Chernobyl and Pripyat
The Chernobyl power plant is located 110km from Kiev and the town of Pripyat was built nearby for the families of the workers at the plant.
The station consisted of 4 reactors with another 2 being 90% completed in 1986. Each of the RBMK-1000 reactors were capable of producing 1 gigawat of power each, which at the time was 10% of the Ukraine ’s
power needs.
On the 25 April 1986 reactor 4 was scheduled to be shut down for maintenance, this was considered the perfect time do run some tests on the reactor, namely to see whether the turbine generator would generate sufficient electricity to power the reactor's safety systems. At 1.23:04 the experiment began the turbines were shut down and disconnected from the reactor, steam bubbles increased the power of the reactor and hence less stable and more dangerous leading to a runaway reaction. At 1.23:40 the operator pressed the emergency button and ordered a shutdown of the reactor 
unfortunately the control rod insertion mechanism was slow and actually increased the reaction rate causing an energy spike in which they started to rupture and one became stuck and therefore the reaction could not be stopped.
At 1.23:47 reactor number 4 jumped to 30 times its usual output levels causing the fuel rods to melt and the steam pressure to build up causing a steam explosion, destroying the reactor lid and blowing a hole in the roof, which caused an inrush of oxygen and started a graphite fire; which in turn contributed to the spread and contamination in surrounding areas.
The radiation levels in the reactor were equal to 20,000 röntgen an hour and a lethal dose is considered to be 500 röntgen over 5 hours, so some of the unprotected workers including firemen that hurried to the accident were exposed to a lethal dose within several minutes.
The fire was extinguished around 5am the next morning, the fire-fighters were not told how dangerous the fallout was and were not totally aware of the dangers they were putting themselves in Lieutenant Vladimir Pravik leader of the fire-fighters was dead by May 9 1986 .
The explosion and fire threw into the air not just the particles of the nuclear fuel but also far more dangerous
radioactive elements like caesium-137, iodine-131, strontium-90 and other radionuclides. The residents of the surrounding area observed the radioactive cloud on the night of the explosion.
In the days and weeks that followed 237 people suffered from acute radiation sickness and 31 died in the first 3 months, most of these were emergency workers.
In the days that followed the Soviet government kept what had happened very quiet only admitting that anything had happened when on the 27 April 1986 Sweden detected fallout in the air over their country and ran tests that deduced that it was not from any plant which they owned.
‘Liquidators’ were called in to contain the disaster and Russian army conscripts were offered 2 years off their National service if they were to spend 2 minutes on the roof of reactor 4 removing contaminated debris! The worst of the contaminated material was collected inside what was left of the reactor. The reactor itself was 
covered with bags containing sand, lead and boric acid thrown off helicopters and by the end of 1986 a large concrete sarcophagus was constructed to seal of the reactor and its contents. Unfortunately its hasty construction has left the sarcophagus in very bad shape 21 years later it is said that a small earthquake of very high winds could remove the top of the concrete seal! There are plans in place to build another more permanent cover that will remove the current risk of recontamination.
The town of Pripyat was ordered to evacuate at 14.00 on the 27 April 1986 and to reduce baggage the residents were told that it would be for a maximum of 3 days. In total 135,000 people were evacuated from the area including 50,000 from the town of Pripyat itself.
When it became clear that the levels of continued radiation through the town were high, plans were made to
remove the rest of the resident belongings from the town although understandably this was done in a hurry and quite a lot of personal effects still remain. Shortly after the disaster the soviet government began to build a new city for the displaced workers and families, Slavutych received its first inhabitants in 1988 and currently houses 25,000 people.
All the buildings now lie empty and are deteriorating rapidly in 2005 the roof of the 4 storey school collapsed and despite heavy security within the exclusion zone a lot of the buildings have been stripped by “gypsies” Experts within the zone give the buildings another 20 years before they are mostly rubble.