Chernobyl's Unanswered Questions: Why Did The Power Level Decrease Under 700MW?
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- čas přidán 15. 12. 2023
- The official reports into the Chernobyl Disaster cover a large amount of information surrounding the fateful events that led to the world's worst nuclear disaster. However, these papers still miss key details pointed out by others that dramatically alter the story even scientists have come to expect. These are Chernobyl's Unanswered Questions.
One of the most misunderstood things in the chain of events leading to the Chernobyl Nuclear Disaster is the power reduction below 700MW beginning at midnight. Countless claims have been made by Soviet officials, however the real reason could completely upend the tales of operator incompetence. Let's delve deep into that mystery.
This script was written by Bobby, who has also crafted an incredible history paper exploring how misinformation and disinformation continues to impact the story of Chernobyl. You can read it here: docs.google.com/document/d/1m...
![[REUPLOAD: IMPROVED AUDIO] Oceangate Titan: analysis of an insultingly predictable failure](http://i.ytimg.com/vi/4eNm8vnKZ38/mqdefault.jpg)
Yeeeees... inject that Chernobyl info straight into my veins... yeeeaaah... that's the stuff... definitely not 3.6 rontegen, just great, not terrible.
I'd like to see a study of how, at each stage, the reactor could've been saved. Such as, how much more time would pressing the AZ5 button would be needed to stop it exploding? There would've been lots of events such as this that could be war-gamed to see how it would've changed things, assuming that the test wasn't just abandoned.
Nothing could be done. Water turned to steam and failed to moderate the reactor. An accident waiting to happen.
So then, why DID the power decrease under 700?
Probably I missed the answer?
I think have to watch this a third time.
It's a lot of information, and I think the answer is there if you understand the process well enough. I don't, so I am a bit lost. I hate to say this again, but the music does detract from the narration. There are some people with hearing problems who probably can't hear all of the words because of the music. The narration is well done and doesn't need music for dramatic effect.
As far as I understood it:
The turbine run down test called for a power of 700-1000MWt. This was more like a "suggestion" and not a strict requirement. Probably because every properly specified test has to state some operating conditions it was added by Dyatlov so the test conditions were properly specified.
However due to the turbine vibration test both turbines were to be disconnected from the reactor. Now you'd have 700MW of thermal power and no proper way to get rid of them. There is a system to dump steam but this is for emergency situations only, so they were hesitant to use it. (Dumping hot radioactive steam, even in some sort of containment, is probably never a good choice.)
This condition (having lots of thermal power and no way to dissipate it) would usually not occur, as the AZ-5 would automatically activate in case of both turbines being disconnected. Again for the tests this system had to be deactivated. Most probably the fact that both tests (vibration and run down) had to be conducted in parallel played a role here.
Now they had to decide what to do. They could either use the emergency steam dump system to dissipate the 700MWt or they could reduce the power down to 200MWt. At this point the witnesses seem to differ in their recollection, but it becomes clear that *someone* didn't wanted to dump steam and due to this they reduced down to 200MWt. Especially as it was understood that the 700-1000MWt stipulated in the test were not a strict requirement.
By going down to 200MWt they probably introduced so much xenon poisoning that the reactor became uncontrollable for them, first going down to 30MWt and then through the roof.
The important piece here is that they were actually allowed to raise power once it had fallen to 30MW. If that drop would have happened from a stable situation (like 700MWt) and was rectified in time there wouldn't have been a big amount of xenon poisoning. But as the situation before the drop was already extremely unstable due to the continued power reduction they were unable to control the power rise from 30MWt properly.
@@user-xx5lb9en6r I understand your point, but you're mistaken on one very important part. The turbines aren't involved with dissipating the thermal load in the system. The turbines are using the expansion of the steam, not the thermal energy. Dissipation of excessive thermal load would be the duty of some kind of heat exchanger setup (and normal loss as a result of the piping/etc... radiating heat)
Perhaps there was something which caused the heat exchangers to be cut off from the system if the steam wasn't driving the turbines, but I find that to be rather unlikely
Can we get a video on the power plant that went down earlier in the night? That forced chernobyl to wait the 10 hours?
00:10 - For the record, the script included "male" scientists. The video was kept at a ParentalGuidance rating.
