Thermal analysis of a spent fuel cask in different transport conditions

摘要

Like all industries, the generation of electricity from Nuclear Power Plant produces wastes to be managed. Spent fuel element casks used for transport of nuclear materials must be designed according to rigorous acceptance criteria and standards requirements, e.g. International Atomic Energy Agency ones, in order to provide protection to people and environment against radiation exposure. The aim of this work was the evaluation of the integrity of spent fuel cask under both normal and accident transport conditions, such as impact (9 m drop impact event onto a flat, essentially unyielding, horizontal surface, in the most damaging orientation) and rigorous fire events (full exposure to an engulfing fire for 30 min (fire test) or to an environment at 800 ℃ temperature for a numerical simulation or for a furnace test). Using the finite element code ANSYS both steady-state and transient thermal analyses were carried out to determine the maximum fuel temperature and the temperatures behaviour into the cask, considering all the heat transfer modes between the cask and the external environment as well as inside the cask itself. Moreover, both wet and dry fuel storage inside the cavity of the body were analyzed. The obtained results, used for the new licensing approval by the Italian competent Authority of the cask for PWR spent fuel transport, are discussed.