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[en] With regard to its great practical importance during the melting of borosilicate glasses, the evaporation of systematically varied borosilicate glass melts was measured at temperatures between 1400 and 1700deg C. The volatilization declines with increasing SiO2 content; depending on the Na2O concentration and B2O3 concentration, a maximum is found in the case of equimolar ratio of both oxides. The influence of the SiO2 is attributed to the incrementing viscosity and the increased fur formation (cristobalite foam). The evaporation products correspond to the composition of the sodium metaborate, NaBO2. This explains the observed maximum of evaporation. (orig.)
[de]Im Hinblick auf die grosse praktische Bedeutung beim Schmelzen von Boroailicatglaesern wurde die Verdampfung systematisch variierter Borosilicatglasschmelzen zwischen 1400 und 1700deg C gemessen. Mit steigendem SiO2-Gehalt nimmt die Verfluechtigung ab; in Abhaengigkeit vom Na2O- und B2O3-Gehalt wird beim aequimolaren Verhaeltnis beider Oxide ein Maximum gefunden. Der Einfluss des SiO2 geht auf die Erhoehung der Viskositaet und vermehrte Pelzbildung zurueck. Die Verdampfungsprodukte entsprechen der Zusammensetzung des Natriummetaborats NaBO2. Daraus erklaert sich das beobachtete Maximum der Verdampfung. (orig.)
[en] As part of international agreement between the United States and Russia, a significant amount of plutonium requires disposition. One of the disposition paths is to immobilize it and dispose of it in a geological repository. The two favored immobilization forms are glass and ceramic. The plutonium, as an oxide, would be reacted with the glass or ceramic to form a homogeneous material. The resulting solid product would then be encased in High-Level Waste (1-ILW)glass for the can-in-canister option. The HLW glass gives a radiation barrier to increase proliferation resistance. The glass canister would then be disposed of by geological emplacement. This paper discusses how glass meets two criteria: the condition of significant actinide volubility, and That the PuO2 feed should be incorporated into the matrix without significant amount of unreacted material
[en] Ultra-low temperature anodic bonding of silicon and borosilicate glass has been described for the first time. The article gives the arguments why the issue of non-standard anodic bonding of silicon and glass is important. Some examples of solutions were indicated, in which the development of a new anodic bonding method was crucial for the development of the final solution. A series of experiments were carried out, the effect of which was the obtaining of a permanent connection of silicon and glass at a temperature of 120 °C. Optimal conditions of the ultra-low temperature of the anodic bonding process were given. The bonding force was tested, which was more than 1.5 MPa. (paper)
[en] Interdiffusion and matrix dissolution corrosion modes are inadequate to describe fully the leaching behavior of the more complicated waste glasses that contain large amounts of iron, manganese, and aluminum as will many other elements. A further process, surface layer formation, that must be considered when developing a model describe waste glass leaching has been identified. This process consists of the formation of a layer of insoluble material such as the hydroxides of iron, manganese and other insoluble compounds on the surface of waste glass as it corrodes. This paper describes work leading to the development of a leaching model in which the effect of surface layer formation is considered
[en] The assessment of the long-term durability of vitrified high-level radioactive waste necessitates the difficult extrapolation of laboratory simulation tests of short duration to geologic time scale. Such an objective implies the knowledge of the kinetics of glass aqueous corrosion and therefore of the basic mechanisms ruling it. In fact, in spite of extensive work on this matter, there is still controversy on these corrosion processes. Indeed the aqueous dissolution of silicate glasses (including HLW borosilicates) has been mainly investigated by systematic chemical analysis of both leachants and solid surfaces. Complex phenomena such as ion-exchange, ion adsorption, secondary phase formation etc...have been recognized to be responsible for the build up of an altered layer at the solid solution interface, the properties of which could rule the long-term behavior of the glass. Several morphological features are exhibited by the altered layer on both nuclear and natural glasses, in particular cup-shaped structures called cupules are easily evidenced by optical and scanning electron microscopies. Three hypotheses have been proposed to explain the origin of such features, namely i. chemical/structural heterogeneities, ii. surface defects or iii. localized electrical charges. The aim of this work was to carefully study the morphological evolution of cupules during dissolution in order to discriminate between these hypotheses
[en] A study of the 150-320 keV proton beam transmission through tapered glass (borosilicate) capillaries with different diameters of the input and output of the capillary was performed. The focusing effect was observed. The areal density of the transmitted beam is enhanced by approximately 20 times. It was shown that changing a taper angle from 0.5 deg to 1.7 deg evidences increase of the transmission coefficient by more than 300 times keeping the initial energy spectrum of ions. The ion transmission through self-ordered nanoporous alumina membranes prepared by anodic oxidation of high-purity aluminium was studied for different energies of ions.
[en] To understand the long-term leach behavior of a borosilicate Waste glass in a repository, the leaching experiment with three kinds of simulated borosilicate waste glasses has been carried out since the middle of 1997. The five years results indicate that a boron would be applied as an indicator of a long-term leaching of their borosilicate waste glasses and that their long-term leach rates have a tendency to be close to about 0.03g/m2-day even though their compositions and their ratios of the surface area to the volume of leachate are different.
[en] The phenomenological behavior of commercial silicate glasses and nuclear borosilicate glasses in confined glass:aqueous solution systems is similar. For commercial silicate glasses the behavior has been described, ''If the neutral solution is unbuffered and confined in a bottle, it becomes alkaline and attack is accelerated, but eventually the accumulated products inhibit further action.'' Similar behavior is observed for nuclear waste borosilicate waste glasses in the MCC-1 Static Leach Test Method, the pulsed-flow test, and other leach tests in which the amount of solution in contact with the glass is restricted. In these tests the concentration of ions in the leachate increases initially (but not congruently, that is, the ratio of ion concentrations in the leachate is different than in the original glass), however, the concentration of each ion tends gradually towards its own steady-state concentration. The ''accumulated products'' that ''inhibit further action'', and result in the tendency toward steady-state leachate concentrations, are found in an altered layer on the surface of the leached glass and are generally considered to arise from solubility constraints. 21 refs., 2 figs., 2 tabs
[en] The laboratory studies described in this report characterize the performance and homogeneity of waste glass from a 2-ft-dia glass slice taken from a full-scale 2 ft by 10 ft canister filled with glass at TNX. The leaching performance of glass samples extracted from the slice was determined as a function of radial position and will be used in support of existing programs. The waste glass produced at TNX and used for the burial tests in WIPP was very homogeneous. The extent of glass leaching in brine (using standard MCC-1 leach tests and based on boron extraction) was 15X less than that of leaching in deionized water
[en] In the present work, a mass spectrometric Knudsen effusion method has been used to study the chemical forms of vapors with Na, B and Te over a borosilicate glass with simple composition 1Na2O-1B2O3-3SiO2-0.15TeO2. (orig./RK)