On April 26, 1986, there was a disaster at the Chernobyl nuclear power plant in Ukraine. Engineers were performing a test to see if the cooling system could still run under low power conditions when emergency shutdown was triggered. However, they had lowered too many control rods, causing instability. As they tried to increase output by raising the rods, power levels surged dangerously and two explosions occurred, blowing off the reactor roof and releasing radioactive debris into the air. This caused massive environmental damage and health issues for those exposed to the radiation. It was the worst civil nuclear disaster in history.

1. Disaster at Chernobyl April 26, 1986 By: Chris Johnson Mrs. Crowder 3 rd Block Plant (left), Control Panel (top right) Gas Mask (middle right) Child Crying after explosion (bottom right)

2. Chernobyl’s Location Chernobyl was built in an area of wooded marshlands in northern Ukraine in 1977. Ukraine already held 10% of the worlds nuclear power production when the Chernobyl nuclear power-station was built.

3. An Experiment Engineers working at Chernobyl's number four reactor did a test on the evening of April 25, 1986. The experiment was to see whether the pumps cooling system could still run using power generated from the reactor under low power if the auxiliary electricity supply failed.

4. The Experiment Begins At eleven o'clock at night on April 25, the control rods which are used to regulate the fission process in a nuclear reactor were lowered. The fission process being the process used to absorb nuetrons thus slowing the initial chain reaction. When the engineers lowered the rods it reduced the output of the reactor by 20% of the normal output required for a test.

5. A Problem Begins When the Engineers lowered the control rods they lowered too many, making the output drop too quickly, causing an almost complete shutdown of the reactor.

6. The Problem Worsens The output dropped so quickly that the safety systems were disabled. The Engineers were concerned about possible instability, so they began to raise the rods in hope of increasing output. At twelve-thirty in the morning on April 26, they decided to continue.

7. Trying To Raise Output By one o'clock in the morning of April 26, the power of the reactor was only about 7%, so the engineers raised more rods to raise the power. The engineers disabled the reactor's automatic shutdown system to allow the reactor to work under low power conditions.

8. Too High :Overload Control rods were again raised by engineers to increase power. By one twenty-three on the morning of April 26, the power reached 12% and the decision was made to carry on with the experiment. Only after a few seconds though, the power levels suddenly surged to dangerous levels.

9. Overheating Begins This caused the reactor to overheat the water in the cooling system started to steam. At this point there were only six control rods remained in the reactor core, the minimum safe operating number was thirty.

10. Boom At one twenty-four on the morning of April 26, the first two explosions occurred and caused the reactor's roof to blow off and the content to erupt out. The roof being blown off caused air to get into the reactor and ignite the carbon monoxide gas causing a reactor fire. The reactor fire burned for nine days.

11. Chernobyl Reactor Explosion

12. Radioactive Debris The reactor was not housed in a reinforced concrete shell so when the reactor exploded the building sustained severe damage and large amounts of radioactive debris went into the air.

13. Amount of radiation “The disaster released at least 100 times more radiation than the atom bombs dropped on Nagasaki and Hiroshima.” -BBC

14. Environmental Damage The amount of radiation that was released caused many farms to perish and many farms today still face post-Chernobyl issues.

15. Health Issues The number of people that could actually eventually die because of the Chernobyl incident is very controversial. The UN-led Chernobyl Forum expects an extra 9,000 cancer deaths are expected. While "Greenpeace", a campaign group, expects up to 93,000 extra cancer deaths because of Chernobyl.

16. Timeline 1977- Nuclear Power Plant is built in Chernobyl, Ukraine. 11 P.M. April 25th - Control rods were lowered, the experiment begins 12:30 A.M. April 26th - Control rods were raised to increase out put after too many rods were lowered. 1 A.M. April 26th - More rods were raised due to low power and the automatic shutdown system was disabled.

17. Timeline (Cont.) 1:23 A.M. April 26th - Rods were raised again and power levels surged. Control rods were removed from the reactor but, the reactor began to overheat and the emergency button was pressed causing control rods to enter the core. Which caused pressure to go into the core. 1:24 A.M. April 26th - Two explosions happen causing the roof to blow off and radioactive gases were released into the air. Modern Times April 26th – There are many health and environmental damages still around from the explosion 21 years ago.

18. Important People Since I could not find any information on the scientists of Chernobyl. My Important people will be the firefighters that helped to put out the fires that raged, the doctors that helped to treat the citizens’ and workers’ cancer, and the scientists that helped to discover more about Chernobyl.

19. Bibliography &quot;Chernobyl.&quot; BBC . 27 Nov.-Dec. 2007 <http://news.bbc.co.uk/2/shared/spl/hi/guides/456900/456957/html/nn1page1.stm>. &quot;Chernobyl.&quot; World Nuclear Association . 01 Dec.-Jan. 2007 <http://www.world-nuclear.org/info/chernobyl/inf07.htm>. &quot;Chernobyl: a Nuclear Disaster.&quot; Chernobyl . 3 Dec. 2007 <http://library.thinkquest.org/3426/>. &quot;Chernobyl.&quot; 28 Nov.-Dec. 2007 <http://www.ibiblio.org/expo/soviet.exhibit/chernobyl.html>. Hampton, Wilborn. Meltdown . 1st ed. Cambridge, Massachusetts: Candlewick P, 2001. 1-104.