In this paper, a storage cell for the high level radioactive wastes is studied in order to identify and demonstrate the coupled phenomena evolving in the high level wasts (HLW) storage. According to the various important processes in the storage structures, special attention is paid on the coupling corrosion/strain processes. Due to the arrival of water from the geological formation, the metallic components will be corroded. As a result, its mechanical resistances reduce and an additional volume will be generated with the progression of corrosion. In the calculations, different materials are taken into account in the numerical simulations: argillite, steel and air. Based on the experimental investigations, different constitutive models are applied to every material. These numerical calculations allow us to obtain some quantitative results describing the mechanical behaviour and coupling thermo-hydromechanical processes for a short-and long-term in the storage cell.
In the framework of feasibility study of underground storage for high level wastes (HLW), some argillite formations are considered as the geological barrier for disposal of radioactive wasters by several countries (Belgium, France, Swiss etc). In addition, various experiments (in situ and in laboratory) have been performed in order to study the coupled Chemo-Thermo- Hydraulic-Mechanical processes due to the excavation, ventilation, subsequent backfilling/sealing, corrosion of metal components and heat release from the radioactive wasters. These phenomena will occur in the storage structures and the geologic barrier for a short/very long period of time. Especially for the High-Level Wasters, due to the important increase of temperature released by the waster packages, the behaviour of geological barrier is strongly perturbed.
The facts which supported the design choices for the HLW are primarily linked to managing the heat given off by the waste, creating a favorable physical and chemical environment and controlling hydraulic phenomena. In addition, due to the reversible management of the wastes packages, a specific set of principles governs choice of materials, their durability and long-term behaviour. In view of this, metallic materials, whose behaviour at temperature is better understood over time, are perfected as over-pack which protects the primary waste package, prevents water contacting the glass and guaranties the reversibility of waste packages. In the underground radioactive wastes storage, due to the arrival of water from the geological formation, the metallic components will be corroded, by step, with a decrease of mechanical resistance and a generated additional volume. The geometry of the studied storage cell is presented in the figure 1.
(Figure in full paper)
This paper consists to simulate the evolution of mechanical behavior of the interface between steel and rock. Different materials are taken into account in the numerical simulations: argillite, steel and air. Based on the experimental investigations, different constitutive models are applied to every material. These numerical calculations allow us to obtain some quantitative results describing the mechanical behaviour and coupling thermo-hydromechanical processes for a short-and long-term in the storage cell.
Based on the experimental investigation realized by different ANDRA's partners.
