Nuclear Physicist Reacts - Chernobyl Episode 5 - Vichnaya Pamyat

[@YourFriendlyNuclearPhysicist]

Episode 5!!! It was great reviewing this series and I’d definitely watch it again! Any suggestions for more short series with physics/nuclear engineering concept you’d like me to react to? ☢️👩🏽‍🔬

[@Infinity-Minus-One]

the demon core scene from 'Fat Man and Little Boy' , where Slotin gets a lethal radiation dose

[@madcow3417]

Can I assume you've seen the movie China Syndrome from 1979?

[@Genin99]

Have you found the Captain Planet episode that I've requested? I just don't want to keep requesting the same things over and over again.

[@ralfbaechle]

I think the series did really well in creating the atmosphere of the Soviet eighties, the environment of the reactor to shoot in, finding a balance between nerdish accuracy on the physical and technical details and something that is watchable by people without a degree in nuclear engineering but rather a bowl of chips and a pint of something refreshing next to the TV. As such no 100% score in any category but a very good overall score.

[@ramooyeido1772]

you are a lovely butterfly and a beautiful rose you are a diamond and a pure gold you are a lovely moon in our nights you are a radiant sun shining soo bright loving you is sooo sweet its the most enjoyable thing for you are a paradise for the heart, soul and mind Everything about you is sooo unique, and attracts the eyes, and captivates the mind God surely perfected you, so glorified is he whom made you too beautiful and made you soo smart/soo bright

[@LeCharles07]

Stellan Skarsgard as Shcherbina is my favorite part of this show. The character arc is great and the acting is top notch.

[@BlackEpyon]

I had my eyes in another window (multitasking), and I was like "I know that voice!"

[@MC_Shaheen1]

💯💯

[@zDerezzed]

He's a phenomenal actor and owns the screen in whatever role he plays.

[@PracticalBibleStudies]

He is one of my favorite actors for sure.

[@lost4468yt]

Dyatlov was so reckless with the reactor because his experience was primarily in submarine nuclear reactors. He was used to dealing with reactors that could be pushed much harder and had much lower power outputs. When he transferred to power plants he kept this attitude and of course ended up running the reactor into the ground.

[@ljubicastafoka5814]

As my reactor kinetics professor used to say " you can lie to people as much as you wish, but cant lie a single time to the nature" This story provens his thesis, like, you can lie that it is safe to do the test ;)

[@Quasihamster]

Human laws say, "you're not allowed to do X without Y also happening." Natural laws say, "you can't do X without Y also happening."

[@sheert]

"...and this at last is the gift of Chernobyl"

[@k.c.sunshine1934]

Note also that an engineer studying the Fukushima plant before the disaster raised the issue that the sea wall was not built high enough - the evidence made available was that "a once in 1000 year tsunami" would over-run the wall. That engineer was over-ridden and no change was made to adapt the as-built design. The resulting disaster proved that one "can't lie a single time to the nature."

[@k.c.sunshine1934]

For those interested, please look up "Why Fukushima Was Preventable" by James M. Acton, Mark Hibbs

[@RMSTitanicWSL]

No... you can lie to nature.... It's just that nature will catch you and make you pay for lying every time..... often for the final time....

[@ab5olut3zero95]

“Why worry about something that’s never going to happen?” “Oh that’s perfect. They should put it on our money.”

[@Allan_aka_RocKITEman]

Watching this reminded me of a book quote, which I was actually able to find in my 'disintegrating' copy of the novel: _"But he suddenly remembered something that one of the ships designers had once said to him, when discussing 'fail-safe' systems: 'We can design a system that's proof against accident and stupidity; but we can't design one that's proof against deliberate malice....'"_ -- 2OO1: A SPACE ODYSSEY {novel}, by Arthur C. Clarke, Part IV, Chapter 28.

[@johnsteiner3417]

"Remove all the control rods." Me with no nuclear physics degree, "JFC, that's not going to work the way they hope."😬

[@dilkushm8008]

"And that's how an rbmk reactor core explodes "... got me chills...🙂and we are really lucky to watch this series with a nuclear physicist...❤

[@saintuk70]

5 is perhaps the best one, along with episode 1. The court room scene, and after, is excellent, if highly "made for tv". Just going back to that first episode too, it was his suicide that started the series. It's also interesting hearing your perception of the USSR as it was before its dissolution in the early 1990's, we lived in a very different world back before that (I'm a 1970's kid)

[@RedRingOfDead]

I'm a 90's kid. And every goddamn time it's spoonfed "nuclear is dangerous" blah blah blah. No it's people that are dangerous. If the idiot didn't do this test with inexperienced people this would've gone very differently. We could be nuclear power dependable now.

[@caroline4323]

I agree. I was glued to the screen when watching the explanation in court. The fifth episode was brilliant because of that. Step by step closer and closer to a catastrophe... The first episode was brilliant because they just threw us in it very quickly: suicide, a few minutes in we watch the explosion and from the perspective of an innocent citizen... And those weird scary sounds since the beginning... Good intro. ... As an Eastern Bloc person I found some things too dramatized in a heroic way and some interactions too hollywood-like, I understand it served a purpose but... And it´s probably difficult to capture what it´s like. How one acted with all the apparatchiks around... (Although watching Putin talking to his people I feel like it could be 1940ties easily. All the people just keep stone face you can´t tell a thing, they just clap at appropriate places etc.)

