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[en] 'The objectives of this report are: (1) To investigate the development of Raman spectroscopy for remote, in-situ, real-time measurement of the processes underlying chemical corrosion of glasses, (2) To conduct Raman spectroscopy measurements and quantum mechanical modelling studies of the transition states, corrosion products, and transition state energies for the hydrate species of higher valence and multivalent ions formed in the reconstructed glass surface. (3) To use these results to model long-term corrosion behavior of complex borosilicate wasteform glasses. (4) To apply the Raman spectroscopy and modelling methods developed here for the remote analysis of leaching processes in waste glasses containing radioactive components, and for imaging of variations in leaching behavior due to composition inhomogeneities in large scale waste glass products. Results of First Year Research During the first year, the authors primarily addressed Objective (1) which is to develop a methodology for the remote monitoring of leaching processes in glasses by Raman spectroscopy. The authors assembled a micro and macro Raman system for examining surface structure in glass samples, in-situ within the leaching vessel. The Raman spectrometer was prepared for imaging by installing a CCD detector which gives 2-dimensional information. The latter can be used to obtain spectrographic data in one dimension and to scan variations in materials behavior across the other dimension. By scanning the sample in a perpendicular direction, it is possible to conduct 2-dimensional spectral analysis of the sample surface. The plan is to select one or several identifying Raman lines that follow the leaching process After that, it will be possible to introduce a slit configuration and use both dimensions of the CCD detector for scanning the sample surface while examining only the selected spectral feature. Glass samples consisting of alkali silicates were first examined. The samples were melted in a conventional electric furnace in 100 gr batches and poured into brass molds. The samples were cut and polished under water-free conditions and then immersed under water in petri dishes. By leaving the upper surface uncovered, the authors focused the objective lens of a microscope on the submerged glass surface. Light from an Argon laser operating at 514.5 nm with approximately 100 mW of power was directed to the glass surface at a large angle of incidence (55 ). Raman spectra were collected in a 0.6 m spectrometer with a 1,200 line/mm grating using a supernotch filter to block the laser line. Typical data are shown in the attached figure. Samples of the following compositions were tested: 20% Na,O--80% SiO, and 30% L and O--70% SiO, . The attached figure reports the results from the Li,O-SiO, glass. The results show a significant difference between the unleached and water-exposed samples. This is evident in the relative amplitudes of the Raman peaks at 436 cm^-2 and 582 cm^-2. These 2 peaks are associated with vibrations of the alkali coordinated non- bridging oxygen. In fact, the ratio of the 582 to the 436 peaks gives a measure of the alkali content of the material. By examining the sample surface only, and conducting the tests while the sample is submerged, the authors observed a decrease in the 582 cm^-1 peak and an increase in the 436 cm^-1 peak with increased exposure of the sample to the aqueous environment. This is shown in the attached figure and is clear indication of the progressive dealkalization of the glass surface by water. The peaks can be fitted to Gaussian shapes and the integrated intensity will yield a direct measure of the alkali content of the glass surface. In addition, the angle of incidence of the laser beam can be adjusted to provide more penetration into the sample and yield composition profiles.'

[en] 'The research objective was to test and develop optical methods for real-time, remote and in-situ testing of corrosion processes on the surface of vitrified nuclear wastes. This report summarizes the research conducted in the first 1.5 years of a 3 year grant. At this point, the authors have identified the conditions for optimal tests and demonstrated that both IR reflection and Raman spectroscopies can be used to determine the dealkalization process in the surface of simple glasses in real time.'

