In Italy a considerable amount of radioactive wastes has been produced during the about thirty years of nuclear activity. In 1996 began activities for the design of a LLW repository and for a site selection. A near surface LLW Repository based on vault concept is considered, for a national total inventory of around 100,000 cubic meters of conditioned wastes, mostly coming from dismantling of the phased out power stations. A near surface LLW Repository based on vault concept is considered.
The design activity under way includes the Engineered Barrier System (EBS) development and qualification. A cementitious material as backfilling barrier is being considered for waste isolation in a disposal module which would then be emplaced in the disposal unit. The construction material of the module is also under evaluation and qualification.
Possible interaction of the barrier with the chemical environment of the Italian waste inventory has also been identified. This paper describes some of the experimental activity under way for the mix-design identification for the cementitious barrier, along with the results of the first campaign of material characterization.
Different concretes and grouts were investigated with the main aim of assessing the long-term durability of these materials. Preliminary results indicate that crack-free and long-term durable concretes and grouts (300 years) can be manufactured even if exposed to aggressive environments. For the sake of brevity, in this paper the following characteristics only of the concretes will be considered:
- compressive, flexural and tensile strength
- carbonation tests
- chloride diffusion.