[@alder2460]

I'm a bit late, but l have to comment on few things. Remember, this is a TV show, certain events and people’s behavior were changed for more dramatic effect. It’s not a documentary. Graphite control rods. They were not tips. Control rods in RBMK reactor are made of two rods connected together, boron one 7m long, and graphite one, shorter by 2.5m which leaves a little space above and below of rods for water - making perfect uniform neutron flux across its height. They are connected together, and always one of them is in a reactor core. Without graphite rods water would fill its place, and water absorbs neutrons like boron. That's why there is a whole graphite rod, to displace water and speed up the reaction. It has to be there, otherwise the reaction wouldn't work. When the boron rod is inserted, it's sliding from the top, pushing graphite rod to the bottom, which displaces remaining water on the bottom of control rod channels, and graphite rod slides out of the reactor from the bottom. To help, there were also a few short boron rods inserted from the bottom, but they were not working yet, and were out of the reactor this whole time. Supposedly those short rods were to be connected to the system after the test was conducted. If they had been connected, the accident might not have happened because they would have inserted negative reactivity in the bottom part of the core where things went so horribly wrong. It was well known what control rods were made of. However none knew how it behaves in low power circumstances when the majority of boron rods are pulled out. The power in the reactor did not increase until the AZ-5 button was pressed - that's when graphite rods started to be slowly withdrawn from the reactor, pushing out remaining water at the bottom of the reactor. Chernobyl disaster happened because when all boron control rods are withdrawn, and reactor is unstable, poisoned and working on low power, the sudden insertion of cotrol rods (which take long 20 seconds) cause the remaining water (absorbing neutrons) on the bottom of control rods channels to be pushed out of it, and replaced by graphite, that accelerate neutrons. That make neutron flux spiked on the bottom of the reactor, where nothing was left to stop it (that short boron control rods, inserted from the bottom would be handy now), and that cause huge energy release, steam rupturing channels that made control rods stuck in that position, infinitely accelerating the reaction. That increase of power in the bottom of the reactor during shutdown was unknown to the operators, but discovered in 1983 in the Ignalina NPP, yet it was not addressed or fixed. The atmosphere in the control room was completely different from what was depicted in the show. Diatlov was also not the person presented on the screen. No screaming, no ordering, no threatening, everyone knew what to do - and that is from the testimony of the people that were that night in the control room. Atmosphere was calm and quiet. Pressing AZ-5 button WAS part of the test, so it wasn't done in reaction to increase of power, there was none before that button was pressed - however only Akimov and Toptunov were near the button and made decision to pressed it, but from others perspective they were calm without any sight of worry. Diatlov was done dirty in this series, he wasn't a villain, he was also a victim. He was strict but not tyrannical, he was respected by his coworkers, he knew his job, he was a specialist. But yes, his actions and bad decisions against safety protocols led to this disaster. After the explosion, he as almost anyone there denied the truth, but he acted in the best interest. He was the first to go to see if everybody is ok, to see fires, he led firefighters to the fires and hydrants, and even led the search for Khodemchuk. He also told staff to go home to save them form more exposure (people in control room were mostly shielded). He was not a bad guy, he had no idea what could have happened that night, he had no clue about the fatal flaw of the RBMK reactor. Noone knew how badly this reactor had been designed. He was the last chain in the chain of the disaster, if it was not him, disaster would happen somewhere else in a similar way. You can watch interviews with him on YT with english subtitles. Surprisingly Polish response to Chernobyl disaster was at first very good - when the radiation monitoring station on 28th picked up reading of extremely high radiation carried from the east, and the Polish government had no information form Moscov of what's going on,so they decided to act in the best interest of Polish people. They learned from western media about Chernobyl. They decided to distribute Lugola medication,which contains stable iodine - within a few hours 18.5 million people received it, mostly children. They stopped cattle grazing, it was recommended to give children powdered milk and to stop consuming fruits and vegetables. They also published in newspapers radiation readings and even cleaned streets with water. But before 1st May celebrations it all ended and people were encouraged to take part in it. But no matter what actions were taken, the radiation over Poland was low and completely safe to people as the average radiation dose received by Poles was 0.3 mSv over a year after Chernobyl (normal yearly background dose is 4 mSv).

[@flok462]

@@alder2460 great response. One addition: people at the institute responsible for the RBMKs knew about the effect and had safety concerns. They were shut down thou by Legasov ironically who was the deputy director at the time. The effect was also especially strong in the latest RBMKs like Chernobyl because they changed the design of the control rods in the early 1980s when they introduced 2% fuel instead of the 1.8%. Also ironically for safety reasons. Legasovs institute didnt think about updating safety procedures when introducing the change although a scientist warned the system was too complex to calculate the effects at the time.

[@ThrUkdr]

What you say at 2:49 is not true. In fact, there were 15 RBMK reactors in 1986, a minority of the ones in the Soviet Union. The majority were VVER reactors (which are pressurized water reactors similar to the ones used in western Europe). And the RBMK reactors were in fact, improved (like a "fast SCRAM", where it takes only a couple seconds to stop the chain reaction, instead of ~20 seconds as before the improvement, and the addition of pure-boron control rods without graphite tips), but of course that couldn't change the fact of the positive void coefficient (which by the way, the Canadian CANDU reactor type also has).

[@Pentium100MHz]

The modernized RBMK reactor complied with the safety regulations of the USSR, the original version did not. The void coefficient was reduced from very big to normal (still positive, but not as much). There are still a few RBMK-1000 reactors in use in Russia.

[@ThrUkdr]

@@Pentium100MHz I'm not sure whether the 'safety regulations' in the USSR were really a thing. Somehow the "SCRAM problem", that pressing SCRAM can function as a detonator in some scenarios, was kept from the nuclear workers, including people like Dyatlov (he probably would have acted differently had someone told him). So someone, possibly in the KGB, decided that this design flaw had to be kept a secret. The USSR was not a country with rule of law, but there were people who basically were above the law and no one dared to defy them, and if some high-ranking KGB official decided that the design flaw of an RBMK reactor should be kept secret, that would not be questioned, certainly not by scientists like Legasov because they had to fear KGB repercussions...

[@zemm9003]

​​​@@ThrUkdr it wasn't kept a secret. This design flaw was known but not considered important enough to be addressed with priority. Why the operators didn't know about it is a completely different question that is indeed very legitimate.

[@jasonrichardson1999]

The thing about brukhanov was that he actually paid money from his own salary into Chernobyl because they were chronically short-staffed, Chronically behind on funds,etc. Viktor loved the staff and Dyatlov was a harsh but loyal man. Also Dyatlov was the most experienced person in the reactor room that night

[@rodoidify]

Yeah it kinda sucks that the show basically got the characters mixed up, the lying apparatchik Legasov with the principled truth seeker Dyatlov and mostly blamed the operators, just like the Soviet Union initially did, because it made good television.

