Pros and Cons of

Pros and Cons of Nuclear Power By: Richard Klimas Jr. Darrel Anderson Nicholas Azadian December 13, 2006 Mechanical Engineering Tools Professors: Dr. Chiang Shih Keith Larson Table of Contents Page # IntroductionPurposeScopeBackgroundNuclear Power OverviewHistory of Nuclear PowerNuclear Process- 2 2 2 2 3 ProsEconomyEfficiencyPortabilityEnvironment4 4 5 5 5 6 6 7 7 8 9 ConsWaste StorageSafetyRadiation ExposureNational SecurityWeapons- ReferencesAppendices- 1 Introduction Purpose This report is a requirement in Mechanical Engineering Tools (EML-3002C) as a final assignment to exercise the ability of students to write a report, present a presentation, and create a group website. . Scope This report covers the history, the process nuclear power is created, pros, and cons of nuclear power. Background Nuclear Power Overview Nuclear power plants provide 20 percent of the world’s electricity. There are more than four hundred nuclear power plants around the world, with more than one hundred in the United States. Nuclear power is the controlled use of nuclear reactions to create energy for propulsion, heat, and the generation of electricity. Today’s use of nuclear power is done by nuclear fission and radioactive decay. Nuclear fission or atomic fission is a process in nuclear physics in which the nucleus of an atom splits into two or more smaller nuclei. The products of nuclear fission include the two or more smaller nuclei, energy and single neutrons. Nuclear fission produces the energy needed for nuclear power and to drive the explosion of nuclear weapons. Fission is a useful power source because of the materials used, called nuclear fuels. Nuclear fuels can be used in a self-sustaining reactor that releases the energy at a controlled rate or in a nuclear weapon that releases the energy at a very rapid uncontrolled rate. The most common nuclear fuels used are uranium 235 and plutonium 239. History of Nuclear Power The first successful experiment with nuclear fission was conducted in 1938 by the German physicists Otto Hahn, Lise Meitner and Fritz Strassman. Otto Hahn was a German chemist and physicist and was considered a pioneer in the field of radioactivity and radiochemistry. Hahn received the Nobel Prize in Chemistry in 1944. Lise Meitner was an Austrian-Swedish physicist who studied radioactivity and nuclear physics. Fritz Strassman was a German chemist. The first self-sustaining nuclear chain reaction was obtained at the University of Chicago by Enrico Fermi on December 2, 1942. Enrico Fermi was an Italian physicist most noted for his work on the first nuclear reactor and his work on quantum theory. Fermi was awarded the 1938 Nobel Prize in Physics for his work on induced radioactivity. During World War II, many nations embarked with programs to develop nuclear energy. The Oak Ridge National Laboratory, created as part of the Manhattan Project in 1943, was established because American scientists feared that Nazi Germany was rapidly developing an atomic bomb. The Laboratory and the city of Oak Ridge were built by the United States Army Corps of Engineers in less than a year on isolate farmland in 2 mountains of East Tennessee. In two years the city of Oak Ridge housed more than 75,000 residents. The goal of the oak Ridge National Laboratory and the Manhattan Project was to separate and produce uranium and plutonium for the use in nuclear weapons. The reactor based on Fermi research was used to produce the plutonium necessary for the Fat Man bomb dropped on Nagasaki, Japan. After the bomb was dropped on Nagasaki, Japan several nations began their own construction of nuclear reactors, primarily for weapons use, though research was also being conducted into reactor use for civilian electricity generation. Electricity was first generated by a nuclear reactor on December 20, 1951 at the Experimental Breeder Reactor I (EBR-I) near Arco, Idaho. It was at 1:50pm when the EBR-I became the world’s first electricity-generating nuclear power plant when it produced enough electricity to illuminate four 200-watt light bulbs. After some changes it generated sufficient electricity to power its building, and continued to be used until it was decommissioned in 1964. On June 27, 1954, the world’s first nuclear power plant to generate electricity for a power grid opened at Obninsk, USSR. The reactor in Obninsk had a capacity of 5 megawatts. The world’s first commercial nuclear power station in Sellafield, England was opened 1956. The capacity of the nuclear power station in Sellafield was 50 megawatts at the beginning and then upgraded to 200 megawatts. The Shippingport Reactor in Pennsylvania was the first commercial nuclear generator in the United States. The Bettis Atomic Power Laboratory is a research and developed facility located in West Mifflin, Pennsylvania that was founded in 1949. In 1960, because of the hard work of the Bettis Atomic Power Laboratory and the Shippingport power plant Pittsburgh, Pennsylvania became the world’s first nuclear