Management of Commercially Generated Radioactive Waste - U.S. ...

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volume of geologic data (stratigraphy, lithology, petrography) exists for potential disposal
areas. These data have been gathered for basic geologic research or as a result of resource
exploration and exploitation. However, the existing data are considered suitable for only
conceptual, generic studies and identification of candidate sites.
Geohydrology. Modeling to predict waste extent and nuclide transport would be required
for both liquid and grout injection. In the past decade, numerical modeling methods using
finite-difference and finite-element techniques have been developed using available highspeed
digital computers (Pinder and Gray 1977, Remson et al. 1971). Two- and three-dimensional
fluid-flow techniques with thermal and stress dependency are available. Computer
codes also exist for the analysis of radionuclide transport, including the effects of decay,
adsorption, and dispersion (Burkholder 1976). However, these analytical techniques are limited
because of an insufficient data base and incompletely defined constitutive parametric
relationships.
State-of-the-art testing techniques include the use of multiple devices to isolate sections
of the borehole. These devices provide for reduction in measurement error through improved
control of bypass leakage. The multiple devices also help determine directional permeability
(Maini et al. 1972). Multiple hole analyses are used to define the direction and
magnitude and measure of rock mass permeability (Rocha and Franciss 1977, Lindstrom and
Stille 1978). Because rock properties are directionally dependent, particular consideration
must be given to methods of analyzing field data before a well injection site could be
chosen.
Drilling and Injection Technology. The well injection disposal would require relatively
simple engineering design, construction, and operation. Oil well drilling technology, funda-
mental to the concept, is available and well proven.
The deep well injection disposal method has been applied in the United States for natural
wastes, in particular, oil-field brines, and for industrial wastes, such as steel pickle
liquors, uranium mill wastes, and refinery and chemical process wastes(a). The deepest
waste injection well completed and operated to date was at Rocky Mountain Arsenal, where
fractured Precambrian gneiss, at a depth of 3,660 m (12,000 ft), was used as the disposal
formation (Pickett 1968).
Shale grout injections of remotely handled TRU wastes have been carried out at ORNL at a
depth of about 275 m (900 ft) (ERDA 1977). Over 6.8 x 106 1 (1.8 x 106 gal) of waste
containing primarily 1 3 7 Cs (523,377 Ci) with a lesser amount of 9 0 Sr (36,766 Ci), toge-
ther with minor quantities of other radionuclides have been injected over 10 years.
(a) Such applications are described in DeWitt 1961, Pinder and Gray 1977, Remson et al.
1971, Burkholder 1976, Maini et al. 1972, Rocha and Franciss 1977, Trevorrow et al.
1977, Lindstrom and Stille 1978, White 1965, Hult et al. n. d., Pickett 1968, Warner
and Orcutt 1973, Lunn and Arlin 1962, Clebsch and Baltz 1967, Spitsyn et al. 1973,
Capitant et al. 1967, and Roedder 1959.