3:32 - The intention here was to switch back to page 53 of INSAG-7 and emphasize the information in the timeline rather than the graph. The graph is illustrative and has some inaccuracies, especially toward the end. This will be a topic in the final planned Unanswered Questions video. The timeline features what is presumably direct data - ORM at 1 in the morning is 31, at about 7 13.2*, at 20 minutes past 3 in the afternoon 16.8 over an hour into the Kiev delay, and at the end of the Kiev delay the ORM is at a whopping 26 rods. Clearly what occurred over the Kiev delay was a depoisoning of the reactor. The HBO/Sky mini-series is complete nonsense.
6:19 - The authors of the international/first section of INSAG-7 tend to be the most annoying. While this was not provided in the original script what was had in mind was something like the top half of page 19 in INSAG-7 where the authors do not stop and think when it turned out that a whole bunch of major stuff was false but instead merely modified their preconceived notions of the actions of the operators.
10:19 - This particular passage is from the article "Why INSAG has still got it wrong" you can access online.
21:05 We've got a boo-boo here. What should be heard and seen is, "It should be noted that these arguments/conversations/disagreements are not to be colored by what happened later that no one expected. Tregub himself notes (/source I cannot link but ends in evid02/ should be displayed highlighting the “Actually, it was an unprogrammed thing… This can all be fixed.”) that even when power was dropped from ~500 MW all the way down to 0-30 MW he didn’t think it was terribly significant."
Both Tregub and Dyatlov, in their supervisory capacities and experience, note that a power drop like the one that occurred at about 0028 was neither that unusual nor significant.
21:30 - Pay particular attention from this point on as this is very obscure, virtually unknown, but very significant information. A user by the name of MinSredMash (ppitm for those familiar with the Chernobyl subreddit) has unearthed a few of these highly significant finds.
25:28 - I think there might be a few sources missing, or substituted for a book or books. There is an accidont site that is used and accessible through auto-translation. It's also the place through where the VNIIAES report featured toward the end of the video was accessed.
I think I'll pass from using anyone from reddit as a voice of authority. Anyone can claim anything on the internet. Just because a person claims expertise or anything of the like doesn't make them automatically correct.
On a different note, do you believe it's productive making this long of a comment, I think it'd be more efficient making a video at this point. I think it would take just about as long.
I do have one question, did you take classes on this or studied on your own.
@@DogDooWinner I was on reddit.
@@markusw7833 I was at one time as well, hence the comment about how the place sucks. Realized there was nothing more than people who thought they knew a lot more than they did overcrowding the people who actually knew what they were talking about because an account was recognized. Somehow, I was dubbed a linguistics expert. I have no idea why. What made me hate that place and know there's much more experts than expertise? The Boston Marathon bombing. When that happened, everyone was a crime scene expert, experts in hand movements, experts in weather patterns. When people called on them to just chill out, they're going to cock things up, they were told they're stupid. Now, I don't care if I'm called stupid. That is what my mother's favorite nickname was for me. But to disregard the possibility of getting something wrong and potentially ruining a guys life that had nothing to do with anything just for their own vanity project? That's nothing but pure evil. I walked away from that site that night. Every time I've checked, it's gotten far worse. As long as you aren't the I'm the final answer so you have to trust me and if you verify, I'll get mad type, were cool.
This is such a fascinating subject, thanks for all the content you're sharing, really appreciated !
Always very informative videos on such a complex subject. Thanks for posting
Always great videos, Thank You.
Somewhere there is a long suffering Russian nuclear engineer saying "I spent 5 fkng years writing that manual. It details everything you need to know about that reactor. Even that thing the 2nd floor bathroom drains do every once and awhile. FFS, DOES NOBODY READ ANY MORE?!?! IT WAS ALL THERE!".
That is what explicitly didn't happen. Both the operating instructions and other reactor documentation was missing key information, as well as the control room itself.
The critical information that would have prevented this incident was known by some experts but was not widely known. It was not taught to the operators, and was not known by anyone who was in the control room that night. It was not in the operating manuals.
@@markusw7833 you are right. It was known by the experts but not shared and was definitely not in the manual. I guess they didn't believe that this situation would ever occur so the operators didn't need to know. Such backwards thinking.
