Microscopic Identification of Progressive Fracturing in Granite Under Triaxial and Uniaxial Stress Conditions from Bátaapáti Radwaste Repository

Abstract

The program for the final disposal of low and intermediate level radioactive waste was established by Paks Nuclear Power Plant, Hungary. Preparation of final disposal has been done as part of a national program since 1993. The Central Nuclear Financial Fund and the Public Limited Company for Radioactive Waste Management (PURAM) have been established to coordinate organizations and activities for all tasks in connection, with nuclear waste treatment. The project was started with a geological screening in order to find the most suitable geological formation for a radioactive waste repository. The selected potential host rock is the Mórágy Granite Formation in the south-western part of Hungary, close to the village of Bátaapáti.This paper show and explain the results of an extensive study of the deformation and fracturing of Mórágy granite samples under uniaxial and triaxial loading conditions. In the investigation, the stress fracturing thresholds (crack initiation, crack coalescence and crack damage) were determined using stress-strain and stiffness curves without acoustic emission (AE) detection technique. Crack initiation was found to be best determined by the volumetric strain curve in both uniaxial and triaxial compression tests. As a detailed investigation, a comprehensive petrographical analysis using a petrological microscope was performed to identify the mode of cracking and the characterization of the cracking pattern.

Back-Analysis of Rock Mass Strength at a Radioactive Waste Disposal Site Using Acoustic Emission Monitoring Data and 3D Numerical Modelling

“…Microcracks form or propagate primarily in a direction parallel to the maximum compressive stress. This is evident from the volumetric strain dilation [23], a direct microscopic observation of test samples [24,25], and numerical modelling results [26].…”

Damage Detection Using a Graph-based Adaptive Threshold for Modal Strain Energy and Improved Water Strider Algorithm

“…Even the local damage detection techniques such as radiography or ultrasonic methods are costly and challenging, especially in the mentioned structures. On the contrary, vibration-based techniques, so-called global methods, are more robust against the structures' size and complexity [2,3]. These techniques are upon the idea that sates when damages occur in a structure, its physical properties change and affect its vibrational characteristics such as mode shapes and frequencies [2].…”