Chernobyl: Worst Accident Ever

[@TheMajorHunter]

Goodbye normal comments section, hello HBO's Chernobyl references

[@DoofusMonkey]

Hello.

[@basedgodstrugglin]

There’s graphite in the comments...

[@maureenleah13]

BasedGod Strugglin' you didn’t see graphite in the comments. You DIDN’T! because it’s NOT! THERE!

[@justajawausingwifi4642]

3.6 normal comment not great not terrible

[@josephastier7421]

You didn't read HBO Chernobyl references. YOU DIDN'T!!!

[@nathanlaframboise8074]

I want this guy to read me bed time stories about science disasters.

[@susbox5554]

Read

[@nathanlaframboise8074]

@@susbox5554 ugh, thanks

[@bernardguynunns5658]

Satan will do that for you in your sleep.

[@susbox5554]

@@nathanlaframboise8074 your welcome

[@AlfredTortelloni]

I want Angela Lansbury to read me bedtime stories about science disasters

[@crimony3054]

The Soviet report concluded that the reactor didn't have a workable fail-safe for when the operators disable all the fail-safes.

[@jermainerace4156]

You say that somewhat in jest, but there are serious engineering applications where "What if someone intentionally tries to make it do the thing we really don't want it to do?" ..is a significant consideration.

[@crimony3054]

@@jermainerace4156 Agreed. Just that the implication is the designers were completely irresponsible and the operators weren't at fault. Interesting idea that a nuclear worker could become suicidal -- maybe with a big enough dose. And the HBO series (the final arbiter of historical disputes) implies that because accident details were made secret, they were not known to those who would have had the need to know them.

[@crimony3054]

@@jermainerace4156 You're embarking on a discussion of quality control philosophy, which is good.

[@zackthompson2505]

@@jermainerace4156 Agreed. I too remove all the oil and coolant out of my car then drive cross country. You know, for quality of craftmanship checks.

[@jermainerace4156]

@@zackthompson2505 Many people do that inadvertently by not fixing slow leaks. Eventually enough leaks out that the car overheats or the oil pressure warning comes on and they are like "ZOMG what happened?"

[@mindelo23]

So now I know how an RBMK reactor works. Now I don't need you.

[@Hannibal_Grim]

You're Delusional. Get him to the infirmary.

[@michalmokrys5010]

Now, you can throw him out of the helicopter.

[@drummonkeystuffuk1875]

*Throws him out of the helicopter into the reactor core*

[@bethlarson7144]

Shut up asshole the Professor did an excellent job,.

[@planet23k]

@@bethlarson7144 You're not getting the meme, are you? Also, quite a few logical simplifications AND omitting very important data, so not really "excellent". I must say though it is explained in a user friendly way. Overall, not great, not terrible (in both literal and meme meaning).

[@jackvphoenix8493]

Not only informative, but how does that guy write everything backward?

[@PentaxSource]

flip the vid horizontal

[@markhowes6575]

He got so much wrong.

[@robh.4584]

@@markhowes6575 what?

[@chrismaguire]

PentaxSource so his actually right handed 🤔

[@ndeepowder]

its a mirrored image, he writes normally and the way it is filmed produces the effect.

[@Kini_the_Fox]

his voice: calm and soothing. his marker: 2:55 screams of the damned, but pitched up

[@rm-qk2fw]

😂😂😂😂😂😂 that marker struck a nerve with me😂😂

[@josephastier7421]

You missed the important point of why the power level spiked. Once the reaction starts, the xenon gets burned off. The Chernobyl core was so huge that it wasn't uniformly controlled by the control rods, and the reaction took off again in the bottom part of it. This started burning off the xenon in a hurry. Now you have a situation where prompt neutrons are causing fission (carbon moderator still there), and all of the control rods are out of the reactor, and the xenon that was keeping fission from happening was getting burned off like dry grass in a self-feeding cycle. In the world of high energy physics, this is what is known as an "Oh [expletive] moment". There was a perfect moment, when ALL of the xenon was gone, and ALL of the control rods were out, and ALL of the fuel - some 200 tons of it - was free to react, completely uncontrolled. And it did. There is at least one paper out today that even claims a nuclear yield. Small, but larger than the chemical explosion could ever have been. The reactor hall was cast concrete, Soviet construction, and could probably have actually withstood a substantial chemical explosion, but was kicked aside like cardboard in the face of this blast. Radiation-resistant windows a meter thick were blown to bits like plain window glass. That is what happened at Chernobyl. A worst-case scenario, with 200 tons of uranium reactor fuel, totally uncontrolled. The United States already knew about xenon poisoning, having experienced it first hand with the startup of the Hanford B reactor, where we too yanked out all the control rods in a futile attempt to jump start a reactor that for some reason unknown at the time just would not react. We were very fortunate that we did not create the same accident here. The only reason we didn't was because Hanford B had been built too small, and could never start properly, given the effects of xenon. Beginners luck

[@sygos]

thanks for the info especially about Hanford B

[@josephastier7421]

@@sygos Extra channels had been built into Hanford B as a contingency, and it was a relatively simple matter to load these and create a bigger core.

[@bluellamaslearnbeyondthele2456]

I've been waiting for this comment all year long. Apparently, many still don't get it

[@MotoScootMech]

But no one is going to mention that the graphite tipped boron control rods caused the power level spike?

[@mjfan653]

@Tom R yeah, the spike was going, but the control rods prob gave an extra kick that didnt help anyone. Ignalina and a few other stations had already modified the rods to be less reactive, but thanks to KGB and the "saying there are problems creates problems so just say its fine" mentality, the information never went to Chernobyl

[@pandiatonizm]

The squeeking of the pen gives me more chills than he actual Chernobyl accident

[@Johnsmith-ry3ef]

How does he write backwards so fast

[@nerissacrawford8017]

Constant 7th octave.

[@FangedBeauty]

Man...this dude is gifted. To be able to explain such difficult stuff, making it easy to understand. And above all, making it interesting and entertaining. Wow.

[@timjohnson1199]

Did you see the series? That was very good.

[@Jlopeztx]

I totally agree with you.

[@1414Adety]

You forgot to mentioned his ability to write the opposite direction while explaining stuff

[@robertjenkins6132]

@@1414AdetySomeone in the comments suggested that he flips the video in post-production, which I think makes sense.

[@markusw7833]

@@1414Adety That's the actually impressive thing.

[@slbr3250]

I want to smack the pen out of his hand and tell him to "Raise The Power"

[@PercivalBlakeney]

Comrade Chief Deputy Engineer, I shall need that order in writing.

[@everyvillainislemons8712]

"He's procrastinating"

[@jordancobb509]

Just do what I tell you. Even as stupid as you are, you ought to be able to accomplish that...

[@hawkeye0927]

“I apologize...” GIMME A PING VASILY!!!!!!! Oops.... wrong movie...

[@PercivalBlakeney]

@@hawkeye0927 Kohai... if you must resort to ballsing up movie references, you've already lost. ....oh sh×t... even wronger movie. 😁

[@brendanyazzie2774]

"Hes delusional, take him to the infirmary"

[@michaelbell8834]

3.2 rontgens....not great, not terrible.

[@hlakegollum1]

@@michaelbell8834 3.6 roentgen not great not terrible

[@steinijg]

I'm very impressed with how well this guy explains the process, step by step.

[@PJL7095]

I’m impressed by how he can write backwards

[@Anistotle]

​​@@PJL7095If he draws the graphs like hundreds of time he's gonna have a whole image of them in his head which is amazing. I got this kind of feeling when I study basic physic during my highschool years.

[@studiotwopointeight]

Too bad half his explanation is simply completely wrong.

[@gmodrules123456789]

"An operator hit the wrong button in the control room..." *Looks at Dyatlov*

[@mercurysarcade8538]

I wasn't in the room I was in the Toilet.

[@WadcaWymiaru]

Akimow DID THAT!

[@Retard634]

i hate how hbo took the soviet party line and simply blamed the guy who followed orders and then went further to lie about his conduct during the explosion etc

[@gallyturndrop5320]

ϟhitlord what did you want them to do

[@Retard634]

@@gallyturndrop5320 blame the overly sized reactor that required seasoned staff to make sure it didnt fubar itself (not the college grads that manned the station) not lie about Dyatlov when it came to his reaction to the meltdown (he knew that the core exploded and never blamed any of his subordinates) not make up some strong female radiation scientist that never existed forgetting the attempts to stop the fires ended up creating the whole radioactive lava problem etc in short they put too much blame on the people involved and not enough on the system itself (they did place some of the blame but the lions share should go to the soviet system itself) the system that put men trained or untrained in charge of what amounted to a gigantic radioactive pressure cooker bomb that would inevitably go boom

[@tensevo]

The expression, "buy cheap, buy twice" comes to mind when thinking about Chernobyl. Skimping on safety measures to save money, ended up costing them a lot more in the long run. It always does.

