On April 26, 1986 at 0123 an explosion in reactor 4 of the Chernobyl Nuclear Power Plant released a

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• On April 26, 1986 at 0123 an explosion in
  reactor 4 of the Chernobyl Nuclear Power Plant
  released a nuclear fallout 400 times that of the
  atomic bomb explosion in Hiroshima. The
  radioactive cloud drifted over Europe and as far
  as North America
• 60 of the fallout landed in Belarus
• Today, few of us are aware of the men and women
  who gave their lives to combat the disaster.
  Their stories are hardly known, but need to be
  told
• These stories are full of heroism, but they also
  contain many lessons that we must learn

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CHERNOBYL
Kabir Ciamaruel John
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Soviet Union
USSR Union of Soviet Socialist
Republics (1955-1991)
At the time of the accident, the Chernobyl Power
Plant, located in modern day Ukraine, contained
four operational reactors and two reactors that
were under construction.
The plant was located in the town of Pripyat,
which had a population of 50,000.
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What went wrong?

• Everything!
• Poor engineering practices
• Poor financial allotment
• Construction shortcuts
• Poor operator training
• Faulty equipment
• Poor casualty response procedures
• Poor communication from the site to the Kremlin

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Most reactors are surrounded by a containment
building, such as this one
Chernobyl, however, had no containment building!
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RBMK Reactor 4 Positive Void Coefficient
Scenario for a supercritical reaction!
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The Day Before (April 25, 1986)

• Reactor was at the end of its fuel cycle
  shutdown was planned for refueling to commence.
• Test of a new voltage regulator device was
  scheduled.
• The day shift had been briefed and understood the
  test.
• An electrical engineering team was present.
• However, the reactor shutdown was postponed!
• The evening shift relieved the day shift.

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The Accident (April 26, 1986)

• New shift on duty, testing procedures unclear and
  improper turnover of conditions. They were
  unsure how to conduct the test.
• One operator rings another and asks What shall
  I do? In the programme there are instructions of
  what to do, and then a lot of things are crossed
  out. The reply Follow the crossed out
  instructions.
• The test required a low power level, so control
  rods were inserted, but inserted too far!
• Why too far? Know one knows, the operator died
  of radiation poisoning, as did the chief of the
  night shift.
• Power was too low to run test due to xenon
  poisoning the operators therefore removed the
  control rods in such a way as to override the
  safety system!
• Pump speed increased, resulting in more water in
  the system, which further reduced the reaction.
• In response, operators also removed all manual
  control rods and disabled the automatic shutdown
  system.

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The Accident (April 26, 1986)

• The reactor output began to increase.
• Operators pressed the Emergency Defense System,
  which issues a SCRAM to the reactor.
• But the rods inserted too slowly to stop the
  increasing reaction.
• Seven seconds after issuing the SCRAM, reactor
  output was 30 GW 10 times its nominal operating
  range!
• Steam pressure increased and the fuel rods began
  to melt into the cooling water.

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The Accident (April 26, 1986)

• The reactor went supercritical and a steam
  explosion blew the top off the reactor.
• Zr H2O(g) ? ZrO2 H2(g)
• Shortly after the first explosion, a second
  occurred. Graphite reacted with steam.
• C(s) H2O(g) ? CO(g) H2(g)

Graphite moderator was ejected out of the reactor
and into the yard (above). Radioactive fallout
spewed into the atmosphere (left).
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The Accident (April 26, 1986)
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The Accident (April 26, 1986)

• Due to the second explosion, more radioactive
  material was ejected from the reactor.
• Burning material landed on the building
  surrounding reactor 3 this building was
  constructed out of combustible material, despite
  safety regulations.
• The shift chief for reactor 3 wanted to shut it
  down, but the chief engineer wouldnt allow it!

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The Accident (April 26, 1986)

• Initial response
• Firefighting was immediate, most firefighters
  died shortly after from radiation exposure. They
  had no idea they were being exposed.
• Operators were initially unsure as to the extent
  of the damage.
• Reactor 3, right next door, was still running
  (Yuri Bagdasarov competency over compliancy).
• Soldiers arrived in Pripyat with radiation
  detectors.
• Civilians were not informed of the radiation
  they went about their business as normal, all the
  while being exposed to high radiation levels.

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The Day After (April 27, 1986)

• Soviets kept silent gave no information to the
  international community.
• Not until three days later, when a high radiation
  alarm sounds in a Swedish nuclear power plant, is
  the world alerted.
• Finally, at 1400, Pripyat was evacuated, but
  after over 24 hours of exposure it is not known
  how many died of cancer.

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Most residents thought they would return in a few
days
Pripyat is abandoned to this day. It is a ghost
town
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A few days after

• Doctors were forbidden to cite radiation as cause
  of death, so little is known about the actual
  causalities.
• It is officially said that approximately 50 died
  the first few days. It is believed, however, that
  many more people actually died.
• Draining the bubbler pool (Alexei Ananenko,
  Valeri Bezpalov, and Boris Baranov).
• Extinguish fire and limit release of radiation
  using boron, sand, clay, lead, and dolomite via
  helicopter.
• Many first responders exhibited signs of
  radiation sickness.
• The helicopter pilots, some of which flew over 30
  sorties, began vomiting and showing signs of
  exposure.
• 600 pilots were fatally contaminated.