[@jedismasher]

@@rodoidify there is a metric fuck ton of blame for all of the engineers in the control room of that reactor. they disabled safety system after safety system to restart a xenon poisoned core. the overload and explosion doesn't happen without both. that's why the Russians never said anything about the instability of the reaction caused by the increase of the reactivity in the reactor because they designed it with a positive void coefficient. the thought was, what fucking retard would put a reactor in this exact configuration that would cause the az-5 button to spike the reactivity in a stressed reactor? only the dumbest of fools would allow this to happen. and this is where the politics of the soviet union and communism as whole idea come in. The soviet union doesn't make stupid men, or greedy men or individualized men. The soviet union only produces the highest quality of socialist men that posses none of these abhorrent, destructive and dangerous ideas. and that's actually an even better explanation of how an RBMK reactor explodes communist lies, and incompetence.

[@steveunderwood3683]

I'm old enough to have been involved in several things widely reported on the outside, from local traffic accidents to significant events in international media. It's very rare for ANY of the publicly told stores to have more than a passing resemblance to what really happened. So, don't put too much faith in anything you may have read. Every one of those stories is probably a gross distortion. Even the ones told by people who would have looked good if they had tried to stick to the truth.

[@meganoob12]

@@rodoidify have we seen the same show? becuase the show I have seen makes it clear that everyone is to be blamed. The operators are just as responsible as the soviet state and the scientists.

[@rodoidify]

The show repeats lies the Soviet state used to falsely blame the operators. It's badly researched television, don't treat it as any kind of a real source that can make things clear.

[@matt_canon]

17:51 I like how we saw Dyatlov's genuinely surprised reaction to the AZ-5 fatal flaw revelation. As arrogant and insufferable as he most certainly was, even he would probably not have run the test had he known about it.

[@reverance_pavane]

Just FYI Ulana Khomyuk (Emily Watson) wasn't an actual person. Instead she was a composite point of view character representing all the Soviet physicists who provided help in the investigation. Which is why she was detecting the initial fire, doing research into the technical design, interviewing the victims, and all the other countless background tasks that all these physicists did. Although their harassment by the KGB and the bureaucracy whilst doing so was all too real.

[@TheOldBlackCrow]

I remember when that happened... I was in the Air Force at the time as an x-ray tech. Quite interesting how little we knew at the time. Great mini series!

[@C42ST3N]

Bit late to the game here but what i notice when checking rbmk designs is, that the control rods don´t have a graphite "tip" but more likely a graphite bottom end which is 50% of the hole length of the control rod. They used the graphite as a moderator and as you said correctly it displaced the water.

[@DUH-rq1fe]

2:45 not all reactors during that time period in USSR were RBMK, they had a lot of (not affected) VVER too

[@HellDuke-]

Maybe fun fact - the scenes for Prypiat city were filmed in Vilnius. I actually live in the neighbourhood and you can sometimes spot things like signs covered

[@SimonWarren28977]

Thank you for this series! It was your reaction to episode 1 that got me to watch the miniseries multiple times, which in turn made me want to read into the incident and others like it, which knowledge has in turn helped me in my new job! 😊

[@herrbrahms]

The trouble with Legasov telling the unvarnished truth in Vienna is that even if he had wanted to, there's no way he would have. The real Legasov was married with children and grandchildren. They were most definitely under surveillance as he spoke in Vienna. Tell the truth to the world and imperil your family? A man cannot do that. Just the notion makes my blood run cold.

[@theatheearthkiller5281]

It’s a bit of a young person’s mentality to think an older person, even knowledgeably sick, would be able to throw in the towel because they don’t have many years left.

[@cjmillsnun]

Legasov wasn't the hero people thought he was. Dyatlov wasn't the villain people thought he was. Unfortunately even many years later Soviet propaganda won out over the facts. Some of the things in the series have more in common with INSAG1 rather than INSAG7. Legasov was apparently jubilant about how Vienna had gone.

[@5tarSailor]

The Actor that plays Boris Shcherbina(Ministry of Construction of the Oil and Gas Industries) was played by Stellen Skarsgård, who also played Captain Viktor Tupolev, who was the captain of the Russian Alfa class submarine, Konovalov in "Hunt for Red October". Just a nice film fact.

[@PV1230]

He recently played Baron Vladimir Harkkonen in the Dune film a couple years back.

[@rodoidify]

@@PV1230 When is a gift not a gift? :)

[@TwoMenandaCanoe]

I absolutely love your passion in reacting to this episode. Fantastic. Thank you.

[@ColCurtis]

The control rods were not graphite tipped they had a long graphite section, so when the control rods were removed, a moderator took its place to change that section around the control rod from slowing to accelerating. It's in the bottom of the reactor where the graphite sections of the rods all were, and on their way out of the reactor. The runaway started at the bottom.

[@JonLusk]

As always, this was a fantastic reaction video. My favorite part might be when you know what's about to happen or be said next and then play the video confirming that you were right. I'd love to see a video on how or if you were personally affected by the aftermath of this event. Did it have any influence on your decision to become a nuclear physicist? Were any of your family or other people you know personally affected? Are there any day-to-day things you deal with at work that are a direct result of Chernobyl (regulations, procedures, etc.)?

[@joeokabayashi8669]

Such a wonderful journey with you covering this series. Although I watched the series when it premiered, your explanations and commentary have made the series more impactful for me. Thank you!

[@juanquireyes6703]

"why worry about something that isn't going to happen?" "that's perfect, they should put that on our money." THAT WAS COLD HOLY-

[@mcsmaria28]

Thank you for explanation of the Xenon problem. I didn’t understand why it was “poison” for the reactor, but your explanation makes perfect sense! It kills the fisson by absorbing neutrons. Thank you!

[@taras3702]

That's half the problem. Xenon-135 eats neutrons 4,000 times more efficiently than Uranium -235 and as it does so it burns away. That means it acts like a control rod, but it's a control rod that can burn away very rapidly. With the control rods all withdrawn, the water boiling away in the fuel channels the only thing holding back the chain reaction was the Xenon-135. When that burned away NOTHING was keeping the chain reaction in check, and the inevitable happened. The final straw was pressing the AZ5 switch which lowered the control rods all at once, and they were tipped with graphite, which accelerates fission. When the water still in the control rods channels was replaced with graphite, the reactor exploded. They didn't even reach the floor of the reactor, they fractured and jammed from the heat precisely where they would do the most damage.

