Tuuma energia (0)

Tartus secondary school of business




Nuclear Power

Helena Nulk
form 11b




Tartu 2009
Table of contents
Introduction 3
What is nuclear power? 3
Nuclear life cycle 3
What is nuclear energy? 3
What is nuclear fusion ? 4
What is nuclear fission? 4
What is radioactive decay ? 5
History of nuclear power 6
Nuclear power today 7
The future of nuclear power 9
Advantages and disadvantages on Nuclear power 10
Advantages of nuclear power generation: 10
Disadvantages of nuclear power generation: 10
Conclusion 12
References 13

Introduction

What is nuclear power?

Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The most common method today is through nuclear fission, though other methods include nuclear fusion and radioactive decay. All utility- scale reactors heat water to produce steam, which is then converted into mechanical work for the purpose of generating electricity or propulsion. In 2007, 14% of the world's electricity came from nuclear power. More than 150 nuclear-powered naval vessels have been built , and a few radioisotope rockets have been produced.

Nuclear life cycle

The Nuclear Fuel Cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, which is delivered to a nuclear power plant . After usage in the power plant, the spent fuel is delivered to a reprocessing plant or to a final repository for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant.

What is nuclear energy?

Nuclear energy was first discovered by French physicist Henri Becquerel in 1896, when he found that photographic plates stored in the dark near uranium were blackened like X-ray plates, which had been just recently discovered at the time 1895. It is energy released by the splitting (fission) or merging together (fusion) of the nuclei of atoms. The conversion of nuclear mass to energy is consistent with the mass-energy equivalence formula ΔE = Δm.c², in which ΔE = energy release ,
Δm = mass defect , and c = the speed of light in a vacuum.
Nuclear chemistry can be used as a form of alchemy to turn lead into gold or change any atom to any other atom (albeit through many steps). Radionuclide (radioisotope) production often involves irradiation of another isotope (or more precisely a nuclide), with alpha particles, beta particles, or gamma rays. Iron has the highest binding energy per nucleon of any atom. If an atom of lower average binding energy is changed into an atom of higher average binding energy, energy is given off.

What is nuclear fusion?

Nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus . It is accompanied by the release or absorption of energy. Iron and nickel nuclei have the largest binding energies per nucleon of all nuclei. The fusion of two nuclei with lower mass than iron generally releases energy while the fusion of nuclei heavier than iron absorbs energy; vice-versa for the reverse process, nuclear fission. In the simplest case of hydrogen fusion, two protons have to be brought close enough for their mutual electric repulsion to be overcome by the nuclear force and the subsequent release of energy.
Nuclear fusion occurs naturally in stars . Artificial fusion in human enterprises has also been achieved, although not yet completely controlled. Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Mark Oliphant in 1932, and the steps of the main cycle of nuclear fusion in stars were subsequently worked out by Hans Bethe throughout the remainder of that decade. Research into fusion for military purposes began in the early 1940s, as part of the Manhattan Project, but was not successful until 1952. Research into controlled fusion for civilian purposes began in the 1950s, and continues to this day.

What is nuclear fission?

Nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons (in the form of gamma rays). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place ). Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom.
Nuclear fission produces energy for nuclear power and to drive the explosion of nuclear weapons. Both uses are made possible because certain substances called nuclear fuels undergo fission when struck by free neutrons and in turn generate neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon .
The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very tempting source of energy; however , the products of nuclear fission are radioactive and remain so for significant amounts of time, giving rise to a nuclear waste problem. Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons may counterbalance the desirable qualities of fission as an energy source, and give rise to ongoing political debate over nuclear power.

What is radioactive decay?

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide. For example: a carbon -14 atom (the "parent") emits radiation and transforms to a nitrogen-14 atom (the "daughter"). This is a random process on the atomic level, in that it is impossible to predict when a given atom will decay, but given a large number of similar atoms the decay rate, on average, is predictable.
The SI unit of radioactive decay is the becquerel (Bq). One Bq is defined as one transformation (or decay) per second. Since any reasonably-sized sample of radioactive material contains many atoms, a Bq is a tiny measure of activity ; amounts on the order of TBq (terabecquerel) or GBq (gigabecquerel) are commonly used. Another unit of radioactivity is the curie, Ci, which was originally defined as the activity of one gram of pure radium, isotope Ra-226. At present it is equal, by definition , to the activity of any radionuclide decaying with a disintegration rate of 3.7 × 1010 Bq. The use of Ci is presently discouraged by the SI.