[@petethewrist]

And in any future events feed in the human element. One day someone in rush to get home for one reason or another will do something wrong and... Bang????

[@MaruskaStarshaya]

It's a communism pure nature. They even speeded up the construction to get bonuses from the government and that speeding was due to hull skin installation skip.

[@BrianLTanner]

True about nuclear energy generation in general. Nuclear in itself is the epitome of that “buy cheap” concept, since the idea of fractional long term fuel costs makes bean counters cream their breaches. They damn sure aren’t lowering power bills because nuclear fuel is cheaper.

[@reactorfour1682]

It’s like when I do any form of carpentry “measure once, cut 3 times, realize I bought shitty materials, quit”

[@johnmclean9382]

Sounds like Soviet logic to me.

[@quicksilver462]

"what is eight feet wide, four feet tall, weighs two tons, and slices apples into three pieces?" answer: "a SOVIET designed and built machine to cut apples into four slices!"

[@AW-nz5st]

You can remove the quotation marks, that's not even close to what was said in the HBO Chernobyl series.

[@sumitanne3840]

AM I ONLY ONE WHO IS MORE IMPRESSED BY HIS REVERSE WRITING THAN HIS EXPLANATION!!!!!

[@HappyDuude]

Unless they just invert the video in post...

[@johnspence8141]

yes

[@nightw4tchman]

You didn't see his reverse writing... YOU DIDN'T BECAUSE IT'S NOT THERE!

[@crockett616]

Instead of the nucular stuff I started thinking about that! At speed of a neutron my brain realized the image has been flipped around. Sort of semi made more likely by the fact that he appears to be writing with his left hand. Now I'm back to thinking about the nucular stuff.

[@GraemeGunn]

@@HappyDuude No.

[@h2owl205]

I barely passed pre calc in high school yet now I am able to explain how a RBMK reactor works and exactly how the Chernobyl disaster occurred. Not exactly the most casual conversation starter lol...

[@0nkelD0kt0r]

Just please mind, that his explaination of what the reactor operators did is very simplified to the point of being wrong. For all its factual faults, the HBO series does show this pretty well. They sceduled the test to a certain time and lowered the power level to half, but then they left it there for hours because Kiev told them they need the power for longer and that they should do the test later in the night. After that period the reactor was already poisioned, and that is why the power level dropped so hard.

[@ahmetkahveci5680]

@@0nkelD0kt0r i completely agree with you. Ive read some articles about it too

[@angelurbina8158]

You're comparing math to theoretical physics. That's your first mistake.

[@0nkelD0kt0r]

@ I fully agree with you, and I was not really tryibg to say this video is bad for it, I just wanted to get accross, that there is a little more to the accident than what was said here, but that does not make this explaination a bad one. For people who just want to know what gernerally happened this is probably one of the best and most accurate descriptions for such a small timeframe.

[@Andytlp]

Secondly, the shut down button did the opposite of what the operators hoped and the fatal flaw was noted years prior. The graphite tips were meters long and lowering them all at once was like a nuclear bomb detonator.

[@chrishansen9910]

No containment would have prevented Chernobyl from exploding. The reactor got into an unstable region producing a phenomenal amount of power. It's simply bad reactor design. "Doctor, it hurts when I do this." "Don't do that!"

[@studiotwopointeight]

Those darn graphite tips on the boron control rods.

[@danielbond9755]

But it would have contained the fallout. Reactor still destroyed, but the whole area isn’t contaminated.

[@Zamolxes77]

I lived in Satu Mare, Romania in 1986, Kiev is about 830 km away, town on Pripyat about 900 km. We actually learned very quickly, and not from the West, back then we were under Iron Curtain, but from our own government who was monitoring things (work started on our own first nuclear power plant at Cernavoda). I remember being a distinct fear of the fallout cloud drifting down to Transylvania since there aren't many high mountains in the way, except the Carpathians. It didn't, and we were relieved.

[@octavianr526]

Where did you hear it didn't? There are weather maps of the time showing the worst radiation reached Romania and all the way to Spain

[@ninam.1560]

​@@octavianr526 absolutely! It was one of the red areas if I can remember

[@ninam.1560]

You need to watch the map of the cloud cause it did in fact hit Romania

[@cjmillsnun]

Sorry, no 10:50 an operator didn't hit the wrong button. It had been run at half power and there was a xenon build up along with a lack of coolant void and graphite cooldown. This made any power change difficult. This is known and is in the WNA page about the accident. From there you are correct.

[@mikloskallo9046]

Agreed, the problem was the electrical grid needed power and those operators didn't allow the power to be reduced, so it stayed around 50% for 19 hours, which contributed to the Xenon poisoning.

[@VComps]

That's not strictly speaking true. One of the operators switch the reactor from local automated operation to global automated operation. Sort of a nuclear autopilot. However, he failed to set the power level that he wished the reactor to stabilize at. Because of this, the reactor went to the power level that had been specified last - near zero. And, of course, and we know from experience now that RBMK reactors are notoriously unstable at low power levels. PARTICULARLY when the fuel rods are older and due for replacement.

[@mikloskallo9046]

@@VComps Not according to the The International Nuclear Safety Advisory Group (INSAG): The drop in power occurred at 00:28 on 26 April during transfer from local to global power control. The INSAG-7 report states: "The INSAG-1 report describes the precipitous fall in power to 30 MW(th) as being due to an operator error. Recent reports suggest that there was no operator error as such; the SCSSINP Commission report (Annex I, Sections 1-4.6, 1-4.7) refers to an unknown cause and inability to control the power, and A.S. Dyatlov, former Deputy Chief Engineer for Operations at the Chernobyl plant, in a private communication refers to the system not working properly." The timeline from the World Nuclear Association words it differently: With the power level at about 500 MWt, control was transferred from the local to the automatic regulating system. The operator might have failed to give the 'hold power at required level' signal or the regulating system failed to respond to this signal. This led to an unexpected fall in power, which rapidly dropped to 30 MWt. So it isn't quite clear what happened, but still, the Iodine pit - Xenon poisoning sequence described by the professor was happening anyway and they should have shut it down, but instead they tried to increase reactivity ultimately ignoring safety standards. Then we have the positive void coefficient making things even worse - the poor souls were doomed. One of the things may not be instantly obvious for someone not living under such a regime is why they ignored so many regulations. It wasn't simply negligence, people in the Eastern bloc, especially in the Soviet Union still remembered the days when a failure to get results was considered sabotage (as the system of scientific socialism was supposed to work flawlessly) and punished severely.

[@albatross5466]

The engineer overseeing the experiment, Dyatlov, had another similar accident earlier in his career. It didn't have the dramatic results as Chernobyl but his son died as a result. The man was dangerous.

[@woopimagpie]

At the time Dyatlov was quite defiant and refused to accept responsibility, claiming that he had been lied to and that vital information about the graphite tipped control rods (and the danger they represented) was kept from him. In the years after his death when more secrets about the Soviet nuclear industry were exposed it turned out he was right. Vital information HAD been kept from him, and all the other RBMK reactor operators working at the time. It has since been learned that an incident like Chernobyl had almost happened before (at the Leningrad plant in 1975), and although the cause was known the authorities chose to keep it a secret lest it expose a failing in Soviet reactor design. In fact the commission who investigated that incident made several recommendations to improve safety but they were ignored and the whole incident was covered up. Was Dyatlov merely a hapless pawn in a deeply flawed system? Many would say yes, now that we know the full extent of how far the obsession with secrets went. Myself I don't think he was totally blameless, but had the authorities chosen to pass on the safety recommendations rather than keep their silence the entire incident would not have happened.

[@andydudley1775]

@@woopimagpie the fault was in the blue prints from the off Dyatlov got the blame.this is why people should not act the cunt in the work place .with nuclear fission.

[@JC-lu4se]

@@woopimagpie Glad to see you've done your research unlike the HBO Chernobyl series minions who think they know everything. From my reading, the reactor was designed by the "Ministry of Medium Machines" which was a USSR top secret government ministry. All secrets were kept away from nuclear engineers.

[@NuclearT3acup]

@@woopimagpie I grew up about 400km from the Chernobyl site. I was only 4 at the time. The soviet mentality you touched on still exists to this day. It's part of the culture at this point. Project power, downplay weakness. It's not until something catastrophic happens that the rest of the world gets a good look at the dysfunctionality that is the Russian system.

[@Matixmer]

Tbh Dyatlov was more or less directed from the politburo to run this test. The whole test was stupid.

[@wattlebough]

YOU DIDN’T SEE ANY GRAPHITE BECAUSE IT’S **NOT THERE** !!!

[@bytebiker1975]

Always be on alert if someone tells you "everything you needed to know about a specific topic". Nuclear power plants are complex machines although the physics behind it may seem simple. Complex machines are prone to failure, human error, negligence and profit-maximizing cost savings in maintenance due to greed or incompetence. It's easy to say that an event, exactly like Tchernobyl, might probably never occur again. But there are myriads of things that can and will go wrong with probably devastating consequences. And that doesn't even take into account the consequences of the still non-existant long-term storage option. Or the nuclear waste that had been dropped to the sea-floor for decades. Just think about Fukushima. Surely not identical to Chernobyl. But still a catastrophe. And a perfect example for human ignorance.

