Preclosure ventilation is a key design feature of the repository to store high-level nuclear waste at Yucca Mountain. The efficiency of the ventilation to remove heat generated by radionuclide decay from the repository is predicted using a lumped parameter heat transfer analysis that considers thermal radiation, convection, and conduction in the drift and the surrounding rock mass. The sensitivity of the ventilation efficiency to uncertainties in key inputs and design parameters is investigated using a statistical approach known as the Delta Method. The standard deviation (normally distributed) of the ventilation efficiency about the mean of 88.0% is 2.6% for a 600-meter long drift. In addition, the influence of each of the standard deviations of the inputs and design parameters on the mean ventilation efficiency and standard deviation is determined. The results show that the most significant variables in the ventilation heat transfer analysis are the inlet air temperature, the air flow rate, the host rock thermal conductivity (as a function of matrix saturation and specific heat), and the convection heat transfer coefficients.

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