Man made Disasters

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Man Made Diasters

• A presntation by
• 7 CVirat Singh Class
• St, Mary s Convent Inter College, Manak Nagar,
  Lucknow, India

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The disaster at Chernobyl The worst manmade
disaster in human history

• By Virat Singh Class 7 C
• St, Mary s Convent Inter College, Manak Nagar,
  Lucknow, India

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Where is Chernobyl?
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Chernobyl

• Built in 1978-1979
• Chornobyl

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Background

• Reaktor Bolshoy Moshehnosty Kipyashiy
• RBMK, a Russian acronym translated roughly
  means reactor (of) high power (of the) channel
  (type)
• It was a reactor cooled by water and moderated
  by graphite

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RBMK Reactor
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Fuel assemblies
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Reactor Plant Scenario

• As the reaction occurs, the uranium fuel becomes
  hot
• The water pumped through the core in pressure
  tubes removes the heat from the fuel
• The water is then boiled into steam
• The steam turns the turbines
• The water is then cooled
• Then the process repeats

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The day of disaster

• 25 April 1986
• 0100 The preparation for the test
• 1347 Lowering of the reactor power halted at
  1,600 MWt
• 1400 The ECCS was isolated
• 2310 The power reduction resumed

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26 April 1986

• 2400 Operation shift change
• 2428 Power level is now 500 MWt and kept
  decreasing to 30 MWt
• 2440 The operator withdrew some control rods
• 0100 Power had risen to 200 MWt
• 0103 Connecting the fourth main cooling pump to
  the left loop of the system 200 MWt
• 0107 Connecting the fourth main cooling pump to
  the right of the loop system - this was a
  violation of NOP
• Continued to next slide

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26 April 1986
Continued from last slide

• 0119 Increased feed water flow to the steam
  drums and removed more control rods -violation of
  NOP
• 0123 The test was started
• 012310 Automatic rods withdrawn from the core
• 012321 Two groups of automated control rods
  were back to the core
• Continued to next slide

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26 April 1986
Continued from last slide

• 012330 Power kept increasing
• 012340 Emergency button pushed
• 012344 Power is at 300000 MW th
• 012348 1st thermal explosion
• 012355 2nd explosion

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Human Errors

• Isolation of the emergency core cooling system
• Unsafe amount of control rods withdrawn
• Connection of the four main cooling pumps to the
  right and left of the system

Continued to next slide
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Human Errors
Continued from last slide

• The mental model
• The operator did not have a good mental model of
  the system itself
• The overconfidence
• By having an electrical engineer on site for an
  electrical test
• The confirmation of cues not obtained from the
  system
• The beta was too high
• Many signals were missed before the accident

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Accident Prevention
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System Analysis

• Use of graphite as a moderator
• Lack of a well-built containment structure
• Inadequate instrumentation and alarms for an
  emergency situation
• There were no physical controls that prevented
  the operators from operating the reactor in its
  unstable state

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Summary of Facts

• April 26, 1986
• Chernobyl nuclear power plant
• Operator errors caused a reactor explosion
• Explosion released 190 tons of radioactive gasses
  into the atmosphere
• Fire started that lasted 10 days
• People
• 7 million people lived in the contaminated areas
  and 3 million of them were children
• Wind
• Carried radiation to far distances

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Far Reaching Radiation
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Radioactive fallout
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Direct Casualties

• 5.5 million people still live in
  contaminated areas
• 31 people died in 3 months of radiation poisoning
• 134 emergency workers suffered from acute
  radiation sickness
• 25,000 rescue workers died since then of diseases
  caused by radiation
• Cancer afflicts many others
• Increased birth defects, miscarriages, and
  stillbirths

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Indirect Casualties

• By the year 2000 there were 1800 case of thyroid
  cancer in children and adolescent
• High number of suicide and violent death among
  Firemen, policemen, and other recovery workers

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Environment Impact

• Areas still impacted today
• Soil
• Ground Water
• Air
• Food
• Crops
• Livestock

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Problems Today

• The Sarcophagus
• After the disaster, a huge cement box was built
  around the radioactive material
• It is falling apart!
• According to a 2003 report by the Russian Atomic
  Energy Minister, Alexander Rumyantsev, "the
  concrete shell surrounding the Chernobyl nuclear
  reactor is in real danger of collapsing at any
  time."
• A new Sarcophagus is scheduled to be completed in
  2012

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Recommendations

• Have proper Standard Operating Procedures (SOP)
  for both normal and emergency situations
• Have scheduled trainings and practices for normal
  and emergency situations

Continued to next slide
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Recommendations
Continued from last slide

• A reactor expert must be always there on site
• Any cues from the system must be confirmed by
  operators before making hypothesis or take action
  
• An environment of team work must be formed so
  that every body is involved

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For viewing this slide show Virat Singh