Thermophysical properties of uo2 and simfuel - simulated high-burnup fuel

Résumé du livre

Within the canadian nuclear fuel waste management program, aecl research is evaluating the concept of safe disposal of nuclear fuel waste in a sealed vault constructed at a depth of 500 to 1000 m in the plutonic rock of the canadian shield. as part of the geoscience research program, aecl has constructed an underground research laboratory (url) in previously undistrubed granitic rock. the mine-by experiment is one of the url experiments designed to improve our understanding of rock mass behaviour around an underground opening. this report introduces a simple approach to estimating the change in the material properties of the rock surrounding an underground opening using a finite-element technique and hoek-brown initial yield criteria. in this method, the first step is to solve for the stresses in a homogeneous elastic medium with constant young's modulus. the output principal stresses are then compared with the initial hoek-brown yield stress value. wherever the major stress value at an element exceeds the yield stress, the young's modulus is reduced. rerunning the problem with the new distribution of young's moduls provides another stress field. the stress comparison and reduction of young's modulus are repeated successively until the stress state everywhere in the model lies within the yield surface. the approach has been used to model the mine-by experiment. the model calculates significant changes in the young's modulus in the high-stress areas immediately surrounding deep underground excavations in hard rock. the stress changes and displacements are presented at the designed locations of the strain cells and extensometers respectively.