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CHERNOBYL TRAGEDYTHE WORST NUCLEAR POWER ACCIDENT IN THE HISTORY.
WHAT??• On April 1986, reactor number 4 of the
Chernobyl plant exploded releasing plumes of highly radioactive fallout into the atmosphere and over an extensive geographical area.
• Worst NUCLEAR POWER plant disaster ever and the only level 7 instance on the INTERNATIONAL NUCLEAR EVENT SCALE.
• Fallout 400 times than that had been in Hiroshima.
• Statistics reveal 56 direct deaths, and about 4000 extra cancer deaths among about 6,00,000 contaminated ones.
• Resulted in evacuation and resettlement of over 4 lakh people.
• With estimated cost of 200 billion USD. It is costliest tragedy in modern history.
WHERE??• Chernobyl at the time of accident
was under former USSR.
• Now it’s in Ukraine. Located to north of Kiev and near town of Pipriyat.
• Ukraine and Belarus were the most affected countries by the explosion.
• Station had 4 RBMK 1000 plant. With first one commissioned in 1977, and fourth in 1983.
• Each produced 1 GW of electricity contributed 10% of Ukraine’s power supply.• Plants 5 & 6 were under construction.
• On April 26, 1986. Plant 4 was running at low power. As it neared its end of fuel cycle. Was to be shut down for maintenance.
• A Test was proposed to check performance of generator, which supplied when main power will be off. Called ‘Power blackout’ experiment.
• Reactor’s design was unstable at low power, and operators were reckless about safety precautions.
• An important safety device was avoided during station building due to financial reasons. Plant worked 2 years without it. Operators desperate to carry out the test
• Experiment was performed at the most dangerous point in reactor cycle.
The REACTOR• Uranium Rods: by
fission produced 3200 MW thermal energy.
• Heat Steam Run Turbine electricity.
• Control Rods. And Graphite rods. Moderate the reactn.
• Unusual accumulation of steam around Uranium rods may lead to uncontrollable fission.
Exactly What Happened…
• Inexperienced crew.• ‘Blackout operation’ started.• Reactor unstable below
700MW.• Operator mistake or system
failure lead reactor power suddenly drop to 30MW.
• Shocked crew took out whole control rod, violating safety procedures.
• Regained to 200MW. Manual taking over of cooling systems.
• Shut down warning systems to continue the test.
• Steam started forming near rods. Operators Unaware.
ON APRIL 26 1986.
Exactly What Happened…• Operators continue test.• Steam continue to build up
inside reactor core. Increasing Power
• 700MW 900 MW 2000MW OUT OF CONTROL.
• Following safety shutdown procedure, control rods fully inserted.
• But graphite tips increased the fission. Power now 10000MW. 100 times more.
• ‘BOOM’, power lids blown off by steam from bottom of reactor.
• Air entered the core, mixed up with the reactants. IInd bigger explosion
CRISIS• Radiation level hit off to 5000r per
second.• The conditions were overlooked,
operators and fire fighters continued to put off fire without any masks, not being aware. Many of them died within a week.
• To reduce emissions, the team bombarded the reactor with 5,000 metric tons of shielding material consisting of lead, boron, sand, and clay. It took 3 weeks.
• Emissions included Cs-17, I-131, Sr-90 and other radio nucleotides.
• Wind carried this to other geographic regions.
• 2 died and 52 hospitalized within 24 hours. High radioactive presence in air remains a concern.
An ejected Graphite from Core
CRISIS• Chernobyl and Pipriyat were
• Evacuation of Belarus and other parts carried out in stages.
• About 4 lakh people had to be resettled.
• Estimated 100 died within 3 months.
• Secretive USSR tried to cover up the facts, and show the world everything was normal.
• Chernobyl was completely sealed.
Chernobyl Arial view right after the incident.
Evacuation of Pipriyat.
Inside the plant
The SARCOPHAGUS• A concrete containment building or a
protective box called ‘sarcophagus’ was placed over the wrecked reactor.
• This was to prevent the additional radioactive materials from escaping.
• 200 tones of radioactive material lie deep within it.
• The plant after isolating from the 4th reactor continued to work due to insufficient power generation.
• But by intervention of IAEA and G-7 countries, the plant was shut down by 2000.
• However after this much years, the outside of sarcophagus is appearing to be degrading.
• A new sarcophagus or NSC will be installed around the reactor by 2011, which will be the largest movable structure ever built.
‘VICTIMS NOT SURVIVORS’
LIVING WITH THE RADIATIONS….
One described.. experience of the radiation as "tasting like metal", and feeling a sensation similar to pins and needles all over his face.
At least one type of cancer attributed to Chernobyl.
Thyroid Cancer increased four folds from 1986, with children the most affected.
AFTERMATH• Evidence of leakage was first
found by Sweden, and then so on. Lastly USSR had to admit.
• Pipriyat river badly affected. Pine forest covering the area turned brown and died. It was then called ‘Red Forest’
• 20% farmlands of Belarus completely removed from production.
• Made USSR less secretive. Became more open society.
• Luckily the contamination were not genetic and the next generation were not affected.
• Evacuated area: a haven for wildlife. New species found due to absence of humans.
MEMORIAL BUILT NEAR THE REACTOR
GHOST TOWN OF PIPRIYAT
Boards showing signs of now extinct towns
20 YEARS HENCE
On Soviet…• Potentially unstable reactor
design. + Incompetent operators + Irresponsible management.
• Resulted into that horrific explosion On that April night of 1986.
• A book by Gregory Medvedev “The truth about Chernobyl” tells about secretive, authoritarian Soviet bureaucracy.
• Chose cheapness over safety. Promoted Incompetent personals.
• Soviet’s policy engineered the tragedy.
A RECENT PICTURE OF THE REACTOR
LAST WORDS…• ‘GREAT POWER COMES WITH GREAT RESPONSIBILITIES’.• Power should be used for Human Development than
• Nuclear Energy although produces large amount of electricity, it is a high risk substance.
• Hence it should be dealt by highly responsible people.• Judicious and specific use.