I. Introduction
II. Radiation
A. Properties
B. Comparison with other types
C. Average annual exposure from various sources
A. Current sources
B. Possible solutions to future energy crisis
IV. Nuclear power
A. Basics of reactor operation
B. Safety measures associated with reactor operation
C. High level nuclear waste
D. Yucca Mountain
E. Plutonium reprocessing
F. High level waste shipping
V. Conclusion
VI. Works Cited
Introduction
As our population increases, so will our demand for electricity.
Air conditioners, computers, televisions, microwaves, and many
other appliances have become necessities for Americans. All methods
of producing electricity have drawbacks. As the earth becomes
warmer, we must look for ways to decrease our use of fossil fuels.
There are several ways to produce electricity without releasing
air pollution. The most feasible method at this time is nuclear
energy. Nuclear energy presents a safe, clean, and inexpensive
alternative to other methods of producing electricity. Nuclear
waste can either be reprocessed or disposed of safely, provided
certain precautions are taken.
Radiation
Properties
In order to understand the risks associated with nuclear energy,
it is necessary to understand the properties of radiation and
their effects. The term radiation refers to a wide range of things.
Ionizing radiation is the kind that can and does cause damage.
Ionizing radiation creates ions when it strikes something, which
can then affect matter such as human tissue. The two main types
of ionizing radiation are electromagnetic and particle. Ionizing
electromagnetic radiation includes x-rays, gamma rays, and cosmic
rays. Ionizing particle radiation involves alpha particles, which
are helium nuclei, beta particles or electrons, and neutrons.
Gamma rays, alpha particles, and beta particles are the main forms
of radioactivity associated with nuclear power (Taylor,
1996).
Comparison
with other types
Radiation has many benefits for humans, but too much of any type
of radiation can be harmful. For example, the sun gives off infrared
radiation, or heat, as well as visible light, another type of
electromagnetic radiation. These forms of radiation are necessary
for humans to live, but too much can cause damage. At one extreme,
too much infrared radiation would cause everything to burn up,
and an excess of visible light would cause everyone to go blind.
Another example is x-rays, which have become a valuable medical
diagnostic tool. However, overexposure to x-rays can increase
a person's cancer risk or even cause immediate death (Taylor,
1996).
Average annual
exposure from various sources
The average American's exposure to radiation (82%) comes primarily
from natural sources. Fifty-five percent comes from radon, which
is given off by radium, a component of soil and rock. Americans
receive a smaller percentage of radiation from other terrestrial
sources, such as uranium in the soil, and from cosmic rays. Eleven
percent of natural radiation exposure is internal, primarily from
radioactive potassium in our bodies. Eighteen percent of American's
radiation exposure comes from man-made sources such as x-rays,
nuclear medicine, and consumer products, much of which is the
necessary byproduct of beneficial products and procedures. Americans
receive only 0.1% of their total radiation exposure from nuclear
energy production. This figure includes exposure from mining,
milling, reactor operation, transportation, and waste storage.
Interestingly, Americans receive 0.5% of their total radiation
exposure from the radioisotopes released into the atmosphere from
coal-fired power plants. We actually receive five times as much
radiation from coal-fired power plants as we do from nuclear power
plants (Taylor, 1996).
Electricity Production
Current sources
As the population continues to grow, energy demands will continue
to rise. The United States Department of Energy has estimated
that energy use in the U.S. will increase by 20% by 2010 and 30%
by 2015, requiring us to find ways to increase the amount of energy
we can produce. Before proposing solutions to this future energy
crisis, it is helpful to examine the sources of our electricity
today before deciding how to fix tomorrow's problems. Coal currently
provides most of the electricity (51%) in the United States. Twenty
percent comes from nuclear power, 15% from natural gas, 9% form
hydroelectric sources, 2% from oil, and 3% from other sources,
such as wind and solar power. Each of these sources of electricity
has its own advantages and disadvantages. Burning coal to produce
electricity is inexpensive, and all of the coal we need can come
from the United States, reducing our dependence on foreign suppliers.
However, burning coal pollutes the air and produces large amounts
of ash that must be disposed of. Natural gas is cheap right now,
but supplies and prices fluctuate. Burning natural gas also produces
air pollution. Hydroelectric power produces no pollution, but
development of these locations can destroy the local ecosystems.
Additionally, nearly all of the potential sites in the United
States have already been developed. Oil is easy to use, but it
creates air pollution and a dependence on foreign suppliers. Neither
wind nor solar power creates any pollution and both have an unlimited
supply, but both are too small-scale to solve all of our energy
problems. Nuclear power also creates no pollution. It is economical,
and there is a plentiful supply of fuel in the United States,
avoiding dependence on foreign suppliers. The only significant
drawback is that high level nuclear waste requires careful disposal
(Nuclear Energy: Power for people).
