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

6.18
Remote determinations of water content and flow and in situ stress would need to be ad-
dressed to permit preemplacement assessment of down-hole conditions to facilitate VDH system
design.
Much of the R&D work under way for logging and instrumentation equipment would be appli-
cable to monitoring equipment for the waste disposal area (DOE 1979).
R&D Costs/Implementation Time
The total cost for research and development for this concept is estimated to be about
$730 million (FY 1978 dollars) as derived from DOE (1979). The major portion of this cost,
or about $600 million, would be for development of drilling techniques and equipment. The
development activity described could be accomplished over a 12 to 15-year period.
Summary
Major uncertainties, shortcomings, and advantages of the concept are summarized below:
* The capability to drill with diameters up to 50 cm holes to a depth of 10,000 meters
does not exist and would require a tremendous advance in the state of technology. However,
should it be demonstrated that considerably lesser depths, e.g., 3,000 m, are consistent
with the concept they can be currently achieved with holes of adequate size.
* The temperature, pressure, and chemical environment at depth would present a potentially
very hostile environment for the waste package. Significant advances in materials technology
might be required to ensure long lived package design.
* Corrective action, defined as retrievability of emplaced waste, would be unlikely after
empl acement.
* The approach is probably not consistent with the philosophy of being able to demonstrate
technical conservatism in that design margins are considered small.
* Current methodology does not permit adequate assessment of the at-depth emplacement
environment, nor are criteria available for site selection.
* The extreme depth of the concept, and the resulting lengthy path to the biosphere might
compensate for many of the drawbacks.
6.1.1.4 Impacts of Construction and Operation (Preemplacement)
During the construction and operation phases, the environmental impacts of the VDH con-
cept would be those common to other drilling and excavation activities. Drilling the hole
would raise environmental considerations similar to those for drilling deep holes for oil and
gas wells, for uranium exploration and production, and for geothermal and deep rock mining.
VDH impacts for these phases would be: the conversion each year of several square kilometers
from present land uses to drilling/mining and waste repository activities; disturbance and
removal of vegetation; temporary impoundment of water in mucking and settling ponds; accumu-
lation of tailings; alteration of the topography at, and adjacent to, the site; and socio-
economic impacts on housing, schools, and other community services. No special environmental
considerations beyond those required for normal drilling would be required.