Abstract: A simplified thermal model of geological disposal repository of high-level waste (HLW) in China is generated by the numerical code FLAC3D. 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: 1) 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. 2) thickness of heat spreader and backfill material are of intermediate sensitivity degree. 3) The rest ten parameters are of low sensitivity degree: thermal conductivity and specific heat of vitrified HLW, overpack, heat spread, backfill material, and specific heat of bentonite and host rock. Some conclusions are drawn from the analysis: in the design of geological disposal repository of HLW, accurate conductivity of bentonite and host rock should be obtained, 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.

Key words: high-level waste (HLW), geological disposal repository, thermal analysis, parameter sensitivity study, FLAC3D