Abstract
This thesis investigated three-dimensional steady state thermal analysis of the High Capacity Dry Storage System (HCDSS) developed by INER. As our first step, we looked into the sensitivity analysis of thermal conductivities of various materials used in HCDSS. We determined the effective thermal resistances for main components in the system analytically. During the transfer cask mode (TFR), the major contributors of thermal resistances are from sleeves group, supporter, the air gap between transportable Storage Canister (TSC) and transfer cask, and neutron shield. For vertical concrete cask mode (VCC), the additional thermal resistances are air channel, and air gap between the concrete cask and add-on shield. Based on such studies, CFD code such as FLUENT 6.12.0 was then adopted for design analysis on heat transfer improvements. The increase of air channel emissivity (from 0.36 to 0.8) could effectively reduce the maximum temperature bye 5 to 6°C inside the canister. We have also proposed to extend the air gap between the concrete cask and add-on shield through the lids at the top and the bottom. This design change enhances the passive heat removal in natural convection, and a drop of 9°C is observed for the canister outer wall temperature. It is important to reduce the maximum temperatures in the system in order to ensure the safety of the system and ample time of operation before any material failure takes place.