Evaluation of mechanical effects of the fault movement on the engineered barrier system - 16269

Experiments and numerical analyses have been conducted to investigate the consequences of an active fault crosscutting the engineered barrier system (EBS) of a high-level radioactive waste (HLW) repository. Experiments were performed using laboratory simulation test equipment at a scale of 1:20, which can simulate the chosen shear displacements of 80 % and 140 % of the buffer thickness, and the chosen shear rates of 0.1 m/s, 0.05 m/s and 0.01 m/s. The experiments have so far demonstrated that the metal overpack will be rotated, but not breached, due to the plasticity of the surrounding bentonite buffer. The total pressure on the bentonite buffer increases with an increase in the shear rate. Numerical analyses were carried out using a finite element method assuming the constitutive model of modified Cam-clay, which was used to assess elasto-plastic behavior of the bentonite buffer. (authors)