The following perspective was presented for discussion at Rockstore ''80. It is intended to address, in very general terms, the following three questions:
Upon what experience can we base geological investigations for subsurface nuclear waste isolation facilities?
What are the additional requirements to be met, for which our previous experience must be extended?
What approaches can be adopted to meet these new requirements?
Geological characterisations provide input to all the subsequent phases of repository development, including performance assessment. Consequently, the quality and accuracy of safety assessments can directly reflect the quality and accuracy of geological characterisations. Before presenting this perspective, it is appropriate to explain the meaning of some terms to be used in this discussion. The word "system" is not used in the traditional geological sense, but in the more universal sense to denote a body of interacting and interdependent parts. The disposal medium is viewed as a part of the system to be employed, not to be treated in isolation from the geological system of which it is only a part. An additional term, characterisation, is used in the recognition that we cannot expect to define all the parts of a system as complex as the geological system within which disposal of waste is to be carried out. The overall objective must be to gain a knowledge of those processes pertinent to containment within the system which is sufficient to rationalise the potential for waste/system interaction.
A new class of industrial development has appeared within the last 30 to 40 years. This class of engineered structures can be identified on the basis of the consequences of operational failure. For these structures, such failure is apparently of potentially far greater severity, in terms of public health, than is the case for other industrial development. In recognition of this fact, a far greater level of effort and care in siting, design, and construction is warranted. Examples of this class of structures are nuclear power plants and such chemical facilities as LNG plants. Commonly, the design lives of such facilities are approximately 40 years. Regulation of such development has been established at a national level.
The relevant national and other regulatory bodies have sought a much more stringent degree of performance assessment than previously known. Because of the potential impact which such a facility can have in terms of escape of hazardous material in the event of operational failure, a knowledge of the natural environment of the facility is required. The process of safety assessment is thus dependent upon a wide range of scientific disciplines, not simply upon that which governs the industrial process of concern, such as chemical or nuclear engineering. Yet it would be unreasonable to assume that man has an equivalent level of understanding of each technical discipline of relevance. To assume that the levels of knowledge of nuclear physics and of geologic processes were similarly advanced at the onset of nuclear power development, for example, would be absurd.