Jan 27

Nuclear Power The Pros and Cons of Nuclear Energy

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Nuclear Power: The Pros and Cons of Nuclear Energy

Special Report: Nuclear Power: The Pros and Cons of Nuclear Energy

A Guide to Nuclear Power Pros and Cons and How it Affects Us and the Environment

Introduction
Nuclear power is a form of energy. It is not dependent on fossil fuels or any fossil fuel, such as coal or natural gas. While many of us associate the word nuclear with atomic bombs, it has many more constructive uses. Nuclear energy can be used to power homes, businesses, and supply electricity to large numbers of people. There are, of course, pros and cons to this form of power. Following is something about what nuclear energy is and how it works, its history, and some nuclear power pros and cons for this type of energy.

What Is Nuclear Energy?
When the nuclei of certain atoms are split, they release energy. The process of atom-splitting is called nuclear fission. Normally, all elements have the same number of protons and neutrons in their nuclei. The exception to this is hydrogen, an atom with an unequal number of protons and neutrons. This makes hydrogen very unstable and therefore easier to split. This is why atomic bombs were also called hydrogen bombs, or H-bombs. Now, uranium is the element that is usually used.

Nuclear Power Pros and Cons

Atoms can also be forced together to produce energy. This process is known as nuclear fusion. But nuclear power plants today use the fission of uranium almost exclusively to produce electricity.

This energy can be harnessed to do essentially the same job that fossil fuels do: heat water to make steam, and the steam is then used to turn the blades of a turbine in a generator. The turning of the turbine runs the generator, producing electricity. This is why nuclear power plants feature enormous “smoke stacks” which are actually cooling towers. The white billows coming out of them are not smoke, but steam.

Nuclear Power Pros and Cons History
In 1905, Albert Einstein published a paper outlining the equivalence between energy and mass. Scientists built on this concept and in the late 1930s and early 1940s, they began to experiment with nuclear energy in earnest. At that time, the focus of such experiments was largely on the development of nuclear weapons. The first successful experiments with nuclear energy involved nuclear fission.

Scientists discovered that fission need not be an isolated occurrence. They found that fission releases energy, but the process also releases neutrons. These neutrons then collide with the nuclei of other atoms, causing those atoms to split. Thus, a chain reaction, or nuclear reaction, occurs, causing an enormous release of energy. The potential for weapons and other power production was evident. This chain reaction has been illustrated using mousetraps with ping-pong balls on top. When one trap is sprung, the ball flies off and hits another mousetrap, setting it off, and so forth.

How is it Produced?
How does the power plant control the powerful chain reaction of splitting atoms? How does it split the atoms to begin with?

Atoms of uranium are considered radioactive, which means they are unstable and will split easily. They are stored in units called pellets, and when it is time to begin fission, the pellets are inserted into metal rods and lowered into the reactor, which is surrounded by water.

As noted above, a neutron colliding with an atom’s nucleus causes it to split. So, in a nuclear power plant, the reaction is initiated by bombarding uranium atoms with neutrons. Once the fission begins, the neutrons naturally produced by the reaction continue to collide with the atoms around them, continuing the reaction. This takes place within a nuclear reactor, which contains the fission and stops it once it begins. It does this via “control rods,” which are made of elements that actually absorb the neutrons, stopping them from running into other atoms and thus stopping the reaction.

if the uranium atoms were split without being contained, they would simply dissipate into the atmosphere (neutron rays). But having the uranium contained in pellets means the released neutrons have to hit their neighboring uranium atoms.

Interestingly, nuclear fission actually occurs naturally. Uranium has been around a very long time, basically since the beginning of planet Earth, and has been undergoing fission since then. Of course, it’s a much slower process in nature. But it is not as though humans invented an entirely artificial and unnatural process when we began using nuclear energy. Essentially, fission was discovered much the same way as electricity. It was always there; it just hadn’t been harnessed or understood.

It doesn’t take much enriched uranium to produce a lot of power. A pound of enriched uranium, for example, is capable of producing the energy of one million gallons of gasoline.

What is “Enriched Uranium”?
To understand what is meant by “enriched uranium,” it’s first necessary to recognize the nature of uranium. It is characterized by how long it takes it to decay, or it’s “half life.” Uranium with a very long half-life is called Uranium-238, or U-238. It is not good for producing nuclear power because it is not as subject to induced fission as another kind of uranium, known as U-235. It is U-235 that is the sought-after element, since it can actually undergo induced fission easily. For uranium to be used in a nuclear reaction, it must contain at least 2 to 3 percent U-235. This is what is required for producing electrical power. Weapons-grade uranium contains at least 90 percent U-235.

Where is it Produced?
As of March 2009, there are 30 countries producing commercial nuclear energy in 436 nuclear power plants. Of these countries that produce nuclear energy, the percentage of power supplied by these facilities varies. For example, 65 percent of Lithuania’s electricity is supplied by nuclear energy, and about 75 percent of France’s power is nuclear. Only 20 percent of the nation’s electricity is supplied by nuclear energy in the United States, generating from 104 nuclear power plants.

