Anatoly Dyatlov on the Chernobyl Nuclear Power Plant Accident

On the night of April 25-26, 1986, Anatoly Dyatlov, deputy chief engineer of the Chernobyl Nuclear Power Plant, supervised an important test at the fourth power unit on the "turbogenerator rundown". However, as a result of a complex confluence of technical factors, design features of the RBMK-1000 reactor and certain procedural errors, a serious accident occurred. The reactor explosion marked the beginning of a global man-made disaster, the consequences of which are still felt today. In 1987, Dyatlov was found to be one of those responsible for the accident and sentenced to 10 years in prison.

After his early release due to his deteriorating health, Anatoly Stepanovich repeatedly tried to convey his point of view to the general public regarding the accident. He wrote a book, “Chernobyl. How It Was,” where he detailed his version of the causes of the disaster and also gave several interviews. We offer you one of them, filled with personal memories and technical details.

In his account, Dyatlov covers in detail the course of the test that night, focusing not only on the actions of the personnel but also on the general atmosphere of work at the nuclear power plant. He explains in detail the design features of the RBMK-1000 reactor, focusing on a number of vulnerabilities hidden from the operators. According to him, many critical characteristics of the reactor, especially at low power, were unknown to the operators, which significantly limited their ability to prevent the development of an emergency.

Dyatlov describes step by step the chain of events that night: preparations for the experiment, the rapid decline in reactor power, attempts to restore stability to the facility, and the tense struggle for control of the situation. He shares his memories of the first moments after the explosion, when the plant's team tried to comprehend the scale of what had happened and take emergency measures to minimize the consequences of the reactor's destruction.

The interview also touches on the broader context – the organisational specifics of preparing for the test, the process of coordinating its parameters and the interaction between different levels of management. Dyatlov talks about working regulations, technical limitations and difficulties in transmitting information. His story allows us to better understand the conditions under which the workers of the Chernobyl NPP operated on the night of the tragedy. This is an important eyewitness account that helps to put together a more comprehensive picture of the events that led to the largest nuclear accident in history. stories humanity.

Comments

[sidorov]

Whatever the reactor, there was an operating manual and it was possible to simply reduce the power to the required value without subsequent attempts to increase it - in automatic mode.True, it takes longer. Did you want it to be faster?

So Woodpecker would explain, but why the hell did they turn off the automation and protection?
They led the crayfish around the corner, got confused and ended up blowing it up.

Those who seek new paths will find them.
A few freaks will always be able to come up with something that even several institutes with academics won't be able to figure out. Even in simpler cases than with a nuclear reactor. If you didn't know the specifics, why did you deviate from the instructions?..... ""... And we thought... "... So he sat down. Together with the director.

[Doctor]

Whatever the reactor, there was an operating manual and it was possible to simply reduce the power to the required value without subsequent attempts to increase it in automatic mode. True, this takes longer. Did you want it faster?

So Woodpecker would explain, but why the hell did they turn off the automation and protection?
They led the crayfish around the corner, got confused and ended up blowing it up.

Those who seek new paths will find them.
A few freaks will always be able to come up with something that even several institutes with academics won't be able to figure out. Even in simpler cases than with a nuclear reactor. If they didn't know the specifics, why did they deviate from the instructions?..... ""... And we thought... "... So he sat down. Together with the director crying

Reducing power, increasing power - all this is normal for the operation of the station and any energy mechanism in general, including in manual mode. You press the gas and brake in a car and nothing.
So they slammed on the brakes, and after that the car, on the contrary, started to accelerate!

The protections on the reactor itself were turned on, and those that were turned off on the turbogenerator did not affect the accident in any way; no signals for their activation were recorded.

[barbos]

Reducing power, increasing power - all this is normal for the operation of the station and any energy mechanism in general, including in manual mode. You press the gas and brake in the car and nothing happens

At nuclear power plants, this is not done so quickly. Plus, there were all sorts of experiments on the generator turbine running out against the backdrop of dispatchers demanding that power be increased that evening. And before that, they had some unpleasant incidents that were ignored.
Academician Aleksandrov's vision and analysis of what happened are interesting. As are the protests of the same Sakharov about the transfer of nuclear energy to civilians.

