Nuclear Power Generation: Safety and Environmental Concerns

1
Nuclear Power Generation Safety and
Environmental Concerns
ECE 333b Final Project Presentation Warren
Berger
2
Outline

• Motivation for Research
• Background Physics/Engineering of Nuclear Plants
• Safety and Environmental Issues in Public
  Perception
• Case Studies
• Conclusions

3
Nuclear Power Statistics

• Nuclear power generates 16 of the worlds
  electricity.
• France, the United States and Japan are
  currently the largest users of nuclear power in
  the world.
• Germany and Switzerland derive very little
  electricity from nuclear power.
• The United States has not built a new nuclear
  power facility since 1979.

4
Nuclear Power Statistics

• Both the United States and Canada are deriving
  less electricity from nuclear power than 15 years
  ago.

5
Background Nuclear Physics

• At the centre of all atoms lies a very dense,
  positively charged nucleus.
• The nucleus contains protons and neutrons. The
  number of protons determines the identity of the
  atom (Carbon has 6 protons).
• However, naturally some atoms of the same
  element may have a different amount of neutrons
  (ie. Carbon-12 vs. Carbon-13).
• Atoms that are unstable naturally undergo
  radioactive decay this releases a lot of
  radiation (energy).

6
Background Nuclear Physics
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Environmental Effects

• There are two main types of radioactive waste
  generated by nuclear reactors low level waste
  and high level waste.
• Low level waste is generated from hospitals and
  industries as well as reactors. They are
  anything that has come in potential contact with
  radioactive substances.
• This can be stored for several years, or
  immediately be buried.

8
Environmental Effects

• High level waste is produced solely by nuclear
  reactors.
• It is the end products of the fission reaction
  in the reactor core.
• Approximately 0.85 metric tonnes are produced
  each year for each power plant in the United
  States.
• This accounts for 95 of the radioactivity
  produced by the nuclear power industry.
• There is no known way to permanently deal with
  this waste.

9
Comparison to Coal Burning

• The combustion of fossil fuels is responsible
  for 24,000 deaths per year in the United States.
• Nuclear power does not produce any greenhouse
  gases or other toxins.
• France has the cleanest/highest quality air in
  the world.
• Certain groups claim that the burning of fossil
  fuels releases more than 100 times the radiation
  to the atmosphere compared to a proper running
  nuclear plant.

10
Chernobyl Accident

• This is the worst nuclear
  accident in history.
• Largely due to design flaws in
  the reactor (RBMK
  1000) and operator errors.
• However was a very efficient and
  economically
  viable plant (producing over
  
  5 of the Ukraines electricity)

11
Chernobyl - Safety Design Flaws

• The RBMK-1000 design has a positive void
  coefficient. Cooling water was also the
  moderator.
• As more power was generated, water was
  converted to steam and generated positive
  feedback. This made the reactor difficult to
  control.
• This system also had a very long emergency
  shutdown time ( 10 seconds).

12
Chernobyl - Safety Design Flaws

• RMBK-1000 reactor also employed positive
  shutdown control rods.
• When the emergency control rods
  are lowered into the reactor,
  there is a brief transient response
  that actually increases the power
  output of the core.
• The plant design around the
  reactor did not have shielding at the top
  of the plant.

13
Three Mile Island Accident

• The worst nuclear accident in North America.
• Did not result in any deaths or injuries,
  however believed to be responsible for the abrupt
  stop in the United States nuclear power program.

14
TMI Reactor and Accident Details

• This Pressurized Water Reactor is designed
  to have a negative void coefficient.
• When the temperature of the reactor
  increases, the water becomes less dense, slowing
  down less neutrons.
• This accident was caused mainly by rushed
  plant construction and operator errors.
• The accident began when the secondary coolant
  system failed.

15
TMI Reactor and Accident Details

• This caused the water in the primary coolant
  system to vaporize.
• A pressurized relief valve automatically
  opened to vent this. Eventually this had to be
  manually closed but was not.
• The TMI plant did not have a dedicated water
  level indicator so the operators were under the
  false assumption the reactor core was full of
  water.
• Eventually this was discovered but not until
  half of the reactor core melted, and significant
  radiation was vented to the atmosphere.

16
The CANDU Reactor

• This is a pressurized heavy water design,
  similar to pressurized water design.
• It uses Deuterium (heavy water) and unenriched
  uranium (CanDU).
• This was the first reactor to separate
  emergency shutdown from automatic control.
• It has two automatic shutdown procedures a
  more conventional control rod option and spray
  that injects a high pressure neutron absorber
  into the reactor core.

17
The CANDU Reactor

• In addition, plant design is a
  completely enclosed.
• In the event of a reactor breach
  piping
  is designed to realize a vapour
  which neutralizes the majority of
  the radiation present.
• The CANDU reactor is recognized
  internationally as a very safe design.

18
The Bruce A Power Plant

• The Atomic Energy Control Board of Canada
  regulates the safety and environmental aspects of
  nuclear power reactors.

19
The Bruce A Power Plant

• The Bruce A Power plant, like many other
  Canadian reactor sites, rarely exceeds 1 of set
  safety margins.
• Tritium Oxide Emissions Iodine -131 Emissions

20
The Bruce A Power Plant

• The Bruce A Power plant, like many other
  Canadian reactor sites, rarely exceeds 1 of set
  safety margins.
• Noble Gas Effluent Beta-Gamma Effluent

21
Brief Conclusions

• Nuclear power generation, when done correctly
  is actually very safe, and poses little health
  concerns and environmental impact (compared to
  coal burning plants).
• It is believed to be the publics perception of
  the dangers of radiation that have led to a
  decrease in nuclear power generation.
• Recently, the United States has order three new
  nuclear power plants to be built and the Bush
  administration has been very supportive of
  nuclear power.