to something so primitive like spinning a steam turbine to turn some magnets around some copper wires...all these years and we still have not found another way, or a better way, to turn heat into electricity !
Can you elaborate why during the Japan 311 nuclear event or decommissioned core, the use of boron rods cannot immediately shutdown the fission. Does it meant even when no reaction, the system need a cycle of half life to reduce the reaction rate and thus the heat generation
Putting in the control rods does immediately stop the fissioning completely because the reactor goes below criticality right away. However, there is still radioactive decay going on inside the fuel, which produces about 7% of the core's normal maximum output. In a commercial nuclear power plant this produces a lot of heat. That's why the core must still be cooled continuously even when the reactor is shut down. If you don't cool the core continuously it will eventually melt down. At Fukushima they had a power failure because the whole local grid went down and the emergency generators got flooded out by the tsunami. This caused the cooling pumps to stop and the core overheated.
mi lenne ha kiikttatnánk a vízbe vezetett hőt és azt egyből egy hőből elektromos áramot előállító elembe vezetnénk? tudom, csak kisebb erőműben megoldható.
It is depending on what kind of reactor you're talking about. all modern reactors, especially the ones in America. Also cannot have a chain reaction without the water. If you're to cut off the water flow to a modern-day nuclear reactor, the neutrons become too fast to cause a chain reaction, and the reactor shuts down. water also acts what's known as a moderator. That's why it is almost impossible for a nuclear reactor now to melt down. Even if the control rods were to freeze and not be able to be inserted into the core as long as you just cut off the water flow, Fission can't happen. This is what makes nuclear energy actually the cleanest and safest source of energy that we have. When people like to think of nuclear energy being unsafe they always talk about things like fukushima or Chernobyl. Fukushima was by poor design. They put the spent to cores Near the reactor which caused a chain reaction when the water came in from The tsunami. And also that nuclear reactor is like over 50 years old which the design has changed due to modern physics and engineering. Chernobyl was also a reactor that is not used anywhere in the West. Its moderator is not water And that's what makes it the most dangerous. Even with the poor design The meltdown was caused by Unknowledgeable engineers who went against protocol and caused the incident. Nuclear energy is the safest form of energy that you can have and it causes 0 carbon emission. All the waste of nuclear energy is only large enough to fill room from all the time we've been using it. 😊
The water that goes in reactor never hits the water that goes in turbine and to cooling towers. The super hot steam stays in its own system and it heats 2nd loop through exhangers.
There are two types of reactors in consideration: boiling water reactors (bwr) and pressurized water reactors (pwr). The one in this vid is a bwr, where the first loop boils water and the steam is run through a turbine. In a pwr, the primary loop is closed, it runs through a steam generator that heats another loop to create steam to run through the turbines. On both, the cooling towers come into play in a final ultimate heat sink loop, in a seperate loop after the steam turbines. After the turbine there is a heat exchanger for keeping an effective delta T in the turbine loop. This excess heat is then routed to the cooling towers.
This represents a boiling water reactor or BWR. The water is boiled right inside the reactor and so it doesn't have a steam generator. You are thinking of a pressurized water reactor or PWR, which does have a steam generator.
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See full video here: ruclips.net/video/T_jcbhE0u-8/видео.html *Note - Modern nuclear reactors can never really explode like a nuclear bomb because the nuclear fuel is not compact enough to cause an uncontrollable chain reaction. The reactor at Chernobyl exploded but this was not a nuclear explosion.
Thank you!
It was a hydrogen explosion. controlling hydrogen is important in a nuclear accident.
It was the rods. They inserted them too late and they couldn't stop the overheating of the reactor or something. Sounds nuclear to me.
The grid is not big enough
We need 5TIMES MORE ELECTRICITY.
Says who?
Just you?
Citations, please.
I used to think nuclear energy was its own thing, like Godzilla's atomic breath. Imagine my disappointment when I found out that nuclear energy is just boiled water making turbine go brrrrr.
Same as it ever was
That’s just how we get energy from it. Otherwise it’s still its own thing.
Haha I agree, steam and turbines! Sounds like something the armish would be using
There are other ways to get energy from nuclear reactors. But for commercial reactors some sort of fluid is generally used to transfer heat to a turbine.
