The Chernobyl disaster occurred 25 years ago today.
On 26 April 1986, at 01:23 (UTC+3), reactor four suffered a catastrophic power increase, leading to explosions in its core. This dispersed large quantities of radioactive fuel and core materials into the atmosphere:73 and ignited the combustible graphite moderator. The burning graphite moderator increased the emission of radioactive particles, carried by the smoke, as the reactor had not been encased by any kind of hard containment vessel. The accident occurred during an experiment scheduled to test a potential safety emergency core cooling feature, which took place during the normal shutdown procedure.
After years of international pressure, independent Ukraine finally shut down the Chernobyl Atomic Power Station for good in December 2000. The sarcophagus remains in place, well beyond its initial lifespan, although work on a replacement has finally started.
Disputes rage on the death toll with some estimates backed by UN committees saying only a few dozen fatalities could be directly attributed to Chernobyl but some environmentalists say the figure is in the tens of thousands.