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Gas generation from Tank 241-SY-103 waste

Description: This report summarizes progress made in evaluating mechanisms by which flammable gases are generated in Hanford double-shell tank wastes, based on the results of laboratory tests using actual waste from Tank 241-SY-103. The objective of this work is to establish the identity and stoichiometry of degradation products formed in actual tank wastes by thermal and radiolytic processes as a function of temperature. The focus of the gas generation tests on Tank 241-SY-103 samples is first the effect of temperature on gas generation (volume and composition). Secondly, gas generation from irradiation of Tank 241-SY-103 samples at the corresponding temperatures as the thermal-only treatments will be measured in the presence of an external radiation source (using a {sup 137}Cs capsule). The organic content will be measured on a representative sample prior to gas generation experiments and again at the termination of heating and irradiation. The gas generation will be related to the extent of organic species consumption during heating. Described in this report are experimental methods used for producing and measuring gases generated at various temperatures from highly radioactive actual tank waste, and results of gas generation from Tank 241-SY-103 waste taken from its convective layer. The accurate measurement of gas generation rates from actual waste from highly radioactive waste tanks is needed to assess the potential for producing and storing flammable gases within the waste tanks. This report addresses the gas generation capacity of the waste from the convective layer of Tank 241-SY-103, a waste tank listed on the Flammable Gas Watch List due to its potential for flammable gas accumulation above the flammability limit.
Date: April 1, 1996
Creator: Bryan, S.A.; King, C.M.; Pederson, L.R.; Forbes, S.V. & Sell, R.L.
Partner: UNT Libraries Government Documents Department

Mechanisms of gas retention and release: Experimental results for Hanford waste tanks 241-AW-101 and 241-AN-103

Description: The 177 storage tanks at Hanford contain a vast array of radioactive waste forms resulting, primarily, from nuclear materials processing. Through radiolytic, thermal, and other decomposition reactions of waste components, gaseous species including hydrogen, ammonia, and the oxidizer nitrous oxide are generated within the waste tanks. Many of these tanks are known to retain and periodically release quantities of these flammable gas mixtures. The primary focus of the Flammable Gas Project is the safe storage of Hanford tank wastes. To this end, we strive to develop an understanding of the mechanisms of flammable gas retention and release in Hanford tanks through laboratory investigations on actual tank wastes. These results support the closure of the Flammable Gas Unreviewed Safety Question (USQ) on the safe storage of waste tanks known to retain flammable gases and support resolution of the broader Flammable Gas Safety Issue. The overall purpose of this ongoing study is to develop a comprehensive and thorough understanding of the mechanisms of flammable gas retention and release. The first objective of the current study was to classify bubble retention and release mechanisms in two previously untested waste materials from Tanks 241-AN-103 (AN-103) and 241-AW-101 (AW-101). Results were obtained for retention mechanisms, release characteristics, and the maximum gas retention. In addition, unique behavior was also documented and compared with previously studied waste samples. The second objective was to lengthen the duration of the experiments to evaluate the role of slowing bubble growth on the retention and release behavior. Results were obtained for experiments lasting from a few hours to a few days.
Date: September 1, 1997
Creator: Rassat, S.D.; Gauglitz, P.A.; Bredt, P.R.; Mahoney, L.A.; Forbes, S.V. & Tingey, S.M.
Partner: UNT Libraries Government Documents Department

Mechanisms of gas retention and release: Experimental results for Hanford single-shell waste tanks 241-A-101, 241-S-106, and 241-U-103

Description: The 177 underground waste storage tanks at the Hanford Site contain millions of gallons of radioactive waste resulting from the purification of nuclear materials and related processes. Through various mechanisms, flammable gas mixtures of hydrogen, ammonia, methane, and nitrous oxide are generated and retained in significant quantities within the waste in many ({approximately}25) of these tanks. The potential for large releases of retained gas from these wastes creates a flammability hazard. It is a critical component of the effort to understand the flammability hazard and a primary goal of this laboratory investigation to establish an understanding of the mechanisms of gas retention and release in these wastes. The results of bubble retention experimental studies using waste samples from several waste tanks and a variety of waste types support resolution of the Flammable Gas Safety Issue. Gas bubble retention information gained in the pursuit of safe storage will, in turn, benefit future waste operations including salt-well pumping, waste transfers, and sluicing/retrieval.
Date: September 1, 1998
Creator: Rassat, S.D.; Caley, S.M.; Bredt, P.R.; Gauglitz, P.A.; Rinehart, D.E. & Forbes, S.V.
Partner: UNT Libraries Government Documents Department