Identification of significant parameters through sensitivity analysis in biosphere assessment of geological disposal

Radiation doses to human beings are calculated by modeling the radionuclide migration processes and the exposure pathways at surface environment in the biosphere assessment of geological disposal. A great effort is necessary when all of the biosphere parameters need to be collected at the actual surface environment of any proposed repository, because a great number of biosphere parameters, such as element-specific parameters, parameters specific to the surface environment or human behavior, are used in the biosphere assessment. Therefore, it is helpful to identify the biosphere parameters that should be collected at the actual environment in advance. For this purpose, the following approaches were developed in this study: (1) Extraction of the significant biosphere parameters through sensitivity analysis including estimation of the influences of variation of element-specific parameters (e.g. soil-to-plant transfer factors, concentration coefficients to animal products) on flux-to-dose conversion factors. (2) Checking the data sources of the significant biosphere parameters on the present dataset. (3) Making the priority list in future data acquisition. So far, steps (1) and (2) have been done, therefore this report summarizes the results obtained from these steps. (author)