A critical Review of the sections in The Main Report of the SR Can project (SKB TR-06-09) relating to the containment performance of the KBS3 canister

The sections of the Main Report of the SR-Can project related to containment performance of the KBS3 canister have been studied in conjunction with the background reports which it cites. The study has taken the form of a critical review of the safety case related to containment by the canister. The report acknowledges that further work is required and is in progress. The cases of acceptance criteria for defects in the insert, creep relaxation following rock shear and NDE procedures for the insert and the copper shell are cited. Useful tools have been developed for deterministic analysis of the response of the canister to isostatic pressure and to rock shear. A probabilistic tool has been developed in order to assess the sensitivity of the canister to failure as a result of material property and manufacturing quality variations or variations in the expected environmental conditions. Much has been learned by the application of these tools to date. Unfortunately the mean mechanical properties for copper and cast iron which were used were inappropriate. They were too fast for the isostatic load case and too slow for the rock shear case. In addition the statistics related to the properties of the cast iron were inadequate. The sensitivities of the predictions to the standard deviations in the mechanical properties indicate that care must be taken to provide reliable data for variations in mechanical properties both within and between casts for the insert. Both analyses need to be repeated using better data. Some refinement of the models may be appropriate, such allowance for separation of the copper and the bentonite for the isostatic pressure case and application of rate sensitivity to the material models for both cases. It is also necessary to extend the rock shear case to test for sensitivity to manufacturing and material property variations