The Chernobyl Nuclear Explosion

Caleb Spencer

Summary

• The 1986 disaster at the Chernobyl nuclear power plant in the Ukraine was the product of a flawed Soviet reactor design as well as mistakes made by the untrained operators of the plant.

• All of the safety precautions were taken offline during a test, which attests to the ignorance of the operators.

• When a series of things went wrong, there was nothing to keep a chain reaction from going off.

• The accident is widely accepted as the worst nuclear disaster in history.

Where It happened• The Chernobyl Nuclear Power Plant is near Pripyat in northern central

Ukraine. • At the time of the accident, Ukraine was apart of the Soviet Union

Timeline

Reactor 4 is scheduled for maintenance on April 25th, 1986

A regional power plant shuts down unexpectedly so the shutdown of reactor 4 is delayed.

At 11:04, the reduction of power was allowed to continue, but the night crew on duty wasn’t aware of the previous postponement so they decreased power too quickly.

The reactors’ power has been reduced to 50%.

The test was to see if the reactor’s turbines' momentum could power the reactor until the backup generator came online.

The reactor was slowed even more than the grid controller wanted, and a buildup of Xe-135

Even though the reactor was in a very unstable condition, the experiment began, at 1/3 of the necessary power, and none of the safety precautions.

Water flow was increased, decreasing the absorption of neutron by the coolant. Steam was built up and Xe-135 was being burned extremely quickly starting a chain reaction.

The control rods that were taken out previously were all put back in at the sign of a rapid increase in power, but they decreased the amount of coolant around them, which actually helped the nuclear reaction.

At1:23:47 The control rods become stuck at 1/3 of the way in and a steam has built up because of the increased temperature causing a steam explosion.

The steam traveled along the coolant lines and blew off the reactor lid. A graphite fire was started after the inward rush of oxygen. This greatly increased the distribution of radioactive materials across Europe.

The Reactor After the Explosion

After the explosion, most of the plant is still standing. Some might think from this picture that the disaster wasn’t all that bad, but what makes the Chernobyl disaster the worst in history is the sheer volume of radioactive materials that where spewed across three continents.

Nuclear Power

You an see in this diagram the components mentioned in the timeline. Some of them are the graphite caps, water lines, and the turbine.

Cycle of Radioactive Materials

• You can see in this diagram how the radioactive materials that came from the explosion could be so widespread and cause so many health and ecological issues.

• It was hard to clean contaminated areas because the robots being used had transistors in them, and transistors don’t function properly in places with high levels of radioactivity. The areas that needed it the most were the hardest to decontaminate.

Radioactivity• As the map shows, the

explosion and the resulting radioactive contamination affected a large area of Europe, not just around where the accident happened.

• Workers at a Swedish nuclear power plant were found to have radioactive particles on their clothes, and after it was determined that the Swedish reactor had no leak, the news of a widespread problem reached mainstream news.

World Consequences• Apart from the 57 direct deaths in

the accident itself, 4,000 additional cancer cases due to the accident have been predicted.

• Many other consequences of the disaster such as groundwater contamination and birth defects have been documented, but there is no real way to know the extent of the damage that the Chernobyl disaster caused.

• Despite all of these negative consequences, the world may be better off now that so much attention has been drawn to the problem of mishandled nuclear projects.

Children of ChernobylA father holding his son

before radiotherapy

A child with a scar from brain surgery Sasha, an orphan

Mentally handicapped children

in abandoned houses.

Mikhail Gorbachev

Mikhail Gorbachev was the General Secretary of the Central Committee of the Communist Party of the Soviet Union and General Secretary of the Communist Party of the Soviet Union when the disaster happened. This means that he was the leader of the Soviet Union at the time. Many people blamed him directly for the explosion but he said that the military leaders prevented him from knowing of the disaster until later. During the time of his leadership before the explosion, reforms were being made, but at a slow pace. Historians believe that because of the Chernobyl nuclear explosion, many reforms were made in Soviet Russia because a large public outcry reached Gorbachev after the rest of the country found out about it.

Valeri Legasov

• Valeri Legasov was the chief of the investigation committee of the Chernobyl Disaster. He made the decisions that prevented larger explosions from taking place and spoke to the governments, as well as his fellow scientist and the press, about the accident.

• Soviet government was uncomfortable because he was so open about the accident and never recognized his contribution.

• He became ill because of the radiation he was exposed to, and suffered from depression over his lack of recognition. He committed suicide on the second anniversary of the disaster.

Mohammad ElBaradei

• Mohammad ElBaradei is the current director of the International Atomic Energy Association. He was the director when the IAEA report on the Chernobyl disaster was released in 2005. That report is the most respected report on the disaster.

• It attributed 56 direct deaths and estimated that there may be 4,000 extra deaths due to cancer among the approximately 600,000 most highly exposed and 5,000 among the 6 million living nearby.

Chernobyl Memorials

A memorial to the firefighters who died after trying to stop the fires that engulfed the

plant. They weren’t even told there was radioactivity.

A memorial to all of those who died at Chernobyl

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<http://en.wikipedia.org/wiki/Chernobyl_disaster>. • "Chernobyl." World Nuclear Association. 18 Apr. 2008

<http://world-nuclear.org/info/chernobyl/inf07.html>. • "Belarusguide." 9 May 2008

<http://www.belarusguide.com/chernobyl1/chfacts.htm>.• "Chernobyl, December 1999." Neutron. 13 May

2008 <http://www.neutron.kth.se/gallery/chernobyl/>.

• "Worlds Worst Poluted Places." Picasa Web Albums. 13 May 2008 <http://picasaweb.google.com/BlacksmithInstitute/WorldSWorstPollutedPlaces2007/>.