[solar]

simply reduce the power to the required value without subsequent attempts to increase it - it was possible in automatic mode.

It is impossible. In transitional modes during start-up and shutdown, the automatic system for leveling thermal distortions on the reactor was not provided for by the project. It was believed that nothing special could happen in this short time, so there was no point in spending public money on this. "The economy must be economical."
In normal mode, this was the case, but according to the conditions of the experiment, it was necessary to first set a certain reactor power and fix it. In normal launch modes, this was not necessary.

[Cartographer]

Quote: sidorov

Why the hell did you turn off the automation and protection?

Because the defense would not allow the experiment to be carried out. A plan was written and approved by the director.
Now no one will tell what really happened at the control post. And the automation was quite archaic back then. To get printouts with the actual position of the rods, you had to run to the next room.

[Edvid]

The reactor designers did not provide "foolproofing"... The personnel were hoping for the last level of protection - a red button that had to be pressed manually. The operator pressed it, but it was too late. The accident had already begun and was going faster than manual control. The moderating rods were stuck halfway...

[Amateur]

A man, under whose leadership everything that could be violated was violated, tries to shift the blame onto others? Aren't you ashamed! Academician Legasov, feeling guilty for the mistakes in the design and organization of the operation of the reactors of this series, committed suicide. Academician Aleksandrov resigned from the post of President of the USSR Academy of Sciences and drank himself to death.

[Doctor]

A man, under whose leadership everything that could be violated was violated, tries to shift the blame onto others? Aren't you ashamed! Academician Legasov, feeling guilty for the mistakes in the design and organization of the operation of the reactors of this series, committed suicide. Academician Aleksandrov resigned from the post of President of the USSR Academy of Sciences and drank himself to death.

The State Commission of Rosatomnadzor of the USSR conducted a detailed inspection in 1991. There is no "everything that could be violated was violated", there are individual minor violations that did not affect the development of the accident.
They are always there, check anyone)).

The cause of the explosion was said to be design flaws in the reactor.

[Amateur]

The cause of the explosion was said to be the reactor's design flaws

7 RBMK reactors are still in operation in the Russian Federation. In the spring of 1986, more than 30 such reactors were in operation worldwide. And not a single one exploded "due to design flaws." Except for Chernobyl. The main "design flaw" of which turned out to be insufficient "foolproofing," who, in violation of all instructions, "drove" the reactor into a mode in which it could not operate due to "design features."
p.s. If you take a Mercedes, accelerate to 150 km/h and enter a turn on an icy road, and end up crashing into a pole - is this a "design flaw" of the Mercedes or the driver's brain?
pps In 1991, the commission could write anything. Read Legasov's "Diary". It's on the Internet.

[Doctor]

7 RBMK reactors are still in operation in the Russian Federation. In the spring of 1986, more than 30 such reactors were in operation worldwide. And not a single one exploded "due to design flaws." Except for Chernobyl. The main "design flaw" of which turned out to be insufficient "foolproofing," who, in violation of all instructions, "drove" the reactor into a mode in which it could not operate due to "design features."
ps If you take a Mercedes, accelerate to 150 km/h and enter a turn on an icy road, and end up crashing into a pole - is this a "design flaw" of the Mercedes or the driver's brain?
pps In 1991, the commission could write anything. Read Legasov's "Diary". It's on the Internet.

Firstly, it exploded. At the Leningrad Nuclear Power Plant. But not very much)).
No conclusions were drawn, although the reason is the same.

No one accelerated the Mercedes, on the contrary, they stopped it. Imagine, you drive up to a stop, step on the brakes, and your Mercedes goes CRAP, instead of stopping, it jumps forward and runs over people.
Such a small "design feature".

The 1991 commission couldn't, it was already inter-industry and independent. And the first one - from the reactor developers, they immediately figured out what was going on and found scapegoats.
And who should they imprison, their bosses, Heroes of Socialist Labor Aleksandrov and Dollezhal?
No, that won't do, it's simpler than engineer Dyatlov, he only has the Badge of Honor and the Labor Banner for impeccable work.

