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					Chernobyl Nuclear Disaster
 Chernobyl disaster
The worst manmade disaster in human
             history




     Czech Technical University In Prague
                23 May 2007
                 Background
   The Chernobyl nuclear
    disaster happened
    April 25 and April 26
    in 1986
   Disaster occurred in
    the former USSR (now
    Ukraine)

   The Chernobyl Nuclear
    Power Plant is located
    80 miles north of Kiev
Where is Chernobyl?
Chernobyl      60 miles
                North of Kiev
                in what is
                now Ukraine

               Breadbasket
                of Russia

               Built in 1978-
                1979
            l
               Background
   Reaktor Bolshoy Moshehnosty
    Kipyashiy

   RBMK, a Russian acronym translated
    roughly means “reactor (of) high power
    (of the) channel (type)”
   reactor cooled by water and moderated by
    graphite
RBMK Reactor
Fuel assemblies
       Reactor Plant Scenario
1.   As the reaction occurs, the uranium
     fuel becomes hot
2.   The water pumped through the core
     in pressure tubes removes the heat
     from the fuel
3.   The water is then boiled into steam
4.   The steam turns the turbines
5.   The water is then cooled
6.   Then the process repeats
       Someone’s Brilliant idea
   On 25 April, prior to a routine shut-
    down, the reactor crew at Chernobyl-
    4 began preparing for a test to
    determine how long turbines
    would spin and supply power
    following a loss of main electrical
    power supply.
   Similar tests had already been
    carried out at Chernobyl and other
    plants, despite the fact that these
    reactors were known to be very
    unstable at low power settings.
   A series of operator actions,
    including the disabling of
    automatic shutdown
    mechanisms, preceded the test
    early on 26 April.
   --Why would you disable an
    emergency system???
            Day of disaster
                25 April 1986
   01:00 The preparation for the test
   13:47 Lowering of the reactor power
    halted at 1,600 MWt
   14:00 The Emergency cooling
    system was isolated
   23:10 The power reduction resumed
              26 April 1986
   24:00 Operation shift change
   24:28 Power level is now 500 MWt and
    kept decreasing to 30 MWt
   24:40 The operator withdrew some
    control rods
   01:00 Power rose to 200 MWt
   01:03 Connecting the fourth main
    cooling pump to the left loop of the
    system 200 MWt
   01:07 Connecting the fourth main
    cooling pump to the right of the loop
    system - this was a violation of NOP
         26 April 1986 (cont.)
   Increased feed water flow to the
    steam drums and removed more
    control rods -violation of NOP
   01:23 The test was started
   Automatic rods withdrawn from the
    core
   01:23:21 Two groups of automated
    control rods were back to the core
        26 April 1986 (cont.)
   01:23:30 Power kept increasing
   01:23:40 Emergency button pushed

Because aof a design flaw, this caused
 a power surge
                 Explosions
   1:23:48 1st thermal explosion explosive
    force of steam lifted off the cover plate of
    the reactor

   01:23:55 2nd explosion threw out
    fragments of burning fuel and graphite
    from the core and allowed air to rush in,
    causing the graphite moderator to burst
    into flames releasing fission products to
    the atmosphere. A second explosion.
   Aerial view of the
    damaged core.
    Roof of the turbine
    hall is damaged
    (image center).
    Roof of the
    adjacent reactor 3
    (image lower left)
    shows minor fire
    damage.
                          Secrecy
   The Chernobyl accident occurred on April 26, 1986, but the Soviet
    government did not acknowledge the event until April 28 and
    denied the extent of the disaster for some days thereafter.

   Radiation was detected and reported in Sweden the day after the
    explosion. Initially Sweden thought it was a problem at one of
    their own facilities.

   soon radiation was monitored by aircraft equipped with radiation-
    detection devices, including the U.S. Air Force's 55th Weather
    Reconnaissance Squadron.

    Because of Soviet reluctance to admit observers or release
    videos, photographs, or accurate announcements about the
    accident, and because downwind radiation measurements could
    give no specific information about what was happening at
    Chernobyl, much news attention in the West focused on the
    satellite photographs
        Summary of 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
         Human Errors (cont.)
   Mental model
    • The operator did not have a good
      mental model of the system itself
   Overconfidence
    • By having an electrical engineer on site
      for an electrical test
    • No confirmation of cues obtained from
      the system
   Beta too high
    • Many missed signals before the accident
Accident Prevention
             Reactor Flaws
   Use of graphite as a moderator
    (unstable)
   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
              Summary of Facts
   April 26, 1986:
   190 tons of radioactive
    gasses released into the
    atmosphere
   Fire starts that lasts 10
    days
   Wind: Carries radiation
    far distances

