Drillcon reports successful completion of 12 x 9 m-diameter test holes in 190 Mpa granite at repository 400 m below surface using 1.8 m-diameter Robbins SBM launched vertically from 5 m-diameter access tunnel. Using 170 bar pressure, or 7 t per cutter, and rotational speed of 8 rev/min, penetration rates of 1 m/h were achieved with high accuracy. Spent fuel in copper canisters will now be placed in the holes and the annuli packed with bentonite. The area will be closed off and studied for 10 years before a decision is made to proceed with the 4,000 holes that will be required for permanent storage of Sweden's nuclear waste stockpile. Visit www.drillcon.se April 2000.
