Nuclear Power
Physics 1303
4/7/03
Outline
The Nucleus
Radioactivity
Fission
Fusion
Nuclear Weapons
Nuclear Power
Nucleus
Composed of protons and
neutrons
239Pu94 or Pu – 239
94 protons
145 neutrons
Isotope of Plutonium
Radioactivity
Some isotopes are
unstable
Spontaneously Decay
Decaying isotopes emit
particles
Radon is a health hazard
Product of the decay of
naturally occurring
uranium
Affects indoor air quality
2nd leading cause of lung
cancer
Regional issue
Half-life
Pu-239 decays to U-
235 with the
emission of an alpha
particle:
The time for half of
the Pu-239 nuclei to
decay is called the
half-life.
24,000 years is half-
life for Pu-239 decay
Aside: Pathetic Joke
Did you hear about the
socially sophisticated
physicist?.
He was the half-life of
the party.
Fission
By bombarding a
nucleus with neutrons, a
stable isotope can be
induced to fission or
split.
U-235 is an example of a
fissionable material.
The release of neutrons
in this reaction means
that we can set up a
chain reaction
Fission Releases Energy
When the fission is
controlled, as in a
nuclear reactor, it can be
a practical source of
power.
When the fission is
uncontrolled it can be the
basis for weapons of
mass destruction.
Fusion
Two light nuclei combine
to form a heavier
nucleus.
The fusion of deuterium
(a hydrogen isotope)
with tritium (another
hydrogen isotope) to
form a helium nucleus
can release a great deal
of energy.
Fusion Power
Using a fission bomb as a
trigger, a hydrogen bomb,
or a H-bomb uses fusion
to create a WMD.
Solar energy originates as
fusion energy in the sun’s
interior.
Fusion power is an active
area of research.
Nuclear Weapons
First nuclear weapon
tested at Trinity site in
1945 used Pu-239.
The fuel for the
Hiroshima and Nagasaki
bombs were U-235 and
Pu-239, respectively.
First H-bomb test in 1952
Nuclear Weapons
Country Strategic Tactical Total
United States 7,300 3,200-4,700 10,500-12,000
Russia 6,000 7,000-15,000 13,000-20,000
China 290 120 400-410
France 400 80 400-482
United Kingdom 100 100 200
India - 85-90 85-90
Israel - 100-300 100-300
Pakistan - 15-25 15-25
Global Total - - 24,700-33,507
Nuclear Reactors:
Boiling Water Reactor (BWR)
Similar to coal plant:
boils water, makes
steam, steam drives
turbine, turbine turns
electrical generator
Fissioning of U-235 is
the fuel.
BWR Components
Containment
building prevents
release of radiation
Water is needed as
coolant and to
prevent meltdown.
Nuclear Reactor is a Heat Engine
Efficiency is similar
to a coal burning
plant, about 33%
So, 2/3 of the
released energy is
waste heat.
Uranium Fuel
Only 0.7% of natural U
is U-235.
U-238 is not
fissionable.
U must be enriched to
2.8% U-235.
Uranium Fuel Supply
Worldwide U-235
resource does not offer
a long-term energy
solution.
Breeder reactor
consuming U-235 can
convert U-238 into Pu-
239.
Plutonium Economy
Breeder reactors
would greatly increase
the availability of
weapons-grade
Plutonium.
Nuclear Power in the US
104 nuclear plants
Produce 20% US
Electricity
No new plants since
1973
Why?
Nuclear Accidents
1979 Three Mile Island
partially core melt
1986 Chernobyl
explosion and fire,
release of radiation
Waste Disposal
WIPP near Carlsbad,
NM. Stores hi-level
waste associated with
nuclear weapons
Yucca Mountain,
Nevada. High-level
waste from commercial
reactors.
Will there be a nuclear renewal?
Economics do not look
good. Very capital
intensive.
Fear of terrorism
Anti-nuclear groups
Waste disposal