Parameter sensitivity study in the thermal analysis of the geological disposal repository of high-level waste in China

A simplified thermal model of geological disposal repository of high-level waste (HLW) in China is generated. Sixteen key parameters having impact on the temperature field of geological disposal repository, including thermal, geometric and time parameters, are carefully selected. Peak temperature of inner surface of the bentonite, which is related to the temperature criterion for thermal design calculation of the geological disposal repository of HLW, is treated as the object temperature in the parameter sensitivity analysis. In the analysis, sensitivity degree is classified as three categories: high, medium and low. The research reveals that the following four parameters are of high sensitivity degree: conductivity of the bentonite; thickness of the bentonite; conductivity of the host rock; interim storage time of HLW. Some conclusions are drawn from the analysis: in the design of geological disposal repository of HLW, we should try to obtain accurate conductivity of bentonite and host rock, the test results must be carefully treated to ensure the appropriate input in the design calculation, the thickness of bentonite may be reduced under the circumstances that the bentonite performs well in the engineered barrier system; more than 20 years of the interim storage time of HLW in China is estimated based on the simplified thermal model. The sensitivity study in the paper is the preliminary work in the conceptual design of geological disposal repository of HLW in China, which plays an important role in the conceptual design, and could provide the basis for the more comprehensive design and analysis in the near future. (authors)