[@humanbeing2420]

I'm most impressed by his ability to write from behind the text he is writing.

[@Thunshot]

Flipped the video horizontally

[@Chiberia]

You record the video writing normally, then mirror it after recording

[@loupgarou-dj3tm]

@@Chiberia - You could have the camera looking at him in a mirror to do it oldschool.

[@humanbeing2420]

@@Thunshot Makes sense.

[@jamesh0224]

@@Chiberiayep. He’s probably right handed and married. You can see the ring on his finger. Flipping the video makes sense

[@TheRealUnconnected]

i have enjoyed many videos from this channel but was expecting this one to be a little more detailed around the neutron flux and the reason why the control rods had graphite 'tips' (the reality is the rods were about half graphite) scott manly has a better explanation with much more detail. I also have my doubts that the containment buildings really could perfectly contain a steam explosion of the scale of chernobyls.

[@nickl5658]

A containment building would not have contained what happened in Chernobyl. Containment buildings are designed to hold up 80psi of pressure. The explosion at Chernobyl is estimated to have reached over 1500psi. Just before the reactor blew, energy output reach 30,000MW thermal, 10x higher than the reactor was designed. There is a hypothesis that Chernobyl was a fizzled nuclear explosion. There were two explosions.

[@taraswertelecki7874]

In a nuclear explosion, over pressures of 12 psi or greater kill virtually everyone and destroys all but specially built facilities above ground in the blast zone, such as a nuclear missile silo.

[@Iwillnotbepushed]

TheRealUnconnected Three Mile Island in Pennsylvania is a good example of out containment buildings. The reactor partially melted down yet no huge release into the air of radiation. Well...not that we were told.

[@metaphorpritam]

@@Iwillnotbepushed 'no huge release into the air of radiation' Radioactive elements in the form of volatile gases, like Iodine, were released. However, unlike Chernobyl, solid matter was not released.

[@berko9608]

@ TheRealUnconnected The main reason for this design of the rods was an attempt to place the reactor in a room of LOWER HEIGHT AND DEPTH. Typical Soviet style of "economy". Also, the designers chose a dangerously low speed of movement of the rods, citing an allegedly sufficient change in the coefficient of reactivity per second. Link to the site created by the engineers of the Chernobyl nuclear power plant (in Russian): accidont.ru/sitemap.html. This site is unmanaged since 2013. No feedback. All tables, graphs and printouts you are interested in are there. As well as different opinions of experts about the causes of the accident. design flaws of the reactor and personnel errors. And descriptions of other emergencies at RBMK reactors.

[@kennethalbert4653]

He wanted to make sure he wore a period correct Soviet suit for this presentation.

[@3vimages471]

Ha ha ha true. Soviet suits are almost as vulgar as their wall tile patters.

[@cow_tools_]

This is just how lecturers dress.

[@ronaldgarrison8478]

And they thought Obama's tan suit was bad.

[@jamesharmer9293]

Yeah, that tie....!

[@spaceghost8995]

Herb Tarlac suit.

[@kenh9508]

Unless you hit 88 MPH, the flux capacitor is useless.

[@kalleklp7291]

Not if you've got some 200 tons Uranium fuel at hand.

[@JonMarc22]

Hahaha... LMAO !!! Great Scott , you are correct.

[@quantumpilot6843]

@@kalleklp7291 wasn’t it plutonium the car ran of?

[@kalleklp7291]

@@quantumpilot6843 Yes, you're right...but with the "Mr. Fusion generator," it can even run on garbage. :)

[@logicplague]

The most fictional thing in that movie wasn't the time travel or the flux capacitor, it was a Delorean doing 88 miles an hour.

[@Olivia-W]

With professors like that, I'd be a lot more motivated in my degree...

[@xBloodXGusherx]

Exactly!

[@peterbradshaw8018]

If you have to get motivated by someone other than yourself you are not ready for university life.

[@darthmom1019]

​@peterbradshaw8018 - I think you missed his point. It's not just self-motivation that makes a difference in college and in life, but having good, engaging teachers that help each student learn & explaining complex ideas, situations, etc that make the most difference.

[@studiotwopointeight]

Too bad half his lecture is just plain flat wrong.

[@zackthompson2505]

*looks at reactor design notes* "Under no circumstances should less than 30 control rods be in place to ensure safe operation" Blyat! *Continues to remove all of them*

[@markusw7833]

You should look at those again.

[@flok462]

The number was 15 not 30. Also the regulation allowed to go lower if Dyatlov gave his ok which was routinely done at all nuclear reactors. There also was a design rule stating a reactor may never ever under any circumstances be able to perform a runaway reation. The designers misunderstood the reactor and when they found out they maybe created a time bomb Legasov covered it up

[@studiotwopointeight]

Also, to reactor designers, "under no circumstances cheap out and cut corners by putting graphite tips onto the boron control rods". Without the graphite tips on the boron control rods, the Chernobyl disaster might never had occurred.

[@flok462]

@@studiotwopointeight you do know the "tips" are about 4.5m long? They did not "cheap out" but it was a design feature to improve the effect of the control rods. It was a economic choice thou. It enables you to use the fuel to a greater efficiency despite it's low enrichment.

[@studiotwopointeight]

@@flok462 Bottom line, the graphite portion of the rods jammed in their slots, could not go in further, and turned the reactor into a 30,000 plus megawatt 40,000 foot tall nuclear blow torch that turned the entire region into an exclusion zone, that people continue to discuss four decades later. Stay focused and don't be pedantic. A better design with all boron control rods probably wouldn't have done with the deadly Chernobyl reactor did.

[@Queretonix]

0:30 RBMK, not RMBK. Also, this explanation is not very accurate. They got the reactor to operate at half power in the afternoon of the 25th of April as they were preparing for the safety test they were supposed to have completed in 1983. Then they got a phone call from the higher ups to not do it during the afternoon cuz it was the end of the month and electricity consumption was at its peak. They were tasked to postpone the test to the night. They left the reactor at half power and because of that a lot of xenon was created but not burned. That's how the xenon poisoning happened. That's why the reactor's power dropped to 30 instead of staying steadily at 700, not because an operator pressed the wrong button.

[@jefersonnl]

As a matter of fact, it may be exactly "because an operator pressed the wrong button". It's impossible to know because it did not took long to Akimov and Toptunov to die after the accident, and we don't even know for how long they held consciousness. You should not take what the series tell you at face value. 50% is approximation and romanticization, we will never know what really happened there for several reasons, some of them may be, 1- they died soon after the accident and maybe didn't have time to tell very well what happened and how it all happened, they might even have been shell-shocked, under severe PTSD, delusional or in and out of a comatose state before they died, unable to put it all to words, or make any sense. 2- they may have told everything from their perspective, however.... USSR, KGB, FSB, and the truth may be buried somewhere rotting in some top secret archive file, never to see the light of the day. 3- they were very green, especially Toptunov, and he was the one responsible to get to the power levels required(I believe Dyatlov stated that during his official debriefing), and maybe he never knew what he did wrong. 4- the cause of the sudden power death in the reactor may be just another design flaw or equipment malfunction, triggered by Toptunov. The series itself does not make clear what really happened when the power fell suddenly to near shutdown levels. We just see the surprise on the face of Akimov and Toptunov, and after that, Dyatlov's rage. I read one of the INSAG's(INSAG-7/1992 official report) reports into the accident and even they are not sure. They oscillate between equipment failure/fault and an operator error on Toptunov's part. Some argue that the action Toptunov took to switch the reactor from local to global power control, IS the operator error itself("....pressed the wrong button."), others argue that the global power control system may have had a FLAW that caused the severe drop in power. Maybe Professor Ruzic knows more than I do, coz he simply studied/investigated more into the matter. I do not have time to read all of the reports nor his credentials to understand it all.

[@richardvaughn168]

@@jefersonnl In "Midnight at Chernobyl" Higgonbotham states that Toptunov, when moving from local to global automatic control, did not reset the reactor power level desired leaving it at near zero. He then failed to act to correct it. Higginbotham also states that Deputy Chief Engineer Dyatlov demanded that the test be done at 200 MW which Akimov initially strongly protested. Under badgering Akimov finally conceded to Dyatlov even though he outranked him in terms of running the reactor. Higginbotham also states that Toptunov knew the reactor was unstable at low power and when Dyatlov demanded that he pull more control rods, he initially refused. But just like Akimov, he conceded to Dyatlov's threats and demands and violated safety protocols by pulling almost all the control rods. Tregub (prior shift Senior Reactor Engineer) had remainded at the reactor control station after his shift and advised Toptunov on which rods to pull - fully complicit in Dyatlov's disasterous intervention to get reactor power going again. Dyatlov, during the investigation and trial, denied that he was even in the room. If Higginbothom's account is correct, then Dyatlov bears most of the responsiblity for violating the published procedure by insisting it be done at 200 MW in an unstable reactor and bullying the reactor engineers (and Akimov) into violating critical safety measures. Poor Toptunov had only been a senior reactor engineer for 2 months when he activated the AZ5 system that was supposed to shut down the reactor but in sad fact became the final insult that initiated the destruction of Chernobyl Reactor #4.

