Possible combustion hazards in 3013 plutonium waste container
Are there combustion hazards in plutonium-contaminated waste containers caused by combustible gas generation? Current gas generation models in which the only reaction considered is radiolysis must inevitably predict eventual complete dissociation of any water present into hydrogen and oxygen. Waste prepared for the 3013 container should be less subject to this problem because organic material and most of the absorbed water should have been removed. Depending on the waste form, moisture content, organic content, temperature, and container material, the pressure rise due to gas generation will be bounded by backreactions, recombination of the hydrogen and oxygen, absorption of the oxygen by plutonium oxide, and possibly other chemical reactions. Examination of a variety of food pack waste containers at Los Alamos National Laboratory (LANL) has shown little pressure rise, indeed often subatmospheric pressures. In a few cases large hydrogen concentrations up to 47% mole fraction were observed, but with negligible oxygen content. The only fuel seen in significant quantities was H{sub 2} and, in one case, CO; the only oxidizer seen in significant quantities was O{sub 2}. Considerable work on measuring gas generation is being done at Westinghouse Savannah River Company and LANL. In a mixture of H{sub 2}, O{sub 2}, and other diluent gases, if the hydrogen concentration is below the value at the lean flammability limit, or if the oxygen concentration is below that at the rich flammability limit, a flame will not propagate from an ignition source. Assuming H{sub 2} is the only fuel present in significant quantities, a mixture leaner than the lean limit will get only leaner if mixed with air and is therefore no combustion hazard. However, when a mixture containing large amounts of H{sub 2} is nonflammable because there is insufficient O{sub 2}, there is a hazard. If the mixture should leak into a volume containing O{sub 2}, or the container is opened into the surrounding air, the mixture will pass through the flammable range. There is the possibility of diffusion flame, deflagration, or even detonation. A wise precaution in opening plutonium waste containers is to use a flowing inert atmosphere (e.g., N{sub 2}). If this is not practical, the container can be slightly cracked open, and hydrogen detectors can be used to measure if there are significant amounts of H{sub 2} present.
- Research Organization:
- Sandia National Lab., Albuquerque, NM (US)
- OSTI ID:
- 20005742
- Journal Information:
- Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 81; ISSN 0003-018X; ISSN TANSAO
- Country of Publication:
- United States
- Language:
- English
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