The Reaction of SRL 202 Glass in J-13 and DIW
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THE REACTION OF SRL 202 GLASS IN J-13 AND DIW W. L. Ebert, J. K.Bates, and E. C. Buck Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4837. ABSTRACT
Static leach tests were performed in both 304L stainless steel and Teflon vessels using a synthetic high-level waste glass with either deionized water (DIW) or a tuff groundwater solution as the leachant to assess the effects of the vessel and the initial leachant composition on the extent and nature of the glass reaction. The tests were performed using monolith samples at 340 m-1 and crushed samples at 2000 m-1 for times up to 1 year. The results show less silicon is released from the glass into the groundwater solution than into DIW at both high and low glass surface area/leachant volume ratios (SA/V), but the alkali metal and boron releases are not affected by the leachant used. Tests performed ina stainless steel vessel resulted in slightly lower leachate pH values, but similar reaction rates to those performed in a Teflon vessel, as measured by the boron release. Blank tests with DIW or EJ-13 in the vessels showed the Teflon vessels to release small amounts of fluoride (1 to 2 ppm) and to acidify the DIW slightly (4.0 < pH < 5.6). The pH values of blank tests with EJ-13 increased from 8.2 to about 8.6 insteel and to about 9.2 in Teflon vessels. The slightly higher pH values attained inTeflon vessels are attributed to outgassing of C02 during the test. INTRODUCTION
Static leach tests are commonly used to measure the durabilities of glasses that may be produced during vitrification of high-level nuclear waste. The response of the glass is usually monitored by measuring the release of soluble glass
components into the solution. Changes in the solution composition that occur during a static leach test include changes due to corrosion of the reaction vessel and alteration of the gas phase present in the test vessel, as well as those due to the glass reaction. Most static leach tests are performed in either stainless steel vessels or in PFA (perfluoralkoxy) Teflon vessels. Neither vessel is inert with respect to the solution composition., The steel surface may adsorb components released from the glass or may corrode to release metal ions into solution [1]. Teflon may release hydrofluoric acid (HF) into solution [2], which may accelerate the glass corrosion and acidify the leachate. Teflon is also permeable to carbon dioxide, which may affect
the solution pH [3]. Itis important to account for effects related to vessel interactions to accurately measure the extent of glass reaction. Because the glass reaction is known to be strongly influenced by the solution chemistry [4-7], both the effects of the initial leachant composition and changes to the leachate chemistry due to interactions other than glass corrosion must be understood to assess the extent and nature of the glass reaction. Static leach tests were performed to assess the effects of the initial leachant composition and reaction vessel material on the measured extent of reaction using SR
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