Work began constructing a new nuclear power plant at Chernobyl. A new town, Pripyat, to house workers at the plant, was also constructed.
It was decided that a RBMK (boiling water reactor) would be built. Although it produces more radiation than other reactors it produced cheaper electricity and was felt to be safer.
The cooling water reservoir was filled.
1977 (26th September)
The Chernobyl nuclear power station became operational with one reactor.
A second reactor became operational.
Pripyat was proclaimed a city.
A partial core meltdown happened in reactor 1 but it was kept quiet.
1983 (early December)
Construction of reactor number 4 was completed.
1983 (20th December)
Reactor number 4 became operational.
The Chernobyl site contained four 1000-megawatt reactors. A further two reactors were being constructed.
1986 (25th April 1 am)
Operators began reducing the power of reactor number 4 prior to a routine safety test.
1986 (25th April 2 pm)
Reactor number 4’s emergency core cooling system was disabled prior to the safety test.
1986 (25th April 2.30 pm)
The safety test was delayed due to the power requirements of the area as a result the power reduction was halted and remained at 50%.
1986 (25th April 11.10 pm)
Night staff at Chernobyl were given permission to test and shutdown reactor number 4. However, the staff were inexperienced and not familiar with the test.
1986 (26th April 12.28 am)
The power level of the reactor fell to dangerous levels due to an operator failing to set the power reduction limit to 30%. The operators decided to remove a number of the reactor’s control rods in a bid to raise power. This failed.
1986 (26th April 1 am)
The power level in reactor 4 stabilised but was still too low. Despite this, the test went ahead.
1986 (26th April 1.23.04 am)
There was a power surge in the reactor.
1986 (26th April 1.23.40 am)
The emergency shutdown button was pressed but the control rods jammed. The power surged and the graphite ends of the rods ignited.
1986 (26th April 1.23.58 am)
A huge explosion blew the 1,000 ton roof off the reactor. Radiation was released together with dust and graphite. Walls collapsed and fires broke out. The engineer in charge mistakenly believed that reactor number 4 was still intact.
1986 (26th April 1986 1.35 am)
Firefighters arrived at the scene. They were not aware that there was a radiation leak and did not have protective clothing.
1986 (26th April 1986 2 am)
Following the explosion, a crowd of people had gathered on a railway bridge outside Pripyat to watch the spectacle. All died from radiation poisoning.
1986 (26th April 2.15 am)
Police officers were sent to stop cars from leaving or entering the city of Pripyat. The officers were not issued with protective clothing.
1986 (26th April 5 am)
Reactor number 3 was shut down.
1986 (26th April 6.35 am)
A total of 186 firefighters had managed to put out most of the fires. However, the reactor core was still alight.
1986 (26th April 8.00 am)
Despite the disaster, work was not halted on the construction of two new reactors and the three remaining reactors remained operational.
1986 (26th April 1986 8 pm)
It was decided that it was not necessary to evacuate Pripyat.
1986 (27th April 1.13 am)
Reactors number 1 and 2 were shut down.
1986 (27th April 7 am)
General Pikalov measured the radiation levels at the site and stated that massive levels of radiation were being emitted.
1986 (27th April 10 am)
Helicopters began dropping sand, clay, boron, lead and dolomite into the burning core in an attempt to minimise radioactive emissions. This went on for four days.
1986 (27th April 12 pm)
Radiation levels dropped slightly and evacuation of Pripyat was delayed.
1986 (27th April 2 pm)
Radiation levels rose again and the residents of Pripyat and other towns and villages within a 6 mile radius were evacuated. They had not been told of the reactor explosion and were told the evacuation would be temporary.
1986 (28th April 9.30 am)
Swedish air monitors detected radiation in the atmosphere. It was traced to the Soviet Union. When questioned Soviet officials admitted there had been an incident but stated it was under control.
1986 (28th April 9.02 pm)
An announcement was made on Russian TV that an accident had happened at the Chernobyl plant.
1986 (29th April)
US spy satellite photos showed the extent of the damage caused by the nuclear explosion.
1986 (29th April evening)
Russian television news stated that two people had died in the explosion and that people had been evacuated from Pripyat and other nearby towns. The severity of the accident was played down.
1986 (1st May)
Even though the wind was blowing towards Kiev, the annual May Day parade was not cancelled. Soviet authorities wanted to avoid a panic,
1986 (4th May)
Liquid nitrogen was pumped under the remains of reactor number 4 in an attempt to cool it down. A huge workforce began cleaning up the area by bulldozing villages, destroying pets and livestock and burying contaminated soil.
1986 (6th May)
The level of radioactive emissions dropped. Schools in Kiev were closed and residents told to remain indoors.
1986 (8th May)
20,000 tons of radioactive water had been drained from underneath the reactor core.
1986 (9th May)
Concrete was pumped under the reactor prior to it being encased in concrete and metal.
1986 (9th May)
Volodymyr Pravik, one of the first firemen to arrive at the disaster, died of radiation sickness.
1986 (10th May)
Aleksandr Akimov, night supervisor at reactor 4 on 26th April, died of radiation sickness.
1986 (14th May)
Soviet leader, Mikhail Gorbachev, finally broadcast to the people. He stated that the worst was over.
1986 (27th May)
It was decided that a concrete structure should be built over the reactor.
1986 (15th June)
The management team of Reactor number 4 were dismissed for irresponsibility.
1986 (3rd July)
Chernobyl Director Victor Bryukanov was put on trial by the Politburo. Bryukanov was sentenced to 10 years imprisonment. He was released in 1991 due to suffering severe effects of radiation poisoning.
1986 (20th August)
A report into the accident blamed careless, mismanagement and violations of safety for the disaster.
1986 (29th September)
Reactor number 1 was restarted.
1986 (10th October)
Construction work on reactors 5 and 6 resumed.
1986 (9th November)
Reactor number 2 was restarted.
1986 (14th December)
The concrete and metal cover, known as the sarcophagus, over the reactor was completed.
Filmmaker, Vladimir Chevchenko who filmed the early stages of the disaster, died from radiation poisoning.
1987 (21st April)
Reactor number 3 was restarted.
1987 (24th April)
Construction work on reactors 5 and 6 was halted.
1989 (23rd May)
It was decided not to complete the building of reactors 5 and 6.
Reactor number 1 was shut down.
1991 (11th October)
There was a fire in the turbine hall of reactor number 2.
Reactor number 2 was shut down.
2000 (15th December)
Reactor number 3 was shut down.
2007 (17th September)
A contract for a New Safe Confinement shelter over reactor number 4 was signed with French company, Novarka.
The Emergencies Ministry of Ukraine deemed it safe for tourists to visit Chernobyl and began licensing tours.
2011 (25th November)
A court in Kiev banned tours to Chernobyl claiming that permission must be given by the Interior Minister.
2013 (19th January)
Pripyat was opened to tourists.
2015 (24th July)
The New Safe Confinement was nearing completion as the two halves of the enormous structure were brought together.
The New Safe Confinement was completed.
2018 (5th October)
A solar power plant was opened at Chernobyl.