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U.S. Department of Energy
Office of Scientific and Technical Information

Subsurface disposal of liquid low-level radioactive wastes at Oak Ridge, Tennessee

Conference ·
OSTI ID:6010180

At Oak Ridge National Laboratory (ORNL) subsurface injection has been used to dispose of low-level liquid nuclear waste for the last two decades. The process consists of mixing liquid waste with cement and other additives to form a slurry that is injected under pressure through a cased well into a low-permeability shale at a depth of 300 m. The slurry spreads from the injection well along bedding plane fractures and forms solid grout sheets of up to 200 m in radius. Using this process, ORNL has disposed of over 1.5 x 10/sup 6/ Ci of activity; the principal nuclides are /sup 90/Sr and /sup 137/Cs. In 1982, a new injection facility was put into operation. Each injection, which lasts some two days, results in the emplacement of approximately 750,000 liters of slurry. Disposal cost per liter is about $0.30, including capital costs of the facility. This subsurface disposal process is fundamentally different from other operations. Wastes are injected into a low-permeability aquitard, and the process is designed to isolate nuclides, preventing dispersion in groundwaters. The porosity into which wastes are injected is created by hydraulically fracturing the host formation along bedding planes. Investigations are under way to determine the long-term hydrologic isolation of the injection zone and the geochemical impact of saline groundwater on nuclide mobility. Injections are monitored by gamma-ray logging of cased observation wells to determine grout sheet orientation after an injection. Recent monitoring work has involved the use of tiltmeters, surface uplift surveys, and seismic arrays. Recent regulatory constraints may cause permanent cessation of the operation. Federal and state statutes, written for other types of injection facilities, impact the ORNL facility. This disposal process, which may have great applicability for disposal of many wastes, including hazardous wastes, may not be developed for future use.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
AC05-84OR21400
OSTI ID:
6010180
Report Number(s):
CONF-860307-1; ON: DE86007318
Country of Publication:
United States
Language:
English