NUCLEAR MELTDOWN!

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NUCLEAR MELTDOWN!

• Three Mile Island and Chernobyl

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Draw Backs to Nuclear Power

• Thermal Pollution
• Nuclear Waste
• Meltdowns
• Three Mile Island
• Chernobyl

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What is a Meltdown

• A meltdown occurs if a reactor loses coolant
  water, exposing the reactor core.
• The temperature reaches 2800C, the fuel melts,
  and becomes a white-hot molten mass.
• This melts its way through all the containment
  vessels to the earth below

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Three Mile Island

• March 29th ,1979
• Harrisburg, PA

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What Happened

• Cleaning a feed water tank
• Clogged, tried to blow out the clog with an air
  compressor
• Compressor lines had been connected to a water
  line
• Water went into the air lines

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Continued

• Water caused the valves to close (designed not to
  close, but never wired)
• Heat and pressure built up (couldnt vent)
• Water couldnt reach the generators(valves
  closed!)
• Back-up valves had been closed a week earlier
  (they were never closed)
• Indicator light covered with something

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And then what?

• A second indicator light showing a false OK
  signal
• Operators struggled with mixed signals from
  control panel
• Finally realized the valve problem and opened
  them.

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Results

• Containment building flooded with radioactive
  water
• Tremendous build up of steam and gas (hydrogen
  and possibly oxygen)
• Worried of possible explosion- made the decision
  to release radioactive gas into the atmosphere
• Water had also been released, fuel rods were
  damaged.
• No immediate deaths

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Chernobyl

• April 26, 1986
• former USSR (now Ukraine)

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What Happened?

• Test to see if the plant could produce enough
  power to run itself during a power outage
• But not everyone was informed
• Lack of cooling and too much pressure caused a
  power surge (massive heat)

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What happened continued

• There were two explosions
• The first explosion was a steam explosion
• Second explosion under debate- hydrogen?
• fuel, core components, structural items sent into
  atmosphere
• Radioactive and hot material set into
  atmosphere
• The plume of smoke went 1 km into the air

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The Fires

• Several broke out after the explosions
• The fires - normal and graphite.
• Graphite fire caused the biggest release of
  radiation
• Graphite fires too hot for water.
• Dropped 5000 tons of boron, dolomite, sand, clay
  and lead to extinguish the graphite fire.
• Extinguished finally after 20 days.

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Radiation Release

• It is estimated that all of the xenon gas, about
  half of the iodine and cesium, and at least 5 of
  the remaining radioactive material in the reactor
  core was released. Most of the released material
  was deposited close by as dust and debris , but
  the lighter material was carried by wind over the
  Ukraine, Belarus, Russia and to some extent over
  Scandinavia and Europe.
• Iodine-131 and cesium-137 were the main
  radioactive hazards.

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In Conclusion

• reactor design was poor from the point of view
  of safety and unforgiving for the operators
• killed more than 30 people immediately
• high radiation levels in the surrounding 20-mile
  radius
• 135,00 people had to be evacuated
• 64 of all Ukrainian thyroid cancer patients age
  15 of younger live in the most contaminated
  regions.

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What are the chances Today?

• The chances of this happening have been estimated
  at one in 100 million 'reactor years.
• A fuel meltdown might be expected once out of
  20,000 years of reactor operation.
• In 2 out of 3 meltdowns there would be no deaths.
• In 1 out of 5 meltdowns there would be 1000
  deaths,
• In 1 out of 100,000 meltdowns there would be
  50,000 deaths.
• Air pollution from coal-burning power plants
  causes tens of thousands of deaths a year.
• There would have to be 25 meltdowns a year for
  nuclear power to be as dangerous as coal.

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Nuclear Power Sites in U.S.
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Daily Radiation
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Where you live
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Radiation Survey