RESPONSE OF A RAIL CASK TO LONG EXPOSURES OF SMALL AND OFFSET POOL FIRES

Through the use of computational fluid dynamics and the finite element method the effects of long exposures of a rail cask for the transportation of spent nuclear fuel to several different pool fire configurations are presented in this paper. For risk assessments, fires other than fully engulfing pool fires specified in regulations are also considered. For example, small rectangular pool fires with durations of more than 30 minutes may be less severe than the regulatory fire, but could be more likely to occur. Better understanding of such fires will lead to improved accuracy in transportation risk studies. For this paper, the cask is placed on the ground at different locations relative to the center of the fire. The three-dimensional Container Analysis Fire Environment (CAFE-3D) and PATRAN/Thermal computer codes are used to assess the effects on the cask of small, long duration fires that do not fully engulf the cask. The purpose of this paper is to compare the temperature response at two critical locations, the seal region and the fuel region, of a steel-leadsteel rail cask when it is exposed to several configurations of sub-regulatory size fires. Results are presented in a format useful to risk analysts.