The accident at the Chernobyl nuclear power plant occurred

The largest in the history of the nuclear industry nuclear reactor accident happened on April 26, 1986, at 1:24 am, Moscow Standard Time, on the territory of the USSR at the Chernobyl Nuclear Power Plant.

Construction of the Chernobyl nuclear power plant began in 1970. At the same time, three kilometers away from it, the erection of a new city of energy workers named Prypiat was going on. RBMK (High Power Channel-type Reactor) were installed at the power plant with specified electrical capacity of 1000 MW (e) and thermal capacity of 3200 MW (t). The first unit was put into operation in September 1977, the second one - in January 1979, the third and fourth - in January 1981 and 1983 correspondingly. Construction of two more units began in 1981 (a third construction stage).

The accident occurred in the course of the scheduled testing of a security system. The authors of the testing program did not take into account the structural deficiencies of the RBMK reactors, and power plant staff was unable to shut down the running processes. As a result, a series of explosions completely destroyed the reactor building along with the fourth power unit.

For liquidation of multiple hot spots were called the firefighters, which, together with the plant’s employees in charge fought fire and heroically fulfilled their duty. Subsequently, many of these people have died from acute radiation syndrome.

Powerful radionuclides releases that occurred at the time of the explosion and had been continuing for the next ten days, consisted of a mixture of gases, concentrated aerosols and light particles of nuclear fuel, spreading through air flows over long distances and settling down on the land surface. Pollution has undergone more than two hundred thousand square kilometers, approximately 70% of which came on the territories of Belarus, Russia and Ukraine. The areas immediately adjacent to the plant were affected the most. The evacuation of Pripyat population began on April 27. The residents of 10-kilometer zone were evacuated in the first days after the explosion, then the 30-kilometer exclusion area was created around the plant, and hundreds of small residential spaces were buried.

A specially created government commission was engaged in taking care of urgent measures on localization of the accident and on protection of the population. Five thousand tons of various materials were dropped from helicopters on the burning reactor for extinguishing the burning graphite, reduction of radioactive emissions and the prevention of a nuclear explosion. During the 15 days a tunnel under the reactor was dug through and the monolithic concrete slab for chilling a possible melt down was mounted in it. The powerful concrete walls, which were covered with a steel roof ("sarcophagus"), were built in an extremely short period of time (from May to November 1986) around the reactor.

More than 800 thousand people from different republics of the USSR - the firefighters, the helicopter pilots, the service members of 210 military units, the specialists with the chemical, constriction and medical majors - were involved in liquidation of post-disaster outcome. More than 90 thousand of them received state awards.

After the accident at the unit 4 a work of the power plant has been suspended because of dangerous radiation environment. However, in October 1986, after extensive work on the decontamination of the area and the construction of "sarcophagus", the 1st and 2nd power units were brought into operation; in December 1987 a work of the 3rd power unit was resumed.

On March 29, 2000, the Government of Ukraine adopted a regulation № 598 "On early decommissioning of the power unit № 3 and the final closure of the Chernobyl Nuclear Power Plant."

Lit.: Книга Памяти героев-чернобыльцев. Орел, 2006; Малеев В. Н. Герои неизвестной войны. Память обретенная М., 2012; Чернобыльская ядерная катастрофа. ООН. URL: https://www.un.org/ru/events/chernobyl/resources.shtml.

Based on the Presidential Library’s materials:

Chernobyl: In Commemoration of the Tragedy: [digital collection].