23:00 Option c, refuse the test, and notably to effect this by the single action of... pressing AZ-5. :|
Right, AZ-5 was not an exclusively emergency button. It was a shutdown button. It is quite possible that just before the reactor exploded AZ-5 was used merely to shut down the reactor rather than to stop an emergency. Another flagrant error of the HBO/Sky mini-series is showing the reactor accelerating hundreds of MW prior to the use of the button. In reality there was a power increase of about 30-60 MW on the high end. Only three seconds after the button was pressed did power reach even 530 MW. As even the international section of INSAG-7 puts it on page 13, "The scram just before the sharp rise in power that destroyed the reactor may well have been the decisive contributory factor." The last planned video in this series will explore the unanswered question of at what ORM/number of inserted control rods did this scram occur. Some pretty interesting things are discussed there.
"Dyatlov did nothing wrong"
Really enjoy this series as a whole - balances the reality against the Sky dramatisation.
It was primarily terribly researched, not dramatized.
@@markusw7833 disagree, it was a dramatisation - which in itself can mean there's a line that doesn't exactly follow the true happenings. Wasn't terribly researched, and it was more about human emotions than cold hard facts.
@@saintuk70 You can disagree all you want. The creator is on record with his intention. "Not exactly following the true happenings" is not exactly the mini-series' issue. Due to how terribly researched it was it ended up, unwittingly and quite witlessly, as a butchered form of Soviet propaganda. If all goes to plan in a few months you might see a video on just this topic - how the "masters of weaponized narration", as creator Craig Mazin calls them, earn their epithet.
@@markusw7833 I'm very curious as to how that miniseries was "Soviet Propaganda", when is clearly showed how much they kept from their own people and how little value they placed on the lives of Soviet citizens. I never expected it to be fully factually accurate, but they definitely weren't going easy on the Soviets.
There will be a future video on this. In the meantime, you could read the first roughly 50 pages of the paper in the description, which will be getting a bit of an update. What the mini-series did was largely blame the operators, as the Soviets intended, while portraying Soviet experts positively, which was a literal part of Soviet propaganda. The mini-series' position is the Kurchatov Institute's 1987 position after they got caught on the positive scram effect, maintaining that the flaw only emerged in egregious mishandling of the reactor. That video is a few months away, maybe I'll prioritize it.
You are doing some great work on these videos! The amount of information that you give, especially on this installment, is incredible. After hearing the information on this video, it changes your entire view and opinion on what the key factor was that caused the explosion. To be honest, it seems like the operators were flying by the seat of their pants. The info given to them wasn't clear. Especially when it came to this kind of test. It sounds like they should have never been given the order to run a test like this in the first place. Too many flaws with the RBMK reactor, too many unclear factors when it came to a test like this. And it's quite typical for the USSR, heck, any government would blame the operators on duty that night to try to save face. I look at the explosion in turret #2 on the USS Iowa. The damn navy tried to blame one man saying that he did it on purpose! You know any government is lying any time their lips are moving. The USSR was much worse in situations like this, but the US can do the same things. Especially how things are being run today.
Great comparison to the USS Iowa cover-up! The US Navy really did those guys dirty in order to try to keep their own hands looking clean.
I agree completely, it sounds like the operators had unclear and conflicting instructions, which is the last thing you want to give to the people testing a nuclear reactor, especially one with known instabilities like the RBMK. Or I should say instabilities that were known, but not to the operators running that test, like you said, by the seat of their pants, which is the last way you should be running a nuclear reactor! In some ways it almost seems like someone was *trying* to see how badly they could run that thing before it just blew up! I'm not suggesting that this is the case, of course, but the lack of clear instructions and miscommunications certainly did the job. If the people in the control room don't know why they're doing what they're doing, or what could be dangerous, it's a recipe for a disaster.
This "by the seat of their pants" narrative is probably ignorant, as often seems to happen with outside perspectives of this disaster. The operators didn't know certain qualities of the reactor, a key one that possibly arose to a critical degree recently, but that doesn't mean they didn't know what they were doing operating the reactor. Before Chernobyl people like Legasov would brag that Soviet operators were better educated than American operators coming from the navy. Dyatlov, for instance, was very far from incompetent.
@@markusw7833 So if even highly competent and expert operators don't know certain qualities of the reactor they're running a test on, how is that *NOT* a "seat of the pants" situation? I'm not saying that they weren't well trained and highly skilled, just that they were lacking certain very important information that might have prevented this accident.
