UNCERTAINTY STUDY OF TRANSPORT PARAMETERS ON TOTAL SYSTEM PERFORMANCE ASSESSMENT OF A SPENT FUEL REPOSITORY

摘要

The purpose of this study includes (1) to examine the importance of two kinds of parameters in geosphere transportrnanalysis for the repository; and (2) to enhance the understanding for spent fuel disposal facility?s safety and to identify thernmajor sources of uncertainty in the analysis. A preliminary total system performance assessment (TSPA) model was newlyrndeveloped under top-down modeling approach on the GoldSim simulation platform. The model provides the capability torndescribe the fate of radionuclides from spent nuclear fuels stored in a hypothetical repository, considering the confinementrnof engineered barriers, the retardation and water-carry transport in geosphere and biosphere impact. This study exploredrnthe importance of hydrologic parameters and partition coefficients in different pathways of host rock, bentonite, drift backfill,rnexcavation disturbed zones (EDZ), fractures in host rock, and intact granite. In addition, the parameters of hydraulicrnconductivity, hydraulic gradient and aquifer dimensions in a surficial aquifer were studied to understand their sensitivitiesrnon dilution degree of nuclide concentrations and further on the biosphere radioactive impact from spent nuclear fuelrndisposal.