Incertitudes liées au calcul de dose annuelle, le rôle des données d’entrées

¹ ANDRA, 1–7 rue Jean-Monnet 92298 Châtenay-Malabry cedex
² ANDRA, CSA, BP 7, 10200 Soulaines d’huys

Abstract

Within the regulatory framework, basic nuclear installations have to estimate the annual radiological impact. This is of particular importance for the aquatic pathway, where release fluxes are more important than for the atmospheric pathway. An estimation of uncertainties associated with these calculations have recently become a requirement.

In the case of the Andra Centre Aube disposal facility for low and intermediate, short-lived radioactive waste, the elaboration process for dose estimations is carried out in 3 assessment stages, namely the estimation of:

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  radionuclide release (input data),

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  riverine concentrations,

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  biosphere transfer and related doses to reference groups.

In all cases output uncertainties are used in the next modelling step together with probability distributions for model-specific parameter values.

After a presentation of the contents of the 3 stages, this contribution discusses in detail the estimation of radionuclide releases (input parameters) based on on-site measurements, such as continuous monitoring or laboratory radiochemical analyses.

The characterization of the flow measurements and activities of radionuclides are presented by taking into account every instrumental and analytical contribution and especially the contribution due to the variability of the sample. An additional example for the improvement of uncertainties related to river flow is developed.

Finally, the contribution of the input parameters on the final evaluation of radiological impact for the aquatic pathway is described by presenting limiting factors and elements to be improved.