Development of filling material for disposal of high level radioactive wastes

The shafts and tunnels of repositories for disposing high level radioactive wastes have to be filled with suitable backfill material, because it is possible that they are the shortest way for radioactive nuclide to migrate from repositories to surface. The disposal pits must also be filled with good buffer material. It was studied which factors are effective for qualities of filling material. Then techniques of backfilling were tested in a small scale compaction test. Full scale buffer materials were producted preliminaly, and they were verified to be not uneven and irregular. (author)