@@thing_under_the_stairs It kind of is, but the most common thing is for people to get the impression that the operators were just unprofessional and didn't really know what they were doing in the control room. In reality the lack of accurate knowledge of the RBMK reactor goes all the way up to the expert level, and in the instance of the coefficients of reactivity Dyatlov claims on the night of the disaster operators were supplied with falsely low values.
@@markusw7833
I completely second this. If even the experts didn't know how the reactor would behave in certain situations, how are the operators supposed to know?!? And from what I understand, back then they didn't have proper simulators (I think only Smolensk NPP had the one) to train for emergency conditions, or to learn in general about the behaviour of the reactor they were going to run. Extensive theoretical knowledge is good, but when it comes to a nuclear reactor, it's nice to have a simulator where one can learn about the practical side of running this big, grumpy reactor in a safe environment.
And I can completely see the experts doctoring the books to hide their own lack of understanding of what they built. It is so much easier to put the blame on some lowly operator instead of taking responsibility for any mistakes you have made.
This was very enlightening video, Big Thanks for the author for the work compiling it up. It really answers some key questions that I found puzzling before, other sources seem to brush away this power reduction or call it unintentional. Now, as an engineer myself I want to add couple of points that video allowed to deduce but didn't quite emphasize:
1. The test program was complied hastily. To me it appears, that in compartmentalized organization, reactor expert Dyatlov made the program himself without properly consulting turbine experts or power network experts. That led to arguments when said experts learned about details of the plan, hence those last minute changes to it.
2. This difference in reactor power and turbine power was the cause of water becoming saturated before main circulation pumps, making pumps prone to cavitation. Not running with low power, as some sources tell. This particular item had puzzled me before, but this video explained it.
3. People involved learned these after the accident, and didn't want to dwell into subject too much, as it weighed on them that they didn't selected the abort option. Hence their memories are not very exact on details and sources contradict each other.
Let me try to go through these point by point.
1) The test program was not really hastily compiled. It had been used some three times before 1986 without any difficulty, with alterations to the power. The programme can be read here:
rrc2.narod.ru/book/app7.html
It was mostly drafted up by Gennady Metlenko, the turbine/electrical expert brought in to do the experiment. The problem was the experiment had been double booked, as some might say, with the turbine vibrations, which wouldn't have happened without the Kyiv delay occurring.
2) More or less, yes.
3) Sources don't really contradict each other, in fact the only time I can think of is the decision to lower the power, and if Dyatlov was present when things went wrong. I don't believe he was, as those who say he was exclusively said it during the trial, and have never repeated it outside of such, but Dyatlov's defence for not being in the Control Room is also pretty shaky, as he claims that, because said eyewitnesses described him as sweating, he must have been somewhere hot, and therefore could not have been in the Control Room as such a power drop would not put him on edge. I hope that makes sense. :)
What do you mean more or less yes on #2?
What they learned after the incident is that the pumps did not cavitate even with excessive flow through some of them.
@@markusw7833 Cavitation or not, issue was reduced subcooling, which increases changes of cavitation in a pump as much as cavity formation in the reactor channel and either would have accelerated the power surge.
@@thatchernobylguy2915 1) As you state in the video, there was practical considerations that mandated power ramp down rather than disconnecting the generator while under load, and original test program didn't address these considerations. And frankly, to me it's obvious that power network engineers don't fancy idea of sudden disappearance of several hundred megawatts.
I really loved the detail of the scrolling translation at 22:06
One thing that I cannot understand at all is why the test was run with reduced power? I mean they were supposed to simulate conditions were external electrical power was cut off and assess if the kinetic energy of the steam turbine could fill the gap until the diesel generator kicks in. If an unpredictable event occurs and external electrical power is off it will likely happen while the reactor is operating at nominal power 3200MWt, how can the test be reliable at 1/5 of the nominal power?
The rotation of the turbine was not dependent on the power level. It tends to be constant. The HBO mini-series presents a fallacy as to the significance of the power figure - it was not written to determine the validity of the test. I don't know how exactly the test determined success and failure (ironically it might have succeeded when the reactor blew up) but no actually authoritative source claims the test was invalid being performed at a lower power level.
