In an off-gas treatment system, a capture material will typically be exposed to a gas stream for months at a time. This gas stream may be at elevated temperature and could contain water vapor, nitrogen oxides (NOx) gas, nitric acid vapors, or a variety of other constituents making up the dissolver off-gas stream in a traditional nuclear fuel reprocessing plant. For this reason, it is important to evaluate the effects of longterm exposure, or aging, on proposed capture materials. One material under consideration is silver-functionalized (AgDG) silica aerogel. Aerogels are being produced at Pacific Northwest National Laboratory (PNNL) and distributed to other labs for testing. Previous studies have examined the effect of extended aging, under dry or humid air conditions, on the iodine capture capacity of these aerogels. After 6 months of aging in dry air, a 22% decrease in iodine retention capacity was observed (Bruffey et al., 2012), from an initial retention capacity of 41 wt % to 33 wt %. After 6 months of aging in humid air, a 22% decrease in iodine retention capacity was seen again, this time from an initial iodine loading capacity of 33 wt% on the fresh material to 24 wt% after 6 months of humid air aging. (Bruffey et al., 2013). The aim of this study was to determine the effect of extended exposure to an air stream containing approximately 2% N02.
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