Adsorption of Iodine and Tritium from UNF Reprocessing Off-Gas Streams

Journal Article · Wed Jun 15 04:00:00 EDT 2016 · Transactions of the American Nuclear Society

OSTI ID:22991829

Spencer, B. B.; Bruffey, S. H.; Walker, Jr., J. F.; Jubin, R. T. ^[1]

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1. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6223 (United States)

The need to control emissions of the gaseous radionuclides to the air during nuclear fuel recycling is widely recognized. Gaseous radionuclides can partition to off-gas streams emanating from the various individual processes used in the recycle plant, such as from the mechanical head end (shear), tritium pretreatment, fuel dissolver, vessel vents, cell ventilation, and conversion operations. In traditional recycle plants, the bulk of the four primary volatile fission products (i.e., {sup 3}H, {sup 14}C, {sup 85}Kr, and {sup 129}I) is released in the head-end processes, for example, the dissolution process. The usual off-gas treatment sequence of operations targets removal of tritium (as {sup 3}HHO), iodine, carbon (as {sup 14}CO{sub 2}), and the noble gases, in that order. Water and iodine are captured first because the other species are relatively unimpeded by the sorbents used for water and iodine, so they flow downstream to additional treatment processes. Water and iodine do react with one another, and many techniques used to collect one of these species also collect some fraction of the other. It is quite desirable to sequester the iodine and water separately because the tritiated water may be disposed of as a low level waste. If not cleanly separated, contamination of the low-level waste by iodine may elevate its classification to high-level waste and result in greater costs for disposal. The proposed sorption sequence was tested in the laboratory. Use of a second column of AgZ permits the detection of breakthrough from the primary AgZ column while protecting the downstream 3AMS column from collecting iodine. (This arrangement is equivalent to enabling intra-column sampling of the primary column.) Neutron activation analysis of the 3AMS revealed that iodine was below, or at, the level of detection. The results successfully demonstrated that iodine can be sequestered in the AgZ while the water is collected free of iodine in the 3AMS column. (authors)

• OSTI ID: 22991829
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Journal Issue: 1 Vol. 114; ISSN 0003-018X
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ADSORPTION
CARBON 14
FISSION PRODUCTS
HEAD END PROCESSES
HIGH-LEVEL RADIOACTIVE WASTES
IODINE
IODINE 129
KRYPTON 85
LOW-LEVEL RADIOACTIVE WASTES
NEUTRON ACTIVATION ANALYSIS
NUCLEAR FUELS
RARE GASES
REPROCESSING
STREAMS
TRITIUM
TRITIUM OXIDES