Abstract
Packages of the non-standard radioactive waste have been, in present conditions of the Slovak Republic, defined as packages intended to be dispose by the producer and originally not covered by “the limits and conditions” of the Mochovce near surface repository, particularly waste acceptance criteria concerning the form of waste. Wastes cemented directly (homogeneous) to standard concrete containers reinforced by metal fibres (FRCs) or conditioned into 2001 drums before (heterogeneous: drums are inserted into FRCs and the FRCs void spaces are filled by cement mortar) were originally the only acceptable radioactive waste form in Mochovce repository. However, there has been an intention to dispose another, so-called “non-standard” types of waste: large metal pieces of waste transported and placed directly into repository vaults (i.e. cut into dimensions of individual vault). Second types of non-standard waste have been: dewatered spent ion exchange resins and storage tanks bottom sludge in drums, inserted into FRC with subsequent backfilling by cement mortar. Third group of these is represented by incinerator ashes in drums inserted to FRC directly or after compaction, again with subsequent backfilling of FRCs void spaces.
As an answer for this challenge, the ALARA approach has been applied for pre-disposal management optimization of large metal pieces of waste. Four examples of waste arising from the Slovak decommissioned plant A-1 have been evaluated for various options of its management. This step is predominant to achieve a decision concerning disposal of the latter kind of waste. Regarding the disposal of mentioned dewatered waste and incinerator ashes in FRC, a new model has been applied to the assessment of long-term behavior of source term in the repository safety analyses. The new approach is sensitive to the form of waste package on the contrary to the source term model applied heretofore.