   People: 7 million lived
    in contaminated areas;
    3 million were children
Radioactive fallout
                     Direct Casualties
   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

   5.5 million people still live in
    contaminated areas
        Listen to this at home
   http://www.youtube.com/watch?v=J
    YkVatvFLsg
              Environment Impact
   Areas still impacted
    today:
    •   Soil
    •   Ground Water
    •   Air
    •   Food
           Crops
           Livestock
Environmental Impact
             Forest were killed
              off.
             Lakes and rivers
              were
              contaminated.
             Fish are above
              accepted
              contamination
              levels to be sold.
    Environmental Impact Today
   A 4,000km² zone
    has been assigned
    around the reactor
    where all
    agricultural
    activities are
    forbidden.
   As of 2001 2,217
    cities are still
    under radiological
    control
                 Pripyat
   Pripyat, the city immediately
    adjacent to chernobyl was once
    home to thousands of workers.
    Today it is abandoned.
   A few individuals enter each day by
    permit and for limited amounts of
    time. Readiation levels are very high
   View Pripyat today
        View Pripyat today at
   http://www.opuszczone.com/galerie/
    uk_prypec/index.php?lang=en

   http://www.youtube.com/watch?v=Z
    RewxKvj4Ig
             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

• Children were born with
  deformities and came to be
  known as “The Children of
  Chernobyl”
         Polices and Legislation
   Safety devices have
    been improved on all
    nuclear reactors.
   Agencies were created
    to help prevent
    another disaster.
   Seven million people
    are now receiving or
    are eligible for
    benefits as “Chernobyl
    Victims”.
    Chernobyl’s political fallout

   Stimulated Gorbachev’s glasnost
    (openness)

   Stimulated nationalism in Ukraine,
    Belarus, and other republics that lost
    clean-up workers.

   Growth of environmental opposition

   Questioning of the heart of technocratic
    power
                  Problems Today
   The Sarcophagus

   After the disaster, a huge
    cement box was built
    around the radioactive
    material

   It is falling apart! Experts
    state that it is in real
    danger of collapsing at
    any time.“

   A new Sarcophagus is
    scheduled to be
          Recommendations
   Have proper Standard Operating
    Procedures (SOP) for both normal
    and emergency situations
   Have scheduled trainings and
    practices for normal and emergency
    situations
      Recommendations (cont.)
   Always have a reactor expert on site
   Have operators confirm any cues
    from the system before making
    hypothesis or take action
   Have a team work kind of
    environment such that every body is
    involved
Pictures
          Radiation and Health
   Health effects as a result of radiation
    exposure:
       -increased likelihood of cancer
       -birth defects including long limbs,
    brain
        damage, conjoined stillborn twins
       -reduced immunity
       -genetic damage
Three-Mile Island, PA 1979
           Health around TMI
   In 1979, hundreds of people reported
    nausea, vomiting, hair loss, and skin
    rashes. Many pets were reported dead or
    showed signs of radiation

    Lung cancer, and leukemia rates
    increased 2 to 10 times in areas within 10
    miles downwind

   Farmers received severe monetary losses
    due to deformities in livestock and crops
    after the disaster that are still occurring
                          Plants
                         near TMI



                            -lack of chlorophyll
                            -deformed leaf
                         patterns
                            -thick, flat, hollow
                         stems
TMI dandelion leaf at right -missing reproductive
Animals Nearby TMI
         Many insects
         disappeared for
         years.

         • Bumble bees,
           carpenter bees,
           certain type
           caterpillars, or
           daddy-long-leg
           spiders

         • Pheasants and
           hop toads have
            Nuclear reaction
   Chain reaction occurs when a
    Uranium atom splits

   Different reactions
    • Atomic Bomb in a split second
    • Nuclear Power Reactor more controlled,
      cannot explode like a bomb
       History of nuclear power

1938– Scientists study Uranium
 nucleus
1941 – Manhattan Project begins
1942 – Controlled nuclear chain
 reaction
1945 – U.S. uses two atomic bombs
 on Japan
1949 – Soviets develop atomic
           “Atoms for Peace”


Program to justify nuclear
  technology

Proposals for power, canal-building,
  exports
        Economic advantages

   The energy in one pound of highly
    enriched Uranium is comparable to
    that of one million gallons of
    gasoline.