Possible solutions
to future energy crisis
An energy shortage in the next decade is inevitable. "Brownouts,"
lowering the operating voltage to prevent a blackout, are already
common in some parts of the country. This approach to energy conservation
can damage some electrical devices and is not a practical long-term
solution to energy problems. Lauriston Taylor has proposed six
practical solutions to this problem of energy shortages. First,
power companies with an energy shortage should buy excess power
from other regions. Electrical companies have been doing this
for a long time; however, this works only as long as there are
companies with extra power. Unfortunately, a power surplus in
California does not help a power shortage in New England. Taylor
then suggests developing and using solar power. The major problem
with this approach is its dependency on the weather. The sun does
not always shine when electrical demands are high. Another problem
is that photovoltaic cells cannot transmit current directly. The
energy from the solar power must be used to convert water to steam
and have the steam turn turbines to produce electricity. According
to Taylor, the large-scale use of solar energy to convert water
to steam is at least fifty years away. A third potential solution
increases our use of petroleum at a higher level of efficiency.
However, this approach would only be practical if we decreased
our use of petroleum in other areas, which is very unlikely. Her
fourth suggestion involves building more coal-fired power plants.
Our electricity production would surely increase, and there is
enough coal to last for 400 years. However, coal adds radioactivity
to the environment and releases toxic sulfur and nitrogen oxide
gases into the air. Additionally, the coal reserves that are currently
being mined are high in sulfur content, making them that much
more harmful to the environment. Fifth, nuclear fusion, if understood,
would solve all of our energy problems. However, development of
nuclear fusion is a long way off, and no one has a good estimate
of when it may be available. Taylor's final and most feasible
solution involves increasing our use of nuclear energy. She notes
that it does not create a dependency on foreign raw materials
and has helped small countries with limited natural resources
(Taylor, 1996).
Nuclear power
Basics of reactor
operation
In order to evaluate the benefits and risks associated with nuclear
power generation, a person must first understand what goes on
inside a reactor. Commercial nuclear reactions use uranium as
fuel for producing energy. One pound of uranium produces as much
energy as six tons of coal or 1200 gallons of oil. Nuclear fuel
is also very cheap, costing just 1/2 cent per kilowatt-hour. Natural
uranium is made up of two isotopes: U-235, which is the fissionable
isotope but accounts for only 0.7% of natural uranium, and U-238,
which makes up over 99% of natural uranium but does not fission.
In order for natural uranium to be used as reactor fuel, it must
be enriched to 3-5% U-235. The first step in the enrichment process
converts uranium to a gas. Solid uranium reacts chemically with
fluorine to produce UF6, uranium hexafluoride, which is a gas
at room temperature. A gas chromatography process then increases
the U-235 content, and the enriched UF6 is then converted to uranium
dioxide, a solid, and pressed into ceramic pellets. Old uranium-containing
nuclear weapons are also being used for fuel. The U-235 content
of these weapons ranges from 20-90% but can be diluted to 3-5%
and used as fuel (NEI: Nuclear fuel, 1998).
The actual nuclear reaction takes place in what is called the
reactor core. The uranium fuel pellets are put into tubes and
then placed in the reactor. Neutrons are released and strike uranium
atoms, which release their own neutrons and cause a chain reaction.
Heat from fission turns water to steam, turning turbines to produce
electricity. Control rods fit between the fuel rods and absorb
neutrons. Inserting control rods into the reactor core slows down
the reaction, whereas withdrawing them allows the reaction to
speed up (NEI: The energy plant, 1998).
Safety measures
associated with reactor operation
Several safety measures exist to protect against any release of
radioactive material into the environment. The ceramic uranium
fuel pellets resist the negative effects of high temperature and
corrosion. Most of the radioactivity remains in the fuel pellets
(NEI: Safety, 1998). The concentration
of U-235 is kept low so that a nuclear explosion is impossible.
Also, the chemical makeup of the fuel provides a natural control.
As the reaction heats up, it slows down, since 96% of the fuel
does not fission (NEI: The energy plant,
1998). The fuel pellets are placed in zirconium fuel rods,
which resist heat, corrosion, and radiation (NEI:
Safety, 1998). Water acts as a moderator of the nuclear reaction
by slowing down the neutrons and increasing the probability that
they will hit and fission a uranium atom. An increased level of
steam slows the reaction, and if all water converts to steam,
the reaction stops completely (NEI: The
energy plant, 1998). The reactor core is located inside a
steel pressure vessel with eight-inch thick walls. A huge steel-reinforced
concrete containment structure with four-foot thick walls covers
everything (NEI: Safety, 1998). Nuclear
power plants also have backup systems to protect against almost
every imaginable problem, including human error, equipment failure,
floods, earthquakes, and tornadoes (NEI:
The energy plant, 1998).