History of nuclear power

The basic process of Nuclear Power is an exothermic chemical decomposition reaction that heats water to steam. This steam pushes the steam turbine that is connected to a generator that converts the mechanical energy of the turbine to electrical energy. For this reason, the history of the steam engine and the steam turbine will also be included on this timeline. Also see the comparison page for Combustion , and the general Comparisons page for more information on the underlying processes of many alternative energy forms.
At 100 BC an Alexandrian (Greek speaking) philosopher by the name of Ctesibius invented the piston – pump.
During 1606, Italian scientist Giovanni Batista della Porta of Naples heated water in a flask until the water turned into steam. This steam filled the empty space of a closed tank of water with the only opening as a pipe from the depth of the water. The water was forced out because of the pressure of the expanding warm air. In the 1600's several scientists continued work on steam powered pumps. Robert Boyle proposed the steam engine in 1678. During the 1680's a gunpowder explosion was used to heat water. Jean de Hautefeuille tried to up water, and Dutch astronomer Christiaan Huygens tried a piston in a cylinder . These experiments were the beginnings of a nuclear power-like
process. In 1712, Thomas Newcom and John Calley built their first successful steam engine.
Nicholas Cugnot built the first mechanically propelled road vehicle in 1769. Cugnot's vehicle was powered through a two - cylinder piston connected steam engine. It used high pressure steam as the power source.
Watt patented late in 1781 a connection from the piston to a rotating gear . This set-up is still used in the internal combustion engine.
Scottish engineer and inventor William Murdock created a vehicle that was powered by a miniature steam engine. In 1813 , the precursors to the steam engine train was built by William Hedly.
Between 1800 and 1825 steam powered travel increased. Boats, vehicles, and trains used steam engines . The method of steam production was by burning some substance.
Superheated steam was produced in an experiment by Jacob Perkins in 1823. His experiment was called a flash boiler . Steam of this type is later used in nuclear power plants to turn the steam turbine.
In 1892, Rudolf Diesel of Germany patented the diesel engine. It operated through fuel ignition that caused highly compressed air to expand against a piston. The diesel engine had a 50% thermal efficiency, and was more efficient than steam engines.
From 1880 - 1890's Carl Gustaf Patrik de Laval developed an impulse type of steam turbine.
Between 1900 to the present, turbine technology improved.
December 2, 1942, Enrico Fermi achieves a controlled nuclear chain reaction with a demonstration reactor, called the Chicago Pile 1.
August 6, 1945,the United States drops an atomic bomb on Hiroshima, then on August 9th on Nagasaki .
December 20, 1951, experimental reactor produces first energy from a nuclear reaction, enough to light four light bulbs.
January , 1955, the Atomic Energy Commission begins program of funding for nuclear power plants between government and industry.
In 1956, the first nuclear power station was built. Using uranium as its fuel. The station was named Calder Hall Power Station, built on coast of Cumberland.
December 2, 1957, in Shippingport, Pennsylvania, the first full scale nuclear power plant goes into service .
1973, American utilities buy 41 nuclear power plants.
January, 1983 President Reagan signs the Nuclear Waste Policy Act.
Hydro power was surpassed by nuclear power in total electrical generation in 1984.
In the unit 4 reactor of the Chernobyl Nuclear plant were two explosions on April 26, 1986. This disaster exposed millions of people to radioactive isotopes. It has been linked many forms of cancer in natives of eastern Europe and Russia , as well as destroying animals and plants.
December 1993, the total number of nuclear power plants in the United States is 109, collectively producing 610 billion kWhs of electricity.

