Long-Term Release Rates of Borosilicate Glass Waste Forms

1986 ◽  
Vol 73 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Pedro B. Macedo ◽  
Aaron Barkatt ◽  
Barbara C. Gibson ◽  
Charles J. Montrose
Keyword(s):  
Borosilicate Glass ◽  
Release Rates ◽  
Glass Waste ◽  
Waste Forms

A Flow Model for the Kinetics of Dissolution of Nuclear Waste Forms; A Comparison of Borosilicate Glass, Synroc and High-Silica Glass

1981 ◽  
Vol 11 ◽  
Author(s):  
Pedro B. Macedo ◽  
Aaron Barkatt ◽  
Joseoph H. Simmons
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Flow Model ◽  
Release Rates ◽  
Waste Forms ◽  
High Silica ◽  
Kinetics Of Dissolution ◽  
Kinetics Of ◽  
Nuclear Waste Forms

A model has been developed to predict the long-term leach or release rates of various waste-form materials under repository conditions.

Dissolution of Technetium From Nuclear Waste Forms

1983 ◽  
Vol 26 ◽  
Author(s):  
M. Yasser Khalil ◽  
William B. White
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Stability Field ◽  
Glass Waste ◽  
Waste Forms ◽  
Reducing Conditions ◽  
Valence States ◽  
The Stability ◽  
Nuclear Waste Forms ◽  
Similar Kinetic

ABSTRACTThe immobilization of 99Tc in both ceramic and borosilicate glass waste forms and the mechanism of dissolution of technetium from these waste forms are complicated by the range of technetium valence states. Metallic Tc,ionic Tc4+ oxides, and volatile molecular species containing Tc7+ all occur within the stability field of water. Tc4+ will substitute readily for Ti4+ in titanatebased ceramics in such phases as perovskite (CaTiO3) and spinel (Mg2TiO4). Tc4+ can be homogeneously distributed in borosilicate glass by re-melting the glass under closed system conditions to prevent the re-oxidation of technetium. The dissolution of technetium from both glass and ceramic waste forms follow similar kinetic behavior although the dissolution rate from the titanate is two orders of magnitude lower. Dissolution under highly reducing conditions is too slow to measure on the time scale of the experiments.

Ion Implantation Damage in Silicate Glasses

1982 ◽  
Vol 15 ◽  
Author(s):  
George W. Arnold
Keyword(s):  
Ion Implantation ◽  
Nuclear Waste ◽  
Silicate Glasses ◽  
Glass Waste ◽  
Leach Rate ◽  
Implantation Damage ◽  
Waste Forms ◽  
Long Term Behavior ◽  
Nuclear Waste Forms

ABSTRACTIon implantation is a rapid technique for simulating damage induced by α-recoil nuclei in nuclear waste forms. The simulation has been found to be quite good in TEM comparisons with natural α-decay damage in minerals, but leach rate differences have been observed in glass studies and were attributed to dose-rate differences. The similarities between ion implantation and recoil nuclei as a means of producing damage suggest that insights into the long-term behavior of glass waste forms can be obtained by examination of what is known about ion-implantation damage in silicate glasses. This paper briefly reviews these effects and shows that leaching results in certain nuclear waste glasses can be understood as resulting from plastic flow and track overlap. Phase separation is also seen to be a possible consequence of damage-induced compositional changes.

The Role of Boron in Monitoring the Leaching of Borosilicate Glass Waste Forms

1984 ◽  
Vol 44 ◽  
Author(s):  
Barry E. Scheetz ◽  
W. Phelps Freeborn ◽  
Deane K. Smith ◽  
Christine Anderson ◽  
Michael Zolensky ◽  
...  
Keyword(s):  
Borosilicate Glass ◽  
Solid Phase ◽  
Waste Form ◽  
Direct Measure ◽  
Glass Waste ◽  
Worst Case ◽  
Waste Forms

AbstractIn the absence of any identified solid phase host (other than the original glass), boron has been assumed to accumulate in the fluid during the reaction of borosilicate glass waste forms with aqueous fluids. Using this assumption, it is possible to define a boron index which can be used to monitor the amount of glass that has been dissolved and to provide a worst-case measure of the degradation of the primary glass waste form. Several boron-containing silicate phases have been identified thus invalidating the assumption that boron does not precipitate. The effect is apparently small and the assumption that boron release is a direct measure of degree of alteration of borosilicate glass is still probably a good one.