[en] A non-porous glass composition containing radioactive material encapsulated and immobilized in the glass matrix, said composition being characterized by: (a) at least 75 mol percent SiO₂, (b) a radiation activity above one millicure per cubic centimeter of said composition, and (c) high chemical durability to aqueous solution

[en] This patent relates to radioactive materials which are fixed, stored, entrapped, encapsulated, or otherwise rendered immobile in a glass matrix for extremely long periods of time. Radioactive material such as radioactive wastes are incorporated into a glass matrix by a process of molecular stuffing a porous glass either with a radioactive gas which is trapped in the porous glass by dissolution during sintering of the glass, or with a salt solution containing radioactive material such as CsNO₃, Sr(NO₃), etc., or with a combination of both salt solution and radioactive gas, followed by drying and sintering of the pores of the glass whereby these radioactive materials upon chemical change to their oxides, excepting of course the noble gases which remain in molecular form, become a part of the integrated glass structure. The resulting glass article may have the radioactive material dispersed essentially homogeneously throughout the glass article, or there may be a layer free of such radioactive waste material over the entire surface of the glass article. In either case such glass articles demonstrate an extremely slow diffusion of the encapsulated radioactive material to the surrounding area. (C.F.)

[en] This invention relates to radioactive materials which are fixed, stored, entrapped, encapsulated, or otherwise rendered immobile in a glass matrix for extremely long periods of time. Radioactive material such as radioactive wastes are incorporated into a glass matrix by a process of ''molecular stuffing'' a porous glass either with a radioactive gas which is trapped in the porous glass by dissolution during sintering of the pores of the glass, or with a salt solution containing radioactive material such as CsNO₃, SrNO₃), etc., or with a combination of both salt solution and radioactive gas, followed by drying and sintering of the pores of the glass whereby these radioactive materials upon chemical change to their oxides, excepting of course the noble gases which remain in molecular form, become a part of the integrated glass structure. The resulting glass article may have the radioactive material dispersed essentially homogeneously throughout the glass article, or there may be a layer free of such radioactive waste material over the entire surface of the glass article. In either case such glass articles demonstrate an extremely slow diffusion of the encapsulated radioactive material to the surrounding area

[en] This invention concerns the fixing of radioactive substances in a glass matrix. The composition is given of non-porous glass containing a radioactive substance enclosed and immobilised in the glass matrix, this composition being characterized by (a) not less than 75 moles per cent of SiO₂, (b) a radiation activity exceeding around 1 millicurie per cm³ of the composition and (c) a high chemical durability in an aqueous solution

[en] This invention relates to radioactive materials which are fixed, stored, entrapped, encapsulated, or otherwise rendered immobile in a glass matrix for extremely long periods of time. Radioactive material such as radioactive wastes are incorporated into a glass matrix by a process of ''molecular stuffing'' a porous glass either with a radioactive gas which is tapered in the porous glass by dissolution during sintering of the pores of the glass, or with a salt solution containing radioactive material such as CsNO³, Sr(NO³), etc., or with a combination of both salt solution and radioactive gas, followed by drying and sintering of the pores of the glass whereby these radioactive materials upon chemical change to their oxides, excepting of course the noble gases which remain in molecular form, become a part of the integrated glass structure. The resulting glass article may have the radioactive material dispersed essentially homogeneously throughout the glass article, or there may be a layer free of such radioactive waste material over the entire surface of the glass article. In either case such glass articles demonstrate an extremely slow diffusion of the encapsulated radioactive material to the surrounding area

[en] A non-porous glass composition containing radioctive materials chemically incorporated in the glass matrix is claimed. It contains up to 5 mol percent B₂O₃, at least 75 mol percent SiO₂ and immobilized oxides of the radio-active material chemically incorporated into the silica structure. Furthermore, it has a radiation activity above one millicurie per cubic centimeter, and a high chemical durability to aqueous solution

[en] A process is given for the encapsulation of high-level reprocessing wastes. The pores of a porous glass preform are impregnated with radioactive material, either in the gaseous state or as a solution, and the preform is sintered to decompose the radioactive material to its oxide and to collapse the porous structure. The preform may be treated with a dopant before impregnation to increase its surface area, and after impregnation steps may be taken to reduce the concentration of radioactive material near the surface of the preform. The final product is a non-porous glass composition containing at least 75 mol percent SiO₂ and having at least one millicurie per cubic centimeter of immobilized radioactive oxides chemically incorporated into the silica structure. The product may be used as a radiation source, in particular for radiosterilization