A reappraisal of some Cigar Lake issues of importance to performance assessment

The AECL/SKB Cigar Lake Analogue Study was published in 1994. Data from this study, relevant for repository performance assessments, have been reappraised in the light of greater exposure to analogue studies and the development of more realistic models used in performance assessment. Several of the areas proved to have been adequately addressed in the original study, but one of the areas that particularly benefited from the renewed analysis concerned radiolysis. In this case a model for radiolysis was developed and tested, significantly narrowing the gap between calculated and predicted oxidant production. Considerable progress was also made in understanding and modelling the initial formation of the deposit under hydrothermal conditions, and using this conceptual model to evaluate the changes that have subsequently occurred under 'ambient' repository conditions over geological timescales. Moreover, the physical properties of clay as a potential buffer to groundwater flow and radionuclide migration were addressed with some success. 99 refs