How Fossil Fuels Produce Power
The process by which fossil fuels are used to produce power is entirely different than how nuclear energy is produced. In order to compare the two forms of power generation, it’s important to look at the other main ways in which electricity is produced.

Coal, oil, and natural gas are the current fossil fuels used to produce electricity. Wood has been and can also be used to generate electricity, but it is less efficient. Basically, fossil fuels produce electricity by heating water to create steam. They are called fossil fuels because they are produced by a process that began millions of years ago. Prehistoric plant matter decomposed under specific conditions to produce coal, oil, or natural gas. What fossil fuel results from the decomposition process has much to do with the type of plants that died, the presence or absence of oxygen, and the type of bacteria that were involved in the decomposition.

Fossil fuels are mined, tapped, or otherwise removed from deep within the earth. They are processed and burned to produce electricity. The burning of the fuel heats enormous amounts of water, which then produce steam. The steam is channeled and harnessed so that it turns the blades of a turbine, which runs a generator – thus producing electricity.

How Solar Power Produces Electricity
While there are creative ways to use the sun’s energy to make electricity, the two main ways are: using the sun’s power to create heat (rather than the combustion of fuels) to convert water to steam, and by a simple conversion from the sun’s light to a battery or wire.

How Wind Power Produces Electricity
Unlike fossil fuels and solar power, wind power produces electricity without generating heat to convert water to steam. The wind simply turns the shaft of the turbine itself, thereby running the generator and making electricity.

How Geothermal Power Produces Electricity
Geothermal power plants use heat trapped in the earth’s crust to heat water into steam. In fact, the earth usually does this on its own, as geysers like Old Faithful and others attest. Harnessing this steam is the essence of geothermal energy production. The earth heats the water for you – geothermal power plants direct the steam to turn the ever-present turbine and generator combination.

How Hydroelectric Power Produces Electricity
Water, not steam, is used to turn the turbine that runs a generator in this form of power. Falling water is harnessed via dams or tunnels to generate electricity.

Is It Renewable?
The answer to this question is yes and no, depending on your viewpoint. Proponents of nuclear energy consider it renewable, noting that, while uranium must be mined and supplies will eventually run out, the time it would take for the world’s supply to run out is so long that it is considered renewable. Also, those in the renewable camp point out that even once the uranium is used up many, many years from now, other options are available for producing nuclear energy, such as using deuterium instead. So many millennium would have to pass before all nuclear energy options are used up that it is considered by many to have renewable status.

Those who do not consider nuclear energy to be renewable point out the fact that once all the earth’s uranium is mined, there will be no more left. Strictly speaking, this would put nuclear energy in the nonrenewable category. Also, those who consider this type of power non-renewable note the problem of nuclear waste and its disposal issues.

A Note on Breeder Reactors
These nuclear reactors actually generate – or breed – a mixture of Plutonium-239 through P-242 and Uranium-235 and U-238 (and a mix of other isotopes). In other words, the potential is there actually to create the isotopes needed for producing nuclear power rather than mining them in the form of raw uranium.

Just How Is Uranium Mined?
Uranium must be removed from the earth. There are three basic ways to remove it: by open pit mining, underground mining, or in-situ leach (ISL).

-Open Pit Mining
If the uranium is near the surface of the ground, open pit or strip mining may be employed. The material above the uranium – the waste rock and soil – is removed and piled nearby. The massive hole then has steps cut into the side, making it look something like a giant coliseum. A road or path is also dug out of the open mine so as to allow trucks carrying equipment, miners, and the uranium ore itself in and out of the mine. Open pit mining is considered safer for miners and is less expensive than underground mining. New mines are more strictly regulated and require rehabilitation of the area after the uranium is exhausted. However, the environmental impact can be significant – piles of waste rock can be massive, and if a drainage pond (where radioactive waste is stored) breaks, nearby communities and the ground water can suffer. And rehabilitation of the area is expensive.

-Underground Mining
When the uranium is deep underground, it can be accessed by underground mining. Like the mining of coal, shafts and tunnels are dug into the ground and miners drill the uranium ore. Then, the ore is carefully exploded, producing debris. This debris is what is then transported up to the surface for processing (called “milling”). Underground mining does not produce piles of waste rock, and leaves the earth’s surface relatively intact. It is expensive, however, and some of the dangers inherent in underground coal mining (collapse, poor ventilation, explosions) are also present in uranium mines.

-ISL
This is probably the cheapest and most environmentally-friendly method of obtaining uranium. However, not all uranium deposits are conducive to ISL. For those that are, however, the method, as followed in the United States, involves pumping water with a leaching agent added to it (such as oxygen or sodium bicarbonate) into the rock where the uranium ore is. The waters leach out the uranium from the surrounding rock, and the uranium-rich water is then pumped to the surface. This water is then filtered to remove the uranium, and subsequently treated with more oxygen or sodium bicarbonate and used again to leach out more uranium. Strict standards must be followed to insure that this water is “cleaned up” once the uranium at the site is depleted.

In other parts of the world, such as Australia and Kazakhstan, sulfuric acid is used instead of oxygen and sodium bicarbonate. The United States considers this unacceptable due to its reclamation standards.

