Nuclear Energy
Kingshuk Majumdar
Department of Physics
Berea College
Overview
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Energy – some numbers
Sources of Energy
Basic Nuclear Statistics
Nuclear Basics 101
Benefits of Nuclear Energy
Nuclear Waste
Facts about coal burning
Energy use in the U.S.
• U.S. Energy consumption in 2000
= 98,976,371 billion Btu = 1.04 x 1020 Joules
• U.S. population in 2000 = 281,421,906.
• Energy use per capita per year = 3.7 x 1011 Joules
• Per capita daily energy use: 1.01 x 1011 Joules
= 2.4 x 107 Kilocalories = 2.4 x 107 Calories
= maintaining daily 9600 adults (each of us need about
2500 Calories per day for our maintenance)
Sources of Energy
Non-renewable
Renewable
Oil (Petroleum)
Solar
Natural Gas
Wind
Coal
Geothermal
Uranium (Nuclear)
Biomass
Hydro power
Ocean
U.S. Primary Energy Consumption by Source and
Sector, 2005 (Quadrillion Btu)
Source: Energy Information Administration, Annual Energy Review 2005
Basic Nuclear Statistics
• Total Operable Reactors: U.S. – 104; World – 443
• Nuclear Electricity Net Generation: 781,986 million
kilowatt-hours
• Nuclear % of Electricity Generation: 19.3
• Largest U.S. Nuclear Plant: Palo Verde - 3,825 megawatts
(3 units)
• Fuel Cost: nuclear vs. fossil steam: 0.45 cents/kwh vs.
2.18 cents/kwh
• Number of States with Commercial Nuclear Plants: 31
• States with Most Commercial Nuclear Plants: Illinois - 6;
Pennsylvania – 5
• First U.S. Commercial Nuclear Plant: Shippingport in
Pennsylvania, 1957
This is one of the three
units of Palo Verde
Nuclear Generating
Station in Arizona.
With all three units
running, enough power
is generated to meet the
electrical needs of
nearly 4 million people.
Nuclear Basics 101
1. Nuclear energy is the energy from the atoms.
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Atoms are tiny particles that make up every object in the
universe. There is enormous energy in the bonds that hold
atoms together.
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Nuclear energy is energy in the nucleus (core) of an atom.
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Nuclear energy can be used to make electricity. But first the
energy must be released.
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It can be released from atoms in two ways: nuclear fusion
and nuclear fission.
Nuclear Fusion:
Energy is released when atoms are combined or fused together to
form a larger atom. This is how the sun produces energy.
Nuclear Fission:
Atoms are split apart to form smaller atoms, releasing energy.
Nuclear power plants use nuclear fission to produce electricity.
A small particle called a neutron hits the uranium atom and it splits,
releasing a great amount of energy as heat and radiation. More
neutrons are also released. These neutrons go on to bombard other
uranium atoms, and the process repeats itself over and over again. This
is called a chain reaction.
2. Nuclear Fuel – Uranium
• Uranium is nonrenewable, though it is a common metal
found in rocks all over the world.
• Nuclear plants use a certain kind of uranium, U-235, as fuel
because its atoms are easily split apart. Though uranium is
quite common, about 100 times more common than silver,
U-235 is relatively rare. Most U.S. uranium is mined, in the
Western United States. Once uranium is mined the U-235
must be extracted and processed before it can be used as a
fuel.
3. Nuclear power plants generate electricity:
• Most power plants burn fuel to produce electricity. Nuclear plants use
the heat given off during fission as fuel. Fission takes place inside the
reactor of a nuclear power plant. At the center of the reactor is the
core, which contains the uranium fuel.
• The uranium fuel is formed into ceramic pellets. The pellets are about
the size of your fingertip, but each one produces the same amount of
energy as 150 gallons of oil. These energy-rich pellets are stacked
end-to-end in 12-foot metal fuel rods. A bundle of fuel rods is called a
fuel assembly.
• Fission generates heat in a reactor just as coal generates heat in a
boiler. The heat is used to boil water into steam. The steam turns huge
turbine blades. As they turn, they drive generators that make
electricity. Afterward, the steam is changed back into water and
cooled in a separate structure at the power plant called a cooling
tower. The water can be used again and again.
4. Nuclear Power and the Environment:
• Nuclear power generation has by-product wastes: spent
(used) fuels, other radioactive waste, and heat. Because
nuclear generated electricity does not emit carbon dioxide
into the atmosphere, nuclear power plants in the U.S.
prevent emissions of about 700 million metric tons of
carbon dioxide. This is nearly as much carbon dioxide as is
released from all U.S. passenger cars combined.
• Most nuclear waste is low-level radioactive waste:
ordinary tools, protective clothing, wiping cloths and
disposable items that have been contaminated with small
amounts of radioactive dust or particles. These materials
are subject to special regulation that govern their disposal so
they will not come in contact with the outside environment.
• High level radioactive waste are the spent fuel assemblies.
They must initially be stored in specially designed dry storage
containers. An increasing number of reactor operators now
store their older and less spent fuel in dry storage facilities
using special outdoor concrete or steel containers with air
cooling. The United States Department of Energy's long range
plan is for this spent fuel to be stored deep in the earth in a
geologic repository, at Yucca Mountain, Nevada.
