HLW Deep Borehole Design and Assessment: Notes on Technical Performance

Abstract

This is a progress report covering work through mid-April 2010 under a Sandia-MIT contract dealing with design and siting/licensing criteria for deep borehole disposal of spent nuclear fuel or its separated constituents. It consists of a collection of short technical notes which scope out the performance-related requirements of a deep borehole repository. Taken together the results highlight the need to focus on water transport as the dominant phenomenon. In this regard, I-129 is singled out as the likely limiting species because of its high, water chemistry-independent, solubility and long half life. Host rock thermal conditions are also examined, but found not likely to be a limiting constraint. They do, however, argue in favor of using a cluster of shorter multibranch boreholes rather than a much deeper single hole.