There’s a 4chan meme that was kinda funny. Everything we do as humans to make power is boiling water brrr
One thing to note from this explanation. The primary loop water, which goes through the reactor, never goes through the steam turbines. There is a heat exchanger to the secondary loop, which carries the energy to the steam turbines. If you ran the primary loop through the steam turbines, the turbines would become so radioactive that you could never service them. Therefore, the primary loop and secondary loop water never touch. This was over-simplified in this video.
That's true for PWRs. The type shown in the video is a BWR, which has only a single loop (activation products do get into the turbine at BWRs, but their dosimetry programs prevent major issues there).
That’s correct for PWR but not for RBMK.
they released first loop to ocean after fukushima accident ... ;P and so far we are fine. except covid like chaoses may or may not be related :D
So simplified it wasn't even there....
As noted above, BWRs operate this way. PWRs have a primary and secondary loop with a tertiary loop to the cooling towers or other ultimate heat sink.
its not just control rods at most plants. at the plant i work at we use boron in the water to absorb neutrons and thats the primary way to control the reaction. Think if we had to insert the control rods from the top a lot of the fuel would be unevenly used therefore the boron allows for a more even use of the fuel as it is in equal concentration through the reactor coolant water
Most plants use valves and pumps to control the plant like cvcs
@@dornog70 there’s a lot of things that go into maintaining plant status. We’re talking about reactivity and that’s controlled through boron. There’s also 31000 valves 😂
@@JonBorpa yea I hate how these “tutorials” aren’t realistic like steam going into the steam generators is crazy
@@dornog70The turbines run on actual steam, but that steam is created with additional steps to avoid steam in the reactor itself (which generally is part of a major accident) .
I always wondered about uneven use of the fuel ....like the bottom would runout first. Boron does gobble up neutrons.
I really like Arvin's presentation style. "How is the chain reaction controlled ...?" "Now how do control rods do that?" Asking questions like that prepares the viewer to receive the next bundle of facts. And it never sounds like he is READING the script; the delivery is always as if he were just talking naturally. Excellent.
The reactor cannot become an atomic bomb due to the much lower enrichment of the uranium.
It can still produce equal amount of nuclear waste spreading over a whole continent. Just research what happened to Tsjernobyl.
Underpaid huh?
@@ThomasConoveryou're comparing apples and oranges dude. Atomic bombs CAN make a crap ton of radioactive materials if the are ground burst. This is from nuetron activation of the earthen materials.
@@kayakMike1000 🤣🤣🤣 you obviously have allowed your doctor to X-ray scan your brain a few hundred times too much. I’m not disagreeing to your statement tho, but your statement was completely irrelevant to my comment whatsoever. 👍😊
@@ThomasConoverChernobyl was a gas explosion, too much steam, xenón-135 and hydrogen caused the seal to explode due to the high preassure and go up and down and when hydrogen meets oxigen it becomes volatile and thats was the big explosion.
Boron or cadmium is used as control rod in different countries .
Control rods are generally made of hafnium. Fuel rods are tubes made of zirconium alloys.
Or Indium*-Silver-Cadmium, I think halfniun is either a GE or a boiling water reactor thing.
Arvin knew this but he didn't wanna say in the video so he don't get on the US watch list
Originally they were made of carbon graphite. But other more exotic materials are used today to better control neutron speed.
Now I know how to build a nuclear reactor
Boron is also used for control rods.
Well, that's one way to boil water.
Wait it’s all just boiling water? Always has been .
I think this is an pwr style reactor, it used pressurized water in the reactor as a moderator, that water is in a closed loop that goes through a heat exchanger that heats water in a secondary loop which creates the steam that spins the turbine which creates the power.
The water isn't boiled in the reactor. It reaches an EXTREMELY high temperature with water kept at high pressure to avoid the creation of steam. Steam is created from a loop within the reactor that brings the high pressure heated water through a pipe into a steam generator tank, where water surrounding the high temp water piping gets coverted into steam.
You’re talking about a PWR. this video is explaining a BWR type reactor
Boiling Water Reactors boil their primary water in the reactor.
A reactor cannot become a bomb because the enrichment of U 235 is far too low at less than 5%. Super criticality would lead to a meltdown. Control depends on the design but criticality is usually maintained through extent of insertion of control rods and/coolant chemistry in the case of water moderated reactors.
