The Chernobyl disaster was the worst nuclear power plant accident in history. In 1986, a flawed reactor design and human error caused an explosion and fire that released radiation into the atmosphere. Over 30 people died immediately from radiation exposure. The radioactive fallout spread over much of Europe. Long term impacts included increased cancer rates and contamination of surrounding land and water. The disaster demonstrated the importance of safety in nuclear power and providing emergency response plans for such accidents.

1. CHERNOBYL DISASTER
THE WORST NUCLEAR DISASTER IN
HISTORY
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3. THE CHERNOBYL NUCLEAR POWER PLANT
• The plant was located 18km north of the city of Chernobyl.
• Its construction began in the 1978 and Reactor 4 was completed in 1983
• The plant consisted of 4 reactors and 2 new were under construction.
• The plant produced 10% of Ukraine’s electricity.
• It was a Reaktor Bolshoy Moshehnosty Kipyashiy (RBMK) type reactor which was cooled by water
and moderated by graphite.
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4. • The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately
trained personnel.
• The resulting steam explosion and fires released at least 5% of the radioactive reactor core into the atmosphere.
• Two Chernobyl plant workers died on the night of the accident, and a further 28 people died within a few weeks
as a result of acute radiation poisoning.
• UNSCEAR says that apart from increased thyroid cancers, “there is no evidence of a major public health impact
attributable to radiation exposure 20 years after the accident”.
• Resettlement of areas from which people were relocated is ongoing. In 2011 Chernobyl was officially declared a
tourist attraction.
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5. REACTOR PLANT SCENARIO
1. As the reaction occurs, the uranium fuel becomes hot.
2. The water is pumped through the core in pressure tubes.
3. The water removes the heat from the fuel.
4. The heated water is turned into steam.
5. The steam turns the turbines to produce electricity.
6. The hot water is then cooled to be reused.
7. This same process is repeated again and again.
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6. WHAT HAPPENED?
• Saturday, April 26, 1986: -Reactor #4 was undergoing a test to test the backup
power supply in case of a power loss.
• The power fell too low, allowing the concentration of Xenon-135 to rise.
• The workers continued the test, and in order to control the rising levels of Xenon-
135, the control rods were pulled out.
• The experiment involved shutting down the coolant pumps, which caused the
coolant to rapidly heat up and boil.
The external relative gamma dose for a person in the open near the
Chernobyl disaster site.

7. • Pockets of steam formed in the coolant lines. When the coolant expanded in this
particular design, the power level went up.
• All control rods were ordered to be inserted. As the rods were inserted, they
became deformed and stuck.
• The rods melted and the steam pressure caused an explosion, which blew a
hole in the roof. A graphite fire also resulted from the explosion.
• To save money, the reactor was constructed with only partial containment,
which allowed the radiation to escape.
• This dispersed large amount of radioactive particulate and gaseous debris
containing Cesium-137 and Strontium-90 which are highly radioactive reactor
waste product.
Pripyat evacuation broadcast

8. REASONS FOR THE ACCIDENT
• Workers’ lack of knowledge of reactor physics and engineering, as well as
lack of experience and training
• Delay
• The night shift was not prepared to carry out the experiment
• The operators were unaware of the xenon poisoning
• Insufficient communication between the safety officers and the operators in
charge of the experiment
• Disabled all safety systems
• Poor quality and rushed design.
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9. INITIAL IMPACT
• Explosion released 190 tons of radioactive gasses into the atmosphere.
• 231 people were hospitalized immediately due to acute radiation sickness and 31
eventually died.
• 3 million children exposed to radiation.
• 7 million lived in contaminated areas.
• Fire started that lasted for 10 days.
• Wind carried radiation far distances.
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10. LONG TERM IMPACT
• International spread of radioactivity.
• Detected over all of Europe except for the Iberian Peninsula.
• The nuclear meltdown provoked a radioactive cloud which
Ukraine and Moldova, but also over Macedonia, Croatia,
Finland, Denmark, Norway, Sweden, Austria, Hungary,
Switzerland, Germany, Italy, Ireland, France and the UK.
• Radioactive release
• Highly radioactive compounds that accumulate in the food
iodine and strontium are particularly dangerous.
• All of the noble gases, including krypton and xenon,
released immediately into the atmosphere by the first steam
• About 55% of the radioactive iodine in the reactor was
particles and as organic iodine compounds.

11. • Fauna and vegetation
• pine forest in the 10km2 surrounding of the reactor turned ginger brown and died,
earning the name of the "Red Forest“.
• Some animals in the worst-hit areas also died or stopped reproducing.
• Socio Economical impact
• The affected territories are mostly rural.
• A total of 7,84,320 hectares of agricultural land was removed from service in the three
countries.
• Timber production was halted for a total of 6,94,200 hectares of forest.
• Health Effects
• Thyroid cancers
• Leukemia and non-thyroid solid cancer
• Cataracts
• Cardiovascular disease
• Mental health and psychological effects
• Reproductive and hereditary effects
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12. WHAT HAS BEEN DONE TO REDUCE
EXPOSURE IN CONTAMINATED AREAS?
• The Soviet and Commonwealth of Independent States (CIS) authorities introduced a wide
range of short and long term environmental countermeasures to mitigate the accidents
negative consequences
• Decontamination of settlements in contaminated regions.
• Exclusion of contaminated pasture grasses from animal diets and rejection of milk based
on radiation monitoring data.
• Feeding animals with “clean” fodder.
• Application of Cs-binders, such as Prussian blue, to prevent contamination of milk and
meat.
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NEW SAFE CONFINEMENT IN 2017

13. LESSONS LEARNED FROM CHERNOBYL
• The scale of the material and the financial losses in mitigating the consequences of the Chernobyl accident
provide compelling evidence of the extremely high price of errors and shortcomings when ensuring the safety
of nuclear power plants.
• The cost of ensuring the safety of nuclear facilities is significantly lower than that of dealing with accident
consequences.
• Hundreds of billions of US dollars’ worth of direct and indirect damages have been reported by Belarus,
Russia and Ukraine as a result of the Chernobyl nuclear power plant accident over the past 20 years.
• The accident has demonstrated the need to establish and support a high-level national emergency response
system in case of man-made accidents.
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NUCLEAR POWER PROTEST IN BERLIN, 2011

14. REFERENCES
• www.world-nuclear.org
• www.greenfacts.org
• www.nrc.gov
• www.britannica.com
• en.wikipedia.org
• www.livescience.com
• www.theguardian.com/environment
• www.un.org
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