Thermal divider insert and method for spent nuclear fuel cask creating both air inlets and air outlets at the top of the overpack

Abstract

Embodiments of a thermal divider insert for a dry storage, spent nuclear fuel cask are disclosed. The thermal divider insert enables safe storage of the hazardous nuclear material when one or more air inlets have been fully or partially blocked to an extent that insufficient air flows into the air inlets and through the cask for adequate cooling of the hazardous nuclear material. A concrete overpack contains a metal canister with the hazardous nuclear material. The overpack has an inside surface that is spaced from an outer surface of the canister to create an annular region that permits flow of air between the surfaces for cooling the canister. Air inlets near the bottom of the overpack communicate air from an outside into the annular region. Outlet vents near the top of the overpack communicate air from the annular region to the outside. The thermal divider insert extends through a respective outlet vent and into the annular region and establishes two separate and opposite air flows through the respective vent and the annular region when the overpack air inlets have been blocked.