RSC-Programme - Interim Report. Approach and Basis for - Posiva

40Performance targets related to groundwater flow and solute transportPerformance target Target value RationaleInflow to depositionholes should be less thanthe target value.Flow rate arounddeposition hole shouldbe limited.Transport resistance(WL/Q) in the vicinityof the deposition holesshould be high enough.Environment should befavourable for matrixdiffusion and sorption.< 0.1 L/min(corresponding toT ~ 10 -9 …10 -8 m 2 /sfor single fracture)in the order of1 L/year(over width of 1 m)In the order of fewthousands of yearsper metreEnsure buffer and backfill functionality andprovide transport resistance.Applies only for unsaturated conditions.Ensure EBS functionality and limitradionuclide transport.Applies only for saturated conditions.Limit transport of corroding agents andRNs.Limit RN transport.Performance targets related to thermomechanical stabilityPerformance target Target value RationaleRock shear in depositionhole should be less thanthe target value.Mechanical disturbances(EDZ, spalling) aroundexcavations should belimited.Sufficient heat transfercapability.< 10 cm* Avoid canister failure due to rock shear indeposition hole.Related to hydraulic properties. Ensurebuffer functionality and limit RN transport.Impact can be mitigated by design andproper excavation methods.To avoid an increase in the buffer andcanister temperatures to an unacceptablelevel. Related to tunnel and canisterspacing.* The target value is based on the work by Börgesson et al. (2004). It is noted that based on ongoingstudies the target value may be changed.