Flammability and Consequence Analysis for MCU Waste Tanks

摘要

The Savannah River Site of Department of Energy will use the new Modular Caustic Side Solvent Extraction Unit (MCU) to process the waste stream by removing/reducing Cs-137 using Caustic Side Solvent Extraction (CSSX) technology. The CSSX technology utilizes multicomponent organic solvent and annular centrifugal contactors to extract Cs-137 from waste salt solution. Due to the radiolysis of the aqueous nuclear wastes, hydrogen generation is expected in the MCU holding tanks. The hydrogen from radiolysis and the vapor from the organic component of the solvent, Isopar-L, may form a composite flammable gas mixture, resulting in a shorter time to flammability than that of a pure hydrogen environment. It has been found that the time-to-Lower Flammability Limit (LFL) and stoichiometric concentration (SC) vary greatly from tank to tank, and could be decreased significantly by the presence of the Isopar-L. However, neither the deflagration nor the detonation event would challenge the Evaluation Guideline for any of the tanks at any liquid level.