High level nuclear
waste
Once the fission process has slowed, the fuel rods are replaced.
The spent fuel rods contain highly radioactive fission products
and must be stored safely. These used fuel rods are considered
high level nuclear waste. Currently all high level nuclear waste
is stored in large pools of water at the power plants where it
was generated. Seven to ten feet of water is enough to stop all
radioactivity (Keeny, 1998). Since the
late 1950's, high level nuclear waste has been stored in this
form, and there has never been any release of radioactivity. There
is actually a relatively small amount of high level nuclear waste.
All of the waste ever produced in the history of commercial nuclear
power production in the United States would cover the area of
a football field four yards high (NEI: High-level
waste, 1998).
Yucca Mountain
In 1982, Congress established the Nuclear Waste Act, which placed
a tax on all electricity from nuclear power (NEI:
High-level waste, 1998). Nuclear power companies have paid
the United States Department of Energy $14 billion in the past
15 years and are adding to that total at a rate of $600 million
per year (Lloyd, 1998). The money was to be used to find a permanent
repository for high level nuclear waste. In 1987, Congress directed
the United States Department of Energy to focus on Yucca Mountain
in the Nevada desert. Yucca Mountain is currently being studied
to determine if it is a safe storage location. The researchers
are concerned with three main issues: volcanoes, earthquakes,
and water movement through the mountain. Yucca Mountain is an
ideal storage site for high level nuclear waste for several reasons.
In order for the radioactivity to reach the environment, water
would have to enter the repository, dissolve some of the radioactive
elements and carry them to the surface. Yucca Mountain receives
very little rainfall each year and has a water table 1800 feet
below the surface. Additionally, scientists everywhere agree that
the best way to dispose of high level nuclear waste is to bury
it deep underground in a repository that will protect people and
the environment (NEI: High-level waste,
1998).
Plutonium
reprocessing
An alternative to burying all of the used fuel is to recycle it.
The original vision of nuclear power in the United States involved
mining uranium, enriching it from the 0.7% U-235 found in nature,
and using it as fuel in nuclear reactors. The spent fuel rods
would then be sent to reprocessing plants. Plutonium, a waste
product and suitable reactor fuel, along with any unburned uranium
would be dissolved, chemically separated, and reused as fuel.
The recycled fuel would first be used in conventional reactors,
then later in breeder reactors, which produce plutonium. Breeder
reactors make more plutonium than they consume, leading to a nearly
unlimited source of energy. The capture of neutrons by U-238 (99%
of natural uranium) forms plutonium. Breeder reactors can eventually
consume all of the U-238 present in natural uranium by converting
it to plutonium, increasing the amount of energy obtained from
natural uranium by a factor of 100. The problem with reprocessing
is that the chemical separation of plutonium for commercial purposes
is the same process used to make nuclear weapons. On April 7,
1977, President Carter announced a ban on all reprocessing in
the United States. He was mainly concerned about proliferation
issues and was hoping to set an example for the world. Currently
reprocessing is illegal in the United States, but some pro-nuclear
activists are trying to change that.
The main fear behind the ban on reprocessing is that the separated
plutonium would be diverted for weapons. Supporters of the ban
on reprocessing point out that if, in the future, breeder reactors
become widespread, each reactor could have several tons of plutonium
stored on site, enough for 1000 nuclear weapons. Even with strict
monitoring, this could obviously be dangerous. Citing a breeder
reactor development attempt in North Korea, Spurgeon M. Keeny,
Jr., chairman of the Nuclear Energy Policy Study Group which helped
persuade President Carter to prohibit commercial reprocessing
notes, "the pursuit of an unnecessary and wasteful plutonium
economy is the last thing we need in a world struggling to prevent
further nuclear proliferation" (Keeny,
1998). Another argument is based on economics. Currently,
uranium prices are low and will remain so for a long time, so
the reprocessing risks outweigh the benefits in the foreseeable
future. In the last twenty years, there has never been a shortage
of uranium or an increase in cost. Adjusted for inflation, uranium
costs half what it did in the early seventies (Keeny,
1998).
Supporters of reprocessing argue that Carter's attempt to set
an example for the world has failed and that the end of the Cold
War has decreased the danger of nuclear weapons proliferation.
They also point out that any country that really wanted reprocessing
for energy purposes would have the incentive to allow international
monitoring which would prevent diversion. Also, reactor grade
plutonium is not ideal for weapons because it has a high concentration
of the heavier isotopes P-240, P-241, and P-242. P-239 is the
best for nuclear weapons. The heavier isotopes give off heat,
causing inevitable cooling and storage problems for those who
attempted to use reactor grade plutonium for weapons purposes.