Good job on your video. I hope you are able to get the notoriety and attention you truly deserve :)
Why? A misapprehension on when xenon would be detected in the core, then deflection of blame to the lowest guy on the totem pole, big plus if he's dead and unable to defend himself?
Hell, the video itself contradicts the central assertion that xenon wasn't poisoning the core, as it's a primary fission product. It's a noble gas, so not exceptionally reactive and takes time to diffuse through the dense uranium fuel pellet, then diffuse out of the rod, into the water coolant and be detected. Obviously, one isn't cutting fuel pellets inside of an operating reactor to check xenon levels!
Add in the graphite tips on the control does, which act as a moderator and were a bit part of some western prompt criticality accidents. Add in what's readily apparent to be misunderstanding of test conditions and reasons, such as one needs a certain excess of power to actually try to spin steam turbines enough to operate the circulation and cooling systems.
And oddly unremarked upon, the rationale for removing control rods that are never removed - ever in the history of that reactor, plus withdrawing rods beyond their normal levels, allowing the xenon to burn off rapidly in the rapidly increasing neutron flux, depoisoning the core and allowing it to swiftly, beyond human ability to react, go prompt critical. Once the pile was at prompt critical, nothing could prevent the disaster, as control rods aren't bullets, they take time to insert and well, you're talking a millisecond or so of instantaneous hundreds of megawatts of anger.
I've not reviewed his other videos, but conditionally agree and disagree on the "no hydrogen explosion" bit. There was a hydrogen explosion, an utterly unconfined one, as water hammer dismantled the reactor core and the overheating rods did allow disassociation of hydrogen from the water, which duly did explosively combust in the now open reactor building. As in, a bit less of an explosion than the resultant Hindenburg fire, after the dirigible initially exploded. A bit whoosh and it was over.
@@spvillano Alright, apparently I can't post links on this wretched platform. Google "xenon transients", first link should be from nuclear-power. Graphite sections rather than tips, and they acted more as an absorber replacer than as a moderator. Indeed, they were called graphite displacers. You also misapprehend what it takes to spin the steam turbines. I can't follow the paragraph above the empty line but it appears even more ignorant than previous statements.
Great video! Do you think you could cover the nuclear explosion theory, or “fizzle” explosion theory next? I would love to learn about it
great video man. I guess the Xe poisoning was still a co-cause then when they intentionally further reduced power level from 700 down to 200. as you show in min 2:4. Another spike of "accumulated" xenon will have occurred, above the equilibrium line at 200 MW, further rendering reactor stability control difficult.
A drop in power doesn't make a reactor unstable, uncontrollable, etc. A former operator believes that the ongoing depoisoning from power being held at 1600 MW was comparable to the poisoning of the later power reduction and drop. It was not that unusual for power in an RBMK reactor to be dropped or reduced. After the incident many things were twisted to fit a narrative and the severity of the event, which obscures the actual causes of Chernobyl.
What is so sad is that history is written in Hollywood. and then youtube comments are flooded with quotes.
Imagine you're working for hours on a well-researched project like this mini documentary, and the first comment you read is about someone whining about the background music.
Well the music ruins an otherwise excellent video.
@@ItsFriscoBaby A change has been made with the past handful of videos to exclude the background music.
The music is distracting me as well. Why is it there at all?
The docu itself ist of course excellent! 👍👍
Actually I would be grateful for such a remark.
Now if you suggest that I shall be shattered by commentators daring to criticize Me and retract to a safe room and search psychological counselling, then please be informed, that there are still normal people around.
@@willyengland
all Pro Pa ganda
is based on
Dis Tracktion!
Air bubbles don't conduct heat
Do you possibly mean vapor bubbles?
Doing an experiment to determine if the rods are ready. Yes they were ready ready for 💕😘
Thank you for another video full good info. I also really like the sources given at the end, so I can search them and read them. One small question; as the reactor had come out of the Xenon poisoning as was mentioned earlier, with the power drop to 30MWt at around 00:28 hrs, wouldn't the whole Xenon poisoning song-and-dance start all over again since they now practically have zero reactor power, but Xenon still gets produced at the former power level because of the delay in its creation (Iodine to Xenon decay)?
