Abstract
Liquid sodium is used as coolant in Fast Breeder Reactors (FBR). There is a likelyhood of sodium spillage in ambient air in the Steam Generator Building (SGB) of the FBR plant. Due to high chemical reactivity with oxygen, especially at temperatures greater than 573 K, it catches fire very easily. In order to carryout safety related experimental studies for different modes of sodium fires and to develop suitable mathematical models for the assessment of their consequences, an experimental facility (SFEF, Sodium Fire Experimental Facility) is being setup at IGCAR, Kalpakkam. The SFEF is having a 540 m^3 volume experimental hall. Stainless steel liner will be provided on the inside surfaces of experimental hall walls, ceiling and floor. Analysis has been carried out for enclosed sodium pool fire scenarios in SFEF by using sodium pool fire code SOFIRE II, which estimates the thermal transients like pressure rise, gas temperature rise, cell wall temperature rise and sodium burning rate. Though the SOFIRE II is a validated code, it is a lumped model code with respect to heat convection and mass transfer and considers 1-dimensional wall heat conduction by finite difference method. So it predicts the average temperatures of cell wall and gas. The spatial variation and their peak values of these parameters are not obtained by this code. To estimate the local peak temperatures of gas, ceiling/walls and also to check the validity of heat transfer models used in SOFIRE II code for larger volume cells, analysis has also been carried out with the commercial CFD code FLUENT and the results are compared with SOFIRE-II predictions. The peak ceiling temperatures estimated by CFD code are 15 to 20 K higher than the SOFIRE II predicted maximum temperatures.
