HLW disposal of in vertical deposition holes with cement backfill - pro and contra with regard to long term safety of geological disposal facility
Usage of cement based material as an engineering barrier for HLW is considered. This option has a verity of advantages concerning: effective chemical barrier creation; iron containers corrosion reduction; high gas permeability; the same types of engineering barriers for HLW and ILW in repository; easy handling of cement. The main challenge in cement application is accelerated corrosion rate of vitrified waste matrix and relatively high permeability for low absorbing nuclides like 129I and 36Cl. However, advantages of cement barrier may override its shortcomings concerning Nigenekansky geological disposal facility where compact HLW emplacement is envisaged within deposition holes of 75 m depth with bentonite barrier and 129I and 36Cl content is insignificant.