powered city. Nuclear Process A nuclear reactor needs enriched uranium to work. Uranium is formed into pellets the size of a dime and the length of an inch. The pellets are arranged into long rods and then the long rods put into bundles. These bundles are submerged in water in a pressure vessel where the water acts as a coolant. Also in the water, there are control rods which are used to absorb neutrons. These control rods are inserted into the bundle using a mechanism to raise or lower them. When more heat is wanted from the uranium core the control rods are raised out of the bundle. The control rods are lowered into the uranium bundle to create less heat. The control rods can be completely lowered into the uranium bundle to shut the reactor down in case of an accident or to change the fuel. The uranium bundle is a high energy source of heat. The bundle heats the water and turns it to steam. The steam then drives a steam turbine. The steam turbine then spins a generator to produce the electricity. In some reactors, the steam from the reactor goes through a secondary heat exchanger to convert another loop of water to steam, which drives the turbine. The advantage to this is that the radioactive water never touches the turbine. The final process is the cooling towers where the steam that was used to turn the turbines are then cooled back to water to be pumped back in the tank to be reheated back it to steam to turn the turbine. 3 Pros Economy Nuclear power’s pros far outweigh the cons. The three main advantages to this form of power generation are economic, environmental and the productivity per unit area/volume. The economic value of nuclear power can be viewed in two possible interpretations, now and later. Currently nuclear energy is the cheapest out of all the other forms of power generation in the sense that its overall production costs are 1.76 cents/per kilowatt-hour. The next cheapest form of power is coal which is 2.21, while the next form of semi-clean energy, natural gas registers at 7.61. In addition, if European energy can be brought into the picture as well, nuclear power is clearly the cheapest form of energy. This is due partially to the number and size of the nuclear plants in Europe. Furthermore, in countries with developing economies, where growth expands faster than infrastructure, nuclear power could be the key to providing cheap power that would not interfere with the rapid expansion. Typically, in periods of time where there is a large amount of growth in a short amount of time, power amongst other things is in short supply. These shortages limit growth and don’t allow the maximum hypothetical expansions. With power being supplemented by additional reactors, this allows for the elimination of one of the many obstacles faced by these expanding countries. In the future assuming things don’t change the current pace and usage of fossil fuels will not be sustainable. In addition, with rising demand on foreign markets and diminishing domestic supplies the cost of such fuels will sky rocket. Amongst other things, this will leave the country in an energy crisis the likes the United States has not seen before. However, assuming directives are implemented an economic disaster can be avoided. To supplement the current methods of energy production, and to partially relieve the countries dependence on coal and foreign oil, the spending on nuclear could be increased. Additional funding could speed up the process of building more reactors to provide power or possibly fund research into building larger reactors which are more fuel efficient. Nuclear power isn’t the solution to country’s energy problems but could remedy the issue for time enough until a sufficient amount of energy is nuclear based or a different form of power becomes more preferable. Efficiency From a different economic standpoint nuclear power provides a unique advantage. The average thermal efficiency of a standard nuclear power plant is 35%; which is comparable to similar sized Coal and natural gas plants. However, the difference comes in fuel. One uranium pellet, can deliver over 17 MBTU of heat energy, which is equivalent to 1780lbs of coal, 17,000 cubic meters of natural gas, or 149 gallons of oil. Also the cost of nuclear is quite cheap in relation to the output of electricity from the fuel. At $100/kg, which initially sounds expensive, but when the amount of heat evolved from just one pellet (which makes up less then 5% of a kilogram) is taken into consideration, the price becomes much less important. In addition, the relative supplies of uranium within the top 3% of the Earth’s crust at that price are will last another 50 years. 