Akhimov deserves a CGI mustache. That thing was glorious.

"The pressure inside the core has been released" yeah that's one way to put it

The best series about the event. No artificial drama, no BS. Top tier quality content on UKposts.

I did not expect a part three this soon, a pleasant surprise.

Imagine flying an airliner where the feedback from changes in the flight controls took two minutes to reach the pilots...

"He's in shock. Get him out of here."

I have seen dozens and dozens of doumentaries and books about this event, and people involved. This 3 episodes are absolutely best. IDK how did you manage that, but keep doing it!

What a phenomenal conclusion of this 3 part series. Very, very well done. And you even included the exercise bike in the CGI representation of the control room, impressive attention to detail! The thing that still has my brains doing triple backflips is "had to wait 5 minutes before the system would spit out the results..." Good grief, when you're dealing with a reactor capable of doing a full about-face in literal nanoseconds, at least give it a computer system that isn't walking at a snail's pace.

This is by far the most nuanced and comprehensive explanation of what was going on inside Unit 4. Bravo! 👏🏻

Quick Note, Beta effective is the effective delayed neutron fraction. Different reactors will have different Beff values, which you are correct in saying define the boundary between a normal operating state and prompt critical. However, an addition of reactivity equal to Beff when the reactor is critical (ie keff=1 or p=0) is what defines the prompt critical boundary, not just the value of Beff. For example, if a reactor's beff value is 0.005 delta k/k, a keff of 1.005 would be prompt critical (the reactor is sustaining criticality on prompt neutrons alone). The value of Beff changes over core life, but remains constant from day to day operations.

"positive SCRAM effect" is a term coined by reactor's designers in attempt to cover their backs and shift the blame to operators. It is like positive results for cancer or Alzheimer's test, you can have plus sign, but there is little positive about it. Purpose of SCRAM system according to USSR reactor designer's regulation is to "rapidly and sufficiently insert amount of negative reactivity needed to shut the reactor down and keep it in that state". It is used in cases of emergency, as a response to violation of safety critical parameters, and also to shut reactor down as last step of routine shutdown procedure. "Positive SCRAM effect" means SCRAM system doesn't meet basic requirement for that system. Moreover, "positive SCRAM effect" implies SCRAM system in some situations does exactly the opposite - it inserts positive reactivity, increasing reactor's power. This also makes various protections of the reactor to behave weird. E.g. during the event, reactor's protection detected abnormally high reactor's power level and abnormally high rate of power increase, and initiated SCRAM. Logically, it should lead to rapid insertion of amount of negative reactivity, enough to shut down the reactor and reliably keep it in shutdown state. With "positive SCRAM effect" the effect is opposite. In combination with slow rate of insertion of control rods that power peak may be rather long and devastating, it took 4 seconds for the reactor to explode with power rise from several percent to 100x of nominal, while insertion time of control rods was about 26 seconds, few time slower than on reactors of similar size, but without such large positive coefficient. That was determined be totally inadequate, while reactor designer's regulatory documents require speed of operation of control mechanisms must be enough to provide robust and efficient control of reaction and reliable shutdown, including cases of emergencies and accident. And of course positive reactivity coefficient not only opened and shortened path to unintended prompt criticality, but it also highlights control system's inadequacy. Positive reactivity coefficient not only makes the reactor unstable and hard to control, producing tendency to power swings, but also, with increase of positive reactivity coefficient, makes swings larger and faster, and this requires much faster control system to fight with than it would be needed without positive coefficient. While negative coefficient does the opposite, making the reactor more stable, self-regulating and able to counteract disturbances. That's why reactor designer's regulation state "the reactor should have negative power coefficient in general; in case the reactor would have positive power coefficient, special attention should be paid to investigate and ensure safety of the reactor in stationary, transient and accident scenarios"

I love the music because it matches the mood with the video and I’m just imagining the chaos that’s going on in the control room.

This guy is the most unbiased presenter of evidence about this event. Thanks for your research and clear understandable presentations.

"Because it's cheaper" sums up the MO of the Soviet era.

