FRACTURE MODELS FOR YUCCA MOUNTAIN: REPOSITORY HOST HORIZON

Synthetic fracture models ( a 100 meter cube) of the repository host horizon at Yucca Mountain were created to evaluate tunnel stability and provide a basis for fluid flow studies. Two TBM tunnels, one approximately 7.5 kilometers long and 7.5 meters diameter and one approximately 2.5 kilometers long and 5.5 meters in diameter, provide the input data for the fracture model. Data are obtained from full-periphery geological mapping and detailed line survey along the springlines of the tunnels.

The model is validated by comparison of the synthetic interfracture distance distribution, the synthetic orientation distribution, and the synthetic tracelength distribution with the observed distributions for each of these parameters for each set of fractures for each host horizon. Synthetic full-periphery geologic maps when compared to the observed full-periphery geological maps enhance confidence in the model as they appear to be geologically similar. By conditioning to these parameters the model is closely consistent with the observed data.