4 However, when the price is doubled then there is around a few hundred years of usage at a growth adjusted pace. Despite doubling the fuel price, this will have very little effect on the overall cost of the electricity only raising prices 5%. However, in comparison to natural gas or coal, when prices are doubled anywhere form a 30 to 70% increases in final price of the electricity can be expected. Portability In a different light, nuclear power generation is unique in how the amount of energy that is contained in a relatively small amount of volume. This is apparent in the various real and hypothetical applications that nuclear reactors are encountered. The military applications are rather broad ranging from aircraft carriers to mobile generators. The U.S. navy has be using nuclear power since U.S.S. Nautilus, the first nuclear powered ship, soon followed up by the enterprise which was the first nuclear powered aircraft carrier. These two types of ships are typically nuclear powered with few exceptions. However, when contrasting the general sizes of both ships and the power demands for both, it is obvious why nuclear power was chosen. Viewed from a civilian standpoint, there are a plethora of different uses. Power generation on the macro scale is the most common but smaller reactors have been used to power malls, schools, and even solitary homes. Hypothetically, nuclear energy could be used to power transportation vehicles but more research is needed on safety protocols for such applications. Environment Possibly one of the greatest strengths of nuclear power, are the environmental ramifications of the operation of large scale nuclear power plants. There are none. Out of all the fuel consuming forms of power, nuclear energy has the lowest impact on the environment. The reaction used for generating heat does not also produce any from of biproduct generally associated with clean air act protocols. The only real external product is excess water that gets released into the atmosphere as steam. In comparison, to a coal burning power plant, more radiation is released from the burning of coal then from a nuclear plant over 50 years with the inclusion of a minor leakage of radiation from the nuclear plant. Furthermore, all of the water used in the nuclear plant can be recycled (when a sufficient quantity of heat has been removed first) either back in the plant or ejected back into the environment with minimal damage incurred in the process. Cons Waste Storage Once certain fuels are used up it’s not a problem anymore, but in the case of nuclear energy, that is not the case. Since the fuel is both radioactive and fissionable is still concern about how the waste should be handled. Most nuclear waste remains radioactive for thousands of years. 5 One possible solution to this is called reprocessing. Reprocessing is a method by which the fissionable materials still left in the nuclear fuel are removed. This too has its downsides because not only is fuel grade uranium removed but weapons grade plutonium can also be acquired by the process. Predominantly, the majority of spent nuclear fuel still goes to waste where it will sit for the next couple thousand years. The half-life of Uranium 235 is about 713 million years long and the half-life of Plutonium 239 is over 20 thousand years long. Due to such large half-lives, much time and money go into making sure that nuclear waste is safely disposed away from civilization. Waste disposal tools usually include containers that are made from multiple layers of lead and steel and rigorously tested to avoid waste leakage. There are also many underground waste disposal sites throughout the United States that have been constructed only to be filled within months. Yucca Mountain is the main waste storage site for the Federal Government. Yucca Mountain is located underground in the state of Nevada where there is very little rainfall. The desert like conditions are ideal for nuclear waste storage along with the added safety of multiple casing to further prevent radioactive contamination in the case of a leakage. Furthermore, the water table is very low a full 2,000 feet from the surface and a full thousand feet from the where the majority of the waste will be stored. Even if there is some seepage into the environment there is still a fair amount rock and dirt the radioactive particles must traverse before they pollute the water table. Safety The largest concern for safety will always be a major impediment in the progress of promoting nuclear power plants. The worst-case scenario for any nuclear power plant is the risk of a meltdown, which has proven to be very deadly in past disasters. A meltdown can be caused from a variety of human errors along with a variety of mechanical failures. In some cases the cause for a meltdown can be a combination of both. In the worst case scenario of a nuclear power plant meltdown, radioactive contamination can reach a radius of over a thousand miles as seen in the meltdown at Chernobyl, Russia (considered the worst nuclear accident in history). The good news is that with many technological advances in the safety of power plants there has not been a meltdown in ten years, although the fear of another “Chernobyl-like” disaster will always be a major concern for the critics of the transition to nuclear power. Radiation Exposure Human exposure to radiation can happen through nuclear power plant meltdowns as well as mistakes in the storage of nuclear waste. Once radioactive contamination is started, there is a variety of different ways that it can contaminate the human body. Radioactive contamination is mainly caught through radioactive elements in the atmosphere, although radioactive contamination can also affect ground water, drinking water, crops, and animals that we may eat (fish, chicken, etc.). The three major effects of radiation exposure are cancer, radiation sickness, and genetic mutation. 