SummaryThis report describes the initial work conducted at Pacific Northwest National Laboratory to study technetium (Tc) removal fiom W o r d tank waste supernates and Tc oxidation state in the supemates. Filtered supernate samples fiom four tanks were studied: a composite double shell slurry feed (DSSF) consisting of 70% fiom Tank AW-101, 20% from AP-106, and 10% fiom AP-102; and three complexant concentrate (CC) wastes (Tanks AN-107, SY-101, ANS SY-103) that are distinguished by having a high concentration of organic complexants. The work included batch contacts of these waste samples with ReillexTW€PQ (anion exchanger fiom Reilly Industries) and ABEC 5000 (a sorbent from Eichrom Industries), materials designed to effectively remove Tc as pertechnetate fiom tank wastes. A short study of Tc analysis methods was completed. A preliminary identification of the oxidation state of non-pertechnetate species in the supernates was made by analyzing the technetium x-ray absorption spectra of four CC waste samples. Molybdenum (Mo) and rhenium (Re) spiked test solutions and simulants were tested with electrospmy ionizationmass spectrometry to evaluate the feasibility of the technique for identifying Tc species in waste samples.The highlights fiom the work are as follows:* Both ReillexTH-HPQ and ABEC 5000 are effective for Tc removal from the composite DSSF waste (70% AW-IOl), exhibiting 93% and 91% removal, respectively, on the first contact. Neither Rei1lex"cHpQ nor ABEC 5000 are effective for Tc removal from the three CC wastes studied. Technetium removal from the CC wastes was in all cases less than 50%. Removal of Tc from these wastes will require either an alternative process such as electrochemical deposition or addition of a feed adjustment step to oxidize the Tc species to pertechnetate.The Tc in CC waste is very resistant to oxidation to pertechnetate in acidified samples generally required for Tc analysis. A vigorous oxidation with C e O was found effective for this purpose, but is time consuming. X-ray absorption near edge spectroscopy indicates that the dominant species in CC waste is not pertechnetate. It also shows that the non-pertechnetate specie(s) in the CC wastes probably has an oxidation state of +IV.The batch contacts, oxidation study, and XANES data all indicate that for the tested wastes containing relatively large (> 10 g total organic carbon per liter), amounts of organic complexants, more than half of the total Tc is not pertechnetate.Inductively coupled plasma-mass spectrometry identified Re species, including polyoxyanions, in simulants and test solutions and was usefid for following the Re species through various changes in solution chemistry. Penhenate, a good surrogate for TcOi, was easily detectable in a CC waste simulant at 200 m a , somewhat higher than the concentration of Tc in CC wastes.

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One of the events postulated in the hazard analysis at the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids with Newtonian fluid behavior. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and across processing facilities in the DOE complex.Two key technical areas were identified where testing results were needed to improve the technical basis by reducing the uncertainty due to extrapolating existing literature results. The first technical need was to quantify the role of slurry particles in small breaches where the slurry particles may plug and result in substantially reduced, or even negligible, respirable fraction formed by high-pressure sprays. The second technical need was to determine the aerosol droplet size distribution and volume from prototypic breaches and fluids, specifically including sprays from larger breaches with slurries where data from the literature are scarce.To address these technical areas, small-and large-scale test stands were constructed and operated with simulants to determine aerosol release fractions and net generation rates from a range of breach sizes and geometries. The properties of the simulants represented the range of properties expected in the WTP process streams and included water, sodium salt solutions, slurries containing boehmite or gibbsite, and a hazardous chemical simulant. The effect of antifoam agents was assessed with most of the simulants. Orifices included round holes and rectangular slots. For the combination of both test stands, the round holes ranged in size from 0.2 to 4.46 mm. The slots ranged from (width × length) 0.3 × 5 to 2.74 × 76.2 mm. Most slots were oriented longitudinally along the pipe, but some were oriented circumferentially. In addition, a limited number of multi-hole test pieces were tested in an attempt to assess the impact of a more complex breach. Much of the testing was conducted at pressures of 200 and 380 psi, but some tests were conducted at 100 psi. Testing the largest postulated breaches was deemed impractical because of the much larger flow rates and equipment that would be required.This report presents the experimental results and analyses for the aerosol measurements obtained in the small-scale test stand. It includes a description of the simulants used and their properties, equipment and operations, data analysis methodologies, and test results. The results of tests investigating the role of slurry particles in plugging small breaches are reported in Mahoney et al. (2012). The results of the...

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