NE410/510 - Lecture 19: A Reactor Physics Explanation of the Chernobyl Disaster
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- čas přidán 25. 04. 2022
- In this lecture we combine the reactor physics knowledge we have gained from this course to explain the worst nuclear power accident in history: the 1986 Chernobyl disaster.
We will examine why the Chernobyl RBMK design's features and the operators' actions led to this accident, and why a similar accident could not occur in a modern reactor.
For those interested in learning more about radiation biology and the health effects of radiation, my Nuclear Criticality Lecture series contains a lecture on this topic:
• NE499/515 - Lecture 2:...
Thank you for explaining the concept of over-moderated regime. Other lectures on this accident don’t give a very good explanation of why RBMK exhibits positive void coefficient but other reactor types don’t. Usually they just say something along the lines of “RBMK uses graphite as a moderator, so water doesn’t act as a moderator”, which is not a very satisfactory explanation.
Glad you enjoyed the lecture!
19:40 missed a detail in the delay of the turbine test. The day shift lowered power from 3200mw to 1600mw over the course of their shift in preparation for the test. This began creating the xenon pit that then became worse when test was delayed and night shift lowered power even more
Of firearms and security, here's a different and difficult problem to think about!
Recently some worthwhile information on the 1986 Chernobyl / Pripyat disaster exists online.
It's all very well to blame Soviet engineering but the final look reveals one terrifying fact!
There were no control room readings could indicate such a disaster and inclusive "compulsory automatic shutdown" had been invoked!
What all this means, particularly with "total opposite effect" is the control system may not been operating the reactor, the compulsory shutdown robotics were operating but failed only because of the overload explosion, not by any other means!
What NEVER has been considered is "resource theft by corruption and direct rechanneling" , one of the problems of scheduling the tests at the time was having to delay the test because full power output had been argued in Ukraine to remain for some extended period.
Was the control room fully connected, one point is clear, the tests ran at half and quarter power to detect vibration, that itself may been enough too for some cover up. It is not known if there are any "talk between" reactor-gemerator sets for power output compensation or with auto balancing.
That is a piece halarious you mention "parts of walls found inside the reactor"!
Two serious points,
1. The person responsible for the building of Chernobyl was also an inspector of the buildings after it was put into operation
2. Dyatlov whom was often present with the reactor controllers although he was not considered a physicist, but a nuclear industry building builder and was present in the control room when the explosion occurred was second in line to the person whom built Chernobyl NPP.
A. The building 4 had many structural and physical faults found but not repaired before the explosion.
B. The record of either of these was found to be awfully close to corrupt and at least "pass by" would been the correct action for the initial project management personnel appointment.
A final note! In essence what little is known from the final reactor readout parameters is difficult to decide a nuclear detonation from a meltdown clearly showing either being beyond achieving by direct concious operation without knowing it would occur! The AZ-5 at no time could ever achieved beginning sequence before the explosion blasted everything straight upward (95 percent of direction everything travelled).
They often blame the AZ-5 but actually ! That is obviously Completely Impossible!!!! - from the.operational time of reactivity and mainly nuclear detonation requirements being similar to meltdown start.(around 30 seconds from start of rapid increase to instrument failure from the explosion).
There is only one other discernable characteristic in the data information a valid clue, the vibration during shutdown at some RPM!
It is cited Toptunov brought the reactor power down below a level of "operation" (where the legal argument goes either way, it's a "shutdown test" not operation! ) and the reactor temperature began to fall uncontrollably and the reactor was considered to be uncontrollable below a particular thermal mega-wattage (this is considered to be a direct operator mistake - the trouble is it is ACTUALLY a run-down EXPERIMENT).
The "vibration" and uncontrollability of the reactor is probably a "main reactor water circulation" ONE WAY VALVE that behaves too violently at lower pressure , rather than compensating with smoother flow it opens and closes sporadically, and could cause violent "hydraulic back pulse" shock waves through the reactor!
why didnt they use hydraulic operated robots?
Hydraulics require electric solenoids valves and tv cameras to operate too but you’re right in that that’s the direction of progress today.
Sir how can I contact with you?
Look to my coming at first light on the fifth day. At dawn, look to the East.
What saddens me most about this entirely avoidable accident is that it has reinforced the western over complicated designs that are problematic from the basic economics standpoint. The economics simply doesn’t stack up with current accepted designs. The western regulatory regime for nuclear power has almost single-handedly destroyed the sector with its excessive zeal.