There will be a poisoning effect, yes. You'll hear a surprising opinion on the relative magnitude of it in the next unanswered questions video from a former operator. It's also crucial to underscore, there is no violation in raising power from 30 MW. The particular figure is pivotal as far as a violation is concerned.
@@markusw7833
This was more a question from the reactor's point of view. I'm trying to get a more clear understanding of the processes going on inside the core of Unit 4 that last few hours. I know no violations were made when they raised the power from 30 MWt. And that's one video I'm going to make sure I won't miss👍🏽
From the reactor's point of view xenon from the power reduction earlier in the day is decaying whereas now iodine from before the drop is creating xenon that there is not enough power to consume and that will take time to decay.
@@markusw7833
Okay. I'm going to assume that whether a reactor's core is "fresh", or almost at the end of its fuel cycle, would also make a difference in how easy/difficult it will be for a reactor to overcome the xenon poisoning (correct me if I'm wrong). My next question then would be; how badly encumbered would Unit 4 have been by the xenon considering where it was in its fuel cycle?
I have no idea on a fuel burnup and core composition effect on xenon transients.
I love the Chernobyl TV series, but I've always been thrown away by its inaccuracies. But it does somewhat tell the story, just too condensed, had it been longer they might have had more time introducing characters. But i can say without a doubt that it would be difficult for most people by trying to keep up with all the names, like it is for me 😂 it is pretty much more about how the Soviet Union tried to evade responsibility, and that is something it does quite well IMO, the SSSR was slowly failing at the time (arguably it failed when Stalin came to power) and they didn't want to seem stupid to the rest of the world i guess? Anyway as a fellow STALKER i really like these videos.
Like our Lord and saviour Phill Collins says, it's always two sides of the story, and the TV series chose one side.
Idk if i read the chart wrong at 2:30 but that doest say 4-6 hours. The time along the x axis is (Hours) so that would be 40-60 hours would it not?
Look at where the power is instantaneously reduced from 100% to 50%. 4-6 hours later the xenon spike hits its maximum and steeply declines in the subsequent hours. This is from a source unrelated to Chernobyl about fundamental nuclear science and basically matches what was observed at Chernobyl in how the number of control rods changed over time at the same power level after a 50% reduction. Control rods/ORM decline with more xenon, then increase with less xenon to compensate for the decreasing neutron absorption.
do an episode on ignalina
Are you telling me Dyatlov wasnt an awful human being that responds to everyone with F*** OFF ?
I could not understand about the mercedes truck.... Anyone can explain? Thanks
The red Mercedes truck carried specialized equipment that was apparently necessary for turbine vibration measurements that needed to be performed after a modified design was implemented using less metal in the turbine. There was cause for concern, potential imbalance or instability. There was only one single truck in the Soviet union with this equipment and it was at a premium - you miss your appointment and you might be delayed by who knows how long. I.e. the turbine vibration measurement task needed to be finished. It is this task that involved the turbine being run down like the separate rundown test that seems to have necessitated keeping the reactor running while the turbine was disconnected so that everything could be completed, which pushed operators to lower the power level intentionally. By lowering the power level they could also disable an automatic protection system to keep the reactor running in accordance with the operating instructions as less steam was being produced, which was deemed less dangerous when the turbines are disconnected and not consuming it.
@@markusw7833 WOW thanks a lot!
bit light on the mercades... its testing had to be fitted in,was that an undue pressure,its testing was to vibration.
The testing having to be fit in meant the reactor needed to be kept running while the turbine was disconnected so that both remaining tests could be completed. At a higher power level like 700 MW this could result in instability whereas at a lower power level the operating instructions allowed the disconnection of an automatic reactor shutdown due to less steam being produced without stressing whatever other intake system may have existed. According to the operating instructions at the time this should have been safer - lowering power was in the interest of safety, in other words. After the disaster the operating instructions were misrepresented to make it seem like a low power level was understood to be extremely dangerous and forbidden.
Isn’t the dead time for a reactor around 50-90 hours? That’s why the reactor has to be shut down for a few days after it is poisoned??? Are RBMK reactors different in this way or is the calculation wrong that you are using in the video?
To answer your last question, neither.
Basically, there are two ways to remove xenon from a reactor. It either decays naturally or it captures a neutron and becomes a stable atom that does not capture anymore neutrons.
