Study plan on biosphere assessment for geological disposal of radioactive waste. 5-year plan for fiscal years 2010-2014

As the biosphere assessment of geological disposal covers an extremely long time period, it is difficult to predict the future human environment and lifestyles. IAEA-TECDOC-1077 addresses that a stylized approach is proposed for selecting critical groups and biospheres in future situations where human behaviour or biosphere conditions cannot be known with any certainty, although it is possible to construct biosphere models based on the characteristics and evolution of the surface environment at the actual site in shorter time period. BIOMASS Methodology is especially effective for treating uncertainty of biosphere in these situations. To address the approaches of biosphere modelling, time period after closure of repository was divided; - period 0 to ca. 102 years post-closure, when evolution of human life style could be described; - approximately 102 years to 104 years post-closure, when major change of hydrological cycle caused by natural phenomena could be described; - beyond 104 years. Critical issues of biosphere modelling with the procedure of safety assessment by OECD/NEA and BIOMASS Methodology were specified through summarising the past progresses in domestic and foreign institutes. Additionally, it is important to develop the procedure of biosphere modelling and database for setting parameters for the use of appropriate information. Based on the critical issues specified, 5-year research plan on biosphere assessment were identified as follows; (1) Development of the methodology for constructing site-specific biosphere models through groundwater flow analysis in surface and near-surface environment and literature survey; (2) Development of biosphere database for setting domestic parameters; (3) Development of methodology for biosphere modelling considering future evolution of surface environment. (author)