The RBMK was\is a splendid piece of value engineering that allowed a clear economic case for nuclear power. From the lack of energy required to produce the low enrichment fuel to the low cost and carbon footprint of the reactor construction were a triumph of design. I understand that the UK reactors used to produce our plutonium actually consumed more power over their lives than they generated.
Chernobyl’s failure required a staggering level of hubris and management system incompetence to induce and has reinforced the myth of the superpowers surrounding the use of containment vessels. If you had removed the gross human error element from Chernobyl then it would never have occurred. Operating procedures are as much a part of the system as the cooling circuit and you might as well set about the plumbing with an angle grinder as deliberately disregard the safe operating procedures.
At the very beginning you say that this design keeps the fission products separate from the water, unlike pool type BWRs.
Could you please expand on that?
My understanding is that, both rbmk and bwr have the fuel assembly is encased in zirconium tubes, and the water in contact with the assemblies, receiving neutron radiation, is converted to steam which moves the turbines directly.
So, in this model, both types of reactors have the same level of isolation from the actual fuel.
What is wrong, with the model I just described?
I only can think that the affected tube's water flow may be closed from the rest of the tubes in case of broken cladding, but I didn't understand it like that in your explanation
@@georgH RBMKs use a pressure tube design where the water coolant is incased in tubes as it flows past the solid fuel. For BWRs it is almost the opposite - the fuel is incased in clad and submerged in water. In a sense, RBMKs = water tubes and BWRs = fuel tubes.
@@NuclearEngineeringLectures So, are you saying that the fuel in an RBMK is not encased in cladding as in BWRs?
@@NuclearEngineeringLectures A little wrong. RBMK have fuel in zirconium clad too (like BWR, PWR and soviet VVER). Water under pressure around the fuel rods and all this inside the tube how you said.
Sorry for grammar.
Neil Breen movies? Really?
Only the best content on this channel.
There is some errors.
1) RBMK not used for produced weapon plutonium. The roots of this myth probably grow from the fact as prototypes of the RBMK, the designs of reactors developed by nuclear weapons (too channel reactors) were used.
2)5:02 - this lego block not part of fuel. This is part of biological protection against radiation and consist of metal sheell and filled with a special mixture of minerals (I won’t write the composition from memory). During overload fuel, this block retrieved and a special mechanism drives up there to reload fuel. On picture (5:09) can see the top fuel assembly (under letters B-B) which placed under "lego block".
Fukushima is way way worse in the long term.
Looks like I will need to make a video explaining Fukushima too! 🙂
@NuclearEngineeringLectures you know alot more about it than me it's different classes or severity of disaster, I understand that, but what do you think on a scale of 1-10 on severity?
Don't forget lots of the children had lead poisoning from the lead and Boron they dropped on the core and still is happening today like children born and never growing but small patches of hair !
A lot of errors and incorrect information in this video.
😢
@@NuclearEngineeringLectures
There is no evidence that RBMK reactors were used to produce plutonium, although it was an option they could pursue. They had other breeder-type reactors producing a lot of plutonium, such as AD/ADE-1/2/3/4/I-1/EI-2/AI/A/AW-1/AW-2/AW-3 and heavy water: OK-180/OK-190. In fact, Efim Slavsky (Chief of MinSredMash), where RBMK reactors was designed, was quoted as saying, "Slaventiy, enough plutonium. Build for me a good power reactor; I have a lot of plutonium without your reactor (RBMK)" here:czcams.com/video/GDonDx_1les/video.html.
The fuel elements did not resemble Lego blocks; those are the channel caps. All the channels, including the control rod channels, have square caps made with concrete and serpentine to minimize radiation leaks. Under the caps is the plug, and under the plug is the upper biological shield. Under the upper biological shield is the actual channel itself, which was cylindrical and passed through the graphite blocks.
Diesel generators did not take 3 minutes to start. They started within 15 seconds of power loss, but they took 60-75 seconds to reach full speed.
According to the INSAG-7 report (International Nuclear Safety Advisory Group), a power station in the region unexpectedly went offline at 2 PM. Thus, the grid controller requested Chernobyl NPP to pick up the load. It wasn't necessary because of the holiday; in fact, "May holiday" is on May 1st, not April.