So, when a reactor enters a xenon pit, the amount of neutrons being produced cannot overcome the amount of xenon present, so you have to shut it down and wait for the xenon to decay, so no more neutrons are being captured.
What the operators did is quite simple. They lowered the power down to the desired level, and then they raised the control rods as much as possible. This maximized the amount of neutrons being produced, which then captured by the xenon-135 and removed it from the equation.
Going off that graph of xenon production, I don't know what reactor it's in, but it will be similar to the RBMK simply because of physics, after less than 10 hours, you have overcome the peak of the xenon pit and it is decreasing. We see this in the graph of the operating reactivity margin early in the video. Control rods removed to maximize the amount of xenon burned, and by the end more than the starting amount of control rods have been reinserted to compensate for all that xenon burned off.
I hope that makes sense :)
What is wrong is you applying a "dead time" to power reductions willy-nilly. Neither in the subject matter of this video nor in the later power drop was there an actual xenon pit, as defined in the link of the source that should be available for you to read yourself as you need to. That Chernobyl Guy scrolls through it in the video and I'm hoping a direct link was provided, perhaps even in the video itself...
I’m still lost as to what the safety test was actually testing? Yes I understand they wanted to know if the turbine had residual rotational energy (presumably without steam) to generate electricity to run the cooling pumps for 60 seconds until the diesel generators kick in? But why would you lose steam? If you need to cool the reactor why don’t you have steam to run the turbines to generate electricity?
Not sure exactly what you are asking here, but you lose steam because the turbogenerators shut down when the reactor shuts down. Any remaining steam gets diverted and you only have the inertia of the turbine to work with at that point. The turbines cannot work effectively or safely with the unstable and declining steam output of a scrammed reactor.
But other reactors do have special devices where steam generated by post-scram decay heat is used to force cooling water into the reactor without any electricity required. Those systems are what delayed the Fukushima meltdowns for many hours and even days.
@@MinSredMashYou are close to what m asking which is in general “why was this test necessary/ what circumstances exist in hypothetical where you would still need to cool the reactor but not able to make power to run pumps AND turbogenerators are still functioning, pumps will still work IF they get electricity. ??”
Because if the hot rocks still need cooling and thus generate steam then you have power to run the pumps. You can say “need to shut down reactor” or “lower reactor power level” but this only applies if you have to shut it down low enough and in less than the sixty seconds before the diesel generators come online. I’m saying this test makes little sense to me.
@@Whitpusmc I think the video explains this. The test scenario is when an 800mm coolant pipe ruptures, depriving half the reactor of coolant supply, while also knocking out power to the building at the same time. In that scenario, obviously the reactor will shut it down automatically. In any kind of serious accident, the reactor will shut down automatically, and if not the operators will do it manually.
@@MinSredMash I will rewatch. But if power is knocked out to the building, doesn’t that mean that they aren’t getting whatever the turbines are producing? Thus whatever the turning turbines can latently produce is immaterial as power isn’t coming in anyway? If I was designing this complex, with multiple reactors, each reactors cooling pumps would be capable of getting power from every other reactor thus as long as one of the four were in operation, all could at least be cooled. I think they avoided this for cost reasons. Thanks for your assistance.
@@Whitpusmc Reactors don't get electricity from their turbines. They get electricity from the grid, which they contribute to. Reactors can't power themselves except at very low power and for short periods. It's a kind of 'special ability' of certain reactors. It's better to just use diesel generators, ultimately.
If the RBMK lost connection to the grid, the rundown capability was supposed to draw power from the reactor's own turbines for a short period. Bypassing the grid entirely.
Was always fascinated with Chernobyl even before the hbo series the BBC I believe had a series on it. The hbo one was just a rip off I think they even used to same cgi the BBC used
How do you verify the sources? I mean when Dyatlov says A and Slavsky says B how can you state which is right? Do we have computer logs of the event? Are we sure that those logs were not modified to support a false statement?
You immerse yourself in the topic. You can be surprised what happens when you do that. For example, where do you even see Dyatlov saying A and Slavsky saying B? Generally speaking I began with what is supposed to be the most authoritative source - INSAG-7. From there I branched out. INSAG-7 provides a priceless premise - the operators were scapegoated. The alleged violations were collectively false.
