Chernobyl Accident

On April 26, 1986, the history of mankind was changed by the Chernobyl nuclear power plant accident. It was the largest nuclear energy disaster in history and one of only two accidents to have ever been classified as a Level 7 on the International Nuclear Events Scale (INES, http://www-ns.iaea.org/tech-areas/emergency/ines.asp), the other being the Fukushima disaster in Japan as a result of the tsunami on 11 March 2011. The explosion took place in Reactor 4 of the Chernobyl nuclear power plant (NPP), which was at that time one of the largest in the world. Eventually, the power plant was to have consisted of 12 reactors, but construction was abandoned part way through the building of Reactors 5 and 6 due to the catastrophe and evacuation of the Zone. The Chernobyl Nuclear Power Plant is located 140 kilometers from the capital of Ukraine – Kiev, and sits very close to the border with Belarus.

The incident occurred due to the coincidence of several factors. On the night of April 26, 1986 an experiment was scheduled. The aim was to test the operation of the plant’s giant turbines to maintain enough power to continue to operate the cooling water pumps in the event of the plant itself losing power. The turbines only had to maintain the flow of cooling water while they spun down, with turbo generators providing enough power to run the pumps no longer than 75 seconds after the plant lost power. By running the pumps from the turbines, the time that the reactor would be without cooling water could have been reduced from 75 seconds to around 15, which was considered to be far from ideal but acceptable. In order to test the reactor’s ability to run through this type of failure, the test required that the emergency control systems be disabled for the duration. The test required that the reactor’s power output be reduced to around 5% of normal. However, it was not realized until later that the RBMK reactors carried a design flaw that made them dangerously unstable at low power output. This, coupled with the shutdown of the emergency control system and an inexperienced and unprepared shift, caused a snowball effect culminating in the worst nuclear disaster the world has ever known.

At 1:23 AM, 40-60 seconds after beginning of the experiment, two large explosions took place. The first explosion blew the concrete roof of the reactor, weighing 2000 tons, 30 meters up into the air. The second explosion followed only 2 to 5 seconds after the first one.

The explosion at the Chernobyl nuclear power plant sent radioactive debris to an altitude of over 1 kilometre, contaminating the clouds. Wind from the southeast took the broad radioactive cloud as far as Scandinavia within hours. The cloud flew over Scandinavia and then turned back towards Ukraine. Further weather patterns sent the radioactive cloud to the west, over Poland, Austria, Germany and France, eventually to the UK and Ireland. Radioactive rain would fall, depositing contaminated water over the continent of Europe.

The most affected territories by radiation were Ukraine and Belarus, which decided to evacuate parts of their countries forever because of the contamination of the environment. There were almost 400 thousand people evacuated from these exclusion zones, and 98 villages and towns completely left abandoned. On ChernobylMaps.com you can find maps of some of them, including basic information.

On ChernobylMaps.com you can also find information about the evacuation of the inhabitants of the Chernobyl area. Figures regarding the number of people affected by the accident vary wildly. There is no officially agreed number. It is estimated that the Chernobyl disaster affected lives of about 600,000 people. Official documents divide the victims of radiation into several categories. The largest group of victims (200-240 thousand) is the liquidators – rescuers, soldiers, miners, firemen as well as police officers. There were also around 120 thousand inhabitants of the polluted areas near Chernobyl who suffered.