It's incredible to me that they had to wait 5 minutes for readings to be returned to them, and that the read outs on the wall were limited to just one parameter at a time. Computing speed aside, it's insane that you couldn't just stick a few more panels there and display those things all the time.

The real reason for the Chernobyl incident? Reality could barely contain the power of Akimov's mustache, and Toptunov was also becoming a threat. A KX-class incident was inevitable, and so the SCP Foundation had to terminate both mustaches under the guise of a "catastrophic reactor failure."

What a really good 3 part series

Excellent as usual. There is nothing on this planet that ignites my hunger for knowledge like the bits and pieces of details we still don't know about what was taking place in the core and how the ingredients came together in such a near perfect way to achieve the result we're all aware of. Hopefully one day I'll have something to contribute to those mysteries. 😅

38th year of the tragedy tonight

I work in the nuke industry and have been to senior reactor operations class. It worries me that the ops folks had such a poor understanding of neutronics that they didn't recognize the impacts of the graphite tipped rods. I'm not blaming them since they weren't trained, but the concept about reactivity margin and the neutron life cycle is covered very thoroughly these days, and rightfully so. An operator should know every potential impact on reactivity that can occur, no matter how slight.

Your finest masterpiece! So well done. Superb computer graphics in stunning detail, no other Chernobyl series comes close to this wealth of information. And yet, I feel a bit sad, what a terrible and needless tragedy it was. Sincere thank you for this great work and all you've done behind the scenes. These will be seen and enjoyed by many.

It's odd how wrong and even misleading HBOs Chernobyl seems to be, especially tragic for a series whose entire leitmotif is "Lies incur a debt to the truth".

A brilliant recreation of events. Just the thing I was seeking. I must now re-watch these videos.

Hey, I was looking forward to this, the series has been spectacular.

This is exactly what I needed. Thank you! Looking forward to the real time video. : )

i just finsihed Chernobyl series an hour ago and had to get the real story and glad i stumbled on this channel because it is explained so well.

Really detailed and interesting. Thank you so much

Excellent series, top notch, thank you!

If you met any of these engineers in the pub the night before and told them 'Hey, don't run that test tomorrow, the reactor will explode' what could you tell them to convince them, rather than write you off a a drunk idiot?

I am very excited because, this is my first year to celebrate the anniversary of the Chernobyl tragedy. It wasn't until a year ago that I researched everything about the tragedy (I had been putting it off for years) and it caught me, now I am interested in everything related to the subject. I am very happy to celebrate with you. Thank you for this video and all information 😃. From El Salvador 🇸🇻👋🏻

Fantastic video and you deserve way more views it is criminal

released on the 26th impressive

Another year passed since it happened. It totally shaped the way we handle nuclear safety today.

Shit, fell asleep listening to one, woke up to the other. Love the upload schedule.

"These next few minutes are critical for the survival or demise of the reactor." How critical? Prompt Critical? Da bum tisss

It feels really counter-intuitive that too much coolant can be bad for a nuclear reactor. Yet we see a problem with flow rates here, and in Three Mile Island, where the operators became convinced that there was too much water in the system.

I watched all of your videos, and they are really great and extremely insightful. To the matter itself: I strongly believe that if one chose to become a reactor operator then you will to accept from day one that you will have zero room for creativity in this profession. Here, it’s all about following regulations to the word without any fail ever. If you can’t live with that then please go for literally anything else.

Excellent video!

lets go part 3 keep up the good work

Great series, and explains very well how the operators ended up in the situation that they did and felt pretty confident they could just hit the SCRAM button and go home without blowing anything up. There was one detail I'm sure I remember hearing on some documentary about the incident years ago, but have never heard mentioned since. Apparently it was necessary to type the required generator output into the control system, i.e. 500MW and this was quite easy to forget/not register properly, and when the shift changed it's possible Toptunov forgot to do this and that's why there was a sudden power decrease which resulted in the mass control rod withdrawal to get back up to 200MW. For me this is the nub of the whole accident, without the sudden power decrease and subsequent actions to correct the low power level there would have been no accident (well at least not on this day, although the inherent problem of the graphite displacers was an accident waiting to happen) I do feel Dyatlov has been given a pretty rough deal from the new series, which more or less pins the blame on him to a large extent, which just seems unfair. Legasov gets a positive representation in the series , biut it could easily be argued he was much more culpable than Dyatlove, he knew about the problems with the graphite tips and was part of the establishment that approved and built RBMK reactors, knowing full well they didn't have the technology to really make them safe (5-15 mins for a computer to tell you if your reactor configuration is safe, lol! that's just bonkers)