Glad u said that. I detected the same error in the story.
You’re absolutely right, either a meltdown or chemical explosion caused by xenon poisoning.
Tsjernobyl entered the chat.
The enrichment is much higher than 5%. Try high 90’s. Source: I am a reactor operator.
@anthonymonge7815 I am a nuclear scientist, working in Uk nuclear power industry for 35 years. Commercial reactors have a maximum of 5% U 235. Our AGRs have an average 3.8% while the water reactors have 4.5%. Only submarine reactors have high enrichments of more than 70 % because of high neutron leakage from their tiny reactors.
Control Rods are used to shut down a reactor not really controlling it. Reactor power is controlled by varying the concentration of boron in the cooling water.
Using Boron in the cooling (water) is one way but originally the control rods were partially lowered into an operating reactor to moderate the neutron velocity, which in turn slowed the reaction. Boron in the reactor fluid does the same thing but can be more precisely controlled and doesn’t leave hot spots like the old method did.
@@richb2229 Using rods to control reactor power is how the US military does it. Commercial reactors operate with all rods completely withdrawn. 10 years military nuc plus 22 years commercial nuc here. All on PWR operations dept.
@@richb2229 they absorb the neutrons. Moderated neutrons (e.g., thermal) are what make the fission happen. Water moderated neutrons.
Military reactor power is controlled by the rods but commercial reactors are controlled by boron concentration. A military reactor uses highly concentrated U235 which is essentially bomb grade. Commercial reactors use very low concentrations which can't produce a nuclear bomb.
10 years military and 23 years commercial nuclear plant operations here.
Actually Boron is used to compensate for lovering amount of fissile U235 in reactor during the fuel campaign.
In the Russian reactor the neutrons are absorbed by cooling water which lead to the disaster because air pockets were forming in the water tubes leading to an out of control temperature rise.
Tell that to RBMK reactors.
It's always an aneurysm-inducing nightmare whenever I read the comment section of anything nuclear-related.
try it with a phd in nuke fizz...but really, the reactor talk is engineering, they never discuss the actual physics.
Facts. This is why nothing can ever progress anymore. Too many uneducated brainwashed fudds who refuse to do a sliver of research think their opinions should matter on a subject they've been made to be scared about.
@@DrDeuteronnuclear mechanical engineer, from what I've seen, you're right it mostly comes down to the application. The fizikz of the reactor are very intriguing, but I can see how it becomes a bit confusing, with all the daughter elements formed briefly and then forming something else almost instantaneously. It's alot of probability curves, esp in breeders in my understanding.
@@Not_Sure_2505 the good news is decay rates (half lives) add just like resistors (capacitors)... so that math is well known.
When I say "physics" I mean things like daughter 1/2 lives and reaction differential cross-sections vs. energy (esp. n + U235 -> X + Nn) and stuff like that. Also those meta-stable intermediate nuclei that gamma decay. That has all been measured and tabulated long ago. It's a massive body of work.
e.g. the national nuclear data center at Brookhaven (one of the few labs I've never been to):
nndc (dot) bnl (dot) gov (slash) nudat3
@@Not_Sure_2505I still can’t fathom nuclear. The people saying it’s primitive and it’s just a steam engine are just dumb imo. it’s so much more than a steam engine. We have a big plant in Ohio. David- bessy. Spelling could be wrong.
Edit: This may no longer be correct.
OP: For those wondering, the neutron-absorbing material is usually cadmium, indeed as in nickel cadmium rechargeable batteries (it’s what we had before NiMH, and they were heavy).
Isn't graphite also used? Just domething I thought I remembered
@@ChaineYTXF I’m beginning to wonder if cadmium was just the first material they used and they changed.
The moment you realize we haven’t actually progressed from steam power.
Most reactors run with all rods out and a Boron solution is used to control the reactions
This is basically a very sophisticated on/off switch.
you forgot the water ( moderator ) they slow down the moving neutrons so that it won't achieve nuclear fission that fast and also it cools down the reactor so it won't create to much heat
A nuclear reactor could NEVER become an atomic bomb.