This cartoon about the staff's guilt was launched first and it is still going around, but the serious analysis that took place later is in the shadows.

Why did Legasov shoot himself if the stupid engineers were to blame?

[Cartographer]

Quote: Amateur

Academician Legasov, feeling guilty for the mistakes in the design and operation of the reactors of this series, committed suicide

He committed suicide because he could not defeat the system. Yes, and your statement "feeling guilty for mistakes in the design and organization of the operation of the reactors" directly speaks of design flaws. The same applies to Alexandrov.

[yuriy55]

There was no point in conducting experiments with dynamite in a powder warehouse.
Such scientists had to be nipped in the bud...
Was there no way to calculate the probable consequences? How many comrades were lost in the aftermath...
* * *
I am increasingly inclined to believe that the accident was caused by idiots with malicious intent...

[Doctor]

There was no point in conducting experiments with dynamite in a powder warehouse.
Such scientists had to be nipped in the bud...
Was there no way to calculate the probable consequences? How many comrades were lost in the aftermath...
* * *
I am increasingly inclined to believe that the accident was caused by idiots with malicious intent...

The "experiment" was carried out for the 4th time.
Before that, in 1982,1984, 1985 and XNUMX at other power units of the station. And Automatic The SAOR (Automatic Reactor Cooling System) protection was also turned off. And this was APPROVED, because they were ready to turn it on manually.
But the automation didn't even try to turn it on, no signals from the relay were recorded, everything happened in 6 seconds.))

This is a production experiment ON A TURBINE, not on a reactor, it is located in a different building altogether. And for it, they even bought a special stand in Germany, in order to measure not only the duration of the flywheel's inertia, but also vibration, the condition of the bearings, etc.

There, turbine operators from the Kharkov plant were sitting with stopwatches (conditionally), all of this was timed to coincide with the PLANNED shutdown of the reactor.

[Amateur]

the accident was caused by idiots with malicious intent...

Morons, in principle, do not have malicious intent because they simply do not understand what they are doing. Here, just above, one in his comments compares the reactor with a passenger car: press the pedal - it goes, press the brake - it stops. He does not realize that high-power cars, in principle, do not like changes in their operating modes. They accelerate to optimal speeds, and then remove power in all sorts of different tricky ways.

[Doctor]

Morons, in principle, do not have malicious intent because they simply do not understand what they are doing. Here, just above, one in his comments compares the reactor with a passenger car: press the pedal - it goes, press the brake - it stops. He does not realize that high-power cars, in principle, do not like changes in their operating modes. They accelerate to optimal speeds, and then remove power in all sorts of different tricky ways.

You compared it with Mercedes initially.))
ANY machines must be controllable, especially high-power ones. And controllability is changing operating modes, and without any "tricky methods".

There are channels in the graphite, into which you can insert either a fuel assembly (FA) with uranium, or a braking rod with boron, or even plug them with a graphite rod.

The more fuel assemblies in the channels, the more they interact with each other and the greater the neutron flux and the hotter the reactor. It's GAS in a car.

The more boron rods (neutron inhibitors) there are in the channels, the slower the reaction and the colder the reactor. This is a BRAKE.

They began to completely shut down the reactor for repairs and pressed the AZ button, which sent ALMOST ALL the boron rods down. Expecting, naturally, that the reactor would stop.

And then he went and exploded.

Design feature.

[Amateur]

ALMOST ALL the bur rods went down.

If they had gone down and stood in their places, nothing would have happened. But since the reactor was "overheated" by this time, the rods got stuck in the middle due to thermal expansion of the metal. In addition, the humidity of the graphite was higher than normal, which caused water vapor to appear, which began to throw out fragments of the graphite rods.

[Doctor]

If they had gone down and stood in their places, nothing would have happened. But since the reactor was "overheated" by this time, the rods got stuck in the middle due to thermal expansion of the metal. In addition, the humidity of the graphite was higher than normal, which caused water vapor to appear, which began to throw out fragments of the graphite rods.