[@mcsmaria28]

@@taras3702 sooo, even without hitting the AZ5 button it sounds like something might have still happened?

[@taras3702]

@@mcsmaria28 The moment they shut off the stream to the turbine, NOTHING they did afterwards would have prevented the reactor from going prompt critical, which is much closer to a nuclear detonation than a nuclear reactor. That is an exponentially expanding chain reaction dominated by fast neutrons, not slow or thermal neutrons a reactor predominantly uses to maintain a steady chain reaction. Those are the result of fast neutrons interacting with the graphite and cooling water which heats them up and slows the neutrons down to where they are far more likely to split more Uranium 235 atoms. This is not a nuclear explosion, because the reactor core destroyed itself before a nuclear blast could occur. It was nowhere near the right configuration to begin with to act as a nuclear weapon. But it was capable of a runaway power "excursion" that took the power hundreds of times beyond it's design limit, and that was what happened. The graphite tips of the control rods caused a surge in nuclear fission on top of the rapidly expanding surge already underway in the bottom of the reactor core. The boron sections of the control rods entered the core too late to halt the nuclear runaway that begun. The two combined caused the explosion within four seconds of the operator hitting the AZ5 switch, which turned out to be a detonator because of the unstable state they pushed the reactor into and the design flaws they were not informed of. There are eleven of these reactors still in operation in Russia, and I syre hope they fixed the deadly flaw in the control rods. So yes once they pushed the reactor past the tipping point, there was no preventing the coming explosion.

[@AdiBiscevic]

Best comment by Elina when the guy asked if they are supposed to follow the crossed out instructions... "I suppose you just wing it and see what happens". Made my exhale some of my coffee...

[@rayhutchinson640]

Thank you so much for your reactions to this series! It made an excellent show even more fascinating!

[@dmytro-shulha]

Hello Elina, I really like your reaction! Your reaction and explanation sounds so professional. At the same time you are based on a tv series that isn't true mostly, missed steps like AZ5 were pressed twice, missed one more person in the control room(with great experience), missed what happens to other reactors. The TV series lost so many things and details. Before the Chernobyl disaster, RBMK had a different name Soviet union reactor... Anyway thank you for your explanation on it, I really appreciate how scientists react on it😊

[@MaxCarponera]

This is not a reaction, it's much more than that. It's a critic and an explanation. Congrats. A pity if it gets demotenized.

[@StMyles]

Thank you for your analytical review of the events. Finally a real scientist I can understand .

[@Allan_aka_RocKITEman]

AFAIK, part of the inspiration for the story of the motion picture *STAR TREK IV: THE UNDISCOVERED COUNTRY* -- particularly the explosion of the Klingon moon at the beginning of the movie -- was the incident at Chernobyl.

[@sheert]

It's interesting to read about the real Valery Legasov. In the TV show he was surprised by the accident, in real life he was already very concerned about the lack of safety in reactors in the USSR.

[@tomleslie6668]

Your reaction to this series is uniquely from the point of view of an expert. It was much appreciated.

[@vplusah]

Thank you very much for the detailed explanation of many points. It was extremely interesting to watch! I really love this show, but it's not something you want to rewatch due emotions... And I was shocked when they told about the really problem in RMBK reactors and this is all about classified materials... It was very interesting when you talked about some non-obvious things that revealed the essence a little more (you did it, it seems, better than Professor Legasov) :) So, thank you again!

[@kratanicverses4805]

I have watched the series several times and I will again. I know nothing of nuclear physics...or any of the physics but I attempt to understand and learn what my tiny, simple brain can comprehend. It has been fun watching your reactions and I appreciate your explanations that help dumb it down even more!

[@pineseeker6162]

I know I’m late to this video but back around 14:02 you said something about the devise. You said it detects how much radiation that you are exposed to and that will give them a way to regulate where you work in the plant if your exposed to radiation at all times then if I may ask what do they do to keep you being overly exposed to radiation ? And you all put yourselfs inside a dangerous work environment so you all can come up with safer and more efficient ways to create energy I just fear for your all’s safety and I’m just curious could you explain it to me please 🙏 🥺

[@АнтонОрехов-о1г]

Sorry for my bad english. It’s funny to watch all this. The tests were not for “safety,” the reactor operates without them. The tests were electrical engineering. There was a task they wanted to complete before the reactor went into a long planned maintenance shutdown. The reactor still had to be shut down before the maintenance and upgrade. The reactor in these tests is generally on the side and could have been turned off immediately after the turbine shutdown. Obviously, in the event of an emergency disconnection from the external electricity, the reactor shuts down immediately. Moreover, it shuts down from any power level and any reactivity reserve. The test takes readings from other electric and pump units. A working reactor is not needed in the test. In fact, there were no fools in the room. There was no toxicity; it’s an invention for the show. For higher ratings, an average viewer needs a target for all their hatred. The problem with that society was that the professors and designers in the institutes were perceived as gods. Propaganda assured citizens of the exclusivity and reliability of the products coming out of the scientific design bureaus. It was the same with the RBMK-1000 reactor. The regulations and instructions were written in such a way that the reactor could be widely managed without going beyond these regulations. The reserve rods were perceived in the documents only as a “control reserve” of reactivity. According to the regulations, this parameter was not considered a safety parameter. At that time, there were no computers to calculate this reactivity reserve in real time. Each rod can be lowered to different depths and interacts with many fields inside the reactor; it cannot be calculated as 1 rod = 1 unit of reserve. The computer calculated the reactivity reserve using a bunch of coefficients every 10 minutes. However, the situation develops much faster. By the way, at that moment the reactor had already begun to be less poisoned by xenon. Everyone knew about the test a week in advance, and Dyatlov himself, as the deputy chief engineer, was heavily involved in its description. He also approved this test. Therefore, the fact that Dyatlov decided to change its parameters during the test does not seem so terrible. But it turned out that under such working conditions, the reactor was unstable. Moreover, a couple of years before the incident, operating teams on different units had already begun to notice these instabilities. But the designers in their institutes didn’t care. They covered their scientific asses. Long story short, no one cursed on the block that day. They were conducting a planned electrical engineering test before the reactor went into planned maintenance and upgrade. This test was a good opportunity to shut down the reactor. No serious protections were disabled. They turned off what could be turned off according to the regulations. They raised the rods because it was allowed by the regulations. There is an opinion that everyone knew about the graphite tips; they couldn’t not know. This effect had already been detected. But this parameter was not considered dangerous. The academicians assured that everything was fine with the reactor they designed, plus the regulations were silent. They began conducting the test planned by the reactor manufacturer. But due to poor modeling of what was happening inside the reactor under the given conditions, what happened, happened. The mistake was that the reactor could have been shut down immediately at the start of the test, but it continued operating for another 40 seconds under deteriorating conditions. BUT IT WAS NO LONGER NEEDED. No one gave the command to shut down the reactor; perhaps the operator was waiting for the leader’s command, and the leader was waiting for Dyatlov since he was no longer the chief, as Dyatlov had arrived. So, everyone stood there for a minute, watching the electrical engineering part of the test. And when they shut it down, it exploded. Six seconds before the explosion, all indicators were normal. Do you think it’s normal for a reactor to explode just six seconds after the first indication? Did the designers create a safe reactor? In the end, not a single academic designer was harmed, so as not to diminish the people’s faith in the Academy of Sciences of the USSR. As usual, they wanted to shift all the blame onto the workers. But they couldn’t make it all smooth.

