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Accession Number DE2012-1042398
Title Deep Bed Iodine Sorbent Testing FY2011 Report.
Publication Date Aug 2011
Media Count 45p
Personal Author N. Soelberg T. Watson
Abstract Nuclear fission results in the production of fission products (FPs) and activation products that increasingly interfere with the fission process as their concentrations increase. Some of these fission and activation products tend to evolve in gaseous species during used nuclear fuel reprocessing. Analyses have shown that I129, due to its radioactivity, high potential mobility in the environment, and high longevity (half life of 15.7 million years), can require control efficiencies of up to 1,000x or higher to meet regulatory emission limits. Deep-bed iodine sorption testing has been done to evaluate the performance of solid sorbents for capturing iodine in off-gas streams from nuclear fuel reprocessing plants. The objectives of the FY 2011 deep bed iodine sorbent testing are: (1) Evaluate sorbents for iodine capture under various conditions of gas compositions and operating temperature (determine sorption efficiencies, capacities, and mass transfer zone depths); and (2) Generate data for dynamic iodine sorption modeling. Three tests performed this fiscal year on silver zeolite light phase (AgZ-LP) sorbent are reported here. Additional tests are still in progress and can be reported in a revision of this report or a future report. Testing was somewhat delayed and limited this year due to initial activities to address some questions of prior testing, and due to a period of maintenance for the on-line GC. Each test consisted of (a) flowing a synthetic blend of gases designed to be similar to an aqueous dissolver off-gas stream over the sorbent contained in three separate bed segments in series, (b) measuring each bed inlet and outlet gas concentrations of iodine and methyl iodide (the two surrogates of iodine gas species considered most representative of iodine species expected in dissolver off-gas), (c) operating for a long enough time to achieve breakthrough of the iodine species from at least one (preferably the first two) bed segments, and (d) post-test purging with pure N2 to drive loosely or physisorbed iodine species off of the sorbent. Post-test calculations determine the control efficiencies for each bed, iodine loadings on the sorbent, and mass transfer zone depths. Portions of the iodine-laden sorbent from the first bed of two of the tests have been shipped to SNL for waste form studies. Over the past three years, we have explored a full range of inlet iodine and methyl iodide concentrations ranging from (approx)100 ppb to (approx)100 ppm levels, and shown adequate control efficiencies within a bed depth as shallow as 2 inches for lower concentrations and 4 inches for higher concentrations, for the AgZ-type sorbents. We are now performing a limited number of tests in the NC-77 sorbent from SNL. Then we plan to continue to (a) fill in data gaps needed for isotherms and dynamic sorbent modeling, and (b) test the performance of additional sorbents under development.
Keywords Emission
Fuel reprocessing plants
Gases
Iodine
Nuclear fission products
Sorbents
Sorption
Streams
Waste forms


 
Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 77I - Reactor Fuels & Fuel Processing
77G - Radioactive Wastes & Radioactivity
Corporate Author Idaho National Laboratory, Idaho Falls, ID. Fuel Cycle Research and Development.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1226
Contract Number DE-AC07-05ID14517

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