Overheated?)) There are actually "thermometers" there. And not just one, evenly throughout the entire zone. So everything would be visible.
And if they had VERY much overheated, the automatics would have turned on the Emergency Reactor Cooling System (which, yes, was turned off manually by the Program), but the signals would have gone to the control panel, everything would have blinked red there and it would have been turned on immediately. But there were no signals on the recorders.

Until the moment when she put on the "brakes".

About the "graphite rod fragments" - no comment...

[Amateur]

About "graphite rod fragments" - no comments... laughing

https://gorsite.ru/news/proisshestviia/rukami_sbrasyvali_goryashchiy_grafit_khronika_avarii_na_chernobylskoy_aes/

[Doctor]

https://gorsite.ru/news/proisshestviia/rukami_sbrasyvali_goryashchiy_grafit_khronika_avarii_na_chernobylskoy_aes/

This is the graphite of the most active zone of the reactor. A masonry of graphite blocks 25x25 cm of different heights 20,30,50, 60 cm. They are stacked on top of each other in 14 layers, a total of 2488 columns. Each column has a through hole with a diameter of 114 mm, in it a pipe made of zirconium and stainless steel. This is the technological channel.
You can put a fuel assembly, a boron moderator or a graphite rod in there. Then the channel will be neutral.

The moderator rod on the RBMK had a two-component design, with 7 meters of boron carbide neutron absorber at the top and 4,5 meters of graphite at the bottom.
When the rod goes down, the graphite part first enters the zone and displaces the water from the channel, and only then the part with the moderator.

But, the designers did not take into account the fact that water slows down neutrons better than graphite, and when the water in the channel is displaced, the neutron flux in this zone INCREASES slightly. While they were working with 1,2,3, 5, XNUMX-XNUMX rods, this effect was not so noticeable (although the channels were torn apart at the Leningrad NPP).

But when Toptunov pressed the AZ button, 187 rods went into the zone at once...

This is the reason for the accident; the brakes, instead of slowing down, accelerated the reactor.

[solar]

There was no point in conducting experiments with dynamite in a powder warehouse.

No dynamite. The experiment itself was simple - when shutting down the reactor, use the energy stored in it for its own needs for the reactor shutdown procedures - in case of an emergency shutdown for some reason. But "the devil is in the details" :((

[Doctor]

No dynamite. The experiment itself was simple - when shutting down the reactor, use the energy stored in it for its own needs for the reactor shutdown procedures - in case of an emergency shutdown for some reason. But "the devil is in the details" :((

Not IN IT. Not in the reactor. In the flywheel of turbogenerator No. 8.

The valves on the turbogenerator were closed, the steam stopped flowing and the TG continued to rotate by inertia. But even by inertia it continued to generate electric current for some time.
This is the TIME that was measured, in case American saboteurs, for example, suddenly cut off power to the station and the mechanisms stopped.
There are reserve diesel engines there, but they also need to be started up in time, and in the meantime, the station itself needs to be powered by the flywheel inertia.

This is the essence of the experiment.

Here they are, turbo generators.

[solar]

Yes, I wrote it unclearly there.

The experiment itself was simple: when the reactor was shut down, use the accumulated energy it (turbo generator) energy for own needs for reactor shutdown procedures

If you had read my other posts, you wouldn't have any questions.

The parent organization has thrown out the idea of ​​shutting down the reactor due to the energy accumulated in the generator (and it is big and heavy, a wagon of tightly packed copper and steel, the inertia is very large) energy.

In the flywheel of turbogenerator No. 8

Not in the flywheel, but in the turbine and especially in the generator. There is no flywheel there, the generator is its own flywheel - a mountain of steel and copper. It was in vain that you provided the photo, I have seen similar ones in real life more than once.