[@jefersonnl]

@@richardvaughn168 I want to read this book! it has been on my list of books to read even before the series premiere. I believe the book is basically in agreement with some sources I came across, like the INSAG and the IAEA.

[@trinalgalaxy5943]

@@jefersonnl there are many things the HBO series either modified or got wrong, but there are plenty of other facts they got right. We know based off records that the test and shutdown was going to happen during the day shift, but they were requested (demanded) to not take the reactor lower so factories could meet their obligations for the month. the reactor then remained at that 50% power level (rather than proceed with the next drop to 700 MW for the test) where simulations have shown xenon to build up to significant levels over the course of the following hours. this combined with the lack of proper training for the test by the operators likely led to the reactor going from almost desired power to almost nothing as the reactor stalled. At that point, the operators started fighting to get the reactors power up to 200 (a power level that would still have failed the test) and took it off automatic control. the politics behind dyatlov being promoted upon a success that night I had not heard (but not unthinkable) but he did push the operators to do things that they were never trained for and violate every rule in the book to get his test, at which point the reactor sprung to life uncontrollably due to the voids and damage caused by smaller scale uncontrolled reactions nobody had any ability to know were occurring. (the RBMK-1000 was fuckoff huge in all dimensions, leading to varying reactions that were unmonitored across the whole thing.

[@jefersonnl]

@@trinalgalaxy5943 Ohhh really!?? Noooo wayyy!!.... seriously, I don't even know what to answer. As a matter of fact, I'm beginning to question the wisdom of coming here and writing this in the first place.

[@jamiewatchorn7639]

I love how everyone watches a TV show and suddenly everyone is now an expert in nuclear fission

[@AdmiralKiko]

I love it. How else do you suddenly get millions of people even casually studying nuclear energy. Imagine how many minds have been peaked to go back to school and study nuclear energy? So crazy.

[@Saavik256]

I've visited actual Chernobyl several times in the past 20 years, and I have very good understanding of how it works and why it is a flawed design. When it is safe to go to Ukraine again, I plan on going again, because I want to see how much Pripyat has changed and I want to see the new shelter project. :)

[@HowlingWolf518]

KZbin commenters aside, I'm willing to bet that most people will want to look for knowledge outside of the HBO series and come away smarter.

[@danansana3589]

@@Saavik256 go to fukushima and report back

[@hahandroo]

It’s the bullet!

[@FloydMaxwell]

The jet doesn't "disappear into vapor". It may disintegrate into smaller pieces, but it doesn't "vaporize".

[@TrumpsEarBandage]

Mr literal

[@TheRadiastral]

At high enough speed it actually can and will vaporize. There is a video of F4 Phantom fighter jet being accellerated on a sled into a concrete wall, at around 500 mph. The whole plane turned into a big cloud of dust. 500 mph is also close to the maximum speed of a typical passenger jet and I'd expect a very similar outcome. One should add that you can accellerate a jetliner to even higher speeds, by entering a vertical dive. That can bring it close to mach 1. At that speed, when hitting a solid concrete wall, there is just so much energy released that everything turns into vapor.

[@dcwarner]

First mistake was to do the test overnight. Sleepy tired third shift performing a simple 1000 step procedure.

[@marianmarkovic5881]

Not only that,... peaple trained for it (who also stoped it like 3 times midway trouth b4 was not there either.)

[@3vimages471]

It was the nightshift doing it overnight. They could not do it during the day because Kiev needed the electricity.

[@fallsdp]

First mistake was in approving the production of the RMBK.

[@seanbailey8545]

Probably government getting bribes from the Energy companies as usual.

[@adamrak7560]

​@@fallsdp they knew about the instability of the RMBK reactors, but it was covered up because it was too embarrassing. The tip of the rods being made of graphite is actually a safe design for smaller reactors, it is also very efficient. But bigger reactors can do unexpected things when you use such rods. (They have naively scaled up the design, without considering safety.) The only way for the graphite ended rod to cause fatal problems was in case of a massive Xenon poisoning, and removal of almost all rods, boiling off all the water (see void coefficient). Everything which can go wrong went wrong at the same time. The Three Mile Island reactor was designed for exactly that, what if _everything_ goes wrong at the same, including an aircraft suicide bombing the reactor. So when thing went wrong (without the bombing), it failed relatively safe (with only a minor leak).

[@edoardobarsotti902]

The first ones who noticed an anomaly were people at a nuclear power plant in southern Sweden.

[@Haan22]

Yes, the morning shift had contaminated shoes which set off the alarms. Needless to say that led to a few very tense hours as everyone first assumed it was a malfunction with our power plant.

[@davyt0247]

The night shift went, “No it’s not us, reactors fine.” “Ok the wind was coming from the direction of Cherno... uh oh.”

[@tim3172]

@@davyt0247 Cher-oh-no-byl?

[@AdolfHitler-du3xx]

sweden is already so degenerate, they don't need to fear defects caused by radiation

[@studiotwopointeight]

Correct. Half this fool's lecture is simply wrong, not just that point. The guy could have made a 2 minute video and explained that the Soviets were just penny wise pound foolish cheapskates who put graphite tips on their boron control rods.

[@link18953]

Professor Ruzic, thank you for your amazing work. You are a great communicator, explaining such complex subjects in a very accessible manner is a valuable skill. My 7yo boy loves your content. Very funny to watch Mr7 explain to his grandfather, a retired professor of finance, how the Chernobyl incident unfolded. “Grandpa, they used the wrong moderator and didn’t know about xenon poisoning”.

[@flok462]

Except most of what he says is kind of wrong and misleading. Please check other sources to gain a better understanding

[@orbea42]

AAAHHH! SQUEAKY MARKER! MY FLESH IS MELTING!

[@tomservo5347]

Yea he needs some WD-40.

[@conzmoleman]

jesus christ i was tearing my room apart thinking a mouse was here. EXACT sound when they get caught on a glue trap.

[@hgbugalou]

Same! yikes.

[@dimaignatiev6370]

Yeah man....This horrible nerve ripping sound....Unbearable...

[@alexroselle]

I'm watching this with my dog and he is NOT enjoying that sound

[@johnolive3425]

"Why worry about something that isn't going to happen"? "Ohh, that's perfect. They should print that on our money"!

[@obsoleteoptics]

*folds US currency to display the events sequence of 9/11*

[@iaunn]

Everyone here using the internet for its intended purpose.

[@aljohnson3717]

That’s the single best explanation of physics of the Chernobyl disaster. There are a couple of the things that professor might have not been aware of. 1. The whole idea of that *experiment* grew from the successful attack on the Soviet built Ozark reactor in Iraq conducted by the Israel Defense Force. The experiment was to prove that the power plant can withstand power cut off due to the attack and to sustain itself just by the power of mechanical inertia of the turbine-generator. 2. They hurried this up because in the Socialist system it was very important to report the success to their Communist Party bosses in the eve of the 1st of May, the major Soviet Holiday. Should the experiment be a success, all the participants would be rewarded by bonuses and promotions to the top managers of the plant.

[@steven8075]

From what I understand, the Experiment was actually to see if the freewheeling turbine can generate enough power to keep the safeties and cooling pumps running during the 1min gap between a power loss event and the backup generators spooling up to make enough power to then support the aforementioned safety systems.

[@afractionahead642]

This prof. should be awarded a prize! I really enjoyed your video and did not even notice how it was over! Thank you very much.

[@WolfHeathen]

Considering he got information wrong, I don't thing awarding him would be the best idea.

[@markusw7833]

@@WolfHeathen lmao

[@T42oqq]

Never thought i would like nuclear disaster so much

[@Odqvist89]

When you realize they mirrored this video...

[@ylette]

...you realize that you're dealing with clever folks.

[@JonnyD3ath]

Mind - blown!

[@rthinds]

Is that what they did? I was wondering why he could write backwards so well

[@Damocles16]

Duuude... You just made me feel so dumb xp. It should have been so obvious!

[@kevinfealy4769]

Wow, yeah hadn't thought of that, LoL

[@HT-ww3zg]

Should call this poisoning of the reactor, The Diatlov Effect."

[@TheJMBon]

This poisoning was known before this event. The Chernobyl operators just weren't qualified or slaves to a Communist system where all that mattered was results.

