April 26 – Accident at the Unit 4. Governmental Commission for investigation of the accident causes and elimination of Chornobyl accident consequences had been created by the USSR Council of Ministers Order No 830. B.E.Shcherbina - Deputy Chairman of USSR Council of Ministers has been appointed as the commission head.
April 27 - Evacuation of the Pripyat and 10-km zone inhabitants.
As a result of the accident the reactor core, considerable part of the technological equipment and constructions of ChNPP’s Unit 4 have been destroyed. Safety barriers and systems protecting environment from the radionuclides, containing in irradiated nuclear fuel, have been destroyed.
During some hours after the 4th Power Unit destruction the ChNPP firemen and personnel managed to liquidate numerous inflammations at the Unit that prevented the threat of fire spreading to other Power Units. Just after the accident at first the 3rd Power Unit, which along with the 4th Power Unit makes the second ChNPP generation, and then the 1st and 2nd Power Units were shutdown.
PE “Kombinat”
In October 1986, to ensure single management of the works performed within 30-km zone of ChNPP, ensure the performance of the state plan on electricity generation, on implementation of measures on improving reliable and safe operation of power units, on performance of Employer’s functions during construction of facilities of production and non-production purpose, the production enterprise “Kombinat” was established under the Order No.6c of USSR Ministry of Atomic Energy dated 17.10.86 based on the Decree of the Central Committee of the Communist Party of the Soviet Union and USSR Council of Ministers dated 02.10.86.
By the decision of Government Commission, at this phase of accident management, started the works on availability of possible core melt at the bottom of protective plate of reactor and also for the creation of supplementary cooling horizon (a special heat-exchanger) under the foundation of reactor plate for the guaranteed excepting of radioactive materials and melted fuel hit into the soil and ground water. The construction of plate started on June 3 and completed on June 28. But the process of accident development didn’t come to the possible melt of foundation plate and this special heat-exchanger wasn’t operated.
The issues on re-operation of the first three Chornobyl NPP Units and carrying out of the required for it activities were among the most important within a plan for accident consequence elimination. They were settled simultaneously with the activities on preserving the fourth Power Unit.
After the accident the first two Power Units remained in normal operable state and were shutdown on April 27, 1986, at 1 a.m. 13 min. and 2 a.m. 13 min. respectively. The third Power Unit, technically connected with the fourth one, was shutdown on April 26, 1986, at 3 a.m. Normal cooling of the shutdown Power Units was performed.
| On May, 15, 1976 according to the Preliminary Design requirement and SES the permanent radiation control in areas adjacent to the Chornobyl nuclear power plant was established |
| On May, 16, 1975 Commission on preparation and commissioning of ChNPP’s Unit 1 was established by Decree of ChNPP Director |