Tuff reaction vessel experiment

Bazan, F.; Rêgo, João Henrique da Silva

doi:10.2172/59933

Cited by 4 publications

(1 citation statement)

References 6 publications

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“…Bazan at LLNL has leached a Tc-99 containing glass in tuff groundwater [11]. The glass he used was A TM-8 glass which has a composition similar PNL 76-68.…”

Section: Leaching In Tuff Groundwatermentioning

confidence: 99%

Leaching Tc-99 from SRP Glass in Simulated Tuff and Salt Groundwaters

Bibler

Jurgensen

1987

MRS Proc.

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Results of leach tests with Tc-99 doped SRP borosilicate waste glass are presented. The glass was prepared by melting a mixture of SRP 165 powdered frit doped with a carrier free solution of Tc-99 at 1150°C. Dissolution of portions of the resulting glass indicated that the Tc-99 was distributed homogeneously throughout the glass. Static leach tests up to 90 da1s were performed at 90°C in J-13 tuff groundwater or WIPP brine A at a SAN of lOOm-.Normalized mass losses were calculated for Tc-99 as well as all the major elements in the glass. Results indicated that under ambient oxidizing conditions Tc-99 leached no faster than the glass-forming elements of the glass. In J-13 water, Tc-99leached congruently with B. In WIPP brine A, it leached congruently with Si. Leach rates for Li were higher in both groundwaters, probably due to a contribution from an ion exchange mechanism. Leach tests were performed under reducing conditions in J-13 water by adding Zn/Hg amalgam to the leachate. In these tests the pH increased significantly, probably because of the reaction of the amalgam with the water. In a 21-day test, the pH increased to 13 and leach rates for the glass were very high. Even though there was si!2nificant dissolution of the glass, the normalized mass loss based on Tc-99 was only 0.02g/m . This result and the fact that reducing conditions at normal pH values do not significantly affect the dissolution of the glass, indicate that the low concentrations for Tc-99 obtained under reducing conditions are due to its solubility and not due to an increased durability of the glass.

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“…Bazan at LLNL has leached a Tc-99 containing glass in tuff groundwater [11]. The glass he used was A TM-8 glass which has a composition similar PNL 76-68.…”

Section: Leaching In Tuff Groundwatermentioning

confidence: 99%

Leaching Tc-99 from SRP Glass in Simulated Tuff and Salt Groundwaters

Bibler

Jurgensen

1987

MRS Proc.

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Leaching of Actinide-Doped Nuclear Waste Glass in a Tuff-Dominated System

1986

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A laboratory leaching test has been performed as part of a project to evaluate the suitability of tuff rocks at Yucca Mountain, Nevada, as a site for a high-level nuclear waste repository. Glass samples were placed in water inside tuff vessels, and then the tuff vessels were placed in water inside Teflon containers. Glass-component leach rates and migration through the tuff were measured for samples of the ATM- 9actinide glass, which is a PNL 76-68 based glass doped with low levels of 99Tc, 237Np, 238U and 239Pu to simulate wastes. Disc samples of this glass were leached at 90°C for 30, 90, and 183 days inside tuff vessels using a natural groundwater (J-13 well-water) as the leachant. Some samples were held by 304L stainless steel supports to evaluate the effect of this metal on the release rate of glass constituents. At the end of each leaching interval, the J-13 water present inside and outside the rock vessel was analyzed for glass components in solution.On the basis of these analyses, boron, molybdenum, and technetium appear to migrate through the rock at rates that depend on the porosity of each vessel and the time of reaction. The actinide elements (uranium, neptunium, and plutonium) were found only in the inner leachate. Sodium, silicon, and strontium are present in the rock as well as in the J-13 water, and the addition of these elements from the glass could not be determined. Normalized elemental mass loss values for boron, molybdenum, and technetium were calculated using the combined concentrations of the inner and outer leachates and assuming a negligible retention on the rock. The maximum normalized release was 2.3 g/m for technetium. Boron, molybdenum, technetium, and neptunium were released linearly with respect to each other, with boron and molybdenum released at about 85% of the technetium rate, and neptunium at 5-10% of the technetium rate. Plutonium was found at low levels in the inner leachate but was strongly sorbed on the steel and Teflon supports. Neptunium was sorbed to a lesser extent. Future analysis of the tuff vessels will determine whether the actinides were strongly sorbed on the surface of the tuff rock.

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Materials Interactions Relating to Long-Term Geologic Disposal of Nuclear Waste Glass

Bibler

Jantzen

1986

MRS Proc.

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In the geologic disposal of nuclear waste glass, the glass will eventually interact with groundwater in the repository system. Interactions can also occur between the glass and other waste package materials that are present. These include the steel canister that holds the glass, the metal overpack over the canister, backfill materials that may be used, and the repository host rock. This review paper systematizes the additional interactions that materials in the waste package will impose on the borosilicate glass waste form-groundwater interactions. The repository geologies reviewed are tuff, salt, basalt, and granite. The interactions emphasized are those appropriate to conditions expected after repository closure, e.g. oxic vs. anoxic conditions. Whenever possible, the effect of radiation from the waste form on the interactions is examined. The interactions are evaluated based on their effect on the release and speciation of various elements including radionuclides from the glass. It is noted when further tests of repository interactions are needed before long-term predictions can be made.

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Tuff reaction vessel experiment

Abstract: DISCLAIMER

Cited by 4 publications

References 6 publications

Leaching Tc-99 from SRP Glass in Simulated Tuff and Salt Groundwaters

Leaching Tc-99 from SRP Glass in Simulated Tuff and Salt Groundwaters

Leaching of Actinide-Doped Nuclear Waste Glass in a Tuff-Dominated System

Materials Interactions Relating to Long-Term Geologic Disposal of Nuclear Waste Glass

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