Development of uncertainty analyses for the transport of radionuclides from a repository for high-level radioactive waste. Stage one

The escape of radionuclides from a repository for high level waste is described by the near field model LCHCAL and the geosphere models GEO1/SU and NUCDIF. These models are used to calculate the radionuclide outflow to the biosphere. The uncertainties in the input parameters to the near field and geosphere models are handled by the uncertainty analysis models PARVAR and SYVAC/SU. The uncertainty analysis models have been tested on two nuclides, 14C and 135Cs, for cases with pure surface sorption and matrix diffusion. In the case of surface sorption five input parameters and for matrix diffusion six input parameters were varied. The results of the uncertainty analyses are presented in the form of histograms, scatter plots, isocontour plots and 3-dimensional plots of the radionuclide release to the biosphere. Also the ten highest maximum release rates and correlation coefficients are presented. (orig.)