The purpose of this experiment was to evaluate the effects of various components of the SKBF/KBS nuclear waste storage system on the leaching of the vitreous waste form. Two cohfigurations of nuclear waste glasses, canisters, overpacks, and backfill mate-7ial were inserted into 5.6 cm x 3 m deep boreholes located at the 350 m level in the STRIPA mine. Some were maintained at 90°C. The others were allowed to equilibrate at the ambient temperature of the mine, approximately 8°C. Two borosilicate nuclear waste glass compositions (termed ABS 39 and ABS 41) compatible with the French AVM process containing 9 percent by weight of simulated fission products were compared. The two compositions ( Table 1) bracket the range of Si02/Na2O/B203 ratios likely to be selected for commercial vitrification operations at La Hague.

The metallic overpacks (Pb, Cu, Ti) have little effect on the corrosion of borosilicate nuclear waste glasses under either 90*C or 8*C burial conditions in deep granite. Corrosion layers for metal-glass-interfaces are generally thinner than for glass-glass interfaces. One possible reason for this is that the ductile metallic materials allow only a very thin water film between the glass and the metal. This thin water film becomes rapidly saturated with corrosion products and further corrosion is consequently slower.

The control of nuclear waste glass leaching in an actual repository environment is important to the safety of an entire nuclear waste disposal system. Leaching of the radioactive elements from a glass surface occurs when underground water reaches the waste form. The dissolved elements from the glass can then be carried away from the burial site by the water. The interaction of the surface of nuclear waste glass with underground water in a granite repository is discussed in terms of elemental mobility and materials in contact with the glass surfaces in the repository. Elemental concentration profiles at the glass surface were obtained and the glass leach rate was calculated. The rate of the interaction between nuclear waste glass surface and underground water was extrapolated to one hundred thousand years based on the leach mechanisms of the glass.

SCK·CEN has been conducting in situ experimental programmes on candidate high-level waste (HLW) glasses, as part of a global approach to evaluate the long-term chemical durability of the HLW glasses. The in situ tests are conducted in the underground research facility high activity disposal experimental site (HADES), located in the Boom Clay at 223 m below the SCK·CEN site. We briefly present the test concepts for three in situ tests: a first type of corrosion test, tests as part of the Control Experiment with Radiation of the BElgian Repository for Underground Storage (CERBERUS) test (involving γ-radiation sources), and the CORrosion of Active gLass in Underground Storage condition (CORALUS) test, that involves both γ-sources and glass samples doped with α-radionuclides (Np, Pu, Am). The glasses are corroded slightly less compared with the first in situ tests (where no γ-radiation was present). By using mass loss data and an extensive analysis of the reaction layer formed on top of the glasses, we managed to identify the main interaction processes: matrix dissolution and selective leaching. The four glasses studied reveal significant differences in dissolution behaviour. We further discuss the status of the CORALUS in situ corrosion test, which is in its first phase. An inactive CORALUS tube has been prepared and is presently in operation.

Two glasses developed as potential radioactive high-level waste (HLW) forms were investigated with respect to long-term corrosion resistance in geological environment. Loaded with simulated reactor waste, including fission products, the SON68 and SM513 HLW glasses were leached for 5 years, buried in Boom Clay at 85°C. The results were evaluated by quantitative secondary ion mass spectrometry (SIMS), using a step-scan technique yielding the in-depth concentration profiles of more than 20 relevant elements in successive sub-surface transformed layers to depths of the order of 500 μm. The observed elemental kinetics provided experimentally convincing evidence of a predominantly selective-substitutional leaching mode in both glasses. The rate of corrosion and element depletion in SON68 (a Cogéma type glass) was found to be by ca 20–40% slower than in SM513 (Pamela-type). In the reacted layers of both glasses, `mobile' elements (e.g., Li, Cs, B) were practically eliminated, but also Si was significantly depleted, while more `inert' elements (e.g., Al, Zr, Cr) remained essentially preserved in the residual network of the `gel'.

The emission of secondary ions of about fifteen different elements, sputtered from Ti-base metal specimens, has been studied by SIMS. Both positive and negative ion yields have been measured at different exit energies up to ca 350 eV. It is found that when the logarithm of ionizability is plotted versus the inverse of the exit velocity, each element suggests a straight line behavior at energies above ca 20 eV. The gradient of the straight line is related to the respective 1st ionization potential (for positive ions) or electron affinity (negative ions). This behavior gives considerable support to the premises of modern theory of ionization in sputtering. Furthermore, the straight line plots for different elements are seen to converge as exit velocity increases; the intercepts at zero inverse velocity are found to be proportional to the respective element concentrations. This in principle offers a means of quantification in elemental analysis by SIMS, a method that does not require any external standards. The usefulness of the new method is demonstrated for ten elements sputtered from two specified titanium-base alloy standards from NIST.

