271 lines
14 KiB
Plaintext
271 lines
14 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[ ]6-8 [ ]Class Notes [Essay on Nuclear Energy ]
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[ ]9-10 [ ]Cliff Notes [ ]
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[x]11-12 [x]Essay/Report [ ]
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[ ]College [ ]Misc [ ]
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Dizzed: 10/94 # of Words:2020 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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NUCLEAR ENERGYÄ
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From Theory to Practice
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The nuclear age began in Germany, in the 1930s in the lab of chemist
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Otto Hahn.
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Hahn was attempting to produce radium (In great need during the war) by
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bombarding uranium atoms with neutrons. To his surprise, he ended up with
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a much lighter element, barium.
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That was 1938, This started the race for the power of the atom. Just
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four years later Canada entered nuclear age in cooperation with the
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british.
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Wartime, 1942: The British wanted a safe place to conduct nuclear
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experiments; Since their country feared invasion by the nazi's or bombing
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attacks, Canada provided the haven the british needed in return for a
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opportunity to work in the project.
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The leader of the team that crossed the atlantic to Canada was Hans von
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Halban, who along with Dr. Lew Kowarski had escaped from the Institute Du
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Radium in Paris one step ahead of the invading german army. They took the
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world supply of 200 Kg of heavy water with them to Canada.
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Having pioneered the chain reaction using uranium and heavy water, the
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scientists applied their knowledge and their heavy water to the new
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Canadian nuclear industry.
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On September 5th, 1945 near Ottawa the team started up the first
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operating nuclear reactor outside the USA. Of course, the output was
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minuscule, but the significance was immense; the principal of getting
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energy from splitting atoms in a controlled chain reaction (fission) was
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established beyond doubt. It was now the job of the scientists and
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engineers to put it to a practical use.
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Nuclear Reactors
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A nuclear reactor is a device which produces heat. In a nuclear power
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station, the reactor performs the same function as a boiler in a
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conventional coal, gas or oil-fired station. Whether from a conventional
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boiler or a nuclear reactor, heat is required to turn water into steam. The
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steam is used to spin large turbines which in turn drive generators that
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produce electricity. A reactor creates heat by splitting uranium atoms.
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This is called 'Nuclear reaction' or 'Fission'.
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When the nucleus of an uranium atom is stuck by a neutron travelling at
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the right speed, it splits into fragments which separate rapidly and
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generate heat. It also gives off a few, new neutrons. In order to sustain a
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continuous nuclear reaction, the speed of these neutrons must be slowed
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down, or moderated. CANDU reactors use heavy water (Deuterium Oxide is
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called heavy water because it is heavier than normal water by about 10%),
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Thus the reactor is named CANDU, for (CAN)ada (D)euterium (U)ranium.
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During Fission (the process used in nuclear reactors) some of the atom
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breaks up, and energy is released. On average, 80% of the released energy
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is carried off by the fragments in the form of kinetic energy. The other
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20% is collected by the heavy water in the form of heat.
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The core of a CANDU reactor
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The core of a reactor is contained in a large cylindrical tank called
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the 'Calandria'. The calandria contains a series of tubes that run from one
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end of the calandria to the other. Inside the calandria tubes are smaller
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tubes which house fuel bundles containing natural uranium in the form of
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ceramic pellets.
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Heavy water is also used as the reactor coolant and is pumped through
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the tubes containing the fuel pellets to pick up heat generated from the
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reaction. The heated, heavy water travels to heat exchangers to produce
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steam from ordinary water. This cooled heavy water is recycled back to the
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reactor. The steam is then piped to conventional turbines and generators
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that produce electricity. In this way the nuclear reactor is separate from
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the equipment used to produce electricity.
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Viable solutions for Energy needs
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Annually, the demand for energy in Ontario increases by 5%. In response
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to this increase, Hydro companies around Canada facing similar situations
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have the responsibility of meeting the increase, usually by adding to their
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arsenal of generators. The question which is brought up at this point is
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how to do this most effectively in terms of impact on the environment,
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cost, efficiency and several other aspects. In the case of Ontario Hydro,
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they have chosen to expand on the method which appears to be best: nuclear
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power. (Note: All of the following data on nuclear generating stations is
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based on information on Canada's CANDU plants.)
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There are four main competitors in the energy race, but only two of
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them are 'technically viable' Those right now are Nuclear and fossil fuels.
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Of the other two, Solar energy is in limited use at the moment to things
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like Solar calculators, or Solar cells used to supplement energy needs in a
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large building. To collect 10^14 kWh (kilo-watt hours) (Average reactor
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output) per year with solar cells, they would take up 1% of the earths
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total land surface, or a area comparable in size to Western Europe!
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Wind energy is an unviable solution because, the wind is not a constant
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energy, unlike fossil fuels or nuclear. Another problem with wind energy,
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is that it would take a space as big, or bigger than Western Europe to
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place all the wind collectors to generate the electricity.
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The problem with fossil fuels is demonstrated below. this makes Nuclear
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energy the best solution for the worlds energy needs.
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Energy sources such as fossil fuels (coal, etc.), and nuclear, emits
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by©products which are often harmful to much of the environment. However,
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nuclear plants are considerably less harmful than coal burning plants in
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this respect. 1 tonne of coal used in coal burning plant produces 2.5
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tonnes of carbon dioxide (which harms the environment in more ways than
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one), 45 kilograms of acid rain (coming from the plant's SO2 and NOx
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emissions) and 90 kilograms of ash. In comparison of emissions, nuclear
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plants are harmful as well, but are not harmful to this degree.
