Preliminary and Scoping Analysis for Uncertainty of HLW Geologic Repository Performance with Multiple Canister Repository Model by Earth Simulator

Abstract

An uncertainty analysis of repository performance has been made by the VR code, which incorporates interference effects of multiple canisters in a repository. A problem of the previous study with the VR code is that the number of connected canisters was determined arbitrarily. In this study, first, the probability distribution functions for the number of canisters connected by the flow-bearing fracture clusters have been determined by the FFDF code, and then uncertainty associated with the peak fractional release rate of ²³⁷Np to the far field resulting from uncertainties with the buffer sorption coefficient, solubility, and the number of connected canisters has been numerically evaluated by the Latin-Hypercube Sampling method. The effects of uncertainty with the total number of connected canisters become less important as the number increases because the radionuclide concentration saturates in downstream compartments. Uncertainty with the buffer sorption and solubility shows an important contribution to that with the nuclide release rate.

KEYWORDS:

• high-level radioactive waste
• repository performance assessment
• uncertainty analysis
• Latin-Hypercube Sampling
• compartment model
• mass transport
• Earth Simulator