Development of the Concrete Cask Storage System for PWR Spent Nuclear Fuel in Korea

Abstract

The concrete cask storage system is under development containing canister loaded with PWR spent nuclear fuel. This storage system consists of dual-purpose canister (DPC), concrete cask, transfer cask and auxiliary equipment. The DPC as a confinement boundary consists of 21 fuel assembly-loaded baskets, canister shell, lid and closure ring. After fuel assemblies are loaded, the canister lid and closure ring are sealed by remote welding. The concrete cask is composed of reinforced concrete with steel-lined shells as a radiation shielding and structural barrier. Sufficient space is provided inside the cask to load canister, and 16 T-shaped channels are attached in radial direction to the surface of inner shell. These channels keep the proper gap between cask body and canister and also reduce the impact load exerted to canister under accident condition. Each 4 of air inlet and outlet ducts is installed at the bottom and top of the cask body, respectively, to cool down passively by natural convection. Inside the air duct, shield grids are provided for shielding purpose, and mesh screens to prevent intrusion of foreign material are installed at the entrance. The thicknesses of cask body and lid are designed to be sufficient to meet the regulatory requirements of radiation shielding. The dimensions of air inlet and outlet ducts are defined to facilitate full natural convection. And shield grids and mesh screen are installed at the entrance of ducts. The DPC and its related components are to abide by the storage requirements of the US NRC 10CFR72 and the standard review plan NUREG-1536 and the domestic transportation requirements.