Chernobyl Disaster


Source: "Chernobyl - Reactor 4" by nertog - Walk With Me is licensed under CC BY-NC-ND 2.0

“Chernobyl – Reactor 4” by nertog – Walk With Me is licensed under CC BY-NC-ND 2.0

On April 25 1986, near a small town in Ukraine the worst nuclear disaster in history happened. A group of young Russian scientists and a more experienced scientist were running test on Chernobyl’s #4 RBMK nuclear reactor to see how long it could last if it lost power. They were running the test because last time they did the test they had suboptimal results and had made some changes. On April 26, at 0:28 AM the reactor experienced a sudden loss of output, the older scientist Dyatlov, ordered them to increase the power, but the power kept dropping. At 1:23 it reversed, instead of dropping the reactor surged. In less than 30 seconds the reactor spiraled out of control.

This was when the reactor exploded. At first there was probably a lot of confusion as the scientists dealt with the sudden turn of events, they would have no idea of what happened at this point, only speculation. The younger scientists would have to deal with conflicting advice from the guidance book and Dyatlov. Dyatlov ordered them to comply saying that they should listen to his years of experience instead of the book, so that’s what they did. He told one of the scientists to go check on the reactor to manually lower the reactor rods because they believed they had seized and stopped midway during part of the test. 

At this point people from the nearby town created to house the workers in chernobyl saw the and some people decided to take their children and go to a train bridge to watch the blue beam of light created by the radiation. At some point it began to ‘snow’, unfortunately this snow was actually ash from the remains of reactor number four, that bridge is known as The Bridge of Death, not a single one of the people on that bridge survived. This is where the accounts get hazy and not much is known, however these are the most believed series of events, they would’ve not believed that the core itself blew because they thought it was impossible, but the scientist that went to put the rods back found the reactor had been destroyed he immediately went to report it. Dyatlov had gone back to town at some point telling the directors of Chernobyl that they had the situation under control, they would probably have received a report by the young scientist about the reactor’s actual state he was not believed. A Geiger counter was brought in to measure how much radiation was being put out by the reactor. It measured 300 roentgens, the maximum that the device could measure. Sometime later a new team was sent to investigate Chernobyl.

The chief scientist investigating the incident was Valery Legasov. He worked with the military and eventually got the actual amount of radiation, 160,000 roentgens. This was when they began to suspect the core truly had blown up. A plan was devised to dump lead, boron, sand, and clay into the reactor to try and smother the reactor to prevent anymore radiation from escaping. It was soon discovered that it was a horrible mistake, the mixture would actually melt under the amount of radiation and heat coming from the reactor, when they melted into the bottom of the reactor the mixture would hit the vast amount of water that had ended up in the lower levels. The water would rapidly turn to steam creating an explosion that would carry nuclear waste and pieces of the core itself all across Europe. A team was sent to drain that water, this can be considered the most important thing to happen after the explosion. The team was successful, they drained the water in time. Everyone was evacuated and Chernobyl was abandoned and quickly faded a way.

So how did the reactor that people thought couldn’t explode, explode? A long series of mistakes, bad leadership, and a lack of consideration for safety. Nuclear reactors rely on a careful balance to operate. The events at Chernobyl showed the danger of disturbing that delicate balance. The first mistake was delaying that first test, instead of having the main crew of scientists do it they let the night shift of younger scientists run it, this delayed the test in the middle of lowering the power to let the shift change.

The power was lowered to a dangerous level, when the computers monitoring the reactor tried to deal with it the lack of power the computers dropped the power to 30 MWt, far from the safety margin of 720 MWt. The scientists were able to raise the power back up to 200 MWt before continuing to run the test. An additional pump was turned on for some reason lowering the reactor temperature, some of the radiation absorbent rods were raised to increase the heat and output of the reactor. This heated up the water too much and too much steam was produced for the reactor to handle. The Balance was thrown of and it quickly became too hot and exploded.

Dyatlov was ultimately the straw that broke the camels back. His constant lack of consideration for safety combined with shortcuts on the reactor to reduce cost caused a chain reaction that caused the worst nuclear disaster in history. The disaster would cost the lives of most of the people in building at the time as well as the firefighter sent to put out the fire caused by the explosion. Although the town near Chernobyl was safely evacuated many pets were left behind and soldiers were forced to go out and kill all the pets they could find. Pets were dangerous because they were pumped full of radiation and they would often run towards people. More soldiers were sent out to go tell people living on small farms and such within the blast zone. Once everything was over Chernobyl was the worst nuclear disaster (not including the bombs) and cost the most in live and money than any other nuclear disaster to date.