Material Properties of Plutonium-bearing Oxides Stored in Stainless Steel Containers

The destructive examination of 3013 containers after storageis part of the Surveillance and Monitoring Program based onthe U.S. Department of Energy’s standard for long-term storageof Pu (DOE-STD-3013). The stored, Pu-bearing materialsmay contain alkali halide contamination that varies fromtrace amounts of salt to about 50 weight percent, with smallerfractions of other compounds and oxides. These materials werecharacterized prior to packaging, and surveillance characterizationsare conducted to determine the behavior of the materialsduring long-term storage.The surveillance characterization results are generally in agreementwith the pre-surveillance data. The predominant phases identifiedby X-ray diffraction are in agreement with the expected phaseassemblages of the as-received materials. The measured densitiesare in reasonable agreement with the expected densities of materialscontaining the fraction of salts and actinide oxide specifiedby the pre-surveillance data. The radiochemical results are generallyin good agreement with the pre-surveillance data for mixturescontaining “weapons grade” Pu (nominally 94 percent 239Pu and6 percent 240Pu); however, the inductively coupled plasma-massspectroscopy results from the present investigation generally producelower concentrations of Pu than the pre-surveillance analyses.For mixtures containing “fuel grade” Pu (nominally 81-93 percent239Pu and 7-19 percent 240Pu), the ICP-MS results from the presentinvestigation appear to be in better agreement with the presurveillancedata than the radiochemistry results.