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

B.7 THE SITE SELECTION PROCESS
B.21
Locating a site for geologic disposal of nuclear wastes must necessarily proceed in a
certain sequence to attain the best available combinations of conditions. This optimization
of siting considerations is employed to offset the uncertainties of geologic prediction.
At each step, appropriate technical criteria as well as optional siting considerations
are required to guide the work and facilitate judgments.of suitability. Licensing criteria
are under development by the Nuclear Regulatory Commission and performance criteria by the
Department of Energy (Gray et al. 1976). Such criteria are based on the need to reduce to
the maximum extent achievable the risk of radionuclides being released from the repository
to the human environment.
The site-selection process can also take on a different character (Gray et al. 1976).
Because the practical aspects of gaining access to land for reconnaissance and exploration,
at least over the near term, may impose severe restrictions on the area considered (Gray et
al. 1976), sites can be selected for detailed investigation based on ownership by
appropriate government agencies. Although satisfaction of appropriate technical criteria
and siting considerations is essential at each stage, other factors also are relevant to the
site-selection process, and could dominate. Among these are ease and cost of access,
distance from other societal activities, and societal acceptance of the locations as a
candidate repository site. Thus, certain sections of the country may be considered
unavailable for further siting even though preliminary reconnaissance indicates generally
favorable geologic conditions.
Also, the criteria for suitability of a site cannot be specified in great detail
because of the complexity of the geologic settings; it is possible that the selection of
initial regions for investigation may be done partly on the basis of nontechnical factors.
Whether the process is begun this way or by a strictly technical approach, sites will
be examined in detail and compared against the underlying radiological and environmental
safety criteria. In the discussion that follows, a sequence of purely technical and scientific
decisions is assumed, although it is recognized that socioeconomic and institutional
factors must be considered in the site-selection.process.
A purely technical approach to site selection begins on a broad nationwide scale in
Stage I. A few basic considerations are used to arrive at candidate regions. Candidate
regions are evaluated on a finer scale in Stage II using other geologic considerations to
arrive at candidate areas. Stage III consists of individual site evaluations leading to
selection of an optimum site from among a small number of possible alternatives. This
selection process provides a systematic method to narrow the geographic area to be studied
from the nation as a whole to smaller identified regions to even smaller geographic areas
and finally to a small number of alternate sites. At each step unsuitable areas are
discarded.
Stage I of the selection process begins with tectonic and hydrologic considerations
that can be applied on a broad national scale (see Figure B.7.1). For each consideration,
criteria need to be defined to serve as a basis for eliminating unsuitable regions and