Corrosion assessment for spent nuclear fuel disposal in crystalline rock,using variant cases of hydrogeological modeling

This paper presents a corrosion assessment of copper spent nuclear fuel disposal canisters in crystalline rock,using hydrogeological modeling.A simplified approach is considered,to avoid complex and time-consuming computer simulations.This simplified case is presented as a base case,with changes in the hydrogeological parameters presented as variant cases.The results show that in Taiwan’s base case,decreasing the hydraulic conductivity of the rock or decreasing the hydraulic conductivity of dikes results in a shorter transport path for sulfide and an increase in corrosion depth.However,the estimated canister failure time is still over one million years in the variant cases.

Modeling of the mechano-electrochemical effect at corrosion defect with varied inclinations on oil/gas pipelines

A 3-dimensional finite element model was built to determine the effect of inclination angle of a corro sion defect on local mechano-electrochemical(M-E)effect in a simulated soil solution.Because of the high effect of the defect inclination angle on the M-E effect,when the inclination angle is 0°(i.e.,the primary axis of the defect parallel to the longitudinal direction of the pipe),the greate st stress concentration level at the defect can be observed,which is associated with the lowest corrosion potential,the greatest anodic current density and the most serious accelerated localized corrosion.When the inclination angle is 90°,the stress concentration level reduces and the corrosion potential becomes less negative,accompanying with the decreased anodic/cathodic current densities.Besides,when the ratio(r_(ca))of the primary axial length of the defect to its secondary axial length is 1,the defect inclination does not affect the stress and the electrochemical corrosion rate at the defect.With the increase of r_(ca),the effect of the defect inclination angle is more apparent.