What happened on April 26, 1986?
Come to an end the second month of spring of 1986. In a block control panel 4 - go the reactor of the Chernobyl NPP pass tests for increase of power. The destiny of the reactor and destiny of the world which is behind its walls that evening completely depend from 3 - x the person:
Leonid Toptunov is the senior engineer of control of the reactor,
Alexander Akimov there is a shift supervisor of the block,
Anatoly Dyatlov there is a deputy chief engineer, he directed experiment.
on April 25, in 01. 06, began deceleration of power of the power unit. Thermal power of the reactor is lowered and stabilized to the level of 50% (1600 MW). Preparation of the power unit for tests is begun. Upon the demand of the dispatcher of Kiyevenergo, implementation of the program of tests is delayed. The reactor continued to work at half power.
After change of personnel of control of the reactor...
the Three of people, led by Dyatlov, rose for a reactor wheel. Tests began.
At power deceleration is lower than of 500 MW (in respect of tests of all reactors of the CNPP decrease in less in 700 MW is forbidden ), power begins to fall uncontrollable. Dyatlov instructs to continue tests, despite Alexander and Leonid`s protests. Power continued to fall. The reactor proved extremely unstably at the low power, the reason for that - a fatal flaw in a reactor design to which engineers at introduction closed eyes 4 - go the power unit in operation.
Dyatlov was going to carry out test for capacities to 200 MW to cut a consumption of the cooling water preventing a reactor overheat. He considered that the risk in a similar situation is minimum. Power reached critical of 30 MW . The personnel do not test the slightest fright as such critical situations were frequent on the control unit of the reactor. The board already showed the value equal to zero. Dyatlov breaks on Akimov: “ The Idiot, you dropped the reactor! Well, give, remove the regulating cores, lift power “.
It is a little about the regulating cores: these are the cores consisting of pine forest carbide.
of All on the reactor is established 211 such cores. They are catalysts and brakes of activity of the reactor at the same time. The raising of those deprives personnel to use them as a brake.
The regulating cores are removed. After unsuccessful revolt in a block control panel the tranquility set in again. Engineers increased reactor power to that level ( of 200 MW ) which was necessary for Dyatlov for carrying out tests.
- Very well, begin tests, - Dyatlov says.
Akimov is not given:
- According to regulations, I can begin tests only at the power of 700 Megawatts. If you want to see off them on 200 MW , I will ask you to bring this fact in the operational magazine.
- Yes will be known to you: I as the assistant chief engineer, I can change parameters of tests. And I will use these powers, - Dyatlov puts an end in dispute.
It is a little about operation of the reactor: as a result of chemical reactions of the uranium which is in the reactor the huge number of heat is allocated. As a result water at the top of the reactor heats up, evaporates, and under pressure twists the big turbine developing the electric power.
Several operating cores still were shipped in the top active part of the reactor where power began to collect. Under a vapor pressure beat out tips of bioprotection of the reactor. 350 - threw kilogram blocks as if they weighed no more than a kilogram. Power begins to grow uncontrollable. The critical lack of the cooling water begins. The situation completely leaves from - under control.
- I include system of emergency power deceleration! - Akimov acts. This system enters the regulating cores into the reactor for the purpose of emergency power deceleration. It was also the fatal flaw. Cores have property - at introduction them in the reactor they at first create a short-term impulse of increase of power, and only after - decrease. As a result of input of cores in badly cooled reactor heat concentrated in the lower part of the reactor, there was an explosion. From entry in the operational magazine of the senior engineer of control of the reactor - “ Strong blows, cores of SUSA stopped, without having reached to LK (lower kontsevik). The key of power supply of " couplings is removed;. On attestations of eyewitnesses, there were two powerful explosions to destruction of part of the reactor block and the machine hall at this time, on the power unit No. 4 of the CNPP there was a fire. By 15 o`clock on April 26, 1986. it was authentically established that the reactor is destroyed, and from its disorder huge amounts of radioactive materials come to the atmosphere.
Undoubtedly, it is the greatest accident of mankind for all the time of its existence. It claimed the lives of people not only being on the power unit during accident, but also those who eliminated accident consequences - liquidators. The amount of the radioactive fuel which came to the atmosphere by 50 times exceeded a charge of a nuclear bomb in Hiroshima. The zone in 30 km from the CNPP on a circle was fenced, and was called “ 30 - ti kilometer Exclusion zone “.
The fourth block was placed in so-called “ sarcophagus “ for prevention of further distribution of nuclear substances. Reactors of the first and second block are stopped and exempted from nuclear fuel long ago. Recently (!) it was taken out of service and the third block is stopped, nuclear fuel is unloaded. The NPP is completely taken out of service.
Dyatlov spent in places of detention four years from ten to which he was sentenced. “ The Reactor was not suitable for operation purely because of Institute of atomic energy. With such bouquet of discrepancy with points of requirements of normative documents, its explosion was inevitable. It an accurate soldier`s step went … “ (Anatoly Dyatlov, 1995)