Nuclear Energy: Benefits for all of us
Reducing Dependence On Imported Oil
The U.S. is importing over 40% of the oil we use - at a cost
of $l billion a week. That dependence would be far worse
without nuclear energy.
• At the time of the 1973 oil embargo, oil accounted for about 17 % of
U.S. electric supply; nuclear energy was about 5 %. In 1990, oil
represented only about 4 % of U.S. electric supply, nuclear energy
about 21 %. So, nuclear energy has drastically reduced our
dependence on imported oil.
• Since l973, nuclear energy has displaced 4.3 billion barrels of
imported oil and reduced our trade deficit by $12 billion.
Powering Our Economy
There is a close and continuing connection between
economic growth and electricity supply:
• Between 1973 and 1990, the U.S. economy (measured by
Gross National Product) grew by about 50 %.
• In the same period, electricity use grew by 58 %. The
lesson is obvious: we must have growing, reliable supplies
of electric power to meet the needs of our growing
population and to keep our economy strong.
Where did this new electric supply come from? Over
95% of our new electric supply since 1973 came from
nuclear energy and coal. More than 80 new nuclear
energy plants have started operating since l973.
Protecting Our Environment
• Nuclear energy plants produce electricity by the fissioning
of uranium, not by burning fuels. As a result, nuclear plants
don't pollute the air with sulfur oxides, nitrogen oxides, dust
or greenhouse gases like carbon dioxide.
• America's nuclear energy plants reduce electric utility
emissions of greenhouse gases by 20%, or 128 trillion tons a
year. Without our nuclear plants, electric utility emissions
of sulfur dioxide would be 5 million tons a year higher.
Emissions of nitrogen oxides would be 2 million tons a year
higher.
• The environmental benefits of nuclear energy can he seen
clearly in France. In the 1980s, because of concerns over
imported oil, France more than tripled its nuclear energy
production. During that same period, total pollution from
the French electric power system dropped by 80-90 %.
High-level Nuclear Waste – A Safe,
Permanent Solution
• Nuclear Energy: A clean source of electricity.
Only concern is the high-level waste which is simply
used up nuclear fuel that has released its energy. About
every 18 months, the oldest fuel assemblies, which have
already released their energy, are removed and replaced
with fresh fuel.
• Nuclear Waste volumes are small:
A nuclear power plant produces about 30 tons of used fuel
each year. All of America's nuclear power plants produce
only about 3,000 tons of used fuel every year. By contrast,
the U.S. produces about 300 million tons of chemical waste
every year.
• Scientists agree on deep underground
disposal:
Geologic repositories deep underground have been endorsed
by independent scientific organizations around the world,
including the National Academy of Sciences, the National
Research Council, and the Congressional Office of
Technology Assessment. Nearly every other country with a
nuclear energy program, including Germany, France, Japan
and Sweden, has determined that deep geologic disposal is
the safest system of permanent nuclear waste management.
• Safety proven by experience:
How can we know it is safe to store spent fuel underground?
Nature herself has told us so. Almost two billion years ago, a
spontaneous nuclear chain reaction occurred in a rich vein of uranium
ore in the Gabon Republic in West Africa. When it ended, radioactive
waste lay within a repository created by nature. Millennia passed,
earthquakes shook the earth, and rains soaked deep into, the land. Yet
the waste remained safely isolated underground, far from man and
nature.
What nature did accidentally, man today can achieve technologically.
The feasibility of underground waste repositories has been
demonstrated in studies and test projects for more than three decades.
In the early 1980s, scientists successfully isolated high-level waste
1,400 feet underground in the abandoned Climax Mine in Nevada,
about 20 miles from Yucca Mountain. They carefully studied how the
stored waste affected the surrounding rock. The results clearly showed
that used fuel could be safely isolated underground without harm to
man or the environment.
• A Secure Tomorrow:
Nuclear energy is a powerful force which should
never be treated lightly. But neither should its risks
be exaggerated. The technology exists to isolate
high-level waste safely and responsibly, without
harm to man or the environment. Creating a
permanent repository will help ensure that with the
help of nuclear energy our nation will have clean,
abundant electricity in the years ahead.
Facts about burning Coal
1. Coal-fired power plants throughout the world are
the major sources of radioactive materials released
to the environment which has several implications.
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Coal combustion is more hazardous to health than
nuclear power and that it adds to the background
radiation burden even more than does nuclear power.
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If radiation emissions from coal plants were regulated,
their capital and operating costs would increase, making
coal-fired power less economically competitive.
2. Coal is one of the most impure of fuels. Products of coal
combustion include the oxides of carbon, nitrogen, and
sulfur; carcinogenic and mutagenic substances; and
recoverable minerals of commercial value, including
nuclear fuels naturally occurring in coal.
3. Coal ash is composed primarily of oxides of silicon,
aluminum, iron, calcium, magnesium, titanium, sodium,
potassium, arsenic, mercury, and sulfur plus small
quantities of uranium and thorium.
For more info:
http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html
Sources:
• US Council on Energy Awareness.
• Energy Information Administration (EIA).