A numerical study on temperature variation of bentonite buffer considering thermal property change by density

Abstract

A buffer in the geological disposal system minimizes groundwater inflow from the surrounding rock and protects the disposed high-level waste (HLW) against any mechanical impact. As decay heat of a spent fuel causes temperature variation in the buffer that affects the mechanical performance of the system, an accurate estimation of the temperature variation is substantial. The temperature variation is affected by thermal and material properties of the system including thermal conductivity, density and specific heat capacity of the buffer. However, while studies considering the effect of thermal conductivity on the temperature variation of the buffer have been conducted, the influence of density and specific heat capacity change by the temperature variation has not been investigated properly. Therefore, in this study, the temperature change in the buffer caused by the variation of thermal properties was investigated through a numerical study which is based on the finite element method (FEM).