Radioactivity

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Radioactivity
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Radioactivity is the spontaneous disintegration
of atomic nuclei. The nucleus emits a particles,
ß particles, or electromagnetic rays during this
process.
After decaying, radioactive atoms change into
other atoms
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• Why does the atom do this?
• the nucleus of an atom attempts to become more
  stable
• In some instances, a new element is formed and in
  other cases, a new form of the original element,
  called an isotope, appears.
• this process of change is often referred to as
  the decay of atoms.
• The rate of Radioactive decay is described in
  half-lives.

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• Energy is released during radioactive decay

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Types of Nuclear Radiation
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• When an unstable nucleus decays, particles and
  energy are given off from the decaying nucleus.
• a and ß radiation is in the form of particles
• ? radiation is in the form of waves-kind of like
  light but higher frequency

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Nuclear Decay
2 protons 2 neutrons
Neutron decays into a proton
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• Biological Effects of Radiation
• Ionizing radiation causes physical damage to
  cells and DNA.
• Radiation can excite DNA and result in the
  destruction on the DNA backbone.
• At high doses of radiation (10,000 - 15,000
  rads), death occurs in a few hours because of
  neurological and cardiovascular breakdown
  (Central Nervous Syndrome).

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• Biological Effects of Radiation
• Medium doses, 500 - 1200 rads, causes death to
  occur in a few days because of the destruction of
  the gastrointestinal mucosa.
• Lower doses, 250 - 500 rads, causes death to
  occur after several weeks due to damage of the
  blood forming organs (hematopoietic syndrome).

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Fission and Fusion
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Fission
Fusion
Splitting a nucleus
Combining of two nuclei.
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• Nuclear power can come from the fission of
  uranium, plutonium or thorium or the fusion of
  hydrogen into helium.
• Today it is almost all uranium.
• The fission of an atom of uranium produces 10
  million times the energy produced by the
  combustion of an atom of carbon from coal.

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• Issues for Fission Power Plants
• Need for a spent fuel disposal facility and a
  decommissioning plan
• Use of large amounts of water for cooling
  purposes (if wet cooling towers are used)
  thermal pollution
• Biological impacts on the ocean due to thermal
  discharge (if seawater cooling is used)
• Public safety concerns

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• Half Life is the amount of time it takes
• for half of the nuclei in a sample to decay

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Mass (kg)