Geological characterizations for nuclear waste repositories are without precedent in terms of scope and intended utilization. Furthermore, the time scale of concern is vast in comparison to those with which previous geological characterizations has been concerned. Geological evolution is to be expected during this time scale consequently, evaluation of future changes must be undertaken. The basis for such evaluation can only be obtained from the geological record. Examples of past changes are outlined and an approach to the use of past changes for evaluation of future change is noted.
The main objective of geologic investigations for nuclear waste repository development is the acquisition and analysis of appropriate data to characterize'' a complex geological/geotechnical system. Input derived from this characterization is required by all activities comprising the process of development of a geologic repository for ultimate disposal. and, permanent isolation of nuclear waste. A geologic nuclear waste repository must satisfy two broad' objectives: isolate the waste from the biosphere for a sufficient time such that release to the biosphere poses- no hazard and, achieve compatibility of the mode of waste storage wi.th any retrieval criteria. ''1''fre, adequacy of the approach adopted to satisfy these objectives must be demonstrated to the general public by means of the licensing procedures. Although these Procedures are not well defined, and in most licensing processes non-technical judgments often prevail, the concept adopted as a guideline for preparation of a licensing application may be to show that, for It given issue: 1. we adequately understand it. 2. We can adequately measure/evaluate it, and 3. We can estimate its long-term effects. The term "adequately" is obviously the key to acceptance of any technical knowledge. Adequate is used to mean a level of understanding, measurement, or evaluation capability sufficient to gain acceptance by the scientific community The characterizations required are without precedent in term's of scope and intended utilization (design and licensing of a repository). Moreover, the time scales which are applicable to repository performance are vast in comparison to those with which previous geological characterizations have been concerned.
Background Prior to the introduction of nuclear technology, geological characterizations intended for immediate technological consumption were relatively simple. The information provided was typically utilized in mineral/petroleum and civil engineering industries. The characterizations seldom involved a wide spectrum of earth-science disciplines and/or a large amount of effort and funds. The attention was focused exclusively on definition of the geologic status quo. This limited participation of earth-science technology was justified by the relatively minor socio-environmental consequences and social commitments resulting and/or associated with the activities of the sponsoring industries. The emergence of nuclear technology, together with its benefits, potential hazards, and by-products, dramatically changed the sophistication of the geological characterizations required. Input involving an in-depth characterization, from a wide spectrum of earth-science disciplines, became an integral and obligatory part of any application for a license to construct and operate a commercial nuclear facility (usually a nuclear power plant).