There is no evidence that Toptunov decreased the power too fast and that led to xenon flooding. The core was already xenon-poisoned, running at half power, but the neutron flux was at an equilibrium to stabilize the reactor output at half power. Decreasing it further flipped the equilibrium in the poison's favor, and it started absorbing all the neutrons, effectively stalling the reactor. Xenon is not produced at a delay; I think you are referring to xenon having a delayed effect. Xenon produced from a couple of hours ago can still poison the core later.
The high coolant flow rate caused the coolant not to have enough time to dump its heat in the steam separator drums or the condensers. This caused the coolant inlet temperature to rise.
Firefighters did not extinguish the graphite fire 5 hours later. They extinguished the roof and surrounding areas. The actual firefighting of the reactor started on April 27th, the next day morning at 10 am, with helicopters dropping sand, boron, dolomite, and clay with lead.
I think your knowledge of nuclear engineering is on point but some of the details regarding the incident itself can be hard to find.😅
@@NuclearEngineeringLectures
There is no evidence that RBMK reactors were used to produce plutonium, although it was an option they could pursue. They had other breeder-type reactors producing a lot of plutonium, such as AD/ADE-1/2/3/4/I-1/EI-2/AI/A/AW-1/AW-2/AW-3 and heavy water: OK-180/OK-190. In fact, Efim Slavsky (Chief of MinSredMash), where RBMK reactors was designed, was quoted as saying, "Slaventiy, enough plutonium. Build for me a good power reactor; I have a lot of plutonium without your reactor (RBMK)" here:czcams.com/video/GDonDx_1les/video.html.
The fuel elements did not resemble Lego blocks; those are the channel caps. All the channels, including the control rod channels, have square caps made with concrete and serpentine to minimize radiation leaks. Under the caps is the plug, and under the plug is the upper biological shield. Under the upper biological shield is the actual channel itself, which was cylindrical and passed through the graphite blocks.
Diesel generators did not take 3 minutes to start. They started within 15 seconds of power loss, but they took 60-75 seconds to reach full speed.
According to the INSAG-7 report (International Nuclear Safety Advisory Group), a power station in the region unexpectedly went offline at 2 PM. Thus, the grid controller requested Chernobyl NPP to pick up the load. It wasn't necessary because of the holiday; in fact, "May holiday" is on May 1st, not April.
There is no evidence that Toptunov decreased the power too fast and that led to xenon flooding. The core was already xenon-poisoned, running at half power, but the neutron flux was at an equilibrium to stabilize the reactor output at half power. Decreasing it further flipped the equilibrium in the poison's favor, and it started absorbing all the neutrons, effectively stalling the reactor. Xenon is not produced at a delay; I think you are referring to xenon having a delayed effect. Xenon produced from a couple of hours ago can still poison the core later.
The high coolant flow rate caused the coolant not to have enough time to dump its heat in the steam separator drums or the condensers. This caused the coolant inlet temperature to rise.
Firefighters did not extinguish the graphite fire 5 hours later. They extinguished the roof and surrounding areas. The actual firefighting of the reactor started on April 27th, the next day morning at 10 am, with helicopters dropping sand, boron, dolomite, and clay with lead.
I think your knowledge of nuclear engineering is on point but some of the details regarding the incident itself can be hard to find.😅
@@NuclearEngineeringLectures
There is no evidence that RBMK reactors were used to produce plutonium, although it was an option they could pursue. They had other breeder-type reactors producing a lot of plutonium, such as AD/ADE-1/2/3/4/I-1/EI-2/AI/A/AW-1/AW-2/AW-3 and heavy water: OK-180/OK-190. In fact, Efim Slavsky (Chief of MinSredMash), where RBMK reactors was designed, was quoted as saying, "Slaventiy, enough plutonium. Build for me a good power reactor; I have a lot of plutonium without your reactor (RBMK)" here:
youtu. be /GDonDx_1les?t=2584.
The fuel elements did not resemble Lego blocks; those are the channel caps. All the channels, including the control rod channels, have square caps made with concrete and serpentine to minimize radiation leaks. Under the caps is the plug, and under the plug is the upper biological shield. Under the upper biological shield is the actual channel itself, which was cylindrical and passed through the graphite blocks.
Diesel generators did not take 3 minutes to start. They started within 15 seconds of power loss, but they took 60-75 seconds to reach full speed.