[solar]

Theoretically, Dyatlov is to blame for not reinforcing the shift. But that's because we are wise in hindsight. There was nothing special about the experiment itself, it was a routine working situation. The lead organization came up with the idea of ​​shutting down the reactor using the energy accumulated in the generator (it was big and heavy, a wagon of tightly packed copper and steel, the inertia was very high). But the reactor's power during its adjustment went beyond the limits required by the conditions of the experiment, the easiest way would have been to cancel it and carry it out during the next reactor shutdown, reinforcing the shift for this - the regular workers couldn't handle a much larger volume of work than during a routine shutdown. But May 1 was just around the corner, the experiment was needed "for the holiday", the party comrades would not have forgiven the shift for this, so they started to twist out what they could, not understanding the consequences (the possible consequences were not specified in the instructions). :((

[UAT]

so they started to twist out whatever they could, without understanding the consequences (the possible consequences were not specified in the instructions).

Why don't you write that you manually raised the moderator rods, which should always be in place? Is it really the instructions that are to blame for this, and not extreme idiocy? The natural result is a reactor explosion, which cannot be stopped by emergency insertion of the moderator rods.

[solar]

Why don't you write that you manually raised the retarder rods, which should always be in place? Is it really the instruction manual that is to blame for this, and not extreme idiocy?

The design is to blame for this. "Economy must be economical." Automation of regulation of thermal imbalances over the reactor area worked in the operating mode, but was not provided for in the starting mode (during start-up and shutdown), it was considered that this was not necessary, since the process was relatively short and it was not important. But in this particular case it turned out to be very important - while they were regulating manually, they went beyond the limits of the experiment program and made a fatal mistake - they again increased the heat release power, which should not have been done. :((

[UAT]

for now we adjusted it manually

drove the reactor into an "iodine pit". Instead of "surrendering to the authorities" - i.e. getting a good beating, since the normal way out of this situation was long and expensive, they started to reinvent the wheel and act within the framework of simple logic - since the reactor is going out - we raise the moderator rods. Naturally, there is no effect. They manually raised those moderator rods that could not be raised under any circumstances. The reactor began to explode - they gave the command to lower the rods. The result is known.

[solar]

Everything was exactly like that. The fault of the personnel is undeniable, the instructions prohibited lifting the rods in such a situation. But it would be wrong to blame everything only on the shift personnel. There was a whole bunch of things - from the choice of the wrong type of reactor, insufficient level of automation, poorly written instructions that did not explain what some "simple" actions could lead to, to "Danish" traditions - adjusting work to important dates in the calendar - May 1, 9, November 7, etc. And the apothesis (or, as Polyakov wrote, the apothegee, was precisely Chernobyl :((

[UAT]

In general, the instructions should not explain anything. The job of the personnel is to follow the instructions. What you call a "bouquet" is simply an incorrect attempt to justify the personnel. What does the reactor type have to do with it? Such enterprising guys will blow up any type of reactor out of fear of losing something insignificant compared to the lives and health of thousands of people.

[solar]

How old are you? Did you work there back then? If not, you won't understand the situation. The staff was under extreme psychological pressure to conduct the experiment by May 1st. Those were the times.
The topic is very well known.
"-Comrade political instructor, we're out of ammunition!
- But you are a communist!
And the machine gun started firing again."

Such proactive guys will blow up any type of reactor out of fear

There was nothing in the instructions about the possible consequences of their decision. They were not going to blow anything up, and they were not even going to allow the possibility of an explosion. Instructions also need to be written wisely. The staff are classic "scapegoats".

[UAT]

Any "scapegoats" are obliged to follow instructions. The main quality of instructions is the unambiguity of the description of actions.

They weren't going to blow anything up, and they weren't even going to allow the possibility of an explosion.

Maybe so. But the unfortunate and fluffy "scapegoats" showed incredible initiative and enterprise, confidently leading the reactor to an explosion. A classic example of a fool and initiative.

[solar]

Any "scapegoats" are required to follow instructions.

Yes, that's what their superiors always say. If the test plan had worked without an accident, the same people would have rewarded them. Hypocrisy was quite widespread in the USSR.

showed incredible initiative

They showed no initiative. The plan to conduct the tests by May 1st was not theirs.

