NUCLEAR FACTS Environment
Nuclear energy and the
environment
(July 2000)
Key Facts
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Because nuclear power plants do not burn fuel,
they do not emit combustion by-products. By substituting for
other fuels in electricity production, nuclear energy has
significantly reduced U.S. and global emissions of carbon
dioxide (CO2), the chief greenhouse gas. |
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Between 1973 and 1999, U.S. nuclear power plants
reduced cumulative emissions of nitrogen oxide and sulfur
dioxide—pollutants controlled under the Clean Air Act—by
31.6 million tons and 61.7 million tons, respectively. Over this
same period, the nation's nuclear plants reduced the cumulative
amount of carbon emissions by 2.61 billion tons of carbon. In
1999 alone, U.S. nuclear plants prevented the discharge of 168
million metric tons of carbon into the atmosphere. |
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Worldwide, about 430 nuclear power plants
reduced the world's emissions of CO2 by about 500 million metric
tons of carbon during 1997, the latest year for which data is
available. In many countries of the Organization for Economic
Cooperation and Development, nuclear energy helped reduce—that
is, mitigate the increase of—carbon emissions per capita.
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Environmental responsibility is an important
part of nuclear power plant management. Plants are designed,
built and regulated to prevent radioactive emissions. And
nuclear power plants voluntarily work to protect nearby wildlife
and their habitats. |
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Nuclear power plants produce relatively small
amounts of used fuel and low-level waste. The management,
packaging, transportation and disposal of this waste is strictly
regulated and carefully controlled by the Nuclear Regulatory
Commission (NRC) and Department of Transportation. |
Helping increase electricity supply, helping
reduce pollution
The use of nuclear energy has increased in the United States
since 1973. Nuclear energy's share of U.S. electricity generation has
grown from 4 percent in 1973 to almost 20 percent in 1999. Part of the
increase is due to improved plant performance. Just since 1990, the
increased output from the nation's nuclear plants has been the
equivalent of bringing 19 new 1,000-megawatt nuclear plants on line.
This is excellent news for the environment. Nuclear
energy and hydropower are the two large-scale means of producing
electricity while keeping the air clean. Because nuclear power plants
do not burn fuel, they emit no combustion byproducts—like air
pollutants and carbon dioxide—into the atmosphere.
Achieving clean air compliance
Emissions of nitrogen oxide and sulfur dioxide are regulated by
the 1990 Clean Air Act amendments.
Nitrogen oxide. Nitrogen oxide (NOx) plays a major
role in the formation of ozone, which is detrimental to human health.
NOx is also a significant contributor to acid rain.
A 1998 final rule from the U.S. Environmental
Protection Agency caps total NOx emissions from the utility sector at
546,181 tons for 22 states in the Ozone Transport Assessment Group
region by 2003. Sixty percent of the affected states generate more
than 25 percent of their electricity from nonemitting nuclear energy.
By substituting for fossil fuels in electricity
generation, U.S. nuclear power plants currently avoid almost two
million tons of NOx emissions annually—four times the proposed level
for a utility sector cap. Between 1973 and 1999, nuclear energy
avoided emission of 31.6 million tons of NOx.
Sulfur dioxide—Sulfur dioxide (SO2) is
thought to contribute to acid rain. A main objective of the Clean Air
Act amendments is to reduce the amount of SO2 emitted into the
atmosphere. Between 1990 and 1995, generation from nuclear power
plants serving the states affected by the act's initial emission
reduction targets increased by more than 16 percent. By displacing
fossil fuels to generate electricity, this increased generation
avoided 480,000 tons of (SO2) emissions, or about 37
percent of the required Phase I reduction.
Long term—since the 1973 oil embargo—nuclear
energy has contributed even more significantly to U.S. air quality. By
substituting for fossil fuels, U.S. nuclear power plants displaced a
cumulative total of 61.9 million tons of (SO2) between 1973
and 1999.
Reducing CO2 Emissions
As sunlight passes through the air and reaches the ground, it
turns into heat. Certain gases in the atmosphere act like the glass in
a greenhouse, preventing some of this heat from escaping back into
space. This trapped heat helps keep the Earth comfortably warm.
But many scientists believe that carbon dioxide
emissions from human activities add to the warming effect, bringing
about changes in climate.
The 1997 Kyoto Protocol, if ratified, would require 38
industrialized nations to achieve a collective 5.2 percent cut below
1990 levels in their emissions of six principal greenhouse gases,
including carbon dioxide, by 2012. The United States would be required
to make a 7 percent reduction, or 272 million metric tons of carbon
equivalent, from today's level of greenhouse gas emissions. Because
emissions continue to increase, the reduction requirement is expected
to be significantly greater by 2012.
Carbon dioxide—Carbon dioxide is estimated to
be responsible for one-half of any global warming.
By substituting for fossil fuels, U.S. nuclear plants
reduced total U.S. greenhouse gas emissions by 168 million metric tons
of carbon equivalent in 1999. Without nuclear energy, U.S. electric
utility emissions of carbon equivalents would have been approximately
30 percent higher.