Nuclear power today

Nuclear power is the world's largest source of emission -free energy. Nuclear power plants produce no controlled air pollutants, such as sulphur and particulates, or greenhouse gases. The use of nuclear power in place of other energy sources helps to keep the air clean , preserve the Earth's climate, avoid ground -level ozone formation and prevent acid rain.
Nuclear power has important implications for our national security . Inexpensive nuclear power, in combination with fuel cell technology, could significantly reduce our dependency on foreign oil.
Nuclear power plants have experienced an admirable safety record. About 20% of electricity generated in the U.S. comes from nuclear power, and in the last forty years of this production, not one single fatality has occurred as a result of the operation of a civilian nuclear power plant in the United States. In comparison, many people die in coal mining accidents every year and approximately ten thousand Americans die every year from pollution related to coal burning.
The nuclear power industry generates approximately 2,000 tons of solid waste annually in the United States. In comparison, coal fuelled power plants produce 100,000,000 tons of ash and sludge annually, and this ash is laced with poisons such as mercury and nitric oxide.
Even this 2,000 tons of nuclear waste is not a technical problem. Reprocessing of nuclear fuel, and the implementation of Integral Fast Reactor technology, will enable us to turn the vast majority of what is currently considered waste into energy.
As of 2005, nuclear power provided 6.3% of the world's energy and 15% of the world's electricity, with the U.S., France , and Japan together accounting for 56.5% of nuclear generated electricity. As of 2007, the IAEA reported there are 439 nuclear power reactors in operation in the world, operating in 31 countries.
In 2007, nuclear power´s share of global electricity generation dropped to 14%. According to the International Atomic Energy Agency , the main reason for this was an earthquake in western Japan on 16 July 2007, which shut down all seven reactors at the Kashiwazaki-Kariwa Nuclear Power Plant. There were also several other reductions and " unusual outages" experienced in Korea and Germany. Also, increases in the load factor for the current fleet of reactors appear to have plateaued.
The United States produces the most nuclear energy, with nuclear power providing 19% of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors—78% as of 2006. In the European Union as a whole , nuclear energy provides 30% of the electricity. Nuclear energy policy differs between European Union countries, and some, such as Austria, Estonia, and Ireland , have no active nuclear power stations.
Many military ships use nuclear marine propulsion (a form of nuclear propulsion) and a few space vehicles have been launched using full-fledged nuclear reactors: the Soviet RORSAT series and the American SNAP-10A.
██ countries building their first reactors
██ countries building new reactors
██ countries planning /considering their first reactors
██ countries planning/considering new reactors
██ countries with reactors, but no plans for expansion or phase-out
██ countries with reactors considering phase-out
██ countries which formerly had commercial reactors, but which have all been phased out
██ countries without commercial reactors
██ countries that have declared themselves free of nuclear power and weapons

The future of nuclear power

As of 2007, Watts Bar 1, which came on-line in February 7, 1996, was the last U.S. commercial nuclear reactor to go on-line. This is often quoted as evidence of a successful worldwide campaign for nuclear power phase-out. However, even in the U.S. and throughout Europe, investment in research and in the nuclear fuel cycle has continued, and some nuclear industry experts[30] predict electricity shortages, fossil fuel price increases, global warming and heavy metal emissions from fossil fuel use, new technology such as passively safe plants, and national energy security will renew the demand for nuclear power plants.
According to the World Nuclear Association , globally during the 1980s one new nuclear reactor started up every 17 days on average, and by the year 2015 this rate could increase to one every 5 days.

Advantages and disadvantages on Nuclear power

Advantages of nuclear power generation:

• Little Pollution – As demand for electricity soars, the pollution produced from fossil fuel-burning plants is heading towards dangerous levels. Coal, gas and oil burning power plants are already responsible for half of America's air pollution. Burning coal produces carbon dioxide, which depletes the protection of the ozone. The soft coal, which many power plants burn , contains sulfur When the gaseous byproducts are absorbed in clouds, precipitation becomes sulfuric acid.. Coal also contains radioactive material. A coal- fired power plant emits more radiation into the air than a nuclear power plant.
  The world's reserves of fossil fuels are running out. The sulfurous coal which many plants use is more polluting than the coal that was previously used. Most of the anthracite, which plants also burn, has been used up. As more soft coal is used, the amount of pollution will increase. According to estimates, fossil fuels will be burned up within fifty years. There are large reserves of uranium, and new breeder reactors can produce more fuel than they use. Unfortunately this doesn't mean we can have an endless supply of fuel Breeder reactors need a feedstock of uranium and thorium, so when we run out of these two fuels (in about 1000 years), breeder reactors will cease to be useful. This is still a more lengthy solution to the current burning of coal, gas, and oil.
  