[UAT]

They showed no initiative.

And who blew up the reactor with their actions in lifting the moderator rods?

[solar]

You have a classic search for a "switchman". Take a different approach, for example. Who decided not to install full automation for starting modes? If there had been automation for regulating thermal imbalances, then the operator's erroneous actions would not have been necessary. After the accident, it was installed at all stations.

[UAT]

Your logic is completely consistent with this: if a switchman pushes his hammer into a switch, causing a serious accident, then the one who gave him the hammer is to blame.
At the same time, you are not interested in the actions of the "scapegoats" in Chernobyl.

[solar]

If you don't know the meaning of the word "switchman" in this context, look it up on the Internet.

[UAT]

You are evading answers to my arguments presented in the last two posts. And, as usually happens with those who cannot object, you move on to incorrectness. At the same time, as usual, the log in your own eye does not bother you at all.

[nachkar67]

What happened at the nuclear power plant is described and analyzed in detail in Grigory Medvedev's book "Nuclear Tan (Chernobyl Notebook), and Dyatlov is not described there as a hero at all.

[Cartographer]

Quote from: nachkar67

Grigory Medvedev's "Nuclear Tan (Chernobyl Notebook), and Dyatlov is not described there as a hero at all

This is fiction in general, which has nothing in common with reality.

[Alexander Odintsov]

A. Dyatlov was under enormous pressure. According to V. Komarov (former deputy director for science at the Smolensk NPP), an official from the department of the Central Committee of the CPSU told Dyatlov: "Conduct an inspection! Either you retire or you will be the chief engineer of the new Chernobyl NPP-2." [He] meant the new Chernobyl NPP with the 5th and 6th blocks, which was then under construction. These facts, which became known thanks to recordings of conversations at the block, were included in full in the textbook by V. L. Gurachevsky, Introduction to Nuclear Power, which is in the Rosatom library.
In turn, the head of the tests, A. Dyatlov, put pressure on the personnel, who disagreed with him more than once, and this is also the reason for the accident. At the same time, the unit was stopped for a technical stop and everyone wanted to achieve success at any cost now and immediately, because the next opportunity could only present itself in a year. There were rumors that the personnel were promised large bonuses, and the experiment was needed for someone's dissertation (which is doubtful).
According to INSAG-1, the main motive of the personnel's behavior was the desire to finish the tests faster or, more precisely, to complete them at any cost. Another factor in the accident was the low nuclear safety culture at the Chernobyl Nuclear Power Plant, the best in the USSR in all respects, but not the best in safety discipline. As follows from the court materials, the personnel often worked in "extreme modes" in pursuit of economic indicators. And then came the moment when, having driven the reactor into an uncontrollable state, they simply did not have time to shut down the reactor in time, which A. Dyatlov himself actually admits.

[Doctor]

. A. Dyatlov was under enormous pressure. According to V. Komarov (former deputy director for science at the Smolensk NPP), an official from the department of the Central Committee of the CPSU told Dyatlov: "Conduct an inspection! Either you retire, or you will be the chief engineer of the new Chernobyl NPP-2." [He] meant the new Chernobyl NPP with the 5th and 6th blocks, which was then under construction. These facts, which became known thanks to recordings of conversations at the block, were included in full in the textbook by V. L. Gurachevsky, Introduction to Nuclear Power, which is in the Rosatom library.

"Data"
Komarov's Tales - that's more accurate.

The recordings of the conversations on the block have been published, there is nothing like that there.

[75 Sergey]

An attempt to justify oneself to people and push everything onto the designers.

[Prometey]

decided to protect himself and shift the blame in the other direction. There were clear instructions with the maximum lower value of the reactor power. But no, we are great, we know everything ourselves.

[pavel.tipin]

Regarding the reactor automation, including emergency automation. If the automation was developed based on programmable logic, then there were likely to be software failures for various reasons, for example, due to surges in the power supply system. If rigid logic was used, then reliability is higher.

[Alexander]

The main reason for Chernobyl was the brain shutdown of staff and management!