Thermal-Mechanical Analyses of a Conceptual Repository for Nuclear Fuel Waste Generated at Cernavoda NPP

A series of three-dimensional near-field thermal and thermal-mechanical analyses were performed using ANSYS workbench software for a conceptual repository design for disposal of the nuclear fuel waste generated by Cernavoda Nuclear Power Plant. These analyses were undertaken to refine the estimates produced in the preliminary analyses performed with TEMPROC code, developed in Institute for Nuclear Research Pitesti. The conditions considered in the near-field finite element analyses included an excavated condition under ambient temperature and sealed condition under elevated temperature. From the results of these analyses, it is estimated that a peak container skin temperature of 116°C or a temperature rise of 101.5°C (assuming an ambient temperature of 14.5oC at the repository level) occurs at 25 years after waste emplacement. The region with the highest stress concentration due excavation is found at the invert of the tunnel near the corners. The region with the highest combined thermo-mechanical stresses is also found in the same locations. (author).