Screening of Candidate Low‐Temperature Glass Waste Forms for Technetium from Hanford Effluent Management Facility Evaporator Bottoms

2018 ◽  
Author(s):  
Rebecca M. Chamberlin ◽  
Ming Tang ◽  
Rosendo Borjas Nevarez ◽  
Gordon Dennis Jarvinen ◽  
Daniel Koury ◽  
...  
Keyword(s):  
Low Temperature ◽  
Glass Waste ◽  
Waste Forms

Glass-Ceramic Foams from Borosilicate Glass Waste

2014 ◽  
Vol 5 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Rosa Taurino ◽  
Isabella Lancellotti ◽  
Luisa Barbieri ◽  
Cristina Leonelli
Keyword(s):  
Borosilicate Glass ◽  
Glass Ceramic ◽  
Glass Waste ◽  
Ceramic Foams

Host Phases for Actinide Elements in the Metallic Waste Form

2002 ◽  
Vol 757 ◽  
Author(s):  
D. E. Janney
Keyword(s):  
Stainless Steel ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Transmission Electron Microscope ◽  
Waste Form ◽  
Dissolution Behavior ◽  
Release Rates ◽  
Waste Forms ◽  
Transmission Electron ◽  
Simulated Waste

ABSTRACTArgonne National Laboratory has developed an electrometallurgical process for conditioning spent sodium-bonded metallic reactor fuel prior to disposal. A waste stream from this process consists of stainless steel cladding hulls that contain undissolved metal fission products such as Tc, Ru, Rh, Pd, and Ag; a small amount of undissolved actinides (U, Np, Pu) also remains with the hulls. These wastes will be immobilized in a waste form whose baseline composition is stainless steel alloyed with 15 wt% Zr (SS-15Zr). Scanning electron microscope (SEM) observations of simulated metal waste forms (SS-15Zr with up to 11 wt% actinides) show eutectic intergrowths of Fe-Zr-Cr-Ni intermetallic phases with steels. The actinide elements are almost entirely in the intermetallics, where they occur in concentrations ranging from 1–20 at%. Neutron- and electron-diffraction studies of the simulated waste forms show materials with structures similar to those of Fe2Zr and Fe23Zr6.Dissolution experiments on simulated waste forms show that normalized release rates of U, Np, and Pu differ from each other and from release rates of other elements in the sample, and that release rates for U exceed those for any other element (including Fe). This paper uses transmission electron microscope (TEM) observations and results from energy-dispersive X-ray spectroscopy (EDX) and selected-area electron-diffraction (SAED) to characterize relationships between structural and chemical data and understand possible reasons for the observed dissolution behavior.Transmission electron microscope observations of simulated waste form samples with compositions SS-15Zr-2Np, SS-15Zr-5U, SS-15Zr-11U-0.6Rh-0.3Tc-0.2Pd, and SS-15Zr-10Pu suggest that the major actinide-bearing phase in all of the samples has a structure similar to that of the C15 (cubic, MgCu2-type) polymorph of Fe2Zr, and that materials with this structure exhibit significant variability in chemical compositions. Material whose structure is similar to that of the C36 (dihexagonal, MgNi2-type) polymorph of Fe2Zr was also observed, and it exhibits less chemical variability than that displayed by material with the C15 structure. The TEM data also demonstrate a range of actinide concentrations in materials with the Fe23Zr6 (cubic, Mn23Th6-type) structure.Microstructures similar to those produced during experimental deformation of Fe-10 at% Zr alloys were observed in intermetallic materials in all of the simulated waste form samples. Stacking faults and associated dislocations are common in samples with U, but rarely observed in those with Np and Pu, while twins occurred in all samples. The observed differences in dissolution behavior between samples with different actinides may be related to increased defect-assisted dissolution in samples with U.

Long-term leaching scenarios for cement-based waste forms

1987 ◽  
Vol 5 (1) ◽  
pp. 55-66 ◽  
Author(s):  
P COTE ◽  
T BRIDLE
Keyword(s):  
Waste Forms

Performance Assessment of Low-Level Waste Disposal Facilities Using Coupled Unsaturated Flow and Reactive Transport Simulators

2002 ◽  
Vol 713 ◽  
Author(s):  
Diana H. Bacon ◽  
B. Peter McGrail ◽  
Vicky L. Freedman ◽  
Giancarlo Ventura ◽  
Piero Risoluti ◽  
...  
Keyword(s):  
Waste Disposal ◽  
Vadose Zone ◽  
Reactive Transport ◽  
Unsaturated Flow ◽  
Filler Materials ◽  
Release Rates ◽  
Glass Waste ◽  
Shallow Subsurface ◽  
Low Level ◽  
Reactive Chemical Transport

ABSTRACTRecent advances in the development of reactive chemical transport simulators have made it possible to use these tools in performance assessments (PAs) for nuclear waste disposal. Reactive transport codes were used to evaluate the impacts of design modifications on the performance of two shallow subsurface disposal systems for low-level radioactive waste. The first disposal system, located at the Hanford site in Richland, Washington, is for disposal of lowlevel waste glass. Glass waste blocks will be disposed in subsurface trenches, surrounded by backfill material. Using different waste package sizes and layering had a small impact on technetium release rates to the vadose zone. The second disposal system involves a hypothetical repository for low-level waste in Italy. A model of uranium release from a grout waste form was developed using the STORM reactive transport code. Uranium is predicted to be relatively insoluble for several hundred years under the high-pH environment of the cement pore water. The effect of using different filler materials between the waste packages on uranium flux to the vadose zone proved to have a negligible impact on release rates.

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