[@daviddixon9991]

I'd like to hear your take on a scene from Episode 2, where Khomyuk claimed that the corium "lava", when it came into contact with the full water tanks, would produce an explosion of 2-4 megatons. That seems WAY too high for a thermal explosion (by a factor of 10^3 or more). In a reddit AMA, Craig Mazin said he got that figure from a Soviet nuclear physicist, but I haven't been able to find any theoretical justification for it.

[@MrJamesBanana]

Wouldn't the Leidenfrost effect reduce that significantly? I would believe that number if all the energy could be dumped into the water simultaneously, but i feel like it would be a much slower boil

[@Jablicek]

If it were a solid lump of uranium then possibly (?), but the corium is a noxious mixture of uranium, graphite, concrete, steel, all the boron they threw on it, and whatever else the reactor and the reactor room floor was made of - all this was melted together and became the corium. Although was wildly radioactive it certainly wasn't dense enough to produce a nuclear fission response of the magnitude needed to explode like a weapon. An article from the National Board of Boiler and Pressure Vessel Inspectors explores the potential from pressure-vessel explosions. You wouldn't want to be near it, but 2-4MT (sometimes said to be 3-5MT) was not it - possibly only 0.4KT. The aquifer acts as a pressure-vessel, as it's contained.

[@rodoidify]

It's simply wrong. Not only is it false, they didn't fear absurd h-bomb sized explosions at the time of the accident, they feared steaming water would spread more radioactivity.

[@taras3702]

@@rodoidify They feared the Corium would cause steam explosions as well as fission further. Water would enable a chain reaction to continue in the white hot Corium blobs. Therefore, the continuing chain reaction generates more dangerous fission products for steam explosions to eject into the environment.

[@jordangifford6544]

Being born in the early 90’s, this series was an eye opener, the acting itself is phenomenal. Absolutely is a thrilling watch

[@pizzafrenzyman]

Such a wonderful series. Thank you for covering it.

[@Limpi43]

I occasionally rewatch some parts of this series. The beginning for what would it have looked like; the miners part; and the trial where they explain what and why did happened.

[@sadunlap]

Starting around 13:20 it appears that you take the dramatic re-enactment at face value. According to journalists in the 80s (and today you can read Masha Gessen's article about this mini-series) to find out that no one in the control room argued at all. Everyone robotically carried out what Diatlov told them to do. But this servile behavior does not make for good television watching so the writers fabricated the control room scenes from whole cloth. I find the reality of how a "shut up and do what you're told" society had nuclear power far more frightening than anything I saw in this mini-series.

[@efreitorsroul9332]

When the say "MOSCW 27th Of April" - Its not, its actually Kiev, Bogdana Khmelnitskogo street. There is a secret intsitute there, though.

[@taras3702]

What's frightening was the fact the design flaws that that caused the explosions were kept hidden from the operators, and near misses caused by the design flaws were also kept from them. If a problem exists with a nuclear reactor, the operators have every right to be warned of it. Just a few of the fuel channels rupturing was enough to fling the 1,000 ton reactor top and all the control rods in it a kilometer into the air right through the roof of the reactor building. That was due to the reactor going prompt-critical.

[@lunagal]

Thank you for your reactions and for sharing your knowledge!! I’v watched the show a few times and an abnormal amount of Chernobyl reactions. Yours was the best because you understood. 👍🏼

[@blacksheep_edge1412]

13:20 What you failed to include the rest of that scene that explains why the men who said no, "it's not safe," instead complied with raising the power back. It is because Dyatlov had the ability (and the motivation, and the means) to have them blackballed from ever working in another power plant for the rest of their lives. He also had the personality to follow through on that threat. It's one thing in the free world to hear someone talking about black balling someone else, but in the former Soviet Union it was a very real thing. Despite having an excellent education and qualifications, the right person could ensure you never got to work as anything more than a farmer if they so wanted to. That's why those men turned back to the control panel and tried to raise the power back on the reactor when they knew it wasn't safe to do so.

[@hanzo2001]

He wielded the power of cancel culture in his fingertips, much like that weirdo Weinstein guy from Hollywood

[@commandosolo1266]

Ms. Charatsidou, and open question for everyone: at the moment when AZ-5 was pushed, was there any way the reactor might have been saved? For example, suppose Akimov had known about the design flaw. Could he have inserted the rods in one at a time to slowly reduce the core reactivity, or was the explosion inevitable by then?

[@Beccinams]

In the show is say no but in real life yes.

