A Framework for Performance Assessment and Licensing of Deep Borehole Repositories

Abstract

This is the initial progress report under a Sandia-MIT contract dealing with development of engineering and geological siting criteria for deep borehole disposal of spent nuclear fuel or its separated constituents. Appendix C to this report reproduces the statement of work. The basic conceptual design used as the basis for assessment is presented, followed by screening for features, events and processes of special relevance, using criteria previously developed in the US for mined repository assessment: specifically those identified in the Environmental Impact Statement and Total System Performance Assessment protocols. Transport of radionuclides dissolved in water through highly impervious igneous bedrock (“granite”) is reaffirmed as the dominant mechanism of concern. The important beneficial role of deep-down water chemistry is also highlighted, in that low solubility under reducing conditions, retardation by adsorption, and inhibition of buoyancy and colloid formation by salinity, are all keys to assurance of effective sequestration. These insights are brought to bear to structure our future work scope.