TY - GEN
T1 - Quantifying conservatism of performance assessment calculations by sorption model reduction: case study on near field Cs migration in Callovo-Oxfordian Clay
AU - Weetjens, Eef
AU - Martens, Evelien
AU - Jacques, Diederik
N1 - Score = 3
PY - 2009/12
Y1 - 2009/12
N2 - 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 paper, 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.
AB - 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 paper, 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.
KW - Sorption processes
KW - Performance assessment
KW - Coupled reactive transport
KW - Benchmarking
KW - HLW
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/ezp_103925
UR - http://knowledgecentre.sckcen.be/so2/bibref/6756
U2 - 10.1557/proc-1193-381
DO - 10.1557/proc-1193-381
M3 - In-proceedings paper
SN - 978-1-60511-166-7
VL - 1193
T3 - Materials Research Society proceedings
SP - 381
EP - 388
BT - Scientific Basis for Nuclear Waste Management XXXIII
PB - MRS - Materials Research Society
CY - Warrendale, PA, United States
T2 - 33rd International Symposium "Scientific Basis for Nuclear Waste Management". MRS
Y2 - 24 May 2009 through 29 May 2009
ER -