Transcript No Slide Title

Chapter 13
Nuclear energy in perspective
 How nuclear power works
 The hazards and costs of nuclear power
facilities
 More advanced reactors
 The future of nuclear power

From mass to energy
 Comparing nuclear power to coal
power

http://www.nv.doe.gov/news&pubs/photos&films/atm.htm
Fission: a large atom of one element is split
to produce two different smaller elements
 Fusion: two small atoms combine to form a
larger atom of a different element
 Isotope: different (mass number) forms of
the same element

 238U
= 92 protons + 146 neutrons
 235U = 92 protons + 143 neutrons
 Energy
is released
 Begins with 235U
 Produces radioactive by-products
 Produces free neutrons
 Splits
a larger atom into smaller
atoms
 Fuses smaller atoms in one larger
atom
 Begins with 2H and 3H
 Produces helium
Fuel rods: rods full of 235U pellets
 Moderator: fluid (water) coolant that
slows down neutrons
 Control rods: moderate rate of the chain
reaction by absorbing neutrons

Sustain a continuous chain reaction
 Prevent amplification into a nuclear
explosion
 Consist of an array of fuel and control
rods
 Make some material intensely hot

Use steam to drive turbogenerators
 Convert steam into electricity
 Produce superheated water in a reactor
vessel
 Prevent meltdown

Requires 3.5 million tons of raw fuel
 Requires 30 tons of raw material
 Emits over 7 million tons of CO2 into the
atmosphere
 Emits no CO2 into the atmosphere

Emits over 300 thousand tons of SO2 into
the atmosphere
 Emits no acid-forming pollutants
 Produces about 100 thousand tons of
ash
 Produces 250 tons of radioactive waste
 Possible meltdown

 Produces
250 tons of radioactive
waste
 Possible meltdown

Radioisotopes: unstable isotopes of the
elements resulting from the fission
process
Radioactive emissions: subatomic
particles (neutrons) and high-energy
radiation (alpha, beta, and gamma
rays)
 Radioactive wastes: materials that
become radioactive by absorbing
neutrons from the fission process

Radioactive emissions
 Radioactive wastes
 Disposal of radioactive wastes
 Nuclear power accidents
 Safety and nuclear power
 Economic problems with nuclear power

Half life = the time for half the
amount of a radioactive isotope
to decay
Molybdenum-99 (half-life = 2.8 days)
 Xenon-133 (half-life = 5.3 days)
 Krypton-85 (half-life = 10.7 years)
 Cesium-137 (half-life = 30.0 years)
 Plutonium-239 (half-life = 24,000 years)






Finding long-term containment sites
Transport of highly toxic radioactive wastes
across the United States
The lack of any resolution to the radioactive
waste problem
Environmental racism
Cost ($60 billion to 1.5 trillion)
To be safe, plutonium-239 would require
240,000 years (10 half-lives) of
containment!
 Discuss the implications of this in terms of
disposal of radioactive wastes.
 Yucca Mountain in southwestern
Nevada = the nation’s nuclear waste
repository


Three-mile Island
› 1979
› Harrisburg, PA
› Loss of coolant in reactor vessel
› Damage so bad, reactor shut down
permanently
› Unknown amount of radioactive waste
released into atmosphere

Loss of water coolant perhaps triggered
the accident. When the water-circulation
system failed, the temperature in the
reactor core increased to over 5,000 oF,
causing the uranium fuel to begin melting
and producing steam that reacted with the
zirconium alloy cladding of the fuel rods to
produce hydrogen gas.

A second reaction between steam and
graphite produced free hydrogen and
carbon oxides. When this gas combined
with oxygen, a blast blew off the top of the
building, igniting the graphite. The burning
graphite threw a dense cloud of
radioactive fission products into the air.
Block cell division
 Damage biological tissues and DNA
 Death
 Cancer
 Birth defects

Passive rather than active safety features
 New generations of reactors (ALWRs, see
Fig. 13-15)
 Terrorism and nuclear power: dirty
bombs or outright attacks

Energy demand estimates were
unrealistic.
 Costs increases (5x) to comply with new
safety standards.
 Withdrawal of government subsidies to
nuclear industry.
 Public protests delayed construction.
 Any accident financially ruins the utility.

Breeder reactors
 Fusion reactors

Creates more fuel than it consumes
 Raw material is 238U
 Splits atoms

Fuses atoms
 Releases energy
 Raw material is deuterium and tritium
 Source of unprecedented thermal
pollution

General distrust of technology
 Skepticism of management
 Doubt overall safety claims about
nuclear power plants
 Nuclear power plants are prime targets
for terrorist attacks
 Nuclear waste disposal problems

Need to address public concerns listed in
the opposition section.
 Waste dilemma must be resolved.
 Strong political leadership capable of
analyzing the full spectrum of problems
associated with the future of nuclear
power is needed.
