Problems of Nuclear ReactorsConcerns about the safety of nuclear fission reactors include the possibility of radiation-releasing nuclear accidents, the problems of radioactive waste disposal, and the possibility of contributing to nuclear weapon proliferation. Although most technical analyses have rated nuclear electricity generation as comparable in safety to coal-powered generation, the low public confidence in nuclear power has blocked further development of nuclear power in the United States. No new nuclear power plants have been ordered since the Three Mile Island accident, and some partially completed projects have been abandoned. As of 1990 about 20% of electricity in the U.S. was generated by nuclear plants, compared to about 75% in France. |
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Reactor AccidentsThe nuclear accident at Chernobyl was the worst nuclear accident to date, spewing about 100 million Curies of radioactive material into the environment. By contrast, the accident at Three Mile Island released only some 15 Curies. Though its health effects were minimal, Three Mile Island did perhaps irreparable damage to the level of public confidence in nuclear reactors for electric power production in the United States. Preceding these two high-profile accidents are a number of nuclear accidents with radiation release. These include accidents at the Fermi I reactor near Detroit, at the NRX reactor at Chalk River, Canada, at the Windscale reactor in England, and the SL-1 Reactor at Idaho Falls. |
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Radioactive Waste DisposalThe nuclear fission of uranium-235 produces large quantities of intermediate mass radioisotopes. The mass distribution of these radioisotopes peaks at about mass numbers 95 and 137 , and most of them are radioactive. The most dangerous for environmental release are probably cesium and strontium because of their intermediate half-lives and propensity for reconcentration in the food chain. When spent fuel assemblies are removed from nuclear reactors, they are transported to "swimming pool" storage facilities to dissipate the heat of decay of short-lived isotopes as well as for isolation from the environment. The long term disposal of these wastes remains a major problem. It was assumed that these wastes would be encased in glass and placed in geologic disposal sites in underground salt domes. The site at Yucca Mountain was chosen as a first site, but both technical and political problems have thus far blocked its implementation.
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Nuclear Weapons ProliferationOne concern about nuclear reactors is that the fuel could be diverted for the production of nuclear weapons. While the the uranium fuel is enriched to only 3-5% and could not easily be further separated to the >90% U-235 needed to produce a bomb, the spent fuel elements contain plutonium-239. The plutonium could be separated chemically and diverted to nuclear weapons production. Security concerns about the plutonium has thus far blocked any reprocessing of fuel from nuclear power plants. A similar concern exists for fast breeder reactors, where the breeding process produces plutonium-239 for future generations of reactors. |
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