Near-Field analysis in the safety assessments for licensing of two rock cavern repositories for low and medium level waste

Repositories for low and medium level reactor waste from the Finnish nuclear power plants will be constructed in the bedrock of the power plant sites, at the depths of 50-125 meters. Preliminary Safety Analysis Reports (PSARs) have been submitted to the regulatory authorities in 1986 and excavation of the repositories is planned to be started in 1988. In the safety analysises several scenarios were considered in analysing release of radionuclides from the repositories into the bedrock. The results of the near-field analysises show that the multibarrier repository concepts consisting of conditioned waste, concrete barriers and crushed rock backfilling constitute compatible systems which effectively retard most radionuclides within the repository