Design and Siting for Large Diameter Well Type Repositories

RADON enterprises are historically responsible in Russia for institutional waste of low and intermediate activity level. MosNPO RADON is a leading organization for 16 enterprises of RADON system, established in the early 60-s, only 14 from which are now in operation and have about 10% of their repositories available for upcoming waste. Construction of new repositories and selection of new perspective sites is very actual problem for RAW management in Russia now. Traditionally near surface repositories are considered to be acceptable for storage or even disposal of low and intermediate level waste (LILW), which decay to safe level in some hundreds of years. Forty years experience in LILW isolation using near surface repositories at Russian RADON facilities has shown that a lot of operational and natural factors impact on the engineered barriers and may cause failure of the isolation (freezing-thawing cycles, construction works). In addition construction of new old-type repositories requires more area. Since 1997 development and testing of Large Diameter Wells (LDW) as a new type of repositories for low and intermediate level waste is carried out at Zagorsk site. MosNPO RADON specialists developed the LDW construction technology with the aim to use such wells for LILW isolation in moraine clays. The diameter of LDW-type repository may range from 1 to 5 m depending on drilling rig capabilities and performance parameters of host rock. The depth of well (repository) depends on geological parameters and hydro-geological conditions at the site. These features affect on the siting process by additional geological and hydro-geological requirements. In result of preliminary studying of Central Russia two regions were found to be perspective for construction of LDW-type repositories.