A three-dimensional conceptual model of fracture system geometry based on a uniform and isotropic distribution of dim-shaped fractures and a fractal relation between the frequency and dimension of the fractures is developed for the site of the Chalk River Laboratories of Atomic Energy of Canada Limited. The model is applied to site and outcrop scale fracture trace length data and is consistent with the data for trace lengths in the range of 1 to 1000 m. Probabilistic results derived from the model confirm the accuracy of the plotting and interpretation of the in situ data and illustrate the three-dimensional form of the estimated fracture system.
The Chalk River Laboratories (CRL) of Atomic Energy of Canada Limited are located 150 km northwest of Ottawa, on the Ottawa River, and have been an important centre for nuclear research for more than 50 years. In 1995, a referendum held in the town of Deep River indicated public support for assessment of the CRL site relative to the disposal of historic, low level radioactive wastes. The CRL are located within a fractured, granitic rock mass where the most likely pathway for radionuclide transport from a subsurface repository to the biosphere is through an interconnected system of fractures. Methods of predicting radionuclide transport in fractured rock have been developed for the geologic disposal of high level radioactive wastes, and form a defensible basis for the performance assessment of a repository constructed at the CRL site. This paper summarizes progress in developing a conceptual model of the fracture system at the site of the CRL that will be used to predict the distribution and rate of groundwater flow at the site.