A model for assessing the radiological impacts of deep-sea disposal of radioactive waste

A model for the assessment of impacts due to deep-sea disposal of radioactive waste has been developed in France. It is described in detail in Part I of this paper. Part III of the paper intercompares the results of a benchmark problem computed by the submodel on marine environment transfer given in Part I and similar models developed in UK by MAFF-NRPB and in US by TASC for SDP. These models are of compartment type. In general, the CEA, SDP and MAFF/NRPB results are consistent for long lived, poorly sorbed nuclides (e.g 129 I). The activities are somewhat different for 137 Cs (due to its short half life) and 239Pu and 230Th (due to their high reactivity with particulates and bottom sediment). Differences in the results have been attributed to two differences in models and data: Interactions between the bottom water and sediment affect the predicted activity in the sediment near site bottom water, and then, play an indirect role in the vertical mixing rate. Differences in the vertical mixing rate and vertical mixing time affect the activity in surface-water boxes for strongly sorbed and short half-lived nuclides