Advances in the self-burial concept for deep geological disposal of radioactive waste

The self-burial concept for deep geological disposal of high-level radioactive waste seeks to utilize the radioactive decay heat emitted by the wastes to melt rock and allow descent by gravity into crystalline rock for isolation. Logan developed the governing equations for the self-disposal process in a paper published in 1973 and 1974 showing that moderate waste concentrations in capsules 1 to 2 m in diameter could descend through granite or basalt to considerable depths, in some cases grater than 10 km. Safety considerations related to filling, handling, and initial cooling of such large capsules prior to release, plus the severe container material environment, has prevented use of the concept. Byalko in Russia recently proposed using a sulfur-filled borehole as a conduit for conveying small capsules down to an accumulation zone at a safe depth of several kilometers. This advance in the self-burial concept overcomes previous problems with self-burial. First, capsules of 0.3 m or less in diameter are relatively simple to fill and handle. Second, investigations indicate that once emplaced at an initial accumulation depth, rock-melting can proceed without an enveloping waste container