According to the INSAG-7 report (International Nuclear Safety Advisory Group), a power station in the region unexpectedly went offline at 2 PM. Thus, the grid controller requested Chernobyl NPP to pick up the load. It wasn't necessary because of the holiday; in fact, "May holiday" is on May 1st, not April.
There is no evidence that Toptunov decreased the power too fast and that led to xenon flooding. The core was already xenon-poisoned, running at half power, but the neutron flux was at an equilibrium to stabilize the reactor output at half power. Decreasing it further flipped the equilibrium in the poison's favor, and it started absorbing all the neutrons, effectively stalling the reactor. Xenon is not produced at a delay; I think you are referring to xenon having a delayed effect. Xenon produced from a couple of hours ago can still poison the core later.
The high coolant flow rate caused the coolant not to have enough time to dump its heat in the steam separator drums or the condensers. This caused the coolant inlet temperature to rise.
Firefighters did not extinguish the graphite fire 5 hours later. They extinguished the roof and surrounding areas. The actual firefighting of the reactor started on April 27th, the next day morning at 10 am, with helicopters dropping sand, boron, dolomite, and clay with lead.
I think your knowledge of nuclear engineering is on point but some of the details regarding the incident itself can be hard to find.😅
@@NuclearEngineeringLectures
There is no evidence that RBMK reactors were used to produce plutonium, although it was an option they could pursue. They had other breeder-type reactors producing a lot of plutonium, such as AD/ADE-1/2/3/4/I-1/EI-2/AI/A/AW-1/AW-2/AW-3 and heavy water: OK-180/OK-190. In fact, Efim Slavsky (Chief of MinSredMash), where RBMK reactors was designed, was quoted as saying, "Slaventiy, enough plutonium. Build for me a good power reactor; I have a lot of plutonium without your reactor (RBMK)" here:
The fuel elements did not resemble Lego blocks; those are the channel caps. All the channels, including the control rod channels, have square caps made with concrete and serpentine to minimize radiation leaks. Under the caps is the plug, and under the plug is the upper biological shield. Under the upper biological shield is the actual channel itself, which was cylindrical and passed through the graphite blocks.
Diesel generators did not take 3 minutes to start. They started within 15 seconds of power loss, but they took 60-75 seconds to reach full speed.
According to the INSAG-7 report (International Nuclear Safety Advisory Group), a power station in the region unexpectedly went offline at 2 PM. Thus, the grid controller requested Chernobyl NPP to pick up the load. It wasn't necessary because of the holiday; in fact, "May holiday" is on May 1st, not April.
There is no evidence that Toptunov decreased the power too fast and that led to xenon flooding. The core was already xenon-poisoned, running at half power, but the neutron flux was at an equilibrium to stabilize the reactor output at half power. Decreasing it further flipped the equilibrium in the poison's favor, and it started absorbing all the neutrons, effectively stalling the reactor. Xenon is not produced at a delay; I think you are referring to xenon having a delayed effect. Xenon produced from a couple of hours ago can still poison the core later.
The high coolant flow rate caused the coolant not to have enough time to dump its heat in the steam separator drums or the condensers. This caused the coolant inlet temperature to rise.
Firefighters did not extinguish the graphite fire 5 hours later. They extinguished the roof and surrounding areas. The actual firefighting of the reactor started on April 27th, the next day morning at 10 am, with helicopters dropping sand, boron, dolomite, and clay with lead.
I think your knowledge of nuclear engineering is on point but some of the details regarding the incident itself can be hard to find.😅
Just one minute into this video, and we are told all of the same misconceptions and propaganda that led to the Chernobyl distaster, which was also the point at which I stopped watching. Because on the contrary, the more that one knows about nuclear science, the more one should fear what nuclear accidents can and will do. Given a long enough timeline all nuclear reactors chances of not having a meltdown drop to zero, with meltdown chances exponentially multyplied by Murphy's Law, the law of averages, and the Wigner effect also known as the discomposition effect or Wigner's disease. This displacement of atoms in a solid caused by neutron radiation, assures old ageing reactor failure, due to the degredation of the materials that a nuclear reactor is made of. Meaning from pipes to concrete structures these events are assured, and guaranteed. So you can spew your Nuclear Death Cult propaganda all you like... but it only takes a bit of common sense to know this nuclear nonsense is untenable.
Stairs accidents do not make a region unsafe to live in for 30000 years