Date sent: Sat, 27 Apr 1996 08:19:33 -0400 Nuclear Power Over the past few years the increase in the use of energy all over the world has increased by incredibly huge amounts. This means, that as the population continues to grow, the increase in energy usage will also continue to grow. So scientist all over the world, are continuously searching for ways to produce the huge amount of energy required by the world. Up until now, a large portion of the energy produced has been from fossil fuel such as oil and gas, that are non replaceable and are running out very quickly. In fact, even with a world policy on the use of fossil fuels, the present increase in the use of energy, all the worlds coal, oil, gas, and uranium will be used up by the year 2023. The fastest increase at the moment is in the use of nuclear power, And all known uranium reserves would be exhausted by the year 2000. This graph shows the consumption of world energy sources Nuclear energy actually refers to the energy consumed or produced in changing the composition of the atomic nucleus. The force that arms the atomic bomb and hydrogen bomb and other nuclear weapons, nuclear energy also powers electricity- generating plants in countries throughout the world. It is seen by many as the source of inexpensive, clean power; but, because of the hazardous radiation emitted in producing that power and the radioactivity of the materials used, others feel that it may not be a viable energy alternative to the use of fossil fuels or solar energy. The following text discusses the science involved in the release of nuclear energy, and the use of that science by the industries that produce electric power. Scientific Definitions The processes that change the state or composition of matter are inevitably accompanied by the consumption or production of energy. Common processes such as combustion produce energy by the chemical rearrangement of atoms or molecules. For example, the combustion of methane (natural gas) is represented by the chemical reaction CH(4) + 2O(2) = CO(2) + 2H(2)O + energy For this example the energy release is 8 electron volts (ev). The electron volt is a unit of energy used by nuclear physicists and represents the gain in kinetic energy when an electron is accelerated through a potential drop of one volt. The most well-known nuclear reaction is fission, in which a heavy nucleus combines with a neutron and separates into two other, lighter nuclei. A typical fission reaction involving uranium-235 is; 92 U235 + 1 neutron = 38 Sr96 + 54 XE138 + 2 neutrons+energy where the energy release is about 200 million electron volts (meV), a factor of 25 million greater than the combustion reaction of methane. Another important nuclear reaction is fusion, in which two light elements combine to form a heavier atom. An important fusion reaction is ; 1 H(2) + 1 H(3) = 2 He(4) + 1 neutron + energy where the energy release of the reaction is 18 million eV. Nuclear power plants harness the enormous energy releases from nuclear reactions for large-scale energy production. In a modern coal plant the combustion of one pound of coal produces about 1 kilowatt hour (kWh) of electric energy. The fissioning of one pound of uranium in a modern nuclear power plant produces about 3 million kWh of electric energy. It is the incredible energy density (energy per unit mass) that makes nuclear energy sources of such interest. At present, only the fission process is used in the commercial production of energy, usually to make electricity, but also occasionally to produce steam for district heating or other industrial applications. Fusion research has not yet produced a feasible power production technology. Advantages and Disadvantages Advantages -Cheapest form of power to date -Lots of power produced -Renewable -Runs for a long time -No air pollution -Fairly low risk of radioactivity -Fairly safe Disadvantages -Radioactive waste -Small chance of radiation -Increased risk of cancer -Radiation is hard to detect -Some chance of meltdown -Many people against it due to previous disasters -Expensive to set up -Large amounts of space needed to occupy the reactor -Chance of large scale disasters Chernobyl The Chernobyl nuclear power plant, about 130 km north of Kiev, in Ukraine, was the site of the world's worst nuclear-reactor disaster on April 26, 1986, when the plant's No. 4 reactor exploded. The accident occurred while an experiment was being conducted with the graphite-moderated reactor running but its emergency water-cooling system turned off. A series of miscalculations permitted neutron build up in one area of the core, where the nuclear reaction suddenly went out of control. The power surge shattered the fuel. This and a second, steam-induced explosion blew the lid off the reactor, whose containment structure was not designed for such pressures. A third, chemical explosion followed, and scattered fragments caused further local fires. The disaster killed 31 persons immediately or shortly thereafter and caused the hospitalization of about 500 others. Over the next few days, persons living within 30 km of the site were evacuated. The force of the explosion and fire carried much of the radioactivity away from the site to relatively high altitudes, where it spread across the Northern Hemisphere. The heaviest fallout descended on the western Soviet Union and portions of Europe, where preventive steps were taken by several nations to protect food supplies. Data on worldwide effects of this fallout remain inconclusive. Although heavily contaminated soil and trees were removed from the 30-km (19- mi) zone near the power plant, authorities acknowledged in 1990 that several million persons were still living on contaminated ground. The incidences of thyroid cancer, leukemia, and other radiation-related illnesses are higher than normal among this population. At the plant itself, reactor No. 4 was entombed in concrete. Two of the three remaining reactors continued in operation, but a series of accidents at Chernobyl persuaded Ukraine's parliament in 1991 to press for a complete shutdown--an unlikely event until another source of power for the region is developed. Three Mile Island The most serious U.S. commercial reactor failure occurred on Mar. 28, 1979, at the Three Mile Island (TMI) reactor near Harrisburg, Pa. The TMI-2 accident began as a small break in which a valve stuck open, allowing coolant to escape from the vessel. The emergency core cooling system (ECCS) operated as designed and provided makeup water for the core. Unfortunately, the operators misinterpreted the information available to them in the control room and shut off the ECCS for several hours. The decay heat from the core boiled off the available water in the vessel, and without adequate cooling, the cladding and fuel started to melt. Before the operators resumed the flow of emergency coolant, a sizeable portion of the core, about one-half to one-third, melted. The molten fuel and cladding dropped into the bottom of the vessel, which was full of water. This water was adequate to quench the molten material. The vessel itself maintained its integrity and kept all of the debris contained. A sizable amount of gaseous fission products escaped from the vessel through the open valve into the containment building. The containment functioned as the ultimate barrier and prevented a release into the local environment. The small amount of activity that did escape was carried by coolant water that leaked out the valve into the containment and then overflowed into an auxiliary building where the gases leaked into the environment. The releases were almost entirely noble gases (such as xenon), which are chemically inert and not retained within the human body. The health effects of the accident proved to be quite small, and virtually undetectable against the normal incidence of background radiation. Our Evaluation of Nuclear Energy After taking a careful look at all the different kinds of options of energy production, we both have decided that despite the chances of radiation leakage, and nuclear meltdown, that nuclear is power is the key to the worlds energy problem, although a fusion reactor would be far the superior to the current fission ones, as there is almost no waste given off. Seeing as now scientist are finding ways to cut the amount of uranium needed, this should mean that there will probably be plenty of uranium around, and that it will take a while to run out.