HR: 11:10h
AN: H22B-04    [Abstracts]
TI: Heat Transfer through Rockfall
AU: * Green, R T
EM: rgreen@swri.edu
AF: CNWRA, Southwest Research Institute, 6220 Culebra, San Antonio, TX 78238 United States
AU: Pohle, J
EM: jap2@nrc.gov
AF: Division of High-Level Waste Repository Safety, U.S. Nuclear Regulatory Commission, No. 2 Whiteflint, Washington, DC, 20555 United States
AU: Prikryl, J
EM: jprikryl@swri.edu
AF: CNWRA, Southwest Research Institute, 6220 Culebra, San Antonio, TX 78238 United States
AB: Thermally induced rock stresses at the potential high-level nuclear waste (HLW) repository at Yucca Mountain, Nevada, can degrade the drifts, possibly causing rockfall onto the dripshield overlying the emplaced waste packages. Thermal-hydrological processes will be altered by changes in thermal conductivity, ventilation, radiation, and convection resulting from such rockfalls. Determining the effects of collapse materials on repository performance is difficult because heat and mass transfer through the engineered barrier and highly heterogeneous collapse materials is a complex and coupled process. Measurements and estimates of thermal conductivity of intact rock samples from geologic units at Yucca Mountain are available, but collapsed rock will be a mixture of broken rock and air. The purpose of this investigation is to assess the thermal conductivity of crushed tuff from the Topopah Spring lower lithophysal unit at Yucca Mountain and identify the important heat and mass transfer mechanisms in the collapsed rock for the range of conditions expected at a potential geologic HLW repository. A laboratory apparatus was used to directly measure steady-state bulk thermal conductivity of crushed tuff for a range of temperatures up to 197§C and thermal gradients as large as 990§C/m. Measured thermal conductivities varied from 0.38 to 0.56 W/m-K. In general, thermal conductivity increased with either increased temperature or increased thermal gradient. This abstract is an independent product of the CNWRA and does not necessarily reflect the views or regulatory position of the NRC. The NRC staff views expressed herein are preliminary and do not constitute a final judgement of determination of the matters addressed or the acceptability of a license application for a geologic repository at Yucca Mountain.
DE: 5134 Thermal properties
DE: 5418 Heat flow
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting