Follow Chernobyl from the origins of the RBMK design and construction of the plant through Unit 4 commissioning, the 1986 accident, the response and investigations, final plant closure and the New Safe Confinement.
The station grew from the Soviet RBMK programme into a four-unit nuclear complex.
The Soviet RBMK design emerged in the mid-1960s as a graphite-moderated, light-water-cooled pressure-channel reactor. Its large individual fuel channels and online refuelling capability distinguished it from most other power-reactor designs.
World Nuclear Association · RBMK reactorsThe USSR Ministry of Energy and Electrification establishes an administration for the nuclear power plant under construction near Kopachi in Kyiv Region.
Chornobyl NPP · Construction historyThe first cubic metre of concrete is placed in the foundation of the main generating building, marking the start of major civil construction.
Chornobyl NPP · Construction stagesTurbogenerator No. 2 is connected to the grid and Chernobyl Unit 1 is commissioned.
Chornobyl NPP · Construction stagesUnit 3 enters service as the plant expands to its second-stage RBMK-1000 units.
Chornobyl NPP · Construction stagesThe first fuel assembly is loaded into the Unit 4 reactor during physical commissioning. The World History Database also records this milestone under plant director Viktor Bryukhanov.
Chornobyl NPP / World History DatabaseTurbogenerator No. 7 is connected on 21 December and No. 8 on 30 December, bringing Unit 4 into grid operation.
Chornobyl NPP · Construction stagesUnit 4 reaches its 1,000 MW design electrical output more than three months ahead of schedule.
Chornobyl NPP · Construction stagesA failed earlier turbine coast-down test led to the repeat test scheduled during the April 1986 maintenance shutdown.
A previous turbine coast-down test did not provide the required electrical result, so a repeat with modified voltage-regulator arrangements was planned for the 1986 shutdown.
World Nuclear Association · Accident sequenceThe scheduled shutdown begins on 25 April. The turbine rundown test starts at 01:23:04 on 26 April; within seconds the reactor enters a destructive power excursion.
IAEA INSAG-7 / World Nuclear AssociationPripyat is evacuated. Helicopter operations begin dropping neutron-absorbing and other materials toward the destroyed reactor.
Chornobyl NPP · Accident and its eliminationAuthorities decide to evacuate inhabitants from the 30-kilometre zone and additional contaminated settlements.
Chornobyl NPP · Accident and its eliminationAfter water-removal, cooling and other emergency measures, specialists conclude that a renewed self-sustaining chain reaction is not expected and airborne releases decrease sharply.
Chornobyl NPP · Accident and its eliminationGovernment decisions establish long-term preservation of the destroyed unit. Multiple Shelter concepts are evaluated, with a solution chosen that uses surviving Unit 4 structures where possible.
Chornobyl NPP · Shelter historySoviet experts present a detailed account at the IAEA Post-Accident Review Meeting. The World History Database records Valery Legasov leading the Soviet technical presentation.
IAEA / World History DatabaseThe preserved Unit 4 and rapidly constructed Shelter are accepted for maintenance. The Shelter is completed in only 206 days.
Chornobyl NPP · Shelter historyLater technical reassessment, especially INSAG-7, placed substantially more emphasis on RBMK design characteristics and shortcomings in the wider nuclear-safety system than the earliest official account.
Soviet investigations examine reactor operation, the test programme and plant management. In July 1987 Viktor Bryukhanov, Nikolai Fomin and Anatoly Dyatlov receive prison sentences.
World History Database / legal proceedingsThe IAEA's updated assessment shifts greater emphasis toward RBMK physical characteristics, control-rod and safety-system design, and weaknesses in safety information supplied to operators.
IAEA · INSAG-7Ukraine, G7 governments and the European Commission sign a memorandum covering closure of the remaining Chernobyl units and international assistance.
Chornobyl NPP / EBRDUnit 1 is permanently closed as the station moves toward complete decommissioning.
Chornobyl NPP · Shutdown historyThe Shelter Implementation Plan establishes the long-term strategy for stabilising the 1986 structure and developing a durable confinement. The EBRD-managed Chernobyl Shelter Fund is established.
EBRDAt 13:17, Unit 3 is shut down permanently, ending electricity generation at the plant.
Chornobyl NPP · Shutdown historyThe international programme stabilised the emergency 1986 Shelter and built a giant movable arch intended to support long-term dismantling and containment.
The contract to construct the New Safe Confinement is awarded to the Novarka consortium formed by VINCI and Bouygues.
EBRDMajor stabilisation work on the 1986 Shelter is completed before erection of the new arch.
EBRDAssembly of the giant steel arch begins in a lower-radiation area away from the destroyed reactor.
EBRDThe second half of the New Safe Confinement is lifted to its full height of about 108 metres.
EBRDThe two halves of the roughly 36,000-tonne structure are joined to create the complete 257-metre-span arch.
EBRDThe arch is moved about 327 metres into its final position over the 1986 Shelter and destroyed reactor.
EBRDA 72-hour trial operation is completed successfully, marking the safe physical completion of the New Safe Confinement.
EBRDConstruction stages, accident and elimination, and shutdown history.
Making Chornobyl safe, covering the Shelter Implementation Plan and New Safe Confinement.