Quantifying conservatism of performance assessment calculations by sorption model reduction: case study on near field Cs migration in Callovo-Oxfordian Clay

Eef Weetjens, Evelien Martens, Diederik Jacques

Research outputpeer-review


Implementation of full thermodynamic models in performance assessment (PA) calculations (large domain and very large timescales) is practically unfeasible due to excessive computational times. The complex competitive sorption processes of radionuclides are often simplified. In this poster presentation, such simple sorption models (i.e. linear Kd and Langmuir isotherms) were compared with more complex thermodynamic models for a reduced geometry and relatively short timescales (compared to traditional PA calculations). Within the context of a safety case the value of this study is twofold. Primarily, it provides support information on how to choose adequate parameter values in a consistent simplified analysis for compliance with safety criteria. For the cases studied in this paper it became clear that a linear model is sufficient to represent sorption, but a proper choice of the Kd values is critical. Secondly, the comparison of results from these compliance calculations with more realistic analyses demonstrates quantitatively the safety margin implicitly present in PA calculations through model abstraction.
Original languageEnglish
Title of host publicationScientific Basis for Nuclear Waste Management XXXIII. Symposium Proceedings. Volume 1193
Place of PublicationWarrendale, PA, United States
StatePublished - Dec 2009
Event33rd International Symposium "Scientific Basis for Nuclear Waste Management". MRS - V.G. Khlopin Radium Institute, St. Petersburg
Duration: 24 May 200929 May 2009

Publication series

NameMaterials Research Society proceedings
NumberVolume 1193


Conference33rd International Symposium "Scientific Basis for Nuclear Waste Management". MRS
Country/TerritoryRussian Federation
CitySt. Petersburg

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