EFFECTIVE DEEP GEOLOGIC WASTE DISPOSAL PRACTICE - EXPERIENCE AND PROSPECTS

Radioactive waste has been finding a safe permanent home in massive Permian salt 655m underneath the surface of southeastern New Mexico since 1999. Thirty percent of the authorized capacity of the Waste Isolation Pilot Plant (WIPP) is already full of transuranic (intermediate activity) waste accumulated during 65 years of research for, and production of, nuclear weapons. Permanent isolation in salt takes advantage of the impermeability of the host rock as well as gradual and complete closure of excavations by viscoplastic deformation (creep).

Deep geologic isolation of radioactive waste has been practiced effectively in several countries since 1953. Host rocks used so far include potash and salt (Germany, USA), limestone (Czech Republic), sandstone (Russia), granite and gneiss (Finland and Sweden), and uranium ore (Czech Republic). Future host rocks will likely include sedimentary iron ore (Germany), claystone (France), and volcanic tuff (USA). Deep geologic isolation of chemically dangerous (hazardous) waste –containing constituents of concern with infinite half-lives– has been practiced effectively in German potash and salt mines since 1972.

This record demonstrates that salt and a variety of other host rocks can provide sufficient long-term confinement of dangerous materials under favorable site-specific conditions. In combination with the plethora of information gained from the study of natural analogues (Oklo, Cigar Lake, etc.) it bodes well for the prospects of safe isolation at other sites under investigation, e.g., Yucca Mountain.