What happened with tschernobyl and fukushima
those are not nuclear bomb level explosions they are meltdowns , totally different things @@matsu8205
@@matsu8205 a meltdown happened, not an explosion
@@matsu8205 Chernobyl: Meltdown to steam/pressure explosion. Fukushima: Chemical explosion (hydrogen gas with oxygen), also with a meltdown
Just a nuclear contamination mess. Small booms from hydrogen and if you live near by, well now you don't.
yeah , those with a graphite tip controls it so good😅
The nuclear reaction is not controlled by control rods. The nuclear reaction is stopped by the control rods. There is a moderator in the reactor coolant, usually boric acid, where the concentration controls the nuclear reaction. If not and control rods were inserted halfway the fuel would be used not evenly over the fuel element so that would not work.
This seems specific to a single design . Multiple designs exist in the original nuclear countries . Some accept the uneven use of rods, some use solid moderator blocks, some vary the number of rods inserted etc. etc.
@@johndododoe1411 Absolutely correct. What I said is true for most pressurized water reactors. By far the most common.
Most people don't realize that a Nuclear Reactor is just a Steam Generator.
Barely beyond Locomotives of the 1940s.
Amazing.
Sounds so easy when explained like that 😊
Great and easy to understand explanation. Thank you!
Thanks bro... So making this so easy... ❤❤
A reactor cannot become an atomic bomb even without control rods
It can melt like a mfr though!
The water that makes contacts with the rods don't get turned into steam. It runs the heated water in a loop to heat secondary water which then turns into steam and turns the turbines. That steam gets returned as water to the 2nd loop and the cycle continues. The water that heats via the fuel rods is radioactive it wouldn't come in contact with anything else.
Understandably scary technology, but equally incredibly fascinating.
I already knew that. Also: nuclear power plants never turn into atomic bombs. That's an urban legend and you should really not promote it! 😅
So how often do control rods need to replaced? Would they be as dangerous as spent fuel?
Along with control rods, other methods of limiting the rate of reactions are commonly used.
Substances like boric acid are typically used as a type of "liquid control rod," or a nuclear poison. It functions essentially the same as the control rods except for the fact it's in solution, and thus as another person mentioned, has a more even effect on slowing a reaction.
Also, the uranium in nuclear reactors is not weapons grade. That is, it isn't refined enough to cause a nuclear explosion when prompt critical.
Its rare to state so many things wrong in such a short video. Well done.
What's wrong?
@@ArvinAsh To begin with, commercial nuclear power plants lack the highly concentrated Uranium-235 necessary to cause a nuclear explosion, as was described and graphically shown.
slightly misleading things:
-Rods inserting from the top despite being a boiling water reactor
-"Steam Generator" is really not a steam generator because of the missing cold leg.
-Steam turbine has incorrect design
-Deaerator Missing
(if im wrong, please tell me)
I worked at the SONGS (San Onofre Nuclear Generating Station) for a couple of refueling cycles. In that system high pressure superheated water heated a secondary source for steam generators. That secondary source was further cooled through a third set of pipes that went out to the ocean.
The dampening rods had a fail safe default to close using gravity if there was a catastrophic system failure or loss of power. In other words the dampening rods were raised to start the reaction and if a total shutdown was required they just dropped. It worked really well until California bureaucrats got involved.
Dependency on rode coating will also reduce an alterations
Control rods are usually made of boron carbide, where the four borons each absorbs a neutron becoming boron 11.
You have 2 separated systems to produce the steam. 1 has the radio active water (or molten sodium), then it goes to a heat exchanger that heats regular water (non radioactive). In your explanation, the cooling towers would be emitting high levels of radiation.
Then there's no way a nuclear power plant can turn into a nuclear bomb. The fuel cells will melt, but they will not have a explosion to compress the uranium. You can get a hydrogen explosion (Fukushima), but that's from super heating the water and the Hydrogen separated.
The water acts as both as whybto get energy out of the system woth steam but also a moderator slowing down the neutrons to increase the probability of collision. As the water turns to steam, it becomes a worse moderator, which makes the fission events less likely, helping to regulate the reaction.
This the basic explanation of a BWR (Boiling water reactor). In a PWR (Pressurized water reactor) the water stays inside the reactor vessel, and is kept under pressure as the name suggests. The water then exchanges its heat through an exchanger and then steam is created. Now the RBMK (Infamous for the Chernobyl disaster) Has instead of just a vessel full of water, has steam channels. It works similar to a BWR, but has channels and is very old.