What Are Some of the Nuclear Power Pros and Cons?

Nuclear Power Pros and Cons: The Pros

-Renewable
Nuclear energy is considered by some to be renewable, or at least to have that potential.

-Inexpensive
Nuclear energy does not cost any more to produce than coal, and in fact, the costs are comparable.

-Lots of Energy
Nuclear energy can produce enormous amounts of energy, but the amount of fuel needed to make so much energy is quite small. In other words, you get more for less. This is significant, since it takes large amounts of fossil fuel to produce a relatively small amount of electricity.

-Clean
There are no emissions or greenhouse gases produced in the production of nuclear power. When fossil fuels are burned, all sorts of pollutants are in the smoke that is produced by the burning. In an age where concerns about climate change are prominent and the search for cleaner energy is fervent, this is probably one of the biggest nuclear power pros.

-Reliable
Nuclear energy is very reliable – the fuel, uranium, is obtained from countries like Canada and Australia, and is even mined in the United States. Its cost is not subject to fluctuating oil and gas prices, either. Because it represents an opportunity to break from reliance on foreign oil sources, this aspect of nuclear power has caused it to be hailed as the energy source of the future.

-Mining
Mining is strictly regulated so as to minimize environmental impact. If there are no accidents and all the rules are followed – including the proper disposal of the radioactive wastes or “tailings” and rehabilitation of the mining site – the mining of uranium is said to be no more environmentally hazardous than any other metal mining.

-Safety Research
New innovations are being developed all the time that will increase safety and decrease danger. Fusion is being explored as an alternative to the now-universal fission. Fusion carries less risk, because the fuel used in fusion is only enough for a reaction that lasts a few minutes (fission reactors have about a year’s supply of fuel). Also, new types of automated reactors, like the Pebble Bed Reactor, rely on a “passively safe” reaction that is self-contained. In other words, the reaction is not reliant on outside forces – such as the insertion of control rods – to stop it. These passively safe reactors do not require a human operator to shut them down in the event of an emergency, either. In the Pebble Bed Reactor, uranium is housed in “pebbles” of graphite. The heat of the nuclear reaction causes the graphite to expand, slowing the reaction.

-Economic Boost
The building of new power plants and the expansion of existing ones would provide much-needed employment. Customers would no longer be reliant on fluctuating energy costs such as occurs with oil, coal and natural gas, freeing up money for other economic activity.

Nuclear Power Pros and Cons: The Cons

-Nonrenewable
Nuclear energy is considered by some to be non-renewable. Once the uranium is used up, it’s used up – no matter how many years in the future that may occur.

-Mining
The mining of uranium can and does cause environmental damage, and has the potential to cause enormous problems if there are accidents. In 1979, a tailing dam accident at a uranium mine in Church Rock, Arizona caused 1100 tons of radioactive waste to spill into the Rio Puerco River. Thirty years later, the indigenous Navajo are still unable to use this water.

-Radioactive Waste
This is probably the most notable “con” with regard to nuclear energy. Once the fuel in the form of uranium pellets is used up, radioactive waste material is present and must be disposed of. It can’t be put into the ground or dumped into water, as some types of nuclear waste remain dangerously radioactive for tens of thousands of years. Other types of waste remain radioactive for centuries. Regardless, that’s a long time to keep something contained. And then there are the parts and equipment that are used in the production of nuclear power – they all become radioactive or “radiated” after their exposure in the power plant.

Nuclear waste is not the result of poorly-functioning power plants; it is an inevitable product from the safe, normal production of nuclear power. This makes it an issue that must be addressed, because it will be an aspect of any nuclear power production. Currently, radioactive waste is allowed to cool for years (yes, years) before being mixed with glass and stored in concrete structures. Sometimes it is stored underground after being cooled contained. But the waste must be guarded and the disposal process takes time and money. Of the biggest nuclear power pros and cons, this is probably the biggest con in terms of using more of this type of energy, along with the dangers associated with this type of energy.

-Dangerous
The potential for accidents is small in properly-run nuclear power plants, but the potential, however small, is there. And when accidents happen, they can be catastrophic. Many people point to the Chernobyl disaster of 1986 as a warning of the dangers of nuclear power production. In that accident, a nuclear reactor actually got too hot (sometimes referred to as a “meltdown”) and exploded. This explosion sent 50 tons of radioactive material all over the surrounding area, causing horrible illness that still exists today. However, it’s worth noting that Chernobyl is considered to have been a poorly-run facility, not designed or operated well.

Another potential danger of nuclear energy is from attack. Should terrorists, for example, hone in on a nuclear power plant and plant explosives or other means of destruction, the resulting crisis would be far more extensive than just the loss of power production. Radioactive exposure could be widespread and catastrophic.

-The Plant Itself
The power plants themselves are not cheap to build, and many contend that they are eyesores. Also, due to the inherent dangers (however small the risk of danger is), many communities do not want nuclear power plants in their immediate area. Thus, there is a problem of where to build these facilities.

We hope that Nuclear Power: The Pros and Cons of Nuclear Energy helps to enlighten you on this energetic subject!

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