Nuclear Accidents
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During the last 50 years, scientists have developed ways of using the energy released from the atom to create an energy industry. Over 460 nuclear power stations today supply about 20 percent of the world’s electrical energy. (See appendix, Table 1: Nuclear Reactors of the World by Country). Nuclear power is a useful alternative to fossil fuels which are quickly being depleted. However, three major environmental problems caused by generating nuclear power are extremely dangerous radioactive waste, thermal waste and nuclear accidents.
The major environmental impact of a nuclear power plant is caused by various types of harmful discharges released into the biosphere. Thermal discharges are a major concern. Most modern nuclear plants are designed with closed cooling cycles, usually based on natural draft cooling towers, which discharge waste heat directly into the atmosphere. The thermal pollution from these enormous plants directly into the atmosphere can have negative effects on national and global meteorology, causing unfavorable conditions from dangerous fogs and icing to global warming. Another negative aspect of the water cooling process of the nuclear reactor is the enormous amount of local water that is required to replenish evaporated water in the cooling towers. The water requirements for a 1,000 megawatt nuclear plant are about 50,000 gallons per minute from a nearby body of water. Nuclear power plants also produce significant amounts of dangerous radioactive waste in the form of solids, liquids, and gases. These wastes must be disposed of so there is no risk to humans and plants. Radioactive materials severely damage living cells that are exposed to it. The effect is similar to being badly burned. Radiation also affects cell division, which can lead to cancer.
There are three levels of radioactive waste produced during the fission chain reaction in the form of spent fuel that must be carefully removed from the nuclear plant reactor and deposited in a secure area. Waste with little radioactivity is called low-level waste. This includes waste rock from uranium mines and the clothing of scientists and personnel working with radioactive materials. Usually low-level contaminated waste is dumped at a site that is covered with a layer of soil to act as a barrier to the radiation. Some low-level waste is sealed in steel drums and dumped in oceans. Intermediate waste has much more radioactivity and needs to be disposed of more carefully. Usually, intermediate waste is encased in steel and concrete and stored near the nuclear power station that created it. (See appendix, Map 1: Location of Nuclear Power Plant in the United States). The latest planning on how to deal with intermediate waste is to bury it. Since intermediate waste can remain radioactive for hundreds of years, the site has to be carefully selected and constructed. The process is to cover the steel drums of waste in concrete and then bury them in a deep pit lined with more concrete. Above the pit, another layer of concrete is constructed as a further precaution. High-level wastes are the fuel rods in a reactor that must be replaced as the radioactive material completes its half-life. The main concern about this waste is that it will remain harmful for more that 100,000 years. Since neutron radiation does not pass through water, some nuclear power plants keep their high-level waste not just in steel and concrete, but also in water pools. However, some waste has been in water pools for over twenty-years and the pools are running out of space. A future plan for the disposal of high-level waste involves encasing high-level radioactive waste in glass, and then burying it in deep mines. In the U.S., scientists have picked a site in Yucca Mountain, Nevada for deep mine burial. However, now scientists believe earthquakes could occur in this area and so the project is on hold.
There are no international agreements on how to deal with any form of nuclear waste. In the United States there is a growing awareness and concern for the preservation and caring for our Earth. Government departments and agencies such as the U.S. Department of Energy and the Nuclear Regulatory Commission are in charge of responsibly managing the issues of nuclear power. Stewardship and environmental groups such as Greenpeace work actively to make the public aware of the dangers of nuclear power and its waste. As a result, people are concerned about living near power stations, near waste disposal sites, and along routes where nuclear waste is transported.
Billons of dollars have been raised for further research on long-term disposal of radioactive waste. One possible solution is to dispose of nuclear waste in deep underground holes. A different solution being researched is to place waste in holes drilled in the ocean floor. It is not clear in these situations how much radioactivity would leak into the