6 National Security Nuclear energy is a very cost efficient way of providing power to society, but it is also very deadly, which makes it very easy to be used as a tool for mass genocide in warlike situations. It is very easy for a hostile nation to turn a nuclear energy program into a nuclear weapons program that has the potential to annihilate a country or even the world. Our own nuclear power plants and waste storage sites can also be seen as a threat to national security. As said before, a radiation leakage can affect a large radius of land making the land quarantined for thousands of years. Knowing this, U.S. waste storage sites as well as nuclear power plants can become potential targets to hostile nations, and terrorist attacks. All it would take is an attack that is strong enough to disrupt a nuclear power plant’s cycle or cause a leakage in a waste storage site to create a devastating situation for a nation. Weapons The final downturn to nuclear power is the speed and ease that a peaceful power producing nuclear program can be turned around to making plutonium which is predominantly used in making nuclear warheads. Typically depending on a countries access to scientists and amount of money a government is willing to spend, a the average expected turn around time of a civilian program to producing weapons grade plutonium is about six months. Granted during normal fission within most reactors plutonium is automatically generated, the fuel must be re-processed for it to be extracted. Countries like Iran and North Korea have working civilian reactors and more then likely to have secretive weapons programs. 7 References Books: Edelson, Edward. The Journalist's Guide to Nuclear Energy. 4th ed., Nuclear Energy Institute, 1994. Florida Power & Light Nuclear Notebook. Florida Power & Light Company, 1990. Morris, Robert C. The Environmental Case for Nuclear Power: Economic, Medical, and Political Considerations. Publisher Paragon House, New York, New York, 2000. Carbon, Max W. Nuclear Power Villain or Victim. Pebble Beach Publishers. Madison, WI, 2005. Waltar, Alan E., Ph.D. America the Powerless: Facing our Nuclear Energy Dilemma. Madison, Wisconsin: Cogito Books, 1995. Internet: Nuclear Power Education, http://www.nuclearinfo.net/Nuclearpower/ TheBenefitsOf NuclearPower, 2006, 12-03-2006. Nuclear Energy Institute, http://www.nei.org/, 2006, 12-03-2006. How Stuff Works, http://science.howstuffworks.com/nuclear-power1.htm, 2006, 12-032006 MIT, http://web.mit.edu/nuclearpower-appdx.pdf, 2006, 12-03-2006. Wikipedia, http://en.wikipedia.org/wiki/Nuclear_fission, 12-01-2006, 12-03-2006. 8 Appendices Fission: The splitting of atoms that results in the release of large amounts of energy. Two or three neutrons are usually released during this event. Fission occurs either naturally or when an atom's nucleus is bombarded by neutrons. Fossil fuel: Carbon based fuel resulting from millions of years of biological decay. Coal, oil, and natural gas are the most common examples. Fuel pellets: The Uranium fuel for nuclear reactors in the form of ceramic cylinders about one-half of an inch long and three-eighths of an inch in diameter. These pellets are stacked in long tubes to form fuel rods. Fuel rod: A long, slender tube that holds the fuel pellets; fuel rods are assembled into bundles called fuel elements or fuel assemblies that are loaded individually into the reactor core. Nuclear energy: Energy, usually in the form of heat or electricity, produced by the process of nuclear fission within a nuclear reactor. The coolant that removes the heat from the nuclear reactor is normally used to boil water, and the resultant steam drives steam turbines that rotate electrical generators. Radioactivity: The transformation of an unstable atom and often results in the emission of radiation. This process is referred to as a transformation, decay, or a disintegration of an atom. Radiation: Particles or rays emitted from the nucleus of an unstable radioactive atom as a result of radioactive decay. Steam generator: The heat exchanger used in some reactor designs to transfer heat from the primary reactor coolant system to the secondary steam system. Uranium: A naturally radioactive and very dense element. Uranium contains 0.7 percent of the isotope Uranium-235, needed for fission. Uranium-235 is the principal nuclear fuel material used in today's nuclear power reactors. http://web.mit.edu/nuclearpower-appdx.pdf 9