• Reliability – Nuclear power plants need little fuel, so they are less vulnerable to shortages because of strikes or natural disasters. International relations will have little effect on the supply of fuel to the reactors because uranium is evenly deposited around the globe . One disadvantage of uranium mining is that it leaves the residues from chemical processing of the ore, which leads to radon exposure to the public. These effects do not outweigh the benefits by the fact that mining uranium out of the ground reduces future radon exposures. Coal burning leaves ashes that will increase future radon exposures. The estimates of radon show that it is safer to use nuclear fuel than burn coal. Mining of the fuel required to operate a nuclear plant for one year will avert a few hundred deaths, while the ashes from a coal-burning plant will cause 30 deaths.
  

• This technology is readily available, it does not have to be developed first.
  

• It is possible to generate a high amount of electrical energy in one single plant.
  

Disadvantages of nuclear power generation:

• The problem of radioactive waste is still an unsolved one. The waste from nuclear energy is extremely dangerous and it has to be carefully looked after for several thousand years (10'000 years according to United States Environmental Protection Agency standards).
  

• High risks: Despite a generally high security standard, accidents can still happen. It is technically impossible to build a plant with 100% security. A small probability of failure will always last. The consequences of an accident would be absolutely devastating both for human being as for the nature (see here , here or here ). The more nuclear power plants (and nuclear waste storage shelters) are built, the higher is the probability of a disastrous failure somewhere in the world.
  

• Nuclear power plants as well as nuclear waste could be preferred targets for terrorist attacks. No atomic energy plant in the world could withstand an attack similar to 9/11 in Yew York . Such a terrorist act would have catastrophic effects for the whole world.
  

• Radiation – Radiation doses of about 200 rems cause radiation sickness, but only if this large amount of radiation is received all at once . The average person receives about 200 millirems a year from everyday objects and outer space. This is referred to as background radiation. If all our power came from nuclear plants we would receive an extra 2/10 of a millirem a year. The three major effects of radiation (cancer, radiation sickness and genetic mutation) are nearly untraceable at levels below about 50 rems. In a study of 100,000 survivors of the atomic bombs dropped on Hiroshima and Nagasaki, there have been 400 more cancer deaths than normal, and there is not an above average rate of genetic disease in their children . During the accident at Three Mile Island in America, people living within a 50 mile radius only received an extra 3/10 of one percent of their average annual radiation. This was because of the containment structures, the majority of which were not breached. The containment building and primary pressure vessel remained undamaged, fulfilling their function.
  

• The energy source for nuclear energy is Uranium. Uranium is a scarce resource, its supply is estimated to last only for the next 30 to 60 years depending on the actual demand.
  

• The time frame needed for formalities, planning and building of a new nuclear power generation plant is in the range of 20 to 30 years in the western democracies. In other words: It is an illusion to build new nuclear power plants in a short time.
  

Conclusion

The IEA (International Energy Agency) voiced their support for nuclear power as a viable way of meeting carbon emission targets and increasing energy security.
This is something the IEA had not done before and they are not alone as the founder of Greenpeace Sir Patrick Moore, Sir David King, the UK Government’s chief scientist and James Lovelock, inventor of the Gaia theory have also voiced their support for nuclear power.
And of course one must add ourselves to that list of pro nuclear figures along with any readers of our Uranium Stocks Newsletter that support nuclear power.

References

http://www.nuclearnow.org/
http://en.wikipedia.org/wiki/Nuclear_power
http://timeforchange.org/
http://members.tripod.com/funk_phenomenon/nuclear/procon.ht m
http://www.uranium-stocks.net/nuclear-power-the-future/