Generating one million kilowatt-hours of electricity
produces about 150 metric tons of carbon from a natural gas-fired
plant, 265 metric tons from a coal-fired plant and 220 metric tons of
carbon from an oil-fired plant—but no carbon from a nuclear power
plant. (In the United States, coal-fired power plants supply
electricity to the facilities that enrich uranium for fuel. About 10
metric tons of carbon are emitted from these plants in the enrichment
of enough fuel to produce one million kilowatt-hours of electricity.)
Long term, nuclear energy reduced total U.S. CO2
emissions by 2.61 billion metric tons of carbon between 1973 and 1999,
by replacing fossil fuels for electricity generation.
Global benefits of nuclear energy
Worldwide, nuclear energy has significantly reduced greenhouse
gas emissions. Approximately 430 nuclear power plants in 31 nations
produce 17 percent of the world's electricity-while reducing CO2 emissions
by some 500 million metric tons of carbon.
Several countries of the Organization for Economic
Cooperation and Development have successfully reduced or controlled
their CO2 per capita emissions. Generally these are nations
that have relied on nuclear energy for a growing percentage of their
electricity, according to data from the U.S. Department of Energy's
Oak Ridge National Laboratory.
Nuclear power plants also helped lower global
emissions of NOx, which contributes to ground-level ozone. Nuclear
energy displaced eight million tons of NOx emissions in 1997. And
between 1973 and 1997, the world's nuclear power plants prevented the
emission of 119 million tons of NOx into the atmosphere.
Nuclear energy also has helped reduce global SO2
levels. In 1997, nuclear power plants, by replacing fossil fuels in
electricity generation, displaced 16 million tons of SO2.
Between 1973 and 1997, nuclear energy displaced a total of 260 million
tons of SO2 worldwide, helping to avoid acid rain problems
around the world.
Nuclear power plants: Environment-conscious
management
Strict standards, careful control—All methods of
producing electricity affect the environment to some degree, but the
impacts from nuclear energy are minimal—one of the lowest on a
per-kilowatt-hour basis.
Because the fuel in nuclear power plants is
radioactive, nuclear plants are carefully designed, built and
monitored to prevent releases of radioactive material. The
Environmental Protection Agency sets—and the NRC enforces—strict
standards governing radiation emissions.
To make sure that nuclear power plants operate well
within those standards, radiation levels at every plant are monitored
24 hours a day, seven days a week. Even soil, cows' milk from
neighboring farms, and fish and sediment in nearby rivers and lakes
are monitored periodically. The monitoring instruments are so
sensitive that they can measure even trace amounts of radiation.
Nuclear power plant emissions are always well below the safe levels
permitted by federal standards. That is why the environment has never
been harmed by radiation emissions from a U.S. nuclear power plant.
Even the people living closest to a nuclear power
plant receive an average of only one extra day's worth of
radiation—about one millirem—each year. In comparison, the average
American is exposed to 360 millirem annually from the natural
environment and man-made sources, like medical X-rays.
Protecting aquatic resources—Before a plant
begins operating, an environmental impact statement examines all
potential impacts to water quality from the operation of the plant.
These include concerns about the discharge of heated water and the
possibility of trapping aquatic life in the intake. All issues are
resolved by the time the plant is licensed. If a license is later
renewed, the plant must certify that no significant adverse impacts
have been observed during the plant's operating life.
Like all steam-electric generating plants, nuclear
power plants must take in water for cooling. That is why many of them
are located on rivers, lakes and bays. After it is used for cooling,
the water—now slightly warmed—needs to be discharged. (This water
has never come in contact with radioactive materials.)
Cooling water discharged from a plant contains no
harmful pollutants, but still must meet federal Clean Water Act
requirements and state standards designed to protect water quality and
aquatic life. If the water is warm enough to possibly harm aquatic
life, it is cooled before it is returned to its source river, lake or
bay. It is either mixed with water in a cooling pond or pumped through
a cooling tower before it is discharged. In addition, power plants
operate under National Pollutant Discharge Elimination System permits,
which specify standards and monitoring requirements for all water
discharges from the plants. These permits, which must be renewed every
five years, require plants to use the best technology available, thus
minimizing environmental impacts.
The Nuclear Regulatory Commission also reviews plant
operations to be sure there is no adverse impact to water quality and
aquatic ecology. Many early aquatic resource concerns have not
materialized at any nuclear power plant.
Protecting wildlife and habitats—Because the
area around a nuclear power plant is so clean, the areas around
cooling ponds are often developed as environmentally rich wetlands,
providing better nesting areas for waterfowl and other birds, new
habitats for fish, and preservation of other wildlife, flowers and
grasses.
Electric utilities voluntarily work to protect the
fish, mammals, reptiles, birds and plants found on or near power plant
sites. Many have created special nature parks or wildlife sanctuaries
on plant sites.
For example, Virginia Power protects a bald eagle
nesting site at its Surry nuclear plant and nesting boxes for wood
ducks and barn swallows at its North Anna nuclear plant. It also built
20 underwater block-and-brush structures in Lake Anna, where young
fish can find cover and large fish can feed and spawn. When the Turkey
Point nuclear power plant in Florida dredged some 160 miles of cooling
canals, they became a safe nesting ground where newly hatched
crocodiles—often hunted for their skin—have a chance to survive.
