Supporting Rock Fall Calculation for Drift Degradation: Quantification of Uncertainties

The purpose of this calculation is to quantify previously unquantified uncertainties associated with the Drift Degradation Analysis (BSC 2001b). The results from this calculation will support the development of a technical report to document supplemental science and performance analyses. This calculation has been developed according to the guidance provided by the ''Technical Work Plan for EBS Department Modeling FY 01 Work Activities'' (BSC 2001a). The specific objective of this calculation is to perform sensitivity studies to assess the impact of the following parameters on rock fall results: (1) parameter M, a multiplier of fracture trace lengths sampled from field data; (2) Terzaghi correction factor for subhorizontal fractures; and (3) number of Monte Carlo simulations. The scope of this calculation includes using the fracture data inputs from the ''Drift Degradation Analysis'' (BSC 2001b) as input to the Discrete Region Key Block Analysis (DRKBA) numerical code. Outputs from this program includes the expected quantities and size distributions of failed rock blocks. This calculation is applicable to unsupported drifts without backfill. This calculation is associated with the engineering and performance analysis activities of the Engineered Barrier System Department, and was developed in accordance with AP-3.12Q, ''Calculations''