An uncertainty analysis has been made by using the multiple-canister model, VR, for performance assessment for the high-level radioactive waste repository. However in the previous VR calculations, the number of connected canisters in the same water stream was determined arbitrary. In this study, the uncertainty resulting from fracture networks in host rock has been taken into account by applying the probability distribution function of the numbers of connected canisters by a fracture cluster obtained by the FFDF code. The release rate of ^<237>Np from a hypothetical repository model containing 100 canisters has been evaluated by using the VR code resulting from variations of the number of connected canisters.