A Study on the Temperature Distribution in the Shipping Cask of Spent Nuclear Fuels at LOCA

Abstract

In this paper, the authors studied the temperature distribution in a shipping cask of spent nuclear fuels at LOCA (loss-of-coolant accident) after a failure of the cask. The calculation was made on a model of a uni-axial (in radial direction) thermal transfer. The result shows that the decay heat which cannot be cooled down will cause the temperature to go over 1000°C at the central part of the cask. A very dangerous accident will occur at such a high temperature ; i.e. , the vapor of cesium, a radioactive isotope, will flow out from the cask into air, and the water-metal reaction will produce a great deal of heat and hydrogen. Because of this, the nuclear fuels at the central part will collapse and melt down.