Biosphere modelling for the assessment of radioactive waste repositories; the development of a common basis by the BIOMOVS II reference biospheres working group

Performance criteria for radioactive waste repositories are often expressed in terms of dose or risk. The characteristics of biosphere modelling for p erformance assessment are that: (a) potential release occurs in the distant future, (b) reliable predictions of human behaviour at the time of release are impracticable, and (c) the biosphere is not considered to be a barrier as the geosphere and the engineered barriers. For these and other reasons, differences have arisen in the approaches to biosphere modelling for repos itory dose and risk assessment. The BIOMOVS II Reference Biospheres Working Group has developed (a) a recommended methodology for biosphere model deve lopment, (b) a structured list of features, events and processes (FEPs) whi ch the model should describe, and (c) an illustrative example of the recomm ended methodology. The Working Group has successfully tested the Interactio n Matrix (or Rock Engineering Systems, RES) approach for developing concept ual models. The BIOMOVS II Working Groups on Reference Biospheres and Compl ementary Studies have laid the basis for considerable harmonisation in appr oaches to biosphere modelling of long term radionuclide releases. (C) 1998 Elsevier Science Ltd. All rights reserved.