[en] Federal regulations require that solid waste contaminated with TRU nuclides > or = to 10 nCi/g be packaged in containers that can be retrieved free of surface contamination for a period of twenty years. At the Savannah River Plant, galvanized 55-gallon steel drums (DOT 17C), with a 90-mil polyethylene liner, are employed as the primary container for most of such waste. A series of tests was designed to verify adequacy of the SRP storage mode. Results after two years are reported for a test in which radiogenic gas composition and pressures were monitored in four typical SRP waste drums and one typical waste culvert. These results indicate that radiogenic gases should not cause breach of containment during storage. All four test drums have exhibited positive internal pressures up to four psig. Pressures have fluctuated considerably. All four drum atmospheres were depleted in oxygen and enriched in hydrogen and CO₂, relative to air. After nearly two years none of the drums contained a flammable mixture of hydrogen and oxygen; however, one drum atmosphere was flammable for a 58-day interval which began 142 days after drum closure. Air in the concrete culvert containing the drums became only slightly pressurized (0.1 psig) and has shown only trace quantities of CO₂ and hydrocarbons