[@HT-ww3zg]

@@TheJMBon Still, the Dyatlov Effect is a really cool name. 😆

[@TheJMBon]

@@HT-ww3zg agreed

[@jefersonnl]

"The Dyatlov Effect" has a nice ringing to it, however, it should be not about nuclear reactors, but about the culture of pushing people and things beyond a limit you shouldn't, all in the name of results. Once I was a spectator to something like that, when I saw a rocky project manager push people to the brink for a couple of days in order to meet a deadline, and it ended up with an assistant DBA overwriting a live production database with a test copy in the middle of the working day. Of course people were nervous and exhausted in the first place, but he put some security issues and good practices aside like allowing trainees root access to production servers, coz the real DBA had to have a break after working for several hours straight. I remember I was part of the 'liquidation effort', we had to put that guy aside, let him have his nervous breakdown, relieve the rest of the guys, and manage the damage. Lessons were learned that day. Never again something like that happened in our department. Of course, one of the most important things we learned is, do not put unstable, authoritarian nor arrogant people in charge of things like management. Sometimes leaders have to act as a buffer protecting his/her team from outside pressure while they do their work to the best of their abilities, and not actually transfer the pressure on to the team. That's part of good leadership, take a few blows in the name of your guys. Of course, Dyatlov was a product of the system that raised and taught him(so was the reactor and its flaws), and that can't be overlooked.

[@adamrak7560]

I would rather call a different thing Diatlov Effect: When you press the SCRAM button and your reactor explodes afterwards... because of reasons. (The SCRAM pushed all control rods inside at the same time, which caused the final fatal runaway)

[@atrumluminarium]

A good way to remember the correct order of the acronym: Really Badly Made Kettle

[@wilburdaffodile]

world’s loudest pen

[@av28379]

Its not a pen its a marker

[@av28379]

And thats completely normal marker

[@CuoreSportivo]

@@av28379 it's a fucking pen

[@shadowbanned111]

@@CuoreSportivo It's a marker. Comrade Sportivo is delusional, take him to the infirmary!

[@ronaldgarrison8478]

It's so low-tech for such a high-tech subject. But I must admit, that backward writing looks really cool. I think maybe this professor made a deal with the Devil.

[@lousimms4766]

Man If I'd had you as a professor in high school my life would be so different because I'd actually pay attention to you because I can understand what you're saying. Can't say the same for the professors I had. So depressing.

[@SmithChameleonMan]

Thank you so much! Seriously…thank you. I have viewed so many explanations of this event, and now I can say that I fully understand it now. This is the single best presentation that I have come across. Thanks again.

[@studiotwopointeight]

Too bad this guy gets more than half his explanation wrong.

[@firstactionhero]

I'm an industrial pipefitter and although this may seem like overkill to learn this kind of stuff, it is incredibly useful to understand the intricacies of the process and history. Thank you very much for posting all your videos. The history and future of power generation is so important to understand, even if people aren't an installer and welder of the process piping like I am.

[@danh.5825]

80s 888888888888888888888

[@TomFynn]

Given that it was badly fitted pipes what sunk the USS Thresher, knowing how to pipe fit it no small matter. My dad had used to work for a company which build compensators for pipe systems and at one point they did them for nuclear power plants. The amount of courses and lectures he had to take in order to do his work was beyond belief.

[@elzar760]

Moral of the story, don’t test your safety systems.

[@rakesrunner]

Test it, but without 200 tons of enriched uranium inside, heated to water vaporizing temperatures.

[@Quadrolithium]

Test it, but make sure for every safety system you have, 2 more should be in standby. One that works with no humans or machines needed, just physics.

[@Seth9809]

Lol

[@jacklynch3333]

Moral of the story: don’t be a commie

[@michaelkregnes9119]

Moral of the story: - Never build positive Void coefficient reactor - Build a good containmentbuilding - Moderator and Coolant must be same water - Every worker needs knowledge of Xenon 135

[@brettallen1874]

"Safety first." "I've been saying that for years." "Now raise the f***ing power."

[@t3hleviathan]

12:54 the "squeak squawk squeak" puts so much more emphasis on the drama

[@Panda-gs5lt]

It had my dogs looking for mice 😅

[@MegaHjansen]

It's a RBMK reactor and fuel rods can be replaced during operation. The reactor doesn't need to be shutdown.

[@bethlarson7144]

So many experts on here and half couldn’t find their own ass with both hands and an Admiral Byrd expedition.

[@studiotwopointeight]

Most of this guy's video is simply wrong.

[@ronjon7942]

I think it’s implied the RBMK should have a containment vessel, analogous to the Western LWR containment configuration - not that the RBMK reactor should use containment as designed for the LWR. Most certainly, the containment for the RBMK would have to be specifically designed for it, one of the specifications being able to contain a hydrogen explosion. Obviously, using a Western design intended for use by an LWR would not suffice for an RBMK. I have read Russian designers discarded the idea of a containment structure because a:) they believed with certainty the reactor characteristics were such that a Western style containment was unnecessary, and b:) the reactor was intended to be refueled while in operation via a large crane above the reactor vessel; hydrogen explosion-proof containment would have impeded this feature, or made it impractical if not impossible. Regarding an operator hitting the wrong button, this is the second video where I’ve heard this, the first being n MIT lecture on nuclear engineering. I believe the source material came from an official report by a nuclear regulatory agency; I’ll post a link to the report and updathe post w the agency. The two presentations are very similar with respect to the technical details and the timeline, causing me to infer they’ve both used the same source material. After reading the NRC’s report and rewatching Professor Ruzic’s essay, I’m unable to substantiate any of the comments who declare this video is full of misinformation and mistakes. Professor Ruzic does interject his dry sense of humor when he’s critical of operator performance, and clearly interprets the actual events and human factors elements with an engineering and professorial point of view with full benefit of hindsight, but that’s how root cause analyses go. I suggest instead that the people who commented that Ruzic made errors have trouble with his perspectives, points of view, opinions and style. That’s too bad, because looking at issues from multiple angles and personalities is a critical benefit of KZbin. Being able to watch many different videos on a singular subject is such an advantage, especially when the videos ultimately prove out a consistent sequence of events and series of facts, along with weeding out the content creators that are less than rigorous in their factual reporting.

[@carrito1981]

When he started with the markers I thought there was a mouse in my room.

[@carrito1981]

@@pavel9652 don't get me wrong, I love these videos. I have watched a lot of them and learned a lot. It was just that I didn't know where the squeaking was coming from XD

[@pavel9652]

​@@carrito1981 Haha, I mistakenly responded to your comment, while responding to the other one. Nice catch, you are fast ;) I already deleted it, sorry for the confusion. I think the squeaky marker is a staple here ;) Stay curious!

[@carrito1981]

@@pavel9652 all good my friend!! :)

[@boonamai8926]

10:00 That was better explained in the Chernobyl series, they actually ran it at half power for the whole day because the power was needed, then they didn't hit the wrong button, they put it into automatic mode and it almost stalled because it wasn't calculating for the Xenon.

[@steveplayz1239]

and it used graphite as a moderator not carbon

[@steveplayz1239]

@@boonamai8926 maybe teaching not to trust this guy because there is quite a bit of mistakes

[@redcrafterlppa303]

10:50 no one hit a wrong button!! Where do you get that miss information from? They where shutting down the plant to round about half power preparing for the test. But then the grid needed more power. So they stayed on this low power for some time. Meanwhile the core got xenon poisoned due to low power operation. Then they started the test by lowering the power to ~2/3 power. Because of the poisoned core the power continued to drop in power. Then they tried to bring the core back up to a power level suitable to perform the test. They did this by removing all but 1 control rod (against all regulations). Then the power skyrocket because the xenon was burning away. In an attempt to shut down the reaktor they pressed az5 causing all control rods to go back into the core. But because the tips of the rods where made from graphite they first caused another spike in power. Which resulted in the explosion of the core.

[@studiotwopointeight]

Half that idiot's lecture is wrong, including your point.

[@fkcnoathcnt]

Writing backwards level: "3.6 Roegents, not great, not terrible."

[@wraith8323]

Well that's not great but its certainly not horrifying Not at all

[@h2owl205]

Well this comment’s not original, but not funny

[@jamesquinney6686]

Michael Solis it not 3 roegent its 15000

[@V1kram]

The footage is mirrored.

[@TheOdderlbert]

This shit comment doesnt even make sense. Wtf

[@DarthAbyss316]

Thank you sir. This was an absolutely enthralling lecture. I watched the 2019 Chernobyl miniseries and while I do understand there may be factual inaccuracies in the HBO series your lecture helps me to comprehend just how dangerous the Chernobyl disaster was in 1986. Thank you once again sir.

[@knutritter461]

Well made video! Just one thing: Even if the RBMK had a containment building many professionals think it would not have survived that explosion. The HEAVY lid of the reactor flew about 30 meters high.

[@BleakVision]

Reinforced concrete is believed to have far more strength when dynamically loaded during an explosion or an impact. A real life example of this the Longarone dam in Italy which survived loads estimated 100 times what it was designed for when a mountainside slid into the reservoir. Unfortunately very little research is done in this area because of the huge costs of blowing up life sized structures.

