Сhronology of events at Chernobyl disaster day
The accident at the Chernobyl nuclear power plant went down in history as one of the most terrible and large-scale disasters, which entailed irreparable environmental consequences. The radioactive cloud covered not only the territory of Ukraine and the CIS countries, but also reached European states.
In 1967, the Board of the State Planning Commission of the Ukrainian SSR recommended the construction of a nuclear power plant on the coast of the river. Pripyat, since this zone optimally corresponded to the requirements for water supply, transport and the ambitious protective zone. Already in 1970, construction began on the city of Pripyat and marking the pit for the first power unit.
The main construction of the Chernobyl nuclear power plant started in 1976. It consisted of four units, each with a capacity of 1000 MW. The explosion of the fourth power unit occurred on April 26, 1986. during experimental testing of reactor safety reserves. It was planned to conduct tests in reduced power mode, after which the reactor was about to be shut down for scheduled repairs.
During the testing, specialists had to show that the power of the electric current created by inertia-rotating turbines after the reactor was shut down was sufficient to provide power to the cooling pumps before starting diesel generators.
Chronology of events
There were many reports covering tragic events. Some of them had intentionally untruthful data designed to hide the true causes of the tragedy. But most of the data in the chronology of those days is the same.
The launch of the tests was scheduled for 04/25/1986:
• At 1:06 Moscow time, the extinguishing of the reactor began;
• At 3:47 a power down is interrupted;
• 14:00 – shutdown of the emergency cooling system, which led to such terrible consequences. Further testing was suspended by the Kyivenergo dispatcher;
• At 23:10 a command was given to continue reducing power;
• 24:00 – shift change.
04/26/1986 at 0:05 the catastrophic experiment was continued:
• 00:28 – switching the control to the automatic control system, loss of control and failure of the reactor power to a critical level of 30MW;
• Only after half an hour, at 1:00, Chernobyl workers managed to increase the reactor capacity to 200 MW;
• At 1:07, additional pumps were connected, which caused accelerated cooling of the reactor and a decrease in the water level in the steam separator;
• At 1:23, the water level stabilized, but the reactor parameter data indicated the need to immediately shut off its operation. However, the station staff decided to continue the study and begin a “coasting mode”;
• After 30 seconds, uncontrolled steam formation began. The shift supervisor gave the command to immediately shut down the reactor by pressing the emergency button, but it was too late. It was not possible to lower the emergency protection rods;
• 1:24 two strong explosions thundered, destroying the fourth reactor, walls and ceilings of the engine room. There was a fire, and employees began an emergency evacuation;
• 4:00 firefighters were able to localize the fire, avoiding the spread;
• 6:00 fire extinguished;
• 9:00 am tasked with transporting the first group of injured employees;
• 23:00 the government made an emergency decision to prepare vehicles for the evacuation of the city population.
In the first hours after the fatal accident, the entire civil defense system was paralyzed. The city authorities did not know how to react or simply did not want to take responsibility. Only the forces and courage of the fire department managed to escape an even larger-scale tragedy.
The explosion released about 8 tons of nuclear fuel and fragments of a graphite moderator, a pair of radioactive isotopes of iodine and cesium into the atmosphere. The accident destroyed not only 4 power units, but also all the barriers, the security system that protected the environment from radionuclides. Fatal release lasted for 10 days.
On the morning of April 27, 1986, the task was set to urgently evacuate the residents of the city and nearby settlements, which began at 14:00 Moscow time. A column of transport allocated by the government within three hours drove about 45 thousand inhabitants. By the end of the year, the number of evacuated people from the exclusion zone reached 115 thousand.
Until the evening of April 28, the media did not provide official statements about the disaster. Until May 10, backfill of protective materials continued at the fault site of the destroyed reactor using air transport. And on May 16, the government decided on the long-term conservation of the 4th unit of the Chernobyl nuclear power plant. On May 20, the first stage of the creation of the Shelter began. From 07/16/1986 to 09/15/1986 the bulk of the construction work was carried out and the second ethan of the creation of the sarcophagus was completed. Until November 30, installation work and the third stage was completed.
Amazing fact! After a terrible tragedy that cost many people their lives, the work of the Chernobyl nuclear power plant was not completely stopped for many more years. The reason for the shutdown of the 2nd power unit in 1991 was a strong fire. The third reactor was stopped only in 1993, and the first was removed
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