So they were running a test on a xenon-poisoned reactor they did not really understand and which was inherently unstable and whose emergency brake acted like an accelerator in the early stage of its employment . Does that sum it up ?

I don't get it... Why is was so hard for reactor designers to add a simple gauge (digital all analog) that will show (in real time mode) the exact number of control rods inserted? Why it needs to be calculated via SCALA with 5min lag every now and then? I get that neutron flow, or core temperature gradient in such enormous stucture like RBMK is rather comlicated and somewhat abstract matter that cannot be measured on the demand. But controls rods have very simple parameters: overall number of rods currently inserted in the core and depth (in meters) on witch those rods are actually inserted

Brilliant!

Its 38 years since the disaster tomorrow too

Wow I'm actually first, "No views".

Happy Chernobyl Eve Everyone!!!!!

No joke, since you started posting videos, I've noticed a lot more people defend Dyatlov. Three years ago, I legit got banned from an engineering discord server for getting into an argument about his role in the disaster.

Call me crazy, but i still think the RBMK is an elegant design. It is a big advantage to be able to use low enriched uranium as fuel. The management is solely to blame here as they are the ones who should have been more cautious assessing the risks involved of operating such a power plant. Also the supporting technology simply wasn't good enough at the time to provide necessary feedback to the operators. Nuclear reactors are simply too complex to be operated by hand, Three mile island is another great example of this. Just like with an F16, without the computer, you would crash.

Petition to change the channel name to That Chernobyl Daddy..

i just saw this video and i clicked instantly on it. I'M CURIOUS!

I'm sorry, is there an exercise bike in the background of the animation of Dyatlov?

what chernobyl video game did you use for thumbnail?

I had a REACTION (sry) to the background music, can you tell which pieces you used?

This video posting lines up with the incident time in my local time

so how could this be avoidable? what should have happened in which situation to avoid the explosion? because i think the design alone is not the only reason for the catastrophe

I just finished the second part. Lucky me

15:14 "Combined, we now have approximately 6 times the reactivity threshold..." I do not understand where you're coming from with this number. There is a beta eff of about 4.5 from the positive void coefficient, and 1.1 from the positive scram effect. Combined, that gives 4.5*1.1=4.95, or about 5. Where does the extra reactivity come from to bring this to about 6?

Another video 😭 you spoil us

Why was there a bike in the control room?

LETS GOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!

Chernobyl Guy, why are you so awesome?

Wow views and likes are skyrocketing

nice

Actually Prompt critical is the wrong term - this is used when the Neutron rate is neither increasing or decreasing but is sustained only by Neutrons emitted immediately following a fission rather than those released from the resulting fission products seconds to minutes later. The term you're looking for is "Supercritical"

Could they have just shut down the reactor during this whole ordeal or no?

Firt youtube video on actual facks is born

First

Safety culture of the USSR was the main issue. Don't say anything that may embarrass the party. Don't call politically advantageous things unsafe. Classify faults so the world and your citezens don't see the problem. So many defective products made in the mismanagement of the planned economy that many things had to be "rigged". This accident was easily avoided.

As American college professors would put it nowadays, The explosion took place cause of lack of diversity in the control room. Why was there no black women, or trans black women?

you don't have technical knowledge to talk about tea kettle let alone nuclear reactors

Ya know how many video's of this are around already? And every video have different versions of what exactly happens. So, DISLIKED. No use to post this after many has done already.

7:00 You see here in the background, the Russian backup power source in case the diesel generators fail. Simply pedal!

2N degrees centigrade is not "double" N degrees centigrade. Since the scale does not start at absolute zero.