We investigated the interaction between Synroc-C and deionized water or Boom clay disposal media. We used powdered Synroc-C to achieve high SA/V (surface area to volume) conditions (100, 1000, 10000 m−1). The temperature was 90 °C. Reaction progress up to 10+6 days/m was reached. We conclude that dissolution in DW is mainly controlled by initial ion exchange, followed by matrix dissolution. In both Boom clay media (a 500 g/1 and a 2000 g/1 clay/claywater mixture) matrix dissolution is dominating. The depletion depth of the main Synroc constituent Ti is below 250 nm in the clay media, and below 2 nm in DW after 110 days corrosion at 100 m−1. The corrosion rates are very small, though we cannot present meaningful values. The effect of Boom clay is mainly to increase the solubility of Ti, Zr and the rare earths in solution.

In-situ corrosion tests on nuclear waste glasses in Boom clay provided direct contact glass-clay at 90 °C, for periods of 2, 3.5 and 7.5 years. The corroded reference glasses (two R7T7 type glasses, four Pamela type glasses), were studied in terms of SIMS (secondary ion mass spectroscopy) and mass losses. The Al2O3 rich Pamela glasses appear to corrode in a selective-substitutional way, the other glasses dissolve almost congruently. Differences in the corrosion extent between the glasses are associated with compositional differences and secondary phase formation. SIMS analysis provides the reaction layer thickness and the relative element behaviour in this layer. Although relatively few, the data have provided a coherent picture of glass corrosion, in terms of corrosion mechanisms, time and glass composition dependence.

The present study includes examples of recent applications of Secondary Ion Mass Spectrometry (SIMS) in different archaeometric projects. Fingerprint mass spectra of different pottery types were studied in order to characterize the wares and to establish a probable kinship to other wares. Mass spectra of the glaze of crucibles were used to establish a relation to alloys possibly melted in the crucibles. Elemental analyses of an Iron Age fibula of both the bronze shaft and the iron needle were performed. The fingerprint mass spectra of the blue paint of a van Dyck painting were compared with both indigo-blue and Berlin-blue samples in order to investigate its authenticity. Diffusion profiles of numerous elements in the enamel of teeth have been shown to reveal a strong potential for archaeological dating (DET).

Accelerated short-term leach tests in a laboratory are neccessary in order to estimate, with reasonable accuracy, the long-term leaching behavior of high-level waste glass. In the present study, static leach tests of an SRL-165 high-level waste glass were carried out in deionized water at two different glass-surface-area to solution-volume ratios (SA/V-ratio), namely 0.85 and 0.079 cm−1 at 90°C, and 0.85 cm−1 at 40°C. First, an equation was examined which related Si-concentrations with time, temperature and SA/V-ratio under the present static conditions. The parameter determined at 90°C, 0.85 cm−1 can be used to calculate the Si-concentration at 40°C, 0.85 cm−1. Second, at the low SA/V- ratio of 0.079 cm−1, the concentrations of Ca and Mg in the leachates peaked and then decreased a little. The equation used above does not explain the variation of the concentrations of Ca and Mg at a low SA/V-ratio. The precipitation of Ca and Mg onto the glass surface is probably caused by the adsorption efficiency of the surface layer or the formation of crystalline materials at the low SA/V-ratio of 0.079 cm−1. Third, the in-depth profiles of some elements obtained by secondary ion mass spectroscopy (SIMS) were qualitatively in agreement with the results of solution analyses. This indicates the particular usefulness of SIMS for analyzing leaching behavior of the glass in in-situ burial studies where solution analyses are often impractical. KEYWORDS: borosilicate glasshigh-level radioactive waste glasssolidificationleach testsleachingdeionized waterradioactive waste disposalgeologic disposal

SIMS studies of glasses indicate that calibration of positive monatomic ion yields via relative sensitivity factors (RSF) is significantly dependent both on the kinetic energyE k and on the massM t of the analyzed ions. Due to elemental differences in the energy distributions of the sputtered ions, relative emissivities at highE k are radically different from those at the tops of the distributions. While the RSF values of cations from glasses range within ca. 3 powers of ten, atE k above ca. 40 eV the range remains within a factor of ten or less, and further change of relative elemental sensitivities withE k is slow. At low exit energy the LTE formalism is reasonably well obeyed. At highE k , a trend is noted towards a relative suppression of the ion yields of lowvalent elements.

