COMPARISON OF VERTICAL AND HORIZONTAL DEPOSITION HOLE CONCEPT FOR DISPOSAL OF RADIOACTIVE-WASTE BASED ON ROCK MECHANICAL IN-SITU STRESS-STRENGTH ANALYSES

In Finland, a spent fuel repository is being planned in hard, crystall ine rock to the depth of 300-800 m. The repository will consist of par allel deposition tunnels which are interconnected by a central tunnel. The spent fuel canisters will be placed in holes drilled according to the tunnel floor-vertical deposition hole concept or in the tunnel wa ll-horizontal deposition hole concept. Based on the numerical stress-s trength analyses, both concepts are found to be feasible. However, whe n the maximum horizontal stress is perpendicular to the axis of the de position hole, the rock in the vicinity of the horizontal deposition h ole seems to have more stable behavior than in the case of the vertica l deposition hole. (C) 1998 Elsevier Science B.V. All rights reserved.