[@FredtheDorfDorfman1985]

I liked that, “Oh that’s perfect. They should put that on our money.” RIP Valery Legasov. Yea, it still amazes me that you could stand over an RBMK at full power, and the upper biological shield is stopping that much gamma and neutrons from melting you, because that get zapped and become a super hero stuff doesn’t work. Radithor showed a whole bunch of unfortunate people that ya can’t supercharge your body with radiation, or radium and thorium ingestion, just rot your jaws off and make your bones decay. Like your channel!

[@Unotch]

The real reason is much more nuts. The tips were not of graphite. Those ractors burned mostly unenriched fuel. Cheap. They had a graphite rod coming in when the control rod was pulled out. All out meant something like centered 4.5m graphite rod over 17m fuel rod so they would have an even neutron flux. But that meant that retracting the rods was not just stepping off the brake, it also floored the gas. The xenon poisoning burned away, the core heated up, the water above became steam, so negative void coefficient, below was light water and in the center is graphite, which shifted the neutron flux to the lower part of the fuel rods. Doppler (increased reactivity of U238) can not stop a runaway reaction, so the fuel temperature coefficient is meaningless at that point especially once they push AZ5 and push the water out from below while jamming a graphite rod between the already very hot lower part of the fuel rods.

[@JJRClassic88]

I came here to say this, specifically the part on how the graphite "tips" were actually displacer rods with gaps on each end.

[@Unotch]

@@JJRClassic88 Yea, it's quite an importtant part and a bit sad that they did not portrait this utter insanity ... but then it might have been already insane enough as they told it. Anyway, by retracting nearly all the rods they unknowingly jammed the gas pedal to the floor and opened nitrous injection while the "xenon hand brake" was rapidly burning away. One other crucial detail is that they took the steam from the top and returned the cooled water from the closed feed water loop at the bottom. So when the reactore went full bore they had void at the top, no more even burn and the "hottest" part of the fission dropped down to the bottom of the fule rods. When they wanted to inject the control rods they pushed the displacers down into the nuclear hell it already was. There she blows.

[@sarahjacobs1779]

I've seen videos of reactor start ups. What makes the blue glow that is seen and what also makes the shock wave?

[@vojtechhoracek7704]

The blue glow is Cherenkov radiation which occurs when the charged particles emitted by the fissile material are passing through (typically) water. For the shock wave, I'd need to know better what you have in mind specifically, but my best guess would be the coolant pumps turning on.

[@sylvainmichaud2262]

At 7:49 _... as if you're running an ice cream making machine ..._ People in North America certainly thought of McDonald's ice cream making machine that are broken down i.e. out of order, most of the time.

[@Beccinams]

Broken down = nobody has had time to clean them

[@TheNativeEngine]

There's only one company contracted to repair it. And sometimes we had it on a cleaning mode or something. There was strict rules around it. Crazy.

[@jeffzaun1841]

There is now a KZbin channel called "The Chernobyl Guy," with a dozen or dozen videos on different aspects. He argues that Anatoly Dyatlov, the reactor control guy, was a scapegoat, that he wasn't as culpable or nasty as the Soviets (and the movie) made him out to be. I would argue the movie wanted a villain and chose him. . According to the Chernobyl guy they seem to have got Mr. Dyatlov's demeanor right but not his arrogant attitude. He did criticize subordinates but was also big on training and quality control. As Chernobyl guy recounts events it was Aleksander Akimov who made the critical errors. . What the movie says about bad design and lack of general understanding seems correct. They movie got that right, it was mostly systematic problems. . kzbin.info/www/bejne/hGW8hqKIfZitY7s

[@manusoftar]

Legazov wasn't killed by the KGB, he actually commited suicide, he made a series of audio recordings (in casettes) and then hang himself so the soviets couldn't just hide his recordings and his findings on the Chernobyl incident. He did the ultimate sacrifice so we could find out why reactor 4 melt down.

[@brianmunyon5669]

I cannot imagine what was going through the minds of the people on ground that knew the extent of that horror playing out. Great video.

[@jet6619]

Awesome insight into this Docu series, thank you! I think the end credits of this episode provides very important parts on how this all went down and the aftermath.

[@catriona_drummond]

It's not a docu series, it's fictional.

[@christopherconard2831]

7:30 At midnight there was a shift change. If you watch any of the channels that deconstruct disasters you realize it could be replaced with "And then they lit the fuse."

[@Wickwok]

This disaster undermined one of the greatest renewable clean energy resources ever created.

[@augustusarbogast9862]

Do you know why the most recent video was demonetized? Have you plead your case? Apologies, I haven't been keeping up with your (great!) work.

[@gingernutpreacher]

Yeah I want to watch it

[@efricha]

Awww, I wanted to see your reaction to the slides in the epilogue. Although based on their testimony, the portrayals of radiation sickness were far more gruesome. Ludmilla's testimony/report was very graphic about that.

[@RumbleDelta]

The best laymans' term I've heard of how Chernobyl happened is that basically they tried to fix the acceleration of a lorry by _cutting the brakes!_

[@john.ellmaker]

I had seen multiple takes on this hbo series when it was initially released, but I have to give you credit, yours is the best

[@trinalgalaxy5943]

Legasov had to commit suicide to ensure that the truth was spread about the RBMK reactors across the SU as we saw way back at the very start of the series.

[@vikingraider1961]

I read, some time ago, that this was almost unique - virtually all other "explosions" are caused by hydrogen - according to the physicist I read - the initial explosion was the core, at least partially, going "prompt critical" - ie it really was a "nuclear explosion".

[@williampezzner4229]

You have a great channel. Your reactions are awesome. You have a great voice and you make nuclear physics interesting and fun to learn. Wish you the best.

[@Draven84]

Just a comment regarding the Soviet reactors in 1986, not all were RBMK but a significant number were VVER which is a fundamentally different and safer design (and is still being constructed/exported in modern iterations). VVER was actually built in larger numbers and abroad (in "Eastern" countries) but RBMK offered higher power outputs at the time.

[@punkinhaidmartin]

"As if you're running an ice cream machine." Seems as though that's more difficult than operating a nuclear reactor judging by the rarity of a working ice cream machine at McDonalds.