[@logicplague]

It couldn't have hurt.

[@BSoDexe]

Even if it did crack it, the hole would've been quite small, and less material outside, meaning less people have to clean it while being in place with 20 thousands Roentgen/hour

[@knutritter461]

@George Thomas It's estimated that the lid has a weight of at least 1000 (metric) tons.

[@michaelwills3311]

I was stationed in West Germany when this happened. The Army canceled all training for months and of course no outside activities.

[@crimony3054]

The Chernobyl guy was a self-taught expert on the RBMK reactor. His previous background was submarine reactors. He was noted for his ability to cite technical manuals. The weakness in RBMK reactors had been identified about a decade earlier and it was published. But someone redacted the part of the report that talked about preventing an explosion. Whether the lead guy had clearance for the redacted portion (probably) and whether he could have accessed it (pre-web) is undetermined (or at least unpublished itself).

[@efeykay]

I can't life like a submarine Reactor because of this Life I am D O I N G like the Prof. In the Video Demonstration is writing behind All and All behinder and behind it... that's not possible... i can't understand it... it's nonsense for us all... Super... Dummel Will Not Life... Amen...Ciao Wiktor Witas Kuhn from Bremerhaven and Amen You All, I try everything to escape this 20000000 ttilliard Super Nintendo... that's impossible... I Love You Math ... ❤❤❤

[@diggydumbo9294]

This is what happens when you choose key people on key departments based on politics

[@samrapheal1828]

@@diggydumbo9294 "Exactamundo."

[@alexanderd.7818]

He could've been self-taught to eyeballs, that woudn't change anything. Simply because submarine reactors are PWR which have nothing to do with BWR.

[@danlorett2184]

I doubt it would have mattered much. The same political pressures and the same lack of care for safety to satisfy those pressures would exist. The problem was not one flaw with one reactor, or one bad decision by an operator without all the information. It was a failure at nearly every level.

[@SlimSlashie]

Did anyone else notice him mention an airplane can hit 3 foot thick, steel reinforced concrete and the PLANE disintegrates? Sir, it was tried. Twice. Maybe we need to rethink this whole concrete v plane thing, eh?

[@alexedelweiss3267]

WTC towers weren't made of concrete. It was used a mixture of A 36 and A 242 steel.

[@MrSummitville]

There were office windows in the walls of building. Duh!!!

[@SlimSlashie]

@@alexedelweiss3267 I was referring to the center concrete column inside the WTC. It's like you don't pay attention on purpose or something... The elevator shafts inside the WTC was a HUGE 40 elevator bank that was surrounded by concrete. (Some might say a city block of concrete) This is the same concrete that the outer steel shell was fastened to. A city block of concrete, 100 and something floors high? Yup. These buildings were massive. Look it's a nice story that the airplanes took down the buildings, but if you know anyone in the architectural world, you'll know it's just that. A story.

[@SlimSlashie]

Dude you literally and metaphorically poked holes in my argument. LOL It's actually f'n brilliant what you did there. Thank you for that. hahaha You rock.

[@raphaeldexel4356]

The radioactivity from Chernobyl was first detected in Sweden at the nuclear power plant of Forsmark......At Forsmark, they first beliefed that there was a problem with Forsmark......then they found out that the radioactivity came from the USSR.

[@Flurgburglr]

If the water-moderator system breaks, you lose the water, won't it cause the reactor to heat up/meltdown since it loses its coolant?

[@mattm3901]

I think it’s about the water acting as both coolant and an enabler of the fission itself. With no water, the fission and the heat generated from fission are minimized, so there is nothing to cool.

[@JC-lu4se]

@@mattm3901 The fuel is still hot for years due to beta decay.

[@Lanse1984]

​@@JC-lu4seyeah but not hot enough to go into thermal meltdown

[@MrSummitville]

​@@Lanse1984Fukushima blew up after a successful shutdown!

[@seekbalance6891]

whenever you conduct a test, you better be prepared to handle a test failure.

[@FalcoGer]

I believe your understanding of the incident is lacking. Nobody hit the wrong button. The city needed more power and people didn't anticipate Xe135 buildup. When they then brought the reactor to half power, the xenon continued to build up (as it was mostly from decay products and came with a 6 hour delay). This brought the power to a very low level that was not enough to generate any steam. With no new neutrons to combine with the xenon it would have to naturally decay. From there they brought the rods out manually to bring the power back up. This started to boil the water with a low water flow rate. The low flow rate meant that the water was starting to boil off the top, creating cavities of steam. The control rods were half carbon, which made them better at controlling. The fuel heated up quickly. The operators then hit the scram controls. The rods move fairly slowly. The graphite tips of the control rods pushed the remaining water out of the way at the bottom of the reaction vessel. With no cooling (the water was displaced) the power spiked, vaporizing the fuel and blowing the pressure vessel. You sound very biased and condescending. Not only that, your impossible scenario happened quite nicely in japan, one of the most modern and technological countries in the world. The water boiled off, the rods got hot and melted through the pressure vessel, steam reacted with the zirconium fuel cladding into hydrogen (and zirconium oxide). The overpressure valves opened and steam and hydrogen was let into the wetwell. Because the coolent was offline (in one case because an operator turned it off, but was unable to turn it back on later), the pressure built up there as well. The operators decided to release the gas (contaminated with radioactive elements). The hydrogen exploded inside the reactor building, bypassing the "invincible" containment building and releasing the crap into the atmosphere. So much for no water - no problem. Oh and they were not RBMK reactors either. I'm not saying Japanese operators are stupid. I'm saying human error is human. And even the russians are human. Mistakes happen, accidents happen when all prevention measures fail or are bypassed. And don't forget about your own great reactor accidents either. You can talk about great new reactor designs all day long, and perhaps they are great. But a great many reactors were built back when such designs were not yet available, and their control software still runs on magnetic tapes and relay computers.

[@stephenfriedenthal8312]

This is a great presentation. I had never considered the role of Xe before, but of course -- the rapid burn off of the accumulated Xe with the control rods removed left little course. I am curious however why the other safety defect of the RBMK, the positive void coefficient was not mentioned. My understanding was that at low power the RBMK had a positive void coefficient so, e.g., a steam bubble is a 'void', which causes power to increase, which makes more steam, more voids, etc. leading to an uncontrolled positive feedback. The control rods as i understood had two design flaws. The graphite follower which would moderate neutrons and the metallic bottom of the rod which would displace water -- and introduce a void.

[@WINuFAIL]

He does mention it when he mentions that when water boils in an rbmk, the moderator (graphite) is still present and allowed to operate even more efficiently bc water isn't absorbing neutrons (water self-dampens it's modeerating ability by absorbing many neutrons). He just doesn't use the technical term.

[@stephenfriedenthal8312]

@@WINuFAIL Not entirely. A positive void coefficient is an increase in reactivity due to a void that creates a positive feedback loop. That is what creates the super critical event. Void --> increase in reactivity --> increased power --> increased temperature --> increased void --> and so forth.

[@WINuFAIL]

@@stephenfriedenthal8312 Yes I understand. What he and I are saying is that the reason the opposite happens in other reactor types is because water is the coolant AND moderator, with no graphite present. A void means no coolant but also no mod, so reactivity and power decrease. He describes this mechanism without mentioning that this creates a feedback loop. So basically he described the first half of it.

[@JC-lu4se]

@@stephenfriedenthal8312 I agree - there is too much talk about the role of xenon. Xenon doesn't explain the pos.void coefficient as you rightfully explained. The RBMK was unstable at low power and the voids were't pushed out by the flow of water and remained in the bottom of the core resulting in potentially dangerous power anomalies.

[@JC-lu4se]

@@WINuFAIL In the RBMK, a void means the water is less dense which means less hydrogen which leads to a decrease in neutron absorption by the hydrogen and an increase in neutrons so power increases' not decreases.

[@tensevo]

This is one of the best, clear, logical presentations I have seen, on what happened, many thanks for doing this. Hopefully this knowledge and wisdom gained can prevent future disasters. For any young viewer, Chernobyl accident was a big deal at the time, it was terrifying at the time knowing that radiation was falling out of the sky and nothing you could do about it.

[@danielparsons2859]

Extremely scary time to live through. The consequences of this accident will last forever. Generations and generations will be dealing with the mess. We were always told - 'A meltdown can't happen'. Nuclear power is dangerous, very dangerous.

[@TomFynn]

What bothered me at the time, even though I was and still am deeply into physics, the information given out on the media was "maddeningly unhelpful". Lots of units like Bq, Gy, rem and Sv but no one seemed to have any hard facts.

[@av.plik.8965]

the kind of dude who makes you asleep talking about the most interesting things ever.

[@peterlohnes1]

I believe this man consumes large quantities of whiskey.