Water in the primary vessel is not turned to steam, it is super heated, and uses a heat exchanger to transfer heat to non irradiated water to produce steam. The cavitations of boiling would allow heat spikes similar to Chernobyl.
Very good explanation sir
The grid is not big enough
We need 5TIMES MORE ELECTRICITY.
this is an old method. today the chainreaction ist mostly controlled by adding bor-acid to the water. btw the material in the controlrods is also most likely bor. further more a reactor that reached criticality is self sutainable and has its balance at the criticality point (0.995 - 1.005)
Wake up people
This is the only sustainable energy of the future.
That means it boils water with out the use of fire 😊
"become an atomic bomb" The rbmks were the only reactors that would blow up; this is because of bad design choices. All other reactors do not blow up but rather melt. The uncontrolled fission of the fuel causes it to melt, not explode. For instance, in Fukushima, the BWR reactors experienced fuel damage by melting (aka a meltdown). The explosions on the plant were hydrogen explosions completely separate from the reactors.
When i hear about even top notch factories have equipment malfunctions its all it takes for the control rods not to drop its scary
One obvious detail is 90% of reactors have a secondary heat transfer system & heat from reactor doesn't directly drive turbine, this isolates radiation.
The superheated radioactive steam does not go to a turbine. It goes to a heat exchanger where it heats clean water for steam that goes to the turbines and all the heat exchangers throughout the ship/facility. It would be bad to spread radiation all throughout your work entire facility!
Everyone tries to oversimply what we call reactor kinetics. You described the reactor shutdown system. Control for the reactor is actually based on the number of neutrons that are born delayed. In other words, those born from the decay of fission fragments. After reaching what is known as the point of adding heat (POH), the reactor is kept slightly subcritical in the power range. This buys the contorl system and operators' time to see how pressure and thermal effects are feeding back into the overall neutron population. There are typically 6 factors in the reactor control equation. Operators monitor these effects with many instruments. Power range nuclear (radiation) instruments, temperature and pressure instruments, and in the case of a pressurized water reactor (PWR) pressurizer level in the primary system. However, the rate that heat is removed by the steam systems affects the temperature of the primary (reactor) cold return water, which also affects the operation of the reactor core. If electrical demand increases, steam output must also increase, and that causes reactor return temperature to decrease. Therefore, the differential temperature of the core is important in keeping the power level constant. A reactor is not simply a boiler. And, criticality is the measure of the time rate of change of neutron density in the core. Exactly critical is where the total number of neutrons born in one generation is exactly equal to the number of neutrons to be born in the very next instance in time. In response to decreasing temperature, an operator withdraws the control rods a little, exposing more fuel to neutron flux in the reactor core so that more heat is generated in the core to make up for the previous loss. The number of new neutrons generated takes the core slightly above critical to cause more fission events and heating the reactor materials, raising hot output temperatures to generate more steam and things balance back out at a new equilibrium. Nothing but physics and math. People should have been told a long time ago that these truths, while moderately complex, are not mysterious. They are, in fact, extremely well understood. If this 61 year old can remember how a reactor works after being away from the industry for over twenty years, certainly young, vibrant minds could be taught this reality. Don't over simplify the facts. Instead, tell it all the way things really are!
tl;dr Ok professor, but this video is for average people and some reactor characteristics have been simplified. Surely you understand this concept.
So if the control rods absob neutrons, they should increase the number of neutrons per atom, making the atoms unstable and therefore radiactive.
Then the control rods will have a short lifespan, during which they will become less and less efficient at absorbing neutrons, I'm right @ArvinAsh?
Controls rods don't limit the heat produced. They absorb neutrons, limiting nuclear fission.
...which limits the fission reactions, which...limits the heat produced.
@@ArvinAsh I understand. Accuracy in the claim is important.
A bit misleading. Control rod is not for stopping, but absorbing 1 out of 2 neutron, keeping the chain reaction linear.
For stopping nuclear reactor, you have to take out the uranium. There is no other way. Even if you bury them by a solid block of "control rod", they just keep splitting, overheat, melting everything. In conclusion, control rod is not for stopping reactor, its for maintaining linear reaction.