   One million times as much energy
    in one pound of Uranium as in one
    pound of coal.
            Emissions Free

   Nuclear energy annually prevents
    • 5.1 million tons of sulfur
    • 2.4 million tons of nitrogen oxide
    • 164 metric tons of carbon

   Nuclear often pitted against fossil
    fuels
    • Some coal contains radioactivity
    • Nuclear plants have released low-level
      radiation
     Early knowledge of risks

   1964 Atomic Energy Commission
    report
     on possible reactor accident

    • 45,000 dead
    • 100,000 injured
    • $17 billion in damages
    • Area the size of Pennsylvania
      contaminated
States with nuclear power
         plant(s)
Nuclear power around the globe

   17% of world’s electricity from
    nuclear power
    • U.S. about 20% (2nd largest source)

   431 nuclear plants in 31 countries
    • 103 of them in the U.S.
    • Built none since 1970s (Wisconsin as
      leader).
    • U.S. firms have exported nukes.
    • Push from Bush/Cheney for new nukes.
   Countries Generating Most Nuclear
                Power
     Country            Total MW
USA                      99,784
France                   58,493
Japan                    38,875
Germany                  22,657
Russia                   19,843
Canada                   15,755
Ukraine                  12,679
United Kingdom           11,720
Sweden                   10,002
South Korea               8,170
           Nuclear fuel cycle

   Uranium mining and milling
   Conversion and enrichment
   Fuel rod fabrication
   POWER REACTOR
   Reprocessing, or
   Radioactive waste disposal
    • Low-level in commercial facilities
    • High level at plants or underground
      repository
       Front end:
Uranium mining and milling
Uranium tailings
 and radon gas




  Deaths of Navajo
 miners since 1950s
         Uranium enrichment

   U-235
    • Fissionable at 3%
    • Weapons grade at 90%


   U-238
    • More stable

   Plutonium-239
    • Created from U-238; highly
      radioactive
Radioactivity of plutonium

  Life span of least
  240,000 years

  Last Ice Age glaciation
  was 10,000 years ago

  Neanderthal Man died out
  30,000 years ago
           Risks of enrichment
           and fuel fabrication

   Largest industrial users of water,
    electricity
    • Paducah, KY, Oak Ridge, TN,
      Portsmouth, OH

   Cancers and leukemia among workers
    • Fires and mass exposure.
    • Karen Silkwood at Oklahoma fabrication
      plant.
      Nuclear Reactor Process
   3% enriched Uranium pellets
    formed into rods, which are
    formed into bundles

   Bundles submerged in water
    coolant inside pressure vessel,
    with control rods.

   Bundles must be SUPERCRITICAL;
    will overheat and melt if no control
    rods. Reaction converts water to
Technology depends on
      operators
        Other reactor accidents
          (besides TMI and Chernobyl)
   1952 Chalk River, Ontario
    • Partial core meltdown
   1957 Windscale, England
    • Graphite reactor fire contaminates 200 square
      miles.
   1975 Browns Ferry, Alabama
    • Plant caught fire
   1976 Lubmin, East Germany
    • Near meltdown of reactor core .
   1999 Tokaimura, Japan
    • Nuclear fuel plant spewed high levels of
      radioactive gas
United States
             Breeder reactor
      “Breeds” plutonium as it operates

Uses liquid sodium metal instead of water for
 coolant
    • Could explode if in contact with air or water

   1966 Fermi, Michigan
    • Partial meltdown nearly causes evacuation of Detr

   1973 Shevchenko, Russia
    • Breeder caught fire and exploded

   Controversial proposals in Europe, U.S.
              Reprocessing

   Separates reusable fuel from waste
    • Large amounts of radioactivity released

   1960s West Valley, NY
    • Radiation leaked into Lake Ontario

   1970s La Hague, France
    • Released plutonium plumes into air
Back end: Radioactive wastes
   Low-level wastes in commercial
    facilities

   Spent fuel in pools or “dry casks” by
    plants

   Nuclear lab wastes

    • Hanford wastes leaked radiation into Columbia
      River
   High-level underground repository
 Yucca
Mountain
           Transportation
               risks

   Uranium oxide spills

   Fuel rod spills (WI 1981)

   Radioactive waste risks
 “Mobile
Chernobyl”
to Yucca Mtn.
                       Kyshtym waste
                       disaster, 1957




                                 Orphans

• Explosion at Soviet weapons factory forces
  evacuation of over 10,000 people in Ural
  Mts.

• Area size of Rhode Island still uninhabited;
    Radioactive Waste Recycling
   Disposal of radioactive waste from nuclear
    power plants and weapons facilities by
    recycling it into household products.

   In 1996, 15,000 tons of metal were
    received by the Association of Radioactive
    Metal Recyclers . Much was recycled into
    products without consumer knowledge.

   Depleted Uranium munitions for military.
                  Summary
   Nuclear energy has no typical pollutants or
    greenhouse gasses

   Nuclear waste contains high levels of
    radioactive waste, which are active for
    hundreds of thousands of years.

   The controversy around nuclear energy
    stems from all parts of the nuclear chain.

				
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