[@trinalgalaxy5943]

Here is something to chew on. At Chernobyl, a power spike occurred following the activation of AZ-5 resulting in several fuel channels rupturing. Now I am talking about Chernobyl reactor 1 not 4 in 1982 in an event that exactly matched a partial meltdown that occurred at the Leningrad Reactor 1 in 1975.

[@LiamDennehy]

After watching the first episode soon after it came out, a colleague asked me what kind of show it was - they were expecting something like a documentary. I told them it was a horror movie. During and after I felt as if I had seen Saw or Nightmare on Elm Street. It is menacing, horrific and at times inhuman. It put on naked display the indifference and evil of that regime. It truly disturbed me. By the third episode I had to talk myself into pressing play.

[@zarabee2880]

Agreed! The bridge scene in the first episode made me wretch with dread 😟 the children dancing around in the flakes of dust 😢😢😢

[@arainbowinthedark2]

Ok so I'm a little confused on the graphite tip part of it because I have watched videos saying that graphite is used to stop/control the nuclear reaction in a reactor not accelerate the process; am I wrong to think that or was there a caveat in this type of reactor and situation?

[@Idsertian]

Not a nuclear physicist, but my understanding is that in the case of the RBMK, the graphite was not directly responsible for the acceleration, so much as its displacement of the water that was in the channels. A weird quirk partly due to its design of being moderated by both the water and the boron of the control rods, as well as the... *unique* situation that reactor #4 was put in. The graphite didn't directly *cause* the increase in reactivity in the bottom of the reactor, but it *did* remove the one thing that was better at moderating the reaction than it was. Ordinarily, it wouldn't be an issue, but this was not an ordinary series of events. Imagine having a pot full of boiling cooking oil over an open fire, and you drop a turkey into it. Similar thing. The oil (water, in the case of Chernobyl) is displaced by the turkey (graphite), which then splashes out into the fire (the now REALLY active bottom of the reactor), and... bang. Crude, and probably really inaccurate analogy, but the best I can explain my admittedly basic understanding of what happened. Anyone with a better explanation, feel free to correct me.

[@steveallen8987]

What I loved Most about the series was the range of people that existed under Soviet boot. The worst of mankind and yet the BEST OF MANKIND. The HEROES.

[@mrbasfed1948]

20:33 Maybe because he had a family? The state could easily destroy their lives by naming them "family of the Enemy of the People" and it would be the end for them. They didn't know that the Soviet Union will collapse in 5 years after the Chernobyl.

[@zbynekurbanek3345]

You should really really really watch the real interview with real Dyatlov. It was done in 1990 after he was back from prison, before he died of cancer. Its on KZbin. Dyatlov says that everything that happened in the control room on the night of explosion was planned. Dyatlov designed the whole thing as a test of the failsafe AZ-5. He says he was workoholic and carrierist and wanted to do the most thorough test of AZ-5 ever done. He says the test of AZ-5 was confirmed by his bosses. Dyatlovs only mistake was to trust soviet science - everything he ever read told him the AZ-5 is always safe. So if this is true the real situation is even more scary - that means no operator mistake at all - only a fatal flaw of the whole system of society and system of government. And in case it didnt happen this way in reality...it still could have. Which is equally scary. All operators in whole Soviet Union believed the AZ-5 is safe. Noone was thinking about if its a bomb or not.

[@vladvitalov]

13:08 Akimov really tried to stop the experiment, because the actions that led to the instability of the reactor were really "outside the instructions". 6 rods against 211. Imagine, 211 needles were stuck in you, then 205 were taken out, and then they were stuck back in at once. Your reaction? That's right, the reactor of the 4th Chernobyl unit reacted in this way....

[@vladvitalov]

15:30 In fact, Dyatlov was a very smart man. He was fully aware of the risks of the experiment. But, as he would later state in his last interview, it was all the fault of the "reactor construction". Although I still find it hard to believe. Because all types of emergency protection of the reactor were disabled. That already sounds bad, doesn't it?

[@WMW-82]

I once heard that the guy responsible was actually responsible for a similar accident on a soviet submarine too and after having a large dose of radiation he survived then went on to cause chernobyl

[@misskitty2133]

I love your channel! I love science and have an advanced degree in chemistry, retired. Love the tee shirt & saving to buy it. Best luck on your new venture!

[@pedroguerrero3862]

The problems that were mention were actually brought up when Chernobyl was being built. The Soviet Union actually brought in several British nuclear reactor engineers to look over the building of Chernobyl. Several of them said that there very several problems in the design but was ignored, one being that they weren't from the Soviet Union and so they knew better.

[@trinalgalaxy5943]

The really sad thing is that if you run the numbers, that reactor was savable up until they shut the pumps off. at that moment the water that was suppressing the reactor was allowed to stagnate and superheat.

[@Beccinams]

The reactor was savable until the moment they pressed the AZ-5. If the rods had been inserted a few of at the time, very slowly, there (potentially because we of course will never know) would have been no explosion. In reality there was still water going into the core and all systems were comparably stable just before they pressed the AZ-5.

[@trinalgalaxy5943]

@@Beccinams the only issue was that the test stopped a significant amount of the water from flowing through the core which allowed a smoldering reaction at the bottom of the core to spring to full force in a matter of seconds. unfortunately the control room had no way of knowing the bottom was alive since the only power monitoring was at the mid point of the reactor. the only thing that kept that reactor in any sort of check was water so a test where you stop intentionally pushing water through the core has only 1 solution, a issue magnified by the design of the control rods.

[@test40323]

It was fun watching Elina watching Chernobyl...getting so riled up!

[@laurdy]

Actually the soviets used several different designs: The RBMK, VVER and BN-350/600

[@Ludvigvanamadeus]

2:49 - not all of the Soviet reactors had this issue, just the RBMK. There was another Soviet design (VVER) that was perfectly safe and it's still being developed and exported by Russia to many countries all over the world this day with no serious incident ever happening in any of them.

[@vojtechhoracek7704]

VVER is basically the Soviet/Russian equivalent to western PWR (pressurized water reactor) technology with three separate cooling circuits.

