As of July 1, 1971, approximately 100 million kw of nuclear-power-plant capacity was in operation or under construction and/or contract. During the 1960s, an extensive research, development, and demonstration program was carried out on the treatment and disposal of all types of gaseous, liquid, and solid radioactive wastes. Geochemical research and extensive field exploration and demonstration studies have been carried out on several deep disposal systems for radioactive wastes, including the application of hydrofracfuring techniques in bedded shale for low-heat-producing wastes and the use of bedded salt and crystalline bedrock for highly radioactive wastes.
The Atomic Energy Commission has adopted a regulatory policy which requires that all high-level liquid wastes from licensed irradiated-fuel-reprocessing plants must be solidified and shipped to a national repository on land owned and controlled by the federal government. A tentative selection of a site near Lyons, Kansas, has been made for an initial salt-mine repository for the demonstration of long-term storage for both solid high-level and long-lived alpha-contaminated wastes.
Because of a general requirement for adequate monitoring to assure the safe and effective operation of a deep-well injection system, this method has not been used generally for disposal of radioactive wastes. It appears that injection into deep permeable formations may be a practical solution for the disposal of large quantities of tritium-bearing wastes from water reactors and nuclear-fuel-reprocessing plants in the future. Additional research is also required on the potential deep disposal of noble gases such as krypton-85 from reactor and reprocessing-plant off-gas streams.
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This publication consists of papers based on oral presentations at a symposium of the same name co-sponsored by the United States Geological Survey and the American Association of Petroleum Geologists. A wide range of technical issues are covered, as well as regulatory and liability concerns. Documentation of two areas in Colorado where earthquakes had resulted from subsurface fluid injection set the stage for modern debates regarding possible similar results elsewhere. A wide range of fluid compositions are subject to subsurface waste disposal. The largest volumes are brines separated during the production of oil and gas wells, but acid-water and industrial wastes of all types can be disposed in significant quantities in local areas. Large hydraulic fracture treatments never recover all of the injected fluids, and the chemical additives in the fluid that remains underground can be a concern. The subsurface injection of radioactive waste is a topic for three of the papers. The possible need for sequestration of carbon dioxide was not a significant concern at the time and was not covered, but many of the papers provide insight into the issues related to modern proposals. When fluids are injected under pressure into subsurface aquifers, they interact in numerous ways. The fluids can potentially migrate for long distances and potentially interfere with other uses for the native aquifer fluids. If the aquifer cannot transport all of the fluids away, the buildup in pressure can cause fracturing of the rock. Differences in composition between the injected and native fluids can cause chemical reactions to occur; in some cases these can be desirable in that they can immobilize certain solutes in mineral form. The long-term environmental consequences are a common theme in many of the papers because of the recognition that the disposed fluids would become a permanent fixture in subsurface aquifers and could have long-term consequences for their future utilization.