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Off-gas treatment systems in used fuel reprocessing which use fixed-bed adsorbers are typically designed to operate for an extended period of time before replacement or regeneration of the adsorbent. During this time, the sorbent material will be exposed to the off-gas stream. Exposure could last for months, depending on the replacement cycle time. The gas stream will be at elevated temperature and will possibly contain a mixture of water vapor, NOx, nitric acid vapors, and a variety of other constituents in addition to the radionuclides of capture interest. A series of studies were undertaken to evaluate the effects of long-term exposure, or aging, on proposed iodine sorbent materials under increasingly harsh off-gas conditions. Previous studies have evaluated the effects of up to 6 months of aging under dry air and under humid air conditions on the iodine loading behavior of Ag0-functionalized aerogels. This study examines the effects of extended exposure (up to 6 months) to NO2 on the iodine loading capacity of Ag0- functionalized aerogels. Material aged for 1 and 2 months appeared to have a similar total loading capacity to fresh material. Over an aging period of 4 months, a loss of approximately 15% of the total iodine capacitymore » was seen. The iodine capacity loss on silver-functionalized aerogels due to NO2 was smaller than the iodine capacity loss due to humid or dry air aging.« less |