Additionally, prohibiting reprocessing affects only one possible
route to nuclear weapons proliferation. Other routes are cheaper,
more reliable, and easier to conceal. One argument against reprocessing
is that it is not economical, since uranium prices are so low.
Supporters of reprocessing respond by saying that the fuel is
actually a very small part of the total cost of producing electricity
from nuclear reactions and that the utility companies who build
and maintain the reactors should be able to decide for themselves
if reprocessing is worthwhile. The United States hoped to set
an example for the world by choosing not to reprocess. However,
the world has not followed this example. Breeder reactors operate
safely in other parts of the world while the United States falls
behind in nuclear technology. According to Dr. A. David Rossin
(1998), former President of the American
Nuclear Society and former Director of the Nuclear Safety Analysis
Center, "The Clinton Administration has accepted the reasoning
of the Carter years. This rigidity…undermined our ability
to work effectively with other nations toward disposition of excess
nuclear weapons." With the ending of the Cold War, it is
now time to take another look at reprocessing.
High level
waste shipping
If all of the high level nuclear waste is eventually going to
be stored at one location or reprocessed, then it must be transported
safely. Opponents of nuclear power call any transport of high
level nuclear waste a "mobile Chernobyl." Nevada Senator
Harry Reid remarked, "There could be accidents. Terrorists
could get their hands on these shipments. And there's no reason
to move it. They can leave it where it is safely for the next
100 years" (Lloyd, 1998, p.4). Senator Reid apparently disagrees
with the consensus among scientists that the safest form of storage
of high level nuclear waste is deep underground, not above ground
like it is now. Senator Reid and those like him who raise objections
to the transport of nuclear waste are just plain wrong. High level
waste can be shipped safely. The typical shipping container consists
of a stainless steel cylinder surrounding the used fuel rods,
several inches of lead shielding, and two more layers of steel.
They are five feet in diameter and seventeen feet long. The shipping
containers have been put through several tests and have passed
with flying colors. The containers were first put on a flatbed
truck, and the truck was run into a concrete wall at 60 miles
per hour and then at 80 miles per hour. Next, the containers were
put on a different flatbed truck and broadsided by a 120-ton train
travelling 80 miles per hour. After this, they were burned in
jet fuel for an hour and a half at temperatures exceeding 2000oF
(NEI: Shipping, 1998).
Conclusion
What are we going to do when we are faced with the inevitable
energy crisis early next century? Will we keep burning fossil
fuels and polluting the environment, or will we choose an alternative
energy source? All forms of energy production, including nuclear
power, have their pros and cons. However, we will be forced to
make decisions about how to provide electricity as our needs increase.
Nuclear energy is safe, clean, and cheap, and it provides the
answers to our energy problems. We must not allow misinformation
and scare tactics to influence those making the important energy
decisions. We, as Christian biologists, should support nuclear
power as a practical way to solve our energy problems while preserving
the earth.
Works Cited
Keeny, S.M. (1998). FRONTLINE: nuclear reaction: Plutonium reprocessing.
http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/keeny.html.
(25 Oct 1998).
Lloyd, J. (27 Feb 1998). Can nuclear waste be safely moved?
Christian Science Monitor. p4. Palni. http://insite.palni.edu/WebZ/FETCH:…fulltext.html:bad=html/fulltext.html.
Nuclear Energy Institute. (1998). NEI: The nuclear energy story:
The energy plant. http://www.nei.org/story/plant_main.html.
(25 Oct 1998).
Nuclear Energy Institute. (1998). NEI: The nuclear energy story:
High-level waste. http://www.nei.org/story/high_level_main.html.
(25 Oct 1998).
Nuclear Energy Institute (1998). NEI: The nuclear energy story:
Nuclear fuel. http://www.nei.org/story/fuel_main.html.
(25 Oct 1998).
Nuclear Energy Institute. (1998). NEI: The nuclear energy story:
Safety. http://www.nei.org/story/safety_main.html.
(25 Oct 1998).
Nuclear Energy Institute (1998). NEI: The nuclear energy story:
Shipping. http://www.nei.org/story/shipping_main.html.
(26 Oct 1998).
Nuclear Energy: Power for people. Booklet from Nuclear Energy
Institute.
Rossin, D.A. (1998). FRONTLINE: nuclear reaction: policy on
reprocessing. http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/rossin.html.
(25 Oct 1998).
Taylor, L.S. (1996). LST Intro. http://www.sph.umich.edu/group/eih/UMSCHPS/lstintro.htm. (25 Oct 1998).