[en] Glass-bonded zeolite is being developed at Argonne National Laboratory in the Electrometallurgical Treatment Program as a potential ceramic waste form for the disposition of radionuclides associated with the US Department of Energy's (DOE's) spent nuclear fuel conditioning activities. The utility of standard durability tests [e.g. Materials Characterization Center Test No. 1 (MCC-1), Product Consistency Test (PCT), and Vapor Hydration Test (VHT)] are being evaluated as an initial step in developing test methods that can be used in the process of qualifying this material for acceptance into the Civilian Radioactive Waste Management System. A broad range of potential repository conditions are being evaluated to determine the bounding parameters appropriate for the corrosion testing of the ceramic waste form, and its behavior under accelerated testing conditions. In this report we provide specific characterization information and discuss how the durability test results are affected by changes in pH, leachant composition, and sample surface area to leachant volume ratios. We investigate the release mechanisms and other physical and chemical parameters that are important for establishing acceptance parameters, including the development of appropriate test methodologies required to measure product consistency

[en] This paper focuses on the reaction of glass-bonded zeolite and sodalite ceramic waste forms, naturally occurring sodalite, and their respective alteration phases that formed after reaction in a Vapor Hydration Test (VHT). Scanning electron microscope (SEM) analysis of the glass-bonded zeolite and sodalite samples indicate that NaCl is the major alteration phase present, along with DCl, Na-Al-Si, and Na-K-Ca-Al-Si phases. The order of precipitation of salt crystals from ceramic waste form occurred in the sequence NaCl r_arrow KCl r_arrow CaCl₂ and MgCl₂. The authors also found aluminum silicate phases containing Ca, Mg, K-Na-Ca, K-Mg, Na-K-Mg, K-Ca-Na-Mg, as well as CaCO₃, SiO₂. The ratio of Si/Al in the alteration phases was noted to increase from approximately 1.5 to 5 during the progressive alteration of the samples. This trend indicates a relative increase in the contribution of silicon from the relatively Si-rich glass regions of the samples over time. Phases enriched in Cs, Ba and rare earth elements (RE) were also observed on the altered samples. Alteration phases initially appeared along the micro-fractures during the early stages of alteration. The number of micro-fractures, density of alteration phase cover, and grain size of alteration phases increased with reaction time and temperature

[en] Stainless steel-zirconium (SS-Zr) alloys have been developed as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The waste forms incorporate irradiated cladding hulls, components of the alloy fuel, noble metal fission products, and actinide elements. The baseline waste form is a stainless steel-15 wt% zirconium (SS-15Zr) alloy. This article presents microstructures and some of the corrosion studies being conducted on the waste form alloys. Electrochemical corrosion, immersion corrosion, and vapor hydration tests have been performed on various alloy compositions to evaluate corrosion behavior and resistance to selective leaching of simulated fission products. The SS-Zr waste forms immobilize and retain fission products very effectively and show potential for acceptance as high-level nuclear waste forms

[en] Stainless steel-zirconium (SS-Zr) alloys are being considered as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The baseline waste form for spent fuels from the EBR-11 reactor is a stainless steel-15 wt.% zirconium (SS-15Zr) alloy. This article briefly reviews the microstructure of various SS-Zr waste form alloys and presents results of immersion corrosion and electrochemical corrosion tests performed on these alloys. The electrochemical tests show that the corrosion behavior of SS-Zr alloys is comparable to those of other alloys being considered for the Yucca Mountain geologic repository. The immersion tests demonstrate that the SS-Zr alloys are resistant to selective leaching of fission product elements and, hence, suitable as candidates for high-level nuclear waste forms

[en] Glass-bonded zeolite is being developed as a potential ceramic waste form for the disposition of radionuclides associated with the Department of Energy's (DOE's) spent nuclear fuel conditioning activities. The utility of several standard durability tests was evaluated as a first step in developing methods and criteria that can be applied towards the process of qualifying this material for acceptance into the DOE Civilian Radioactive Waste Management System. The effects of pH, leachant composition, and sample surface-area-to leachant-volume ratios on the durability test results are discussed, in an attempt to investigate the release mechanisms and other physical and chemical parameters that are important for the acceptance criteria, including the establishment of appropriate test methodologies required for product consistency measurements

[en] We have used an electrochemical sample chamber to modulate the surface charge of Ag(111) in spectral measurements (over a range of the incident photon energy from 1.4 to 2.23 eV) of the isotropic contribution to the second-harmonic reflectance. When the charge modulation was positive, and the harmonic energy was below the onset for interband transitions, the results compared favorably with a previously published prediction of the same phenomenon which was based upon time-dependent local-density-functional theory for jellium having the same bulk electron density as Ag. The correlation between this theory and our experiment was poor for negative charge modulation. However, this was not unexpected, since the jellium model makes no allowance for the influence of the d bands. We have tentatively assigned a localized feature in the spectrum for negative charge modulation, which appears at a harmonic energy of 3.4 eV, as a two-photon resonance involving crystal-potential and image-potential surface states