[@velinr]

Well, it could happen to western reactors too. And it has happened. Fukishima Daichi runs on General Electric reactors. The containment vessel failed, because of poor design. Still leaks radiation in the sea. Most of the reactors running today are designed in 60s and 70s. To say, that it is impossible to happen, because it hasn't napened yet, is not very smart. The scenario will be different, for sure, but the result will be the same - contamination.

[@DanielFolsom]

To be fair, what happened at Fukushima was VERY different than what happened at Chernobyl: in particularly, highly different explosion locations and causes (and that's saying nothing of the earthquake/tsunami impetus).

[@velinr]

@@DanielFolsom , you are right. But, isn't true, that every nuclear accident happened because of different reasons? If some nuclear accident happens in the future, do you think that somebody in the neighborhood will care if it is the same or different compared to Chernobyl or Fukushima? Western reactors have their own problems, that also can cause similar or worse contamination. The biggest problem of them all - neglegence. It is common everywhere. So we can't sit back and relax, because Chernobyl can't happen in the Western world. It will be TMI, Fukushima or god knows what else...

[@leviheidle524]

Remember, a meltdown hadn’t happened yet in Chernobyl, but did that mean it couldn’t, no!

[@marianmarkovic5881]

@@velinr There is no industry in world, literaly NONE that work in safety lewels of Nuclear power plants. and results are here,... Nuclear power is Cleanest and safest of them all. period. Like it or not. amout of peaple dying per Watt of nuclear power is waaaay below any other energy source, including renewables. Sadest thing about Fukushima that trouble over power plant overshadowed 15000 causalities of earthquake and tsunami.

[@velinr]

@@marianmarkovic5881 , I'm not against nuclear energy. I believe that the future of the energy is nuclear. But the efficiency, at current level of applied technology, is very bad. And there is lot of waste. And there are lot of problems. And we should not be nearsighted nor one-sided about. Appearantly, the safety is not high enough, after such incidents happens.

[@mariaviklund4546]

The first to notice was engineers at the Swedish Forsmark Nuclear power plant. Alarms starting to go off about external contamination and after doing checks and coming to the conclusion that "It ain't us" they alerted the IAEA that "Something has happened, somewhere, and we think we know where".

[@SamnissArandeen]

"Water drains away, the reaction stops" works until you realize there's decay heat and that too can cause catastrophic problems. Fukushima Daiichi was caused by the decay heat cooling systems' power sources being washed away, and replacements not making it there in time.

[@sspringbok]

that caught my ears as well. In this lecture the prof suggests that LWR is bulletproof because when water vapourises then fission stops end of story. Then in his next video about Fukushima he explains how the fuel overheated when the water vapourized, ending up in fuel meltdown in 3 LWR reactors.. Nevertheless a great presentation, but the Japanese and the nuclear scientists after 10 years still do not have a clue what to do with the melted fuel in the Fukushima reactors. And they were kept under water for 10 yrs and still needs to be permanently cooled, so taking away the moderator does not seem to stop fission completely... I assume you still need the control material(rods) to absorb neutrons to be able to drive fission further down, but that does not work with melted fuel anymore, right? Or if you have an LWR reactor with fully inserted control rods, when the water is taken away, it would still melt? Which basically means you need both water and control rods...

[@lynel1985]

@@sspringbok modern reactors will maintain stable enough temps without coolant just through the convection of air. Intrinsically safe by design. Older ones however would still need water coverage. Spent fuel in the pools are typically now arranged in a way that supports convection cooling to sufficiently cool them ans thus need water coverage.

[@loreak128]

@@lynel1985 only gen 3 can passively cool with convection I believe, all reactors in the US are gen 2

[@sambo9855]

Has anyone noticed that every word he's writing on his clear board is backwards to his point of view?

[@drewgehringer7813]

Notice the buttonhole on his jacket's lapel appears to be on the wrong side: its actually the video that's backwards he's writing normally from his point of view, then the entire video is mirrored horizontally before upload

[@jettrooper212]

Yeah I noticed and it blew my mind.

[@TheEulerID]

UK Magnox and AGRs also use graphite moderators, but they differ from the RBMK reactors in that they use a gas coolant (carbon dioxide) in the primary circuit and boil water via a heat exchanger (which does not come into contact with the actual reactor). Also, the gas will naturally circulate via convection to take away decay heat, but do require control rods to drop in to shut the reactor down in the event of a fault. It also doesn't have the positive void coefficient issue that the RBMK reactor does. The AGRs also don't have a separate containment building, but have a 5-7 metre thick reinforced concrete pressure vessel. In any event, that seems to be a bit of an omission. The last AGRs are due to close down in the next decade or so. Their biggest problem appears to be the expense of decommissioning, as there is a large amount of irradiated graphite to deal with, and the reactor core is a lot larger than in a PWR. It's also that very large core which means it's not prone to runaway decay heat issues as there's a lot of thermal mass involved which slows down events. It means that the sort of thing that happened at Fukushima ought to be impossible as it doesn't rely on powered cooling systems after an emergency shut-down. nb. there was never an issue of Kiev losing all its power during the planned exercise. There were four RBMK reactors at Chernobyl, and only one (reactor #4) of them was to be shut down for refueling.

[@sulphurous2656]

You didn't see comments from before the HBO miniseries because they're not there.

[@studiotwopointeight]

lol - At least the HBO show got more of the facts right than this video does.

[@timmbacher]

Fakse - 2019 there were still 10 RBMK reactors (graphite-moderated) and three small EGP-6 (also graphite moderated) light-water reactors operating in Russia,[1][5] though all have been retrofitted with a number of safety updates.

[@JonnyD3ath]

Timm Bacher 'we - meaning the rest of the world' lol

[@InvictusEternal]

Admittedly I did come here after watching Chernobyl because I wanted a focused breakdown, but before here I probably watched 30 other videos. This was so well explained and I enjoyed every second of it - I wish I had you as a professor back in the day. Thank you very much.

[@DoctorEnigma01]

I like how so many people in the comments think they know nuclear physics and engineering because they watched HBOs Chernobyl

[@Rooster---ooo]

I watched it twice, ergo I know better than Mr Brown jacket!

Only you apparently.

[@basedgodstrugglin]

Yeah, each atom is like a bullet and 3.6 roentgen. I know all there is to know about nuclear physics.

[@richardl4420]

That makes us more qualified than Nikolai Fomin was.

[@3vimages471]

And you call yourself Doctor Enigma!!! So who is the pretentious prat?

[@goodsamaritan343]

The University of Illinois is lucky to have Professor David Ruzic. He delivered the best description of the conditions surrounding the Chernobyl nuclear disaster. His presentation style is simple, direct and clear. I wish all my professors had his style of teaching.

[@Smokr]

No they're not. No he didn't. No it isn't. Then you are an idiot. I'm no professor or specialist, but even I (along with many others in this thread) spotted his multiple mistakes, omissions, and outright errors. You want to know more than the kindergarten coloring-book version this dolt delivered, try the one given by Scott Manley. More detailed, more accurate, more interesting. And he didn't make mistakes so obvious even I can spot them. This is the kind of crap professors today give their students? No wonder so many of them are in the streets acting like moronic children with mental disorders.

[@hg6996]

The first to realize that there was a nuclear accident somewhere in the world weren't from Germany, they were operators of a nuclear reactor in Sweden.

[@viarnay]

Not only in Sweden they had telephone calls from many other countries..

[@piotrl.5298]

Actually first detection was made in North-East part of Poland. On April 28, at 7 a.m., radiation detectors showed levels exceeding normal by 500,000 times then the report came from a Swedish nuclear power plant...

[@MrSummitville]

​@@piotrl.5298 Is that enough to cause cancer?

[@maiwennlilas9662]

"We, And by 'we' I mean the entire world..." hahahahahahahh LOL

[@b1rito]

There was 2 explosions if i recall, one where the steam blew the biological shield, as in the lid of the reactor and the caps, off and the other came few seconds after where oxygen combined with the red hot graphite + hydrogren to cause the big boom!

[@lexinexi-hj7zo]

14:04 So that says 2014" on it. Looks glowing red hot, but those lamp shade things were lowered after the accident. So what is glowing that hot? The carbon fire was not that big from videos from after the accident. So what is that? And how if it was that hot could you or your camera not get blasted with a lethal dose of gammas?

[@pokernightcoordinator6766]

RMBK rolls off the tongue way better than RBMK...so I'm going with that, too

[@studiotwopointeight]

Why should viewers trust a so called expert who can't even get the name of the type of reactor right?

[@TheWolvesFan520]

“Worst accident ever” Lab in China: Hold my beer

[@user_7239]

Whats with these commies

[@lucaschneider1613]

@@user_7239 They hate people...

[@ITSecurityNerd]

Things a Communist country shouldn't be allowed to do. 1. Run a nuclear reactor. 2. Run a lab studying infectious diseases 3. Be Communist.

[@lucaschneider1613]

@@ITSecurityNerd Freedom is non negotiable.

