MODEL VALIDATION - A SYSTEMIC AND SYSTEMATIC-APPROACH

The term 'validation' is used ubiquitously in association with the mod elling activities of numerous disciplines including social, political, natural, physical sciences, and engineering. There is however, a wide range of definitions which give rise to very different interpretation s of what activities the process involves. Analyses of results from th e present large international effort in modelling radioactive waste di sposal systems illustrate the urgent need to develop a common approach to model validation. Some possible explanations are offered to accoun t for the present state of affairs. We believe that a rigorous approac h to validation must necessarily be based on a thorough understanding and application of the theory of simulation and modelling. The methodo logy developed treats model validation and code verification in a syst emic and systematic fashion. In fact, this approach may be regarded as a comprehensive framework to assess the adequacy of any simulation st udy.