Where do the neutrons that get absorbed by the control rod or slowed down by the moderator eventually go ? Because if they just stay in the reactor and accumulate in the control channel or moderator they would eventually hit atoms of uranium 235 and causing a reaction
If we're going nuclear, it should be Thorium Molten Salt Reactors...
Problem is, regulations. LWRs have already been in commercial operation for a long time with lots of OPEX data and regulatory scrutiny. Unfortunately, but also fortunately, the regulations take a long time to go through, but it makes sure things all work correctly.
Using a nuclear reactor to heat water as the main coolant working fluid is quite ingenious and not primitive. Water is excellent at this task. Water has high heat retention and it blocks some of the radiation. It can be pumped so that the energy from the core becomes portable and can be transferred to somewhere else, usually to another loop of water that becomes steam to run an electrical turbine. Turbines are important because the AC electricity used in our distribution infrastructure is most easily generated by a rotating armature in a magnetic field.
Control rods are made of boron if u wondering
Where are the triple redundancy rods? Can we not get a 3 sided reactor with multiple incertion points? Can we not include an emergency manual separate incertion rod? Considering the alternative this seems reasonable
Now imagine if the control rods had graphite tips, and a guy named anatoly dyatlov was running the operations....
In most PWRs the control is through the boric acid concentration in the coolant water. The control rods are reserved for shutdowns and emergencies.
just sayin ...
I have a doubt ✋,
If atoms are splitting appart again and again so that means the rods will degrade Right? And the water will be contaminated with radioactive waste and fission products right? And these things have to be changed over and over ? And again fission produces so heat per atom fission so these plutonium and uranium rods will take couple of time to degrade?
To start atomic weapons need 90% U-235, power plants have 3 to 5% fuel.
Secondly a weapon needs amazing amount of pressure and heat in instateneous combustion... This is caused by exploding uranium with explosive charges to compress and heat the isotope...
The control rods do not stop the reactor from becoming a bomb. Reactor fuel rods are too far apart and then do not move so the fuel cannot become super critical and explode. They can over heat and the rods will melt forming a puddle of extremely hot radio active fuel that can spread radiation if exposed to water that explodes into steam. But it cannot explode by nuclear fission.
not me having the urge to jump on the lids
How long can a one set of control rod stop the reactor.
Is it hours, days, or months?
But a running reactor is at temperature so the fuel rods are still hot, even though the control rods have been dropped into the core and the nuclear reaction has ceased .
The fuel rods are still very hot and need to be cooled for a very long time after the nuclear reaction has stopped.
This is why we have meltdowns as in Japan !
It looks so simple and environmentally friendly. Why don't we have more of those everywhere?
Can control rods get saturated with neutrons and stop absorbing anymore?
If the rods can't be lowered, use a basic heat fuse to open a big bottom hatch and drop the whole mess into a pool of control rod chunks. No threat of China Syndrome. Not that I actually know what I'm talking about, of course - take with a grain of molten salt.
A China Syndrome is not a legitimate accident scenario for nuclear reactors - the movie kinda hyped that up with no backing.
Yet it almost happened at Chernobyl, the infamous "elephants foot" is the molten core on its way down, but stopped by a block of concrete .
So the water in the reactor doesn’t actually evaporate into steam which would be dangerous
Correct, there are at least 1-2 recirculating systems to isolate any radioactivity.
and to think, all this high end tech. is coupled to something so primitive like spinning a steam turbine to turn some magnets around some copper wires...all these years and we still have not found another way, or a better way, to turn heat into electricity !
Ok-but a SCRAM of a reactor typically poisons the fuel rods, so full SCRAMS are avoided if at all possible.
Can you elaborate why during the Japan 311 nuclear event or decommissioned core, the use of boron rods cannot immediately shutdown the fission. Does it meant even when no reaction, the system need a cycle of half life to reduce the reaction rate and thus the heat generation
The control rods were damaged due to an earthquake followed by a tsunami causing the rods to get stuck
Putting in the control rods does immediately stop the fissioning completely because the reactor goes below criticality right away. However, there is still radioactive decay going on inside the fuel, which produces about 7% of the core's normal maximum output. In a commercial nuclear power plant this produces a lot of heat. That's why the core must still be cooled continuously even when the reactor is shut down. If you don't cool the core continuously it will eventually melt down. At Fukushima they had a power failure because the whole local grid went down and the emergency generators got flooded out by the tsunami. This caused the cooling pumps to stop and the core overheated.
