Architecture and management of a geological repository - Andra

11 – Operational SafetyTable 11.7.2Estimations of the deformations undergone by the packages at the end of the fallon the shock absorberPackage typesB (B2.1)C (CSD-V)CU1 (bareassemblies)CU1 (assembliesin canister)LocationPrimarypackagePrimarypackageSquarecompartmentof thedisposalpackagecontainingfuel assemblyCylindricalcanistercontainingthe fuelassemblyMaximumdeformation(%)ACV(%)25.9 350.3 351.2 2617.4 40Surface forwhich thedeformationexceeds ACVNo overextensionisobserved forthe varioustypes ofpackages.Theirenvelopewould not bebrokenThe results obtained from the simulation studies underline the advantage of installing in the packagetransfer shaft a fall shock absorber. This absorber should allow preventing the breakage of the metallicenvelope of the transfer transfer cask in case the cage falls.Inside this transfer cask, first estimations tend to show that the C waste primary packages, as well asthe tubes or claddings containing spent fuel should resist the shock without breaking. Regarding the Bwaste primary packages, a damaging of some of the most fragile packages (such as the type B2packages) can’t be completely excluded.11.7.2 Assessment of the radiological consequences of a cage falling in a shaftBy taking into consideration the results obtained from the studies on the mechanical consequences of acage fall, it could be considered that there is no loss of containment of radioactive materials during thetransfer of packages in a shaft.However, because of the uncertainities on how the fall in a shaft takes place and the definition of themoving body, scenarios of a release of radioactive materials were imagined in order to estimate theassociated radiological risk [107].11.7.2.1 Scenarios of a release of radioactive materialsThe assumption is made of the transfer transfer cask being opened, the disposal package being broken,and the primary package being broken, which would lead to a release of radioactive materials insuspension in the shaft atmosphere and rejected into the environment. The studied packages are thosewhich have the most penalising radiological content within each category. Thus, the B5 package (Bwaste), the C3 package (C wastes) and the CU1 package (for spent fuels) are retained.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM475/495