ASCE will be sunsetting the Civil Engineering Database (CEDB) in the coming months. We encourage you to start using the ASCE Library to perform content searches. In the ASCE Library, you can save your search results as well as receive email content alerts when new content relevant to your area of interest is published. Try it out today at https://ascelibrary.org.

 

Apparent and Simple Diffusion Coefficients in Compacted Bentonite

by J. L. Conca, Washington State Univ Tri-Cities, Richland, United States,
T. Ashida, Washington State Univ Tri-Cities, Richland, United States,
H. Sato, Washington State Univ Tri-Cities, Richland, United States,



Document Type: Proceeding Paper

Part of: High Level Radioactive Waste Management 1991

Abstract:

Diffusion coefficients were experimentally determined in bentonite to evaluate the effectiveness of bentonite layers as a diffusion barrier to ionic transport away from high-level radioactive waste packages. The electrical conductivity was measured using a 1 kHz conductivity bridge on bentonite-NaCL solution samples packed into conductivity cells. The diffusion coefficient was calculated from the electrical conductivity value using the Nernst-Einstein equation. These results were compared to apparent diffusion coefficients obtained using long-term, tracer diffusion tests in the same compacted bentonite with ³H, ¹²⁹I, ⁹⁹Tc, ²⁴¹Am, ⁹⁰Sr, ¹³⁷Cs and ²³⁷Np. As expected, the retardation effects were much lower than predicted from batch tests, and the retardation behavior of all species changed with increasing compaction density. ⁹⁰Sr, ¹³⁷Cs and ²³⁷Np behave especially non-linearly at high compaction densities.

Subject Headings: Diffusion (porous media) | Bentonite | Radioactive wastes | Diffusion (chemical) | Compaction (material) | Electrical conductivity | Waste disposal

Services: Buy this book/Buy this article

 

Return to search