105K East NLOP sludge is an exceptionally benign environment with respect to producing large volumes of hydrogen quickly. In fact, should the uranium metal-water reaction become the dominant reaction for production of hydrogen, only 96 liters of hydrogen gas per m(sup 3) of sludge can be produced before the uranium metal in the sludge is consumed by the reaction. Accordingly, in an LDC containing 2.5 m(sup 3) of sludge, only 240 liters of hydrogen can be produced from the uranium-metal-water reaction. One of the conservatisms applied in this model is that the consumption of uranium metal in the reaction is not considered. The only flammable gas of interest in the calculation is hydrogen because the LDC will be vented through HEPA-type filters making it impossible to exclude aid-oxygen from reaching the interior of the LDC. Accordingly, it is assumed that sufficient oxygen to support combustion is always present in the headspace of the LDC. Two hydrogen limits are examined: (1) The Lower Flammability Limit (LFL) for hydrogen when argon is initially used as the cover gas. Since the LDC will be vented through two 2 inch ports fitted with HEPA-type filters, air will enter the LDC, diluting and eventually replacing the argon cover gas by: (1) Barometric breathing of the LDC during storage prior to processing. (2) Breathing by thermal expansion and contraction of the headspace gases during and following the transportation process. (3) Diffusion of air through the HEPA-type filtered vents during storage and processing. The LFL for hydrogen in an argon-lair mixture is the same as the LFL for hydrogen when air is the only cover gas in the LDC headspace (4%). Regardless of the exact mechanism for diluting and eventually replacing the argon with air, the headspace of a vented LDC will be diluted and will eventually contain only air. When 25% air (5% oxygen) is present, flammability is possible. Accordingly, 4% (the bounding value) will be used as the LFL for hydrogen in all calculations. The limit for hydrogen for the transportation window calculations (5%), (i.e., the normal transportation time shall not exceed 1/2 the time for hydrogen to reach 5% in any void space of the shipping container). Unlike the four case methodology used in SNF-18133, and the three case methodology used in the NLOP Addendum to SNF-18133 Revision 0, this analysis presents only the analysis necessary to establish the Safety Basis for LDCs filled with 105K East North Loadout Pit sludge using the normal (flow-through fill) method and the alternate (batch fill) method for two storage/processing locations: storage and processing at Building 325 or storage and processing at T Plant.
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