Used nuclear fuel: Successful byproduct and
waste management
Management of used nuclear fuel is one of the most successful
solid waste management programs ever for dealing with the byproduct
material of our industrial society. The fuel is radioactive and,
therefore, is kept safely stored away from the environment.
What is used fuel? Like other power plants, nuclear
plants create electricity by boiling water into steam, which turns a
turbine-generator. Nuclear power plants do not burn anything to create
this heat. Instead, they fission—or split—uranium atoms in a chain
reaction. This is a clean, non-polluting process.
Uranium fuel, in the form of small ceramic pellets, is
placed inside metal fuel rods, which are grouped into bundles, called
assemblies. Over time, the fuel's energy is consumed. Thus, every
18-24 months the reactor is shut down and the oldest fuel
assemblies—which have released their energy but have become
radioactive as a result of fission—are removed and replaced.
Relatively small volume—All of the country's
nuclear power plants together produce about 2,000 metric tons of used
fuel annually. All the used fuel ever produced by the U.S. nuclear
energy industry in more than 40 years of operation—some 40,000
metric tons—would cover an area only the size of a football field to
a depth of about five yards, if the fuel assemblies were stacked side
by side and laid end to end.
Losing its radioactivity—Used fuel is highly
radioactive when it is removed from the reactor, but it loses its
radioactivity as time goes by. Most used fuel loses about 50 percent
of its radioactivity after three months and about 80 percent after one
year. Less than 1 percent will remain radioactive for thousands of
years. (In contrast, chemical waste remains toxic forever.) All used
fuel is carefully isolated from people and the environment.
Safe storage—Today, this used fuel is stored
at the plant sites, either in steel-lined, concrete vaults filled with
water, called used fuel pools, or in above-ground steel or
steel-reinforced concrete containers with steel inner canisters.
On-site storage is an interim measure, however, and licenses issued by
the NRC limit the amount of used fuel that a utility is permitted to
keep on site. Although the NRC determined that used fuel could be
stored at plant sites for 100 years without adverse health or safety
consequences, it also believes that timely disposal is necessary.
In the Nuclear Waste Policy Act of 1982 and its 1987
amendments, Congress created a timetable for a long-term solution: a
deep, mined geologic repository built in an unpopulated desert area in
Nevada. A scientific study of that site, called Yucca Mountain, is
under way and is nearing determination of its suitability.
Low-level waste—Safe and permanent
disposal—Low-level radioactive waste is produced by nuclear power
plants, hospitals, clinics, universities and manufacturers across
America. It is created during the testing of new prescription drugs,
research for cures for diseases, treatment and diagnoses of disease,
breeding better varieties of seed, generation of electricity, and
thousands of other beneficial activities.
Low-level waste consists largely of ordinary items
like protective clothing worn by people who work with radioactive
materials, test tubes and vials from hospitals and doctors' offices,
radioactive machine parts, nuclear power plant equipment, and filters
used in industrial processes.
The system used by the United States to manage
low-level waste has proved effective at mitigating any adverse impacts
on the environment.
Relatively low volumes—In 1999, U.S. nuclear
power plants, hospitals, research laboratories, universities and
manufacturers disposed of 272,262 cubic feet of low-level waste—a 93
percent reduction since 1980. They have reduced the volume in many
ways: segregating radioactive from non-radioactive material to prevent
radioactive contamination; incinerating waste at specially designed
and strictly regulated facilities; using hydraulic presses to compact
waste, reducing its volume as much as 90 percent; and decontaminating,
reusing or recycling radioactive materials whenever possible.
Losing its radioactivity—Many radionuclides
in low-level waste decay to safe levels within a relatively short
time. When wastes are safely stored at their generation sites for a
few days to a few years (depending on available storage space), the
radioactivity may be reduced to safe background levels. On-site decay
of low-level waste is regulated by the NRC and/or "agreement
states"—those states that have an agreement with the NRC to
regulate facilities licensed to use radioactive materials.
Safe passage—The Department of
Transportation, and in some cases the NRC, regulates the packaging and
shipping of low-level waste. More than 90 percent has such low levels
of radioactivity that it can be shipped safely in strong, tight boxes
or drums. Waste with higher levels of radioactivity must be protected
by specially shielded containers to prevent radiation exposure and the
release of radioactivity. Before they can be approved, these kinds of
containers must be able to survive "torture" tests. These
tests include a 30-foot fall onto a flat, unyielding surface; a
40-inch drop onto a six-inch steel spike; a 30-minute exposure to a
fire of 1,475 degrees F; and submersion in 50 feet of water for eight
hours. There has never been a serious transportation incident
involving low-level radioactive waste in which people or the
environment were harmed due to the release of radioactivity.
Secure disposal—Today, low-level waste is
disposed of at facilities in Washington state, South Carolina and
Utah. Federal legislation requires that such disposal facilities be
operated and controlled after closure so that no member of the public
receives an annual radiation exposure greater than 25 millirem. In
practice, existing and planned disposal facilities limit exposures to
much lower levels.
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