When Boron or Cadmium heated due to reaction, how they lower it's temperature?
How is ensure that thermic errora not avoiding incoming of control rods. ?
mi lenne ha kiikttatnánk a vízbe vezetett hőt és azt egyből egy hőből elektromos áramot előállító elembe vezetnénk? tudom, csak kisebb erőműben megoldható.
What are the control rods made of?
Can you make a short of Thorium reactors?
That would mean uneven distribution of used/unused material on the rod.
It is depending on what kind of reactor you're talking about. all modern reactors, especially the ones in America. Also cannot have a chain reaction without the water. If you're to cut off the water flow to a modern-day nuclear reactor, the neutrons become too fast to cause a chain reaction, and the reactor shuts down. water also acts what's known as a moderator. That's why it is almost impossible for a nuclear reactor now to melt down. Even if the control rods were to freeze and not be able to be inserted into the core as long as you just cut off the water flow, Fission can't happen. This is what makes nuclear energy actually the cleanest and safest source of energy that we have. When people like to think of nuclear energy being unsafe they always talk about things like fukushima or Chernobyl. Fukushima was by poor design. They put the spent to cores Near the reactor which caused a chain reaction when the water came in from The tsunami. And also that nuclear reactor is like over 50 years old which the design has changed due to modern physics and engineering. Chernobyl was also a reactor that is not used anywhere in the West. Its moderator is not water And that's what makes it the most dangerous. Even with the poor design The meltdown was caused by Unknowledgeable engineers who went against protocol and caused the incident. Nuclear energy is the safest form of energy that you can have and it causes 0 carbon emission. All the waste of nuclear energy is only large enough to fill room from all the time we've been using it. 😊
Your Fukushima summary seems wrong . Your RBMK/Chernobyl summary is only partially right .
We are steampunks deep inside
Will it cost less than 1 cent per kWh? If not it is too expensive for the hassle. Solar is below 1 ct/kWh
Tell me comrade legasov, how would an rbmk reactor explode?
Couldn’t help but hear this all in Jared Harris’ voice 😂
me seeing some cool metal sticks on the floor outside a nuclear reactor:
I love how nuclear power plants are basically just coal plants but with uranium
So what makes the uranium split it's electrons inside the fuel rods?
Neutrons split the uranium nucleus (protons and neutrons jumbled together) apart - no electrons involved.
I thought most reactor control rod come from the button up except for rmbk
Can you just tell me. If the water in the reactor is a closed loop, then how does the cooling tower work.
The water that goes in reactor never hits the water that goes in turbine and to cooling towers.
The super hot steam stays in its own system and it heats 2nd loop through exhangers.
There are two types of reactors in consideration: boiling water reactors (bwr) and pressurized water reactors (pwr). The one in this vid is a bwr, where the first loop boils water and the steam is run through a turbine. In a pwr, the primary loop is closed, it runs through a steam generator that heats another loop to create steam to run through the turbines. On both, the cooling towers come into play in a final ultimate heat sink loop, in a seperate loop after the steam turbines. After the turbine there is a heat exchanger for keeping an effective delta T in the turbine loop. This excess heat is then routed to the cooling towers.
It is most likely not U-235, as it isnt as effective. The common uranium type used in reactors is U-238
Mostly U-238 and enriched to 3-6% U-235, as it is more fissile.
@@Not_Sure_2505 yes but it is energy inefficient too.
@@zoleedevofficial compared to what?
Absorbs neutrons? Or change his Wave lenght
I remember Superman back in the 1950s saving the planet by putting those rods back in the holes😮
Thank you Enrico Fermi and Leo Szilard. Take a bow.
But have you heard of positive void coefficient?
Inside the RBMK reactor, which physically can not explode btw… 😂
You forgot about the heat exchanger, turning heavy water into steam to power a turbine would be a very very dangerous thing
This represents a boiling water reactor or BWR. The water is boiled right inside the reactor and so it doesn't have a steam generator. You are thinking of a pressurized water reactor or PWR, which does have a steam generator.
Reactor CAN NOT explode like nuclear bomb!