Improvement of biosphere assessment methodology for performance assessment of geological disposal facility (II)

Miki, Takahito*; Yoshida, Hideji*; Ikeda, Takao*

This report contains results on study of Geosphere-Biosphere Interface (GBI), development of biosphere assessment model for gaseous and volatile radionuclides, review of biosphere assessment and research on safety indicators. Regarding study of Geosphere-Biosphere Interface (GBI), FEP database for the Geosphere-Biosphere Transitions Zone (GBTZ) were compiled. Furthermore, release scenarios were identified from the FEP database, and review of conservativeness and robustness of the conceptual and mathematical models developed previously by JNC were undertaken. Regarding development of biosphere assessment model for gaseous and volatile radionuclides, the conceptual and mathematical models were developed, and it was confirmed that the impact of the exposure pathway regarding gas release to flux-to-dose conversion factor is small. Regarding review of biosphere assessment data, the parameters which were used on JNC second progress report were reviewed and classified using the biosphere data protocol categories. Furthermore, the data for key parameter(important but poorly characterized parameters) were revised. Regarding research on safety indicator, some kinds of safety indicators, especially for the non-radioactive contaminant and for the non-human biota, are reviewed.