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

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6.107<br />

Shale deposits in the United States have been studied for suitability for underground<br />

waste emplacement (Merewether et al. 1973). The studies conclude that shale, mudstone, and<br />

claystone <strong>of</strong> marine origin in areas <strong>of</strong> little structural deformation, low seismic risk, and<br />

limited drilling are generally most promising. These include the Ohio shale <strong>of</strong> Devonian age<br />

in northern Ohio and the Devonian-Mississippian Ellsworth shale and the Mississippian-<br />

coldwater shale in Michigan. In the Rocky Mountain states, the Pierre shale and other thick<br />

shales <strong>of</strong> late Cretaceous age are also potential host rocks.<br />

The overall site area for shale grout injection has not been determined yet, but it would<br />

be greater than the 1270 ha (3140 acres) initial injection area and would depend on the maxi-<br />

mum horizontal dimension <strong>of</strong> the injection area and the size <strong>of</strong> the control zone required<br />

around the repository.<br />

Drilling System. The drilling system for shale grout injection would be similar to that<br />

for deep well injection.<br />

Repository Facilities. Repository facilities for shale grout injection would be iden-<br />

tical to those for deep well injection with the exception <strong>of</strong> additional high-pressure pumps<br />

for fracturing and equipment related to mixing the grout with the liquid waste prior to<br />

injection (see Figure 6.1.19).<br />

Sealing Systems. The repositories would be sealed in the same manner as deep well holes.<br />

Retrievability/Recovery. <strong>Waste</strong>s disposed <strong>of</strong> by this concept would be essentially irre-<br />

trievable because <strong>of</strong> the fast solidification and stability <strong>of</strong> the waste-grout mixture. Total<br />

recovery <strong>of</strong> the wastes would likely involve extremely difficult and extensive mining opera-<br />

tions to excavate the rocklike waste form.<br />

6.1.6.3 Status <strong>of</strong> Technical Development and R&D Needs<br />

Present State <strong>of</strong> Development and Technological Issues<br />

The basic techniques required for well injection <strong>of</strong> fluids and grouts have been devel-<br />

oped in the course <strong>of</strong> many projects undertaken by the oil and chemical industries for the<br />

disposal <strong>of</strong> nonradioactive toxic and nontoxic wastes. In addition, limited disposal <strong>of</strong> radi-<br />

oactive waste grouts has been successfully completed at ORNL (ERDA 1977, Delaguna et al.<br />

1968).<br />

Geology. The geology <strong>of</strong> sedimentary basins in the United States has been examined ex-<br />

tensively with a view to suitability for deep well liquid injection <strong>of</strong> radioactive wastes,<br />

and reports are available covering several areas.(a) In addition to these studies, a large<br />

(a) See Repenning 1962, Sandberg 1962, Beikman 1962, Maclachlan 1964, Legrand 1962,<br />

Repenning 1959, Colton 1961, and DeWitt 1961.

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