Hybrid heat pipe module for dry cask with enhanced cooling for extended storage of spent nuclear fuel

Abstract

Hybrid heat pipe, which is a combination of heat pipe and control rod takes a role of both criticality control and passive decay heat removal for dry cask. Hybrid heat pipe module by integrating canister lid with each rod was introduced as updated version of hybrid heat pipe-integrated dry cask, called UCAN. In this paper, recent design work of UCAN considering all functional requirements of dry storage facilities such as containment, radiation shielding, criticality control and thermal management was discussed. In terms of decay heat removal of dry cask, full scale UCAN and single hybrid heat pipe was analyzed by means of CFD simulation using ANSYS-CFX. As a result, hybrid heat pipe has 902.8 W heat removal capacity in normal dry storage condition for dry cask having 21 PWR spent nuclear fuel assemblies. Considering working principle and unique geometry of hybrid heat pipe, enhancement of maximum heat transfer capacity has been currently under developed.