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The weeks after

• Problems compounded
• Concrete was deposited beneath the building for
  reactor 4.
• Radioactive graphite had to be removed from the
  roof of reactor 3.
• Robots failed due to radioactivity.
• Conscripts were drafted to remove the graphite
  from the roof.
• They were allowed less than one minute on the
  scene.
• Most were in their early twenties at the time
  20,000 of them are dead today.
• Streets and buildings were sprayed with
  chemicals.
• Most Soviet information on the clean up is
  unavailable.
• Nearby movable objects were buried in concrete.
• Cars, topsoil, trees.
• Twenty years later, the vehicles used during
  clean up still release radiation.
• Entering/exiting vehicles were chemically washed
  down. Many were covered with lead to protect the
  soldiers.

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Distribution

• Red indicates the extent of the radiation cloud
  on April 27

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Becquerel

• SI unit for radioactivity
• Symbol Bq
• 1 Bq is defined as the activity of a quantity of
  radioactive material in which one nucleus decays
  per second

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Radioactive Decay and Half-Life

• Radioactive Decay
• Process in which an unstable nucleus loses energy
  by emitting ionizing particles and radiation
• Half-life
• Time it takes for a half of the atoms of a
  radioactive sample to disintegrate
• Half-Lives of various isotopes released
• 137Cs - 30 years
• 134Cs 2 years
• 131I 8 days
• 90Sr 28.8 years
• 144Ce 285 days

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The weeks after

• Total worldwide deposition of 137Cs estimated to
  be 100PBq.
• 1 month after incident 137Cs level at 10.0 TBq at
  exclusion zone.
• 250,000 km2 area in Belarus, Ukraine, and Russia
  were contaminated with a 137Cs level of 37
  Gbq/km2 in 1996 at exclusion zone.
• Reports (1997) say 137Cs levels continue to rise
  in trees.

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Residual Effects

• Thyroid cancer incidence increased in Belarus,
  Ukraine, and Russia.
• Bq levels increased in agricultural and wild
• food sources.
• Debatable Predicted death toll is 4,000-60,000.
• 270,000 Predicted Cancer Cases (WHO).

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Reactor 4 today. It is covered by a large
sarcophagus. The hastily built structure is
showing massive signs of deterioration. Radiation
is still 100 x normal background.
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After effects

• Red forest Pines died from radioactive fallout.
• one of the most contaminated areas on earth.
• Some argue the benefits to wildlife of removing
  people from the zone, have far outweighed any
  harm from radiation.
• Animals to radioactive to be eaten are otherwise
  healthy.
• No humans depleting natural resources.
• Reoccurrence of species not seen in centuries.

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Long-term Effects

• Contaminated areas continue to be inhabited by
  Humans in spite possible health risks.
• Poor Epidemiological studies due to lack of
  funds, experience, and necessary scientific
  infrastructure.
• Screening a major part of studies
• Both Local and International efforts have been
  unsuccessful

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Political Agenda

• Public not properly informed about the
  seriousness of the contamination
• Purposely published false reports on the overall
  consequence of the disaster
• Possible prosecution for questioning authorities
• Yury Bandazhevsky scientist imprisoned for 4
  years.

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Long-term Effects

• High Dosage
• Difficult to connect radioactive contamination to
  health issues vs. health issues due to other
  causes
• Thyroid Cancer in children increased occurrence
  in highly contaminated areas.
• Belarus, Ukraine, and Russia
• In 1995, approximately 700 cases reported

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Long-term Effects

• Low Dosage
• Possibly affected the entire European populations
• Affect on Humans not fully understood
• Possibly increase cancer and other fatal illness
  related to radiation exposure, but complex
  research needed to properly analyze Chernobyl
  overall effects.

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Food Consumption

• 137Cs (caesium) and 90Sr (strontium)
• Half-lives about 30 years
• Found in surface layers of soil
• Taken up by plants, insects, and mushroom

• -Issue entering the local food supply
• Other Issues
• 137Cs levels rising in trees
• Possible contamination of lakes, ponds, aquifers,
  etc

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Food Restrictions

• Most wildlife and wild-growing plants, like deer,
  mushrooms, and berries.
• Varies depending on region and how it was
  affected
• Direct and indirect contamination
• 1986 approximately 9,000 farms were considered
  restricted areas
• Presently reduced to about 369 farms

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Chernobyl Published Reports

• Chernobyl Forum
• September 2005
• Predicted death toll
• 4,000 people (total)
• Radiation levels had returned to acceptable
  levels outside 20 miles from site
• 99 of thyroid cancer not lethal

• However, the report was heavily criticized by
  other organizations
• Now proven to have unlikely predictions

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Other Reports (predictions)

• Greenpeace
• 270,000 cases of cancer with 93,000 being fatal
  between 1990-2004
• Other health issues such as immune, respiratory,
  and circulatory problems

• IPPNW
• 10,000 affected (today) by thyroid cancer
• 50,000 cases expected
• 10,000 deformities in newborns
• 5,000 newborn deaths

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