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One harmful by-product which is virtually unique to nuclear plants is
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'spent nuclear fuel' coming from the fission reaction. Much of the waste
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from nuclear plants is radioactive. Coal plants produce radioactive waste
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as well, but the amount is so small that it is not insignificant. While
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coal burning plants produce 450 grams of radioactive residue per 90
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kilograms, 9 kilograms of radioactive residue are produced from 90
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kilograms of 'spent nuclear fuel'. From this it is possible to see that
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nuclear plants produce 20 times as much radioactive waste as coal plants
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do.
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Radioactive waste is widely considered to be nuclear plants' biggest
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problem, currently. More specifically, the problem of storage and handling
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of it has not yet been permanently taken care of. Meanwhile, temporary
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storage sites carry the radioactive waste until a later time when permanent
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locations might be found. Research is still being done on what methods
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should be used to store the waste over long periods of time.
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It is feared that the idea of keeping it inside containers buried
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beneath the ground will be faulty since the containers may break with time
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or when occasional earthquakes hit. Radioactive waste does, however, become
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stable after several hundreds of years.
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One solution for the disposal of nuclear plant waste draws a large
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amount of criticism. Tritium produced in the fission reactions in Canadian
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plants is sold to the United States for use in their nuclear weapons. Many
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people object to this as they do not wish to support the use of nuclear
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weapons.
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Nuclear energy is extremely efficient when compared with coal burning
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plants. 1 tonne of coal produces the same amount of energy as 50 grams of
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nuclear fuel. Since mining is often a very disruptive process to the
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environment around the mining operation, this relatively small amount of
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fuel needed is better for the preservation of some land.
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Public Concerns
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The public and the workers who operate nuclear plants have concerns
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about the amount of radiation which they are receiving. Radiation is
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measured in millirem. Any dose of radiation is considered safe if it is
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under 3500 millirem. Operators of the plants usually only receive 700
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millirem per year, as long as there are no problems. This dose is 20% of
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the 3500 millirem limit. Office staff on the site receive less than 20
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millirem per year (which is equal to the amount of radiation received by a
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person living 4 months in Denver). Should a person live at the fence of a
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station, the dose would be equal to that of a round trip (flight) between
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Toronto and Vancouver: 5 millirem. Residents living closest to nuclear
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stations only receive 3 millirem per year, however. Also the amount of
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radiation coming directly from fission of 1 Lb of Uranium 238 is the same
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as the combustion of 6000 barrels of oil, or 1000 tons of oil. When
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presented with these facts, I am in support of nuclear power. Overall the
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effects to the environment are less, and if the spent nuclear fuel is taken
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care of appropriately, I only see benefits for the world with nuclear
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power.
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In the case of the Chernobyl meltdown in April 1986, one of the
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generation site's 4 units failed, which was because of poor design. The
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remaining 3 units should be out of service soon, however, another 9 units
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of the same design are still in operation. A similar accident is not
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likely to happen in a CANDU plant because of the many fail safe devices.
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Nuclear Energy and It's Costs
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Large generators such as nuclear and fossil fuel plants often cost
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several billions of dollars. In terms of cost, nuclear stations cost
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considerably more than fossil fuel stations to begin with. The Darlington
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nuclear generating station (with 4 units) is currently having construction
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completed. When it was first planned, Darlington was to cost $2.5 billion.
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After 7 revisions of this price, it is 5 times higher at $12.63 billion. In
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contrast, a fossil fuel plant would cost approximately $7 billion.
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However, in operation, nuclear stations do not cost as much as fossil
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fuel ones do. On April 7th, 1990, the distribution of energy sources, and
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their prices went as follows:
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Kilowatt hours
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of electricity Source Cost ($)
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----------------------------------------------------------------
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157 561 000 Nuclear 1 016 268
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102 399 000 Fossil fuel 3 870 272
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113 630 000 Water 153 400
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37 856 000 Purchased 979 296
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411 446 000 Total $6 019 296
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----------------------------------------------------------------
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(1 kilowatt = 1000 watts. 1 kilowatt hour = 1 kilowatt per hour of use.)
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Clearly, although nuclear generation was used on this day more than
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fossil fuel generators, the operation of the fossil fuel ones was more
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expensive.
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The difference between the initial costs of nuclear ($12.63 billion)
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and fossil ($7 billion) stations is $5.63 billion. However, since nuclear
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plants cost considerably less in operation ($0.79 billion yearly), this
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difference is paid for after several years of use. At $0.79 billion being
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saved annually, the difference of $5.63 billion is met in roughly 7.1 years
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of operation. As nuclear plants normally last for approximately 40 years,
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at the end of this time one nuclear plant will have saved $31.6 billion
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dollars for energy consumers. In terms of cost, nuclear power is less
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expensive than other sources which can equal its amount of energy output
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(water, for instance, cannot). Nuclear Plants do not create a lot of jobs
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directly but because of money big industries may be able to save because of
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nuclear energy more money can be put into hiring.
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Summary
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Of the energy sources that can currently be used on a large scale, none
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are harmless to the environment and none are extremely inexpensive.
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Nuclear energy is far from a perfect source, but no source of this size is.
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While people wait for advancements in energy technology (such as cold
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fusion or efficient solar and wind generation), with all aspects
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considered, nuclear plants can supply the public with energy in the best
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possible way.
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Bibliography
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Atomic energy council of Canada.
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"Nuclear facts" Toronto: AEC, 1989.
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"Understanding Nuclear power" Toronto: AEC, 1989.
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"What is Radiation?" Toronto: AEC, 1988.
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"CANDU Operations" Toronto: AEC, 1988.
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"A Journalists guide to nuclear power" Toronto:
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Ontario Hydro, 1988.
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