Martin Antonenko
A Fixture
- Joined
- Jul 11, 2008
- Messages
- 8,995
Today I'm writing about one of those rare days that each of us still remembers where he was that day and what he was doing...
But a word first:
Today you get to see some pictures that are hard to bear - I show them anyway because they stand for the misfortune of the people there and this misfortune never ends...
Chernobyl...
On April 25, 1986, an experiment is planned in the 4th block of the Soviet nuclear power plant named "Lenin" at Chernobyl, in which it is to be checked whether the turbines can still supply enough electricity to ensure the emergency cooling of the reactor in the event of a complete power failure in the power plant.
In order to allow the experiment to take place under realistic conditions, the "Emergency Protection" emergency program, in which all important safety devices such as emergency cooling and retracting the brake rods are combined, was switched off beforehand.
But the start of the experiment was postponed, so that the unprepared night shift of April 26, 1986 had to take over the implementation of an experiment whose test arrangement left the reactor practically defenseless.
Due to an operating error by the inexperienced reactor operator Leonid Toptunov...
...the reactor output drops sharply shortly before the start of the experiment.
To raise it again, the operators remove brake rods (which can be used to control the atomic chain reaction), falling below the minimum allowed limit of 28 rods...:
This makes the reactor even more difficult to control and in a dangerously safe state.
The deputy chief engineer of the power plant, Anatoly Dyatlov...
…orders the start of the experiment anyway.
The operators switch on too many cooling pumps so that the reactor, which is working with little power, can no longer evaporate the water flowing around it.
The water begins to boil and the first hydraulic hammers can be heard.
Aleksandr Akimov…
... the shift manager, and Toptunov want to stop the test immediately.
Chief engineer Dyatlov replies: "Another minute or two and everything will be over! A little more agile, gentlemen!"
It is 1:22:30 a.m.
When the operating crew switched off the power and only the turbine's run-down energy drove the water pumps, less cooling water was pumped through the reactor core again. The water gets hotter, but only reaches boiling temperature.
Since the reactor can only be adequately cooled when the cooling water is evaporating, its performance began to increase.
It is 1:23:04 am.
At this point at the latest, the emergency protection would have started completely and would have prevented the catastrophe, but it is switched off!
When Akimov noticed the sudden increase in power in the reactor, he manually triggered the emergency protection at 1:23:40 a.m. All brake rods that were not in the active zone were immediately run in (over 200 pieces!).
But it is precisely at this point that the RBMK reactor shows its most serious design flaw: the insertion speed of the fuel rods is far too low!
In addition, there are graphite heads on the lower tip of the brake rods, which only accelerate the chain reaction. The retraction of the fuel rods should stop the chain reaction.
The safety mechanism of every nuclear power plant is based on this concept. The design flaw of the RBMK now leads to exactly the opposite!
The effect that occurs is best compared to a car accelerating sharply: You slam on the brakes hard to slow down, but instead the car only accelerates even more...
Because the graphite tips were introduced first, power surged for a moment - the final thrust, the "death knell" for the runaway reactor.
A chemical reaction now begins between the zirconium encasing the now ruptured fuel chambers and the steam. Hydrogen and oxygen are formed - oxyhydrogen!
And then Dyatlov's sentence comes true: In less than two minutes it's really all over!
On April 26, 1986 at exactly 1:23:58 a.m., a massive oxyhydrogen explosion ruptures the reactor and everything around it.
A large part of the radioactive contents of the reactor was ejected outside, huge amounts of radioactivity are released into the environment.
Glowing parts also ignite the tar roofing felt on the roofs of the engine house and the neighboring 3rd block.
**continued next post**
But a word first:
Today you get to see some pictures that are hard to bear - I show them anyway because they stand for the misfortune of the people there and this misfortune never ends...
Chernobyl...
On April 25, 1986, an experiment is planned in the 4th block of the Soviet nuclear power plant named "Lenin" at Chernobyl, in which it is to be checked whether the turbines can still supply enough electricity to ensure the emergency cooling of the reactor in the event of a complete power failure in the power plant.
In order to allow the experiment to take place under realistic conditions, the "Emergency Protection" emergency program, in which all important safety devices such as emergency cooling and retracting the brake rods are combined, was switched off beforehand.
But the start of the experiment was postponed, so that the unprepared night shift of April 26, 1986 had to take over the implementation of an experiment whose test arrangement left the reactor practically defenseless.
Due to an operating error by the inexperienced reactor operator Leonid Toptunov...
...the reactor output drops sharply shortly before the start of the experiment.
To raise it again, the operators remove brake rods (which can be used to control the atomic chain reaction), falling below the minimum allowed limit of 28 rods...:
This makes the reactor even more difficult to control and in a dangerously safe state.
The deputy chief engineer of the power plant, Anatoly Dyatlov...
…orders the start of the experiment anyway.
The operators switch on too many cooling pumps so that the reactor, which is working with little power, can no longer evaporate the water flowing around it.
The water begins to boil and the first hydraulic hammers can be heard.
Aleksandr Akimov…
... the shift manager, and Toptunov want to stop the test immediately.
Chief engineer Dyatlov replies: "Another minute or two and everything will be over! A little more agile, gentlemen!"
It is 1:22:30 a.m.
When the operating crew switched off the power and only the turbine's run-down energy drove the water pumps, less cooling water was pumped through the reactor core again. The water gets hotter, but only reaches boiling temperature.
Since the reactor can only be adequately cooled when the cooling water is evaporating, its performance began to increase.
It is 1:23:04 am.
At this point at the latest, the emergency protection would have started completely and would have prevented the catastrophe, but it is switched off!
When Akimov noticed the sudden increase in power in the reactor, he manually triggered the emergency protection at 1:23:40 a.m. All brake rods that were not in the active zone were immediately run in (over 200 pieces!).
But it is precisely at this point that the RBMK reactor shows its most serious design flaw: the insertion speed of the fuel rods is far too low!
In addition, there are graphite heads on the lower tip of the brake rods, which only accelerate the chain reaction. The retraction of the fuel rods should stop the chain reaction.
The safety mechanism of every nuclear power plant is based on this concept. The design flaw of the RBMK now leads to exactly the opposite!
The effect that occurs is best compared to a car accelerating sharply: You slam on the brakes hard to slow down, but instead the car only accelerates even more...
Because the graphite tips were introduced first, power surged for a moment - the final thrust, the "death knell" for the runaway reactor.
A chemical reaction now begins between the zirconium encasing the now ruptured fuel chambers and the steam. Hydrogen and oxygen are formed - oxyhydrogen!
And then Dyatlov's sentence comes true: In less than two minutes it's really all over!
On April 26, 1986 at exactly 1:23:58 a.m., a massive oxyhydrogen explosion ruptures the reactor and everything around it.
A large part of the radioactive contents of the reactor was ejected outside, huge amounts of radioactivity are released into the environment.
Glowing parts also ignite the tar roofing felt on the roofs of the engine house and the neighboring 3rd block.
**continued next post**
