Modeling lithium reactions with steam-air mixtures

The computer code, LITFIRE, was modified to enable it to model lithium interactions with steam-air mixtures. Three groups of accidents were investigated and the results were compared to dry air cases under the same conditions. The first group was performed with the one-cell geometry, simulating a spill on the containment building floor. The second group was performed with the two-cell geometry, simulating a spill inside the plasma chamber (primary cell). The third group was like the second, except that steam was injected into the containment (secondary) cell simulating a steam line leak. The results of all three groups showed that the most important effect of the presence of water vapor was the increased heat transfer to the cell gases, primarily due to the higher gas thermal emissivity. In the one cell case, where the lithium pool was relatively insulated, the higher gas emissivity served to increase the gas temperature and pressure with slight effect on the lithium pool. The maximum predicted lithium pool temperature was approximately 1000deg C. In the two cell cases, the lithium pool was cooled indirectly by the secondary cell gas and the maximum pool temperature was found to be approximately 600deg C. The gas temperature and pressure were changed only slightly while the structural temperatures were reduced below those of the dry air cases. These results indicate that lithium spills inside the plasma torus may be less consequential than has been assumed to date. (orig.)