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Chernobyl Disaster
A timeline of the events leading to, during, and following the 1986 Chernobyl nuclear disaster and its long-term consequences.
19 events · 12 ▲ · 7 ▼ · by community
2022-03
Site Returned to Ukrainian ControlRussian forces withdraw from the Chernobyl Exclusion Zone, allowing Ukrainian authorities to regain control and restore monitoring operations.
Russian Forces Occupy SiteDuring Russia's invasion of Ukraine, Russian forces seize the Chernobyl site, raising concerns about nuclear safety and radiation monitoring.
2022-02
2019
Containment Structure CommissionedThe New Safe Confinement is officially commissioned and begins full operational service for dismantling the old sarcophagus and managing radioactive waste.
2016-11
New Safe Confinement InstalledThe New Safe Confinement is successfully moved into place over Reactor Unit 4, significantly improving long-term containment of radioactive materials.
2010
New Safe Confinement ConstructionConstruction begins on the New Safe Confinement, a giant arch designed to safely enclose the damaged reactor for decades.
2000-12-15
Final Reactor ShutdownReactor Unit 3, the last operating reactor at Chernobyl, is permanently shut down, ending electricity production at the site.
1995
Closure AgreementUkraine agrees with the G7 and international organizations to permanently close the remaining reactors at Chernobyl in exchange for financial assistance.
Fire at Unit 2A turbine fire severely damages Reactor Unit 2, leading to its permanent shutdown.
1991
1986-11
Original Sarcophagus CompletedA massive concrete and steel structure known as the sarcophagus is completed to contain the destroyed reactor and reduce radioactive emissions.
Exclusion Zone EstablishedSoviet authorities create a 30-kilometer exclusion zone around the plant and relocate more than 100,000 people from contaminated areas.
1986-05
Evacuation of PripyatNearly 50,000 residents of Pripyat are evacuated approximately 36 hours after the explosion due to dangerous radiation levels.
1986-04-27
Emergency ResponseFirefighters and plant workers respond to the explosion, many receiving fatal doses of radiation while attempting to extinguish fires and stabilize the site.
1986-04-26
Reactor ExplosionAt 1:23 a.m., Reactor Unit 4 explodes during the safety test, releasing massive amounts of radioactive material into the atmosphere.
1986-04-26
Safety Test PreparationOperators prepare Reactor Unit 4 for a turbine rundown safety test, during which several safety procedures are not properly followed.
1986-04-25
1983
Unit 4 Begins OperationReactor Unit 4 becomes operational, completing the first phase of the power station.
1981
Unit 3 CommissionedReactor Unit 3 enters commercial service, increasing the plant's electricity generation capacity.
1978
Unit 2 Starts OperationReactor Unit 2 is commissioned and begins supplying electricity to the Soviet power grid.
1977
First Reactor CommissionedReactor Unit 1 begins commercial operation, marking the start of electricity generation at the Chernobyl Nuclear Power Plant.
1970
Construction BeginsConstruction of the Chernobyl Nuclear Power Plant begins near Pripyat in the Ukrainian SSR of the Soviet Union.
Chernobyl Disaster
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