Depleted Uranium Dioxide Powder Flow Through Very Small Openings

Release of plutonium dioxide from a breached shipping container was simulated using depleted uranium dioxide. Microgram quantities of the powder were carried by pressurized air through very small openings in a vessel approximately the same dimensions as a shipping container. Powder transmission was measured as a function of upstream pressure above and below the static powder level. Controlling parameters for the powder transmission were the cross-sectional area of the opening, opening characteristics, i.e., orifice or capillary, and chamber pressure. After a decision on leak location and configuration, powder leakage can be estimated using the relationship ln(A√P), where A is the area and P is the gauge pressure. Given a once-a-month event rate, expected maximum powder transmitted per event through a 38-µm opening by 6895-kPa (1000-psig) pressure would be 287 µg for a leak below the static and 46 µg above. Average values would be 11% of this maximum.