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No abstract

A program has been established for DOE Environmental Restoration and Waste Management (EM) to evaluate factors that are likely to affect waste glass reaction ,during repository disposal, with emphasis on an unsaturated environment typical of what may be expected for the proposed Yucca Mountain repository site. This report covers progress in FY 1991 on the following tasks: 11 A critic_ review of those parameters that affect the reactivity of glass in an unsaturated environment is in progress. This effort involves a search of the literature to identify the important parameters. Temperature and glass compositions are the first parameters examined in detail. 2, An interface between waste producers and the repository program is being implemented. 3. A series of tests has been started to evaluate the reactivity of fully radioactive glasses in a high-level waste repository environment mad compare it to the reactivity of synthetic glasses of similar composition. 4. The effect of radiation upon the durability of waste glasses at a high glass surface. _ea-tc)-liquid volume fSA/V) _ttio m3d higl_ gas-to-liquid volume ratio will be assessed. These tesLsaddress both vapor m_d high SA/V liquid conditions. 5. A series of test:_ is being performed to compare the extent of reaction (_t" nuclear waste glasses at various SA/V ratios, Such differences in the SA/V ratio may significantly affect glass durability. 6. An_ytical electron microscopy (AEM), infrared spectroscopy, and nuclear : resonant profiling are being used to assess the glass/water reaction pathway by identil'ying intermediate phases that appear on the reacting glass. Additionally, colloids trom the leach solutions are being studied using AEM.

Thisisa preprint of a paper intended for publication in a joumalorproceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.

A critical analysis of experimental data for the Nb‐H system shows that the partial molar entropy data are best interpreted by assuming a random solution of hydrogen in the metal on one site per metal atom even in concentrated solutions. A possible geometrical interpretation of this result is suggested.