Chernobyl disaster explained in 60 seconds (VIDEO)

April 25, 1986, 1 a.m.  

Chernobyl nuclear plant operators begin reducing power at reactor No. 4 in preparation for a safety test.  

The test is supposed to determine whether, in the event of a power failure, the plant’s turbines can produce enough electricity to keep cooling the reactor before the emergency generators kick in.   

April 25, 1986, 2 p.m.  

The reactor’s emergency core cooling system is disabled to keep it from interfering with the test.   

April 25, 1986, 11:10 p.m.  

Operators start the shutdown.   

April 26, 1986, 12:28 a.m.  

Power falls below the level at which the reactor is considered stable.  

Operators respond by removing most of the control rods from the core violating the plant’s safety guidelines.   

April 26, 1986, 1 a.m.  

The power stabilizes and plant supervisors order the test to proceed.  

The automatic emergency shutdown system and other safety features are turned off.   

April 26, 1986, 1:23:04 a.m.  

The test officially begins, and an unexpected rise in power occurs.   

April 26, 1986, 1:23:40 a.m.  

An operator presses the emergency shutdown button, but the control rods jam as they enter the core.   

April 26, 1986, 1:23:58 a.m.  

An explosion blows the 1,000-ton roof right off the reactor and shoots a fireball high into the night sky.  

The air fills with dust and graphite chunks, radiation begins spewing out and dozens of fires start up.