Pressure Development in Sealed Containers with Plutonium-bearing Materials

Gas generation by plutonium-bearing materials in sealed containershas been studied. The gas composition and pressure are determinedover periods from months to years. The Pu bearing materialsstudied represent those produced by all of the major processesused by the U.S. Department of Energy (DOE) in the processingof plutonium and include the maximum amount of water (0.5percent by weight) allowed by DOE’s 3013 Standard. Hydrogengeneration is of high interest and the Pu bearing materials can beclassed according to how much hydrogen is generated. Hydrogengeneration by high purity plutonium oxides packaged under conditionstypical for actual 3013 materials is minimal, with very lowgeneration rates and low equilibrium pressures. Materials withchloride salt impurities have much higher hydrogen gas generationrates and result in the highest observed equilibrium hydrogenpressures. Other materials such as those with high metal oxideimpurities generate hydrogen at rates in between these extremes.The fraction of water that is converted to hydrogen gas as equilibriumis approached ranges from 0 percent to 25 percent underconditions typical of materials packaged to the 3013 Standard.Generation of both hydrogen and oxygen occurs when liquid wateris present. The material and moisture conditions that resultin hydrogen and oxygen generation for high-purity plutoniumoxide and chloride salt-bearing plutonium oxide materials havebeen characterized. Other gases that are observed include nitrousoxide, carbon dioxide, carbon monoxide, and methane.