Performance of Silver-Exchanged Mordenite and Silver-Functionalized Silica-Aerogel Under Vessel Off-gas Conditions
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
US regulations 40 CFR 61, 40 CFR 190, and 10 CFR 20 govern release limits for volatile radionuclides contained in the gaseous effluents of used nuclear fuel (UNF) reprocessing facilities. Of the four volatile radionuclides that are restricted by the release limits (3H, 14C, 85Kr, and 129I) 129I will require the greatest degree of abatement. Previous studies have shown that overall plant decontamination factor (DF) for 129I must, at minimum, exceed 1,000 to meet regulatory requirements. Iodine-containing off-gas will be present in the dissolver off-gas, the cell off-gas, the vessel off-gas (VOG), the waste off-gas, and the shear off-gas. The VOG will most likely contain 1%–5% of the total iodine at part per billion (ppb) concentrations. A number of studies have examined iodine abatement from the dissolver off-gas, which contains greater than 95% of the iodine inventory of the plant, but very few have examined the recovery of iodine from the VOG stream. Reduced silver-exchanged mordenite (Ag0Z) has been considered a promising iodine sorbent for use in UNF reprocessing plants, but recent efforts have identified silver-functionalized silica-aerogel (AgAerogel) as a potential alternative. The testing reported here reflects a substantial increase in the body of work available on iodine adsorption by both silver sorbents under prototypical VOG conditions. Both I2 and methyl iodide (CH3I) adsorption tests have been conducted with Ag0Z and AgAerogel at a range of concentrations up to 1,000 ppb. These experiments were performed with two specific aims: (1) to assess the effect of iodine concentration on its adsorption by the sorbent and (2) to compare the performance of Ag0Z and AgAerogel in the removal of iodine from a prototypical VOG stream.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE), Fuel Cycle Technologies (NE-5)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1427666
- Report Number(s):
- ORNL/TM-2017/447; NTRD-MRWFD-2017-000034
- Country of Publication:
- United States
- Language:
- English
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