[@romanmartinez3701]

Recently discovered your channel, very awesome.

[@informationcollectionpost3257]

In a country like Russia you have to understand that you have do what you are told or they will send you to the Gulag. (Siberia) If they were smart they would have let the reactor shut down and just let it sit until they found a way to remove Xeon gas.

[@swokatsamsiyu3590]

Completely concur, they should have let the reactor sleep it off for at least 24 hrs before even thinking about a restart. Especially because an RBMK is so sensitive to it due to its large core size and low fuel enrichment. We don't have to remove Xenon-135. It will disappear on its own through beta decay. It has a half-life of 9.2 hrs, so after 1-3 days (depending on reactor type/size) your reactor should be Xenon free and you can safely restart it.

[@informationcollectionpost3257]

@@swokatsamsiyu3590 I am not a nuclear engineer but spent 17 years of my life as mechanical engineer with an emphasis in energy production, fluids, heat transfer, and more than average self education in materials. I didn't know that Xeon gas had such a short half life.

[@swokatsamsiyu3590]

@@informationcollectionpost3257 It's all good, neither am I^^ I'm a retired Master Welder that took up studying nuclear reactors as a not-at-all nerdy hobby, with a strong emphasis on the RBMK and CANDU reactor types. Xenon poisoning happens to be one of the reactor fundamentals popping up real early in any literature you pick up about any reactor. I just have the good fortune to be able to memorise these little titbits of information without much effort. Xenon poisoning is weird. It's a noble gas and it just sits there. However, it has a really bad craving for available free neutrons (in physics speak they say it has a very large cross section). Just imagine it as a big invisible sponge that is soaking up all the neutrons in the core. If not managed very carefully, it can (and will!) severely interfere with your reactor's ability to sustain an ongoing chain reaction. It will throw the reactor's internal balance all out of wack if you force it to restart when Xenon levels are that high. You run the risk of introducing way too much positive reactivity without knowing it. The horrible Xenon poisoning mismanagement is what got the good folks at Chernobyl Unit 4 into the fine mess they found themselves in. That reactor was so poisoned out of its mind that they should have let it be, and wait until the Xenon had sufficiently decayed away. But no, they wanted to do the test NOW. Not their finest decision...

[@petchard]

Do you think there was ever a safe way to run the safety test they tried?

[@sam93931]

It's very enjoyable and interesting to watch your reactions, thx a lot :) One suggestion I have for you, a movie based on actual events, K-19 the Widowmaker. The story of Russia's first nuclear submarine malfunctioning.

[@carkawalakhatulistiwa]

3:18 Of course he has a family and children. only in this film it is not shown 3:39 you need political power to change things. not wealth and intelligence. but political support from other institutions 4:13 the reason they used female scientists was because 50% of the scientists in the Soviet Union were women. Hadi only pointed to one of the positive al in the Soviet Union 8:30 they are not arrogant but they are commanded. so it must be run no matter what 9:25 you need permission from the department and manager. You can't just ask people to work more than 40 hours. especially in the Soviet Union workers' country which always had ideals where everyone only worked 32 hours a week.

[@wildpendulum]

thank you for this comment

[@paulthing]

I really enjoyed the show as well. thank you for sharing your thoughts

[@RandomNeat]

its cool to see an actual expert talk about the issues and see actual concerns definitely exposed to me how little i knew about the subject lmao - then definitely agree on the female scientist perspective my mom is a chemist and i know from interactions i've seen as summer help as a sample prep and stories she's told that a female scientist's opinions can't go as far as they should most of the time

[@zombiehaiku7527]

Just discovered you. Heading back to the first episode.

[@NickJohnCoop]

Imagine the people who actually saw that reaction. To actually see the radiation with your eyes. It’s something that will be with us for thousands of years.

[@Evasion381]

apparently this supervisor was exposed to high radiation a couple of times before this happened, once on a submarine and had become very arrogant with regards to the dangers of it

[@aussietaipan8700]

Hey Elina, I would like to your thoughts on the first episode on that actions in 20 20 hindsight could have been done better to mitigate the issues and effects, even to stop the issue from happening at all. Subscribed and liked.

[@alexchistyakov760]

Aw you have no idea how clearly HBO displayed personal relations in Russia. You remember first episode, when Akimov was forced to evaluate reactor status from reactor rooftop in that management bunker? I've been having such episodes since Elementary School in Russia and it took too much time for me to learn how to resist it.

[@ReddwarfIV]

That was Sitnikov, not Akimov, IIRC.

[@alexchistyakov760]

@@ReddwarfIV aw, you're right. I didn't check at all.

[@paulmichaelfreedman8334]

If anything, "Chernobyl" demonstrated how in Soviet Russia, propaganda and the greatness of the state and how the state is always right, goes above all reasoning. It hit the nail on the head so hard, it went right through. The people are made stupid out of fear, constantly struggling with their conscience. Putin has done his best the last 20 years to restore this mentality, and he's succeeded by the looks of it.

[@lingeshkirsh]

In fission reaction 3 neutron will released, xenon absorbs all neutron and gets poison then core must stop the reaction. Graphite act as moderator it absorbs remaining neutron. Why the core got exploded

[@Beccinams]

18:04 Dyatlov was fully aware of the fatal flaw at this point in time.

[@wermagst]

People should not think, that problems like this only existed in the Sowjet Union. "Because it was cheaper" is pretty much the cause for most disasters caused by "western" companies too.

[@albatross5466]

As I understand it, Chief Engineer Dyatlov (the arrogant one) was responsible for a previous nuclear incident, at a different plant, in which he was so irradiated that he brought it to his home and exposed his young son and his son died. Ironically Dyatlov lived for many more years.

[@ErebosGR]

I don't think Dyatlov was driven by arrogance or greed. I think he was deeply traumatized and in denial.

[@albatross5466]

@@ErebosGR Most arrogance is a manifestation of some fear. I agree with you that he wasn't driven by arrogance, but by fear which was a prime motivating tactic in the USSR system. That fear comes across as arrogance.

[@wildpendulum]

where did you take this information from?

[@ontarioguyincalgary4845]

Good reaction thank you 😀!