Two simulated nuclear waste glasses were corroded in an in-situ experiment in the STRIPA mine up to one year at 90°C. Changes in compositional in-depth profiles for glass/glass interfaces were measured using SIMS. Both glasses showed a depletion of Na, Cs, and B, but for the more corrosion resistant glass, the lower depletion depth is ascribed to the formation of a thin (2.0 m) coherent and dense outer layer, enriched in Mg, Ca, Sr, Ba, Zn-Al, Fe, and Si, which impedes both the ion exchange and network attack of the bulk glass underneath.

Two simulated nuclear waste glasses were leached for periods up to one month at 90°C in high-purity water, following standard MCC-1 test procedures. The changes in composition of the surface layers were determined using ESCA and SIMS, which analyses layers of different depths. The results are discussed with reference to the different pH values in the tests performed.

The penetration of Ga in films of amorphous Si3N4 about 2000 Å thick on Si substrates has been studied. The films were produced by pyrolysis. Diffusion profiles were obtained by surface exposure to Ga vapor, and the implantation profiles by ion bombardment in an isotope separator. Evaluation of the profiles was effected by means of sputtering in a secondary ion microanalyzer. For depth calibration, ion yield profiles of 69Ga+ of 71Ga+ were compared with the profiles of 30Si+, 70(Si2N+, SiN+3) and 72Si2O+. The integration of implantation peaks furnished a means of obtaining absolute values of Ga concentrations from the secondary ion intensities. Hence the surface concentration of vapor-deposited Ga at 1100°C was assessed to be of the order of 8 × 1020 atoms cm-3. The diffusion coefficient of Ga in Si3N4 at 1100°C was found to be about 5 × 10-17 cm2 s-1. The method, which combines sputtering and mass spectrometry, appears to be applicable for measuring diffusion coefficients in this system down to about 3 × 10-18 cm2 s-1.

The book, containing 60 invited contributions from international first rank specialists, gives a comprehensive "state of science" review of the field and outlines the present trends of theory and experiment as well as technological applications.The most modern aspects of atomic mobility in metals, semi conductors and ionic media are discussed with the aim to unite the physical and chemical approaches and to coordinate the advanced research in different countries.Special attention is given to the behaviour of thermally activated atoms subjected to electrical, thermodynamical and mechanical forces; atom transport under varying pressures; mobility models of liquids, thin films, surfaces and extended defects; isotope effects and ion conduction as means of identifying defect mechanisms.

The diflusivities of 110Ag and of 121Sn in liquid Ga have been measured and compared with recent data for 115Cd and 114In in Ga. The results can be reasonably well expressed by Arrhenius-type relations D = D0 exp{-Q/RT}, with D0=2.2×10-4cm2/s, @ = 1.68 kcal/mole for Ag, and D0=1.6×10-4, Q = 1.49 for Sn. At temperatures above some 380 ° K the diffusion coefficients of Ag, Cd and In in gallium are practically equal, while that of Sn lies about 10% lower. Even at the lowest temperatures the D-values of the different tracers vary by less than 10% from a mean. The low temperature points appear to fall somewhat below the best straight lines in the D vs T diagram. No obvious dependence on valency is discerned; the only reasonable systematics implied by the behaviour of the four elements of period 5 is the inverse root dependence on tracer mass.

In studies of F concentrations in apatite crystals by means of secondary ion micro-analysis, it is found that even in a sample with a known and constant F/Ca ratio the recorded ratios of the F and Ca secondary ion currents can vary widely, depending on the experimental conditions of primary bombardment. An attempt has been to explain this behaviour and to devise a way to obtain quantitative atomic F to Ca ratios independent on measuring conditions. Simultaneous recording of the mass peaks of F+, Ca+ and another matrix ion (P+ or C++) appears to offer a solution of the reproducibility problem. This is demonstrated by ion probe measurements under varied conditions in three groups of materials where the F concentrations had previously been determined by macroscopic methods: apatite crystals with about 3% F, whale teeth of about 10-1 % F, and human enamel ob about 10-2 % F.