Measurement of effective diffusion on andesite rock, Amchitka Island, Alaska

Abstract

Between 1965 and 1971 three nuclear weapon tests were conducted on Amchitka Island, Alaska. Currently research is being conducted to understand the possible movement of radionuclides through the Island subsurface into the marine environment so that a monitoring system can be developed. The possibility of radionuclide diffusion into matrix rock surrounding facture pathways needs to be better understood. This thesis presents ongoing research with the goal of determining the effective diffusion coefficients for andesite rock found in the Island subsurface. These studies are being conducted in a bench scale reactor consisting of two chambers separated by a sliced rock core obtained from the Island. The increase in conservative tracer over time is measured in the receiving chamber. The effective diffusion coefficients are then determined by applying these results to a solution to Fick's Second Law. Results from these studies will be used in the development of a long term monitoring program for the island.