GEOSCIENCE AND NUCLEAR WASTE DISPOSAL POLICY

The United States may become the first country in the world to open a high-level nuclear waste repository. Recently, the Bush Administration and the Congress supported the Energy Department’s contention that Yucca Mountain, in Nevada, is a suitable site to dispose of the nation’s spent nuclear fuel and nuclear weapons complex waste. The Energy Department (DOE) has based much of its case for site suitability on geoscientific analysis. How important is that geoscientific analysis and has the DOE done an adequate job in collecting and modeling data? These questions illustrate the interaction of geoscience, policy-making, and public opinion.

The evaluation of the suitability of a particular site as a repository for nuclear waste disposal is essentially a geologic issue, though one for which geology is not particularly suited to address. Because nuclear waste will remain dangerous for millennia, site suitability requires prediction of geologic processes over geologic periods of time. But geology is a historical science, not a predictive one, and does not have the tools to provide well-constrained predictions.

Two issues are particularly important for policy-makers to grasp in determining site suitability: the time scales and the complexity of the geologic processes involved. In the case of Yucca Mountain, it is not clear that policy-makers have grasped either issue.

For example, the time over which the Yucca Mountain repository must meet Environmental Protection Agency (EPA) regulations is 10,000 years. This designated period is arbitrary in that some radionuclides (such as Np-237) will pose a potential threat long after 10,000 years. The National Academy of Sciences pointed this out but was ignored when EPA rewrote their standards.

Another example is the complexity of the geohydrology at Yucca Mountain. Originally, the DOE planned to depend on the geology of Yucca Mountain for containment of radiation. Once studies began to show that water transport was a complex combination of matrix and fracture flow, DOE shifted to almost complete dependence on engineered design features; in particular, the waste canister.

Geology, in terms of policy-making, has been somewhat marginalized at Yucca Mountain. This is not the experience in all countries that are developing nuclear waste repositories.