[@Hobbinski]

Bhopal, India: “I beg to differ”

[@frankdeak2397]

I’m confused. Is he writing backwards? I have to rewind this until I stop thinking about him writing on glass infront of him and we’re seeing it from behind. What are we talking about again?

[@bagner5]

9:53 "Now the reactor is humming along" reactor: beeep I found that very funny

[@kornisonkiseli3248]

😆 I missed that.

[@julinho218]

like your vital signals are dead... beeeeeep

[@bulgingbattery2050]

Because Chernobyl reactor 4 had been running at low power for so many hours before the accident occurred, it was filled with xenon gas, which reduces reactivity, and is the reason why they were only able to get 200MW of power to run the safety test, AFTER removing nearly all of the control rods. The test was supposed to be run at between 700-1000MW

[@ejkk9513]

Everyone has turned into a nuclear Physicist after the 5 hour drama.. lol we know. You watched that great show. We all have.. no need to explain it like you knew that before the show told you.

[@edwardteach8452]

@@ejkk9513 Problem is that this guy gives accurate information, show or no show

[@puncheex2]

Yes, you're right.. The rector is designed to burn up (that is, neutron activate) the xenon as fast as it is created when the reactor is running at near capacity. The xenon started building up when the reactor slowed to half capacity. There are two things you can do then: stop the reactor and wait 3 days until the xenon substantially decays, or return to high capacity, which, as he says, is difficult. You are riding on a knife-edge of positive feedback - if the reactivity does start to rise because of xenon burn, the lowering of the poisoning will cause it to rise higher, burning off more, rising higher, etc, and you gave up your control when you pulled all the control rods out to get it started. In engineering terms a positive feedback loop. You have bare seconds before the rising power level boils all the water in the reactor in one massive steam explosion.

[@Bialy_1]

@@puncheex2 Tip of the rods was made out of graphite so when they started to put them all back in the same time... boom!

[@MikkoRantalainen]

Lots of interesting information but saddly also stuff that's not true, like the "maintenance break" or "hitting the wrong button". Chernobyl was designed to be refuelable while running so the test they were doing was not related to maintenance break. The test was about trying the check if the reactor can be cooled for 90 seconds in case of total factory blackout until the diesel generators kick in to generate backup power. This test had failed in similar reactors for 3 times and this was the 4th time they were trying to successfully execute the test. The accident happened because grid operators requested different power levels compared to the original test routine and the reactor operators didn't understand that the test couldn't be executed given the grid requirements. If you watch the dramatised HBO miniseries about this accident, it's more accurate description of the real accident than this video. And technically the control rods didn't have "graphite tipped rods" but the graphite was on the other end of the control rod than the boron. The problem is that the control rod was so short that if the rod was fully pulled out (allowed by the operators disabling safety systems for the test and then running the system for 10 hours without safety systems), the bottom of the rod is replaced with just water. And when you start to push the control rod downwards into the reactor, the *at the bottom of the reactor* water will be first replaced by the graphite part of the rod that was in the middle of the reactor. This increases power of the reactor near the bottom of the reactor and this was the final critical mistake after already running the reactor totally unstable after removing too many control rods. The operators in the control room indeed used control rods in a way that the reactor wasn't designed to be operated. The reactor had to have minimum of 30 control rods inserted at all times to stay safe but the operators decided to pull all but 8 rods while they were trying to increase reactor after (accidentally?) running it into xenon-poisoned state. In reality, the only safe way would have been to wait for about 20-30 hours to wait for xenon-poisoning to burn away naturally. And it's still unsafe if even a containment building could have controlled this accident because there was both steam explosion and hydrogen explosion rapidly followed by each other. The hydrogen explosion was caused by superheated zirconium in the reactor reacting with oxygen and water producing hydrogen. (This is the best available theory about the accident. We don't know the true events because there were no data collecting systems in the reactor to record enough details to be sure.)

[@stuskivens4295]

Surely the AGR power stations in the UK also use a carbon moderator?

[@Daeraxia]

Glad somebody else noticed this. Sure it isn't water cooled but we most certainly are still using graphite moderated reactors, admittedly not building any more new AGRs though.

[@nathski72]

I worked at a UK AGR, they were inherently safe IMHO. Main protection was automatic trip of control rods, they relied on gravity, followed by numerous secondary and tertiery shutdown systems. . Water filled reactors have accounted for quite a few of the accidents in the past. .

[@nathski72]

ieer.org/resource/factsheets/table-nuclear-reactor-accidents/

[@hoopahtroopah]

He’s delusional get him to the infirmary

[@carlblaskowitz7817]

Been around the feedwater all night, this was his moment... to shine.

[@valentinopopa1686]

He’s infirmary get him to the delusional

[@hoopahtroopah]

Mlj Fmdfmd go watch HBO ‘s Chernobyl then you’ll understand

[@valentinopopa1686]

Mlj Fmdfmd dude..i think them NUCULAR reactors are leaking because your “Americans grammer” is 3,6 roentgens per hour-not great not terrible 👍

[@hoopahtroopah]

Frank Heuvelman go watch HBO’s Chernobyl then after you see the last episode google “hbo Chernobyl memes “ and only then you will get the meaning of these comments

[@ThePorpoisepower]

A containment building may have helped, I may even agree to most likely have helped. But the steam explosion, lifted a 1,000 ton "biological shield" highenough go through the roof of the building before coming back down... I'm not sure 3 feet of concrete and steel is gonna stop something like that. Also RBMK's could be refueled without powering down, so I'm not sure where's getting that it couldn't.

[@Stephen-wb3wf]

I love watching this once a month or so. When can we see some new videos Prof? They are so informative yet relaxing.

[@LiveFreeOrDie2A]

It’s here under the floorboards!- it’s the squeaking of the hideous marker!!

[@Kohdok]

"Can a Chernobyl happen here? Absolutely not!" >SL-1 has entered the chat...

[@ItsFriscoBaby]

Yeah but usa good, russia bad

[@clint6716]

You're referencing SL-1 as if it were an industry standard and not an experiment. Not to mention it was 25 years before Chernobyl. Nice try to draw false comparisons though. The same incident wouldn't happen here. Just look at France.

[@Kohdok]

@@clint6716 Ah, yes, comparing a steam explosion caused by improper control rod operation to a steam explosion caused by improper control rod operation is totally a "False Comparison"...

[@clint6716]

@@Kohdok you missed the more important parts of my response. This was in 61, before most of the safety precautions that were ignored in Chernobyl even existed. There 'containment' structure was 1/6th the size it needed to be and not made of the right material. Comparing these two incidents disingenuously ignores all the research that took place between the two events, and more so discounts the even more modern advancements since. The answer is still no, it wouldn't happen here.

[@crypticgaming4485]

@@Kohdok yeah because one happened 20 years before the other, before we even knew how to deal with all of the bullshit that comes along with the shit. Long island was an unfortunate reality, but he's right. A chernobyl could never have happened after long island, cause we wisened up, while the Russians didn't know.

[@koshycheese8957]

Sweden: yeah, I think we detected some radiation USSR: you DIDNT! Because it’s NOT there!

[@nicwilson58]

This description is not totally accurate, the description of why the power dropped "wrong button press" is wrong, and the reason it spiked is inaccurate. This needs updating.

[@professorrinse8028]

Don't bother wasting your time Nic, any attempts to correct all the inaccuracies in this video will be deleted. It's rather sad that this 'professor' would rather educate people with garbage misinformation about Chernobyl.

[@bridgerectifier7711]

@@professorrinse8028 - That's not strictly true. If you watch the next vid in this series called "Xenon can be a problem", it goes on to explain in detail about xenon poisoning. More interestingly, there are several posts from a licenced nuclear operator who has posted a staggering number of pages detailing his criticisms to the vid and countering with his actual experience. kzbin.info/www/bejne/iIu0qH9jZ7yHnaM

[@bridgerectifier7711]

Nic Wilson - Please watch the next vid in this series called "Xenon can be a problem" kzbin.info/www/bejne/iIu0qH9jZ7yHnaM

[@professorrinse8028]

The 'Professor' says it's an RMBK reactor in the description, and states the Chernobyl technicians simply pushed the wrong button which caused reactor 4 to explode. This whole video is laughably inaccurate, but hey, this is KZbin, all one needs to do is dress like a professor, say a few technical words and everyone thinks your spiel is true.

[@bridgerectifier7711]

@@professorrinse8028 - It's not that inaccurate if the button he was referring to was the "AZ" button which inserted all the control rods. He very briefly mentions that the operators were not aware that the Boron Steel rods were poorly designed and that a surge of power could be observed when the rods were inserted.

[@Jlopeztx]

The best explanation of the Chernobyl disaster I have heard. Thank you.

[@Multichick]

I love your visual presentation style, extremely effective, thank you! 🙏🏼

[@jaxman1235]

It was a RBMK reactor. Not a RMBK Reactor.