ANALOGUES AS A MEANS OF FACILITATING COMMUNICATION WITH THE PUBLIC

Communicating geologic concepts to the public can be challenging, especially if there is strong skepticism surrounding the subject matter. Analogues are an effective tool for explaining scientific concepts to nonscientists. The predicted long-term, total system performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, is based on geologic concepts that have been represented by a complex mathematical model. The results from this model are not easily understood by the public. Furthermore, predictions based on the model extend further into the future than recorded history extends into the past.

At Yucca Mountain, models for the unsaturated zone predict that most of the water moving through the unsaturated zone at Yucca Mountain will flow around the tunnels. Consequently, seepage into tunnels is predicted to be a small percentage of available infiltration, and thus most water will not seep in or contact the stored radioactive waste. This concept has been verified experimentally using caves as analogues and measuring both infiltration and seepage. This concept can be tested qualitatively using a variety of analogues, such as (1) caves in the comparatively wet climate of Europe that have remained dry enough to preserve Paleolithic to Neolithic paintings, (2) caves of the southwestern U.S. that have well-preserved biological remains, and (3) Carlsbad Caverns, New Mexico, that has stalactites most of which are not dripping even though currently there is infiltration at the site. Note that each of these examples also addresses the concepts of time and long-term stability, and information about these examples is readily available in popular publications and media presentations.

The use of analogues to represent geologic concepts has limits that also must be explained. In the examples cited, it should be emphasized that not all water is diverted around underground openings, nor are the analogues given intended to address the larger concept of total system performance at Yucca Mountain. Analogues do not provide exact comparisons or proofs, but offer a simplified means of illustrating geologic concepts of public interest and concern.