@@markusw7833 basically what I miss is the discussion on whether the operating manuals (do we have them?) forbid or not the operating conditions under which the test was executed. "Midnight in Chernobyl" states that Toptunov knew about the positive void coefficient as well as the counterintuitive SCRAM initial behavior
You will see a discussion on this very topic in two upcoming videos titled "Masters of Weaponized Narration". At the moment it seems like they'll be released some time in May - we'll see. Midnight in Chernobyl makes mistakes. For instance it claims that the dependence of reactivity insertion on ORM/number of control rods in the core was calculated before the disaster citing INSAG-7 whereas if you actually read what is cited that was determined after the disaster. I highly recommend you watch the next video in this series that was released a couple of weeks ago on the ORM topic. As for the coefficients, Soviet experts themselves appeared confused (previous video of this series). I highly doubt Toptunov of all people would have known about a positive power coefficient. A positive void coefficient was common knowledge. Its disastrous potential was a different story, and the authors you're reading don't take the time to properly familiarize themselves with the topic. They pursue "their own research", ironically and amusingly enough.
@@andreacaldarone4909 Toptonov and others knew, but the information was not widely known and not part of the operator training. It makes no sense to me that this wasn't shared, but I don't think they believed a situation like this would ever occur. I always remember how strong the belief was that an RBMK reactor cannot blow up. Comparable, I think, to the Titanic is unsinkable.
They are waiting for you, Anatoliy. In the test chambeeeeer..
Bizet's Carmen is a strange choice of music for this video.
all Pro Pa ganda
is based on
Dis Tracktion!
This is assuming Dyatlov had some way of calculating what control rod positions were needed to lower the power down to 200mw and no less without stalling it completely given the abnormal operating parameters from the high level of xenon poisoning. The reason for the experiment is, in the aftermath of Operation Opera it was assumed that in the event of a war, Americans and their allies would bomb the plant, and it would be necessary to immediately shut down the reactors. The emergency diesel generators take too long to start generating enough power to drive the cooling pumps in the event of a power grid failure, and someone had the idea to try to use the residual rotational inertia of the downspooling turbine to drive the generator until the emergency diesel generators were fully online.
Where did you pull this nonsense from?
Your characterization of the rationale for the rundown test is incorrect. The diesel generators WERE fast enough to provide cooling in the event of a power outage, thanks to the intertia of the still-spinning circulation pumps maintaining coolant supply for a few extra seconds. Otherwise the plant design would have been totally suicidal and it's amazing that anyone ever believed this myth.
The turbine rundown necessary in the even that an 800mm coolant pipe split in half at the same time as a power outage. The turbines were to provide voltage to power the feedwater pumps until the generators were online.
when ignalina episode>
Power decresed most likely due to core poisoning by xenon.
:/
Fascinating. But the music is distracting, IMHO.
Also, some of the captioning on the screen cannot be read because the white lettering blends into the white in the background.
Subbedj
Suwhat?
get better in chess
The background music is quite distracting.
At what point was the background music?
Lol, good question.
It wasn’t to me
Agree, it's just too restless.
I found it distracting because it's just straight bangers lol I love classical music and as a piano player I couldn't help but shuffle my fingers around to the music 😂
Bottom line is the engineers who administered the test are responsible for its outcome.
They either didn’t understand how their reactor worked or willfully conducted an experiment knowing they didn’t follow all the steps necessary to complete safely. Either way it’s their fault.
Watch the second pre-Chernobyl history video coming out this Saturday and the Masters of Weaponized Narration videos coming out in June.
How can you blame someone who didn't understand the dangers and the results of their actions? The critical information should have been part of operator training, but it wasn't. This was also the night shift which was less experienced than the day shift. For some reason those who held the knowledge I could have prevented this incident decided not to share that information widely. It wasn't even known by some of those who wrote papers at the time. Remember, the common thinking at the time was that an RBMK reactor cannot explode.
Are you suggesting that there was no system failure which resulted in a total loss of power, but rather a delibrate take down to 200MwT ?
Yet in Deatlov's own testimony he states he was not present during the drop in power and upon his return the operarots were already trying to raise it... to which he agreed was the correct course of action, if the power drop was delibrate then why would they be pulling rods to increase it ? Sorry if i am totally confused i could not hear it all very well....
Two different events - continued power reduction at around 00:05 and unintended drop in power at around 00:28.