Leaching Behaviour of Ion-Implanted Simulated HLW Glasses and Tentative Prediction of Their Alpha-Recoil Aging
- PDF / 1,163,792 Bytes
- 9 Pages / 417.6 x 639 pts Page_size
- 43 Downloads / 164 Views
Inc.
651
LEACHING BEHAVIOUR OF ION-IMPLANTED SIMULATED HLW GLASSES AND TENTATIVE PREDICTION OF THEIR ALPHA-RECOIL AGING. J.C. DRAN, Y. LANGEVIN, M. MAURETTE, J.C. PETIT, B. VASSENT. Laboratoire Rend Bernas, B.P. N01, 91406 Orsay, France. ABSTRACT The ion implantation-based simulation of a-recoil aging in radwaste glasses has been applied to several simulated HLW glasses. The results are qualitatively described by a new model of leaching for the implanted glasses although several specific features of irradiated surfaces are not clearly understood. This model suggests that for the most likely case of diffusion-controlled corrosion, where the reaction scheme involves several steps (hydration, dissolution of hydrated silica gel, etc...), the kinetics-controlling one would not necessarily be radiation sensitive. Indeed for these more representative glasses, no evidence for a drastic increase in the dissolution rate of the silica gel, induced by ion implantation has been so far detected, whereas the hydration rate seems in some cases more significantly enhanced. However the implications of these observations for the durability of the glasses remain to be assessed. INTRODUCTION Last year we reported on preliminary results of ion implantation-based simulations of a-recoil aging in various glasses, showing that the radiation induced modifications of etchability of implanted glasses markedly depend on the glass composition and the etching conditions in a way which was not clearly understood [1]. Moreover our sampling included only two representative simulated HLW glasses namely SON 69.14.15 C3 prepared at Marcoule and BONI prepared at Ispra. For these two glasses of very close chemical composition, the relative increase of etchabia 2 sodium brine (250g.-I ) at 100'C, for a dose of implanted lead ions of lity 1 in 3 10 cm, was 1 and 50 respectively. These results showed that no drastic radiation effect was detected for the first glass in accordance with the results of actinide doping simulations [21, whereas a significant increase in etchability was inferred for the second. Moreover even for this apparently radiation sensitive glass, an increase of only % 3 was evaluated when using pure H 0 at 100'C 2 as a leachant instead of the sodium brine. These puzzling results lead us to extend this type of study to a wider range of glass compositions and environmental conditions in order to first better understand the behaviour of implanted glasses exposed to aqueous corrosion and second to compare the results obtained by ion implantion to those of actinide doping on a larger number of representative glasses exposed to the same leaching conditions. We will first described the widely variable leaching behaviour of implanted glasses, which is described by a model that considers separately the two classical corrosion regimes in order to assess the specific effect of radiations. We will then concentrate on the particular case of 5 representative simulated radwaste glasses leached in experimental conditions that allow a tentative comparis
Data Loading...
