-
April 25th 1 a.m.: Prep for Test Begins
-Chernobyl’s operators begin reducing power at reactor No. 4 in preparation for a safety test, which they have timed to coincide with a routine shutdown for maintenance
-The test is supposed to determine whether, in the event of a power failure, the plant’s still-spinning turbines can produce enough electricity to keep coolant pumps running during the brief gap before the emergency generators kick in.
-This test causes the following collapse -
2 p.m.
-Reactor No. 4’s emergency core cooling system is disabled to keep it from interfering with the test.
-Though this doesn’t cause the accident, it worsens the impact.
-At around the same time, the test and shutdown are temporarily delayed to accommodate the region’s power needs. -
11:10 p.m.
-Operators receive permission to continue with the test and shutdown
-The less-experienced night shift is on the job
-They never purportedly received proper instructions on how to perform the test. -
1 a.m.
-The power stabilizes
-Plant supervisors order the test to proceed
-The automatic emergency shutdown system and other safety features are subsequently turned off. -
April 26, 1986, 12:28 a.m.
-Power plummets to far below the level at which the reactor is considered stable
-Operators respond by removing most of the control rods in violation of the plant’s safety guidelines
-Xenon buildup in the core. -
1:30 a.m.
-The test officially begins, and an unexpected power surge occurs.
-An operator presses the emergency shutdown button, but the control rods jam as they enter the core.
-The first explosion, to be quickly followed by at least one more, blows the 1,000-ton roof right off the reactor and shoots a fireball high into the night sky. -
2 a.m.
-The first firefighters arrive at the scene. They have no knowledge of the radiation and wear no protective clothing.
-Local Soviet officials convene an emergency meeting at which they decide to block cars from exiting or entering Pripyat
-Police officers assisting with the roadblock -
5 a.m. - 10 a.m.
-Officials shut down reactor No. 3, to be followed the next morning by reactor Nos. 1 and 2. They are re-opened months later.
-By now, all fires have been extinguished except for a blaze in the reactor core, which will burn for days.
-Helicopters begin dumping sand, clay, boron, lead and dolomite into the burning core in an attempt to slow radioactive emissions. -
Period: to
27th-29th
-After telling residents nothing about the disaster for some 36 hours, Soviet officials finally begin evacuating roughly 115,000 people from Pripyat
-An exclusion zone is set up around Chernobyl
-Swedish air monitors detect a large amount of radiation in the atmosphere, which is traced back to the USSR.
-Spy satellite photos provide U.S. officials with their first glimpse of the devastation wrought by the Chernobyl disaster. -
Period: to
May 1st - 6th
-Soviet officials refuse to cancel the May Day festivities in Kiev, even as radiation continues to be released unabated.
-Liquid nitrogen is pumped underneath the dead reactor in order to cool it.
-Radioactive emissions drop sharply, possibly because the fire in the core has burned itself out. Meanwhile, Soviet officials finally close schools in Kiev and advise residents to stay inside and to not eat leafy vegetables.