This is one of two papers discussing the findings in an in situ-burial experiment, presently being performed in the Stripa mine in Sweden. The purpose of the experiment is to evaluate the effects of various components in the SKBF/KBS waste storage system on the leaching of the vitreous waste form. Two configurations of glass, canister, overpack and buffer/backfill materials were designed (Figs. 1 and 2). Both configurations were inserted into 56 mm diameter boreholes in the Stripa mine and maintained at 90°C. One of the configurations (Fig. 2) was also kept at ambient temperature, 8°C. In the experiments two glass types were used, ABS 39 and ABS 41 (Table 1). These glasses, developed by Dr. T. Lakatos of the Swedish Glass Research Institute, contain 9% simulated fission products by weight and are compatible with the French AVM process.