W. E. Daniel's research while affiliated with Savannah River National Laboratory and other places

The Savannah River National Laboratory (SRNL) will perform lab analyzes on samples from the June 2009 THOR Fluidized Bed Steam Reforming (FBSR) Engineering Scale Test Demonstration (ESTD) Phase 3 with Tank 48H simulant at the Hazen Research Inc. (HRI) in Golden, Colorado. The purpose of the 2009 ESTD Phase 3 testing at the Hazen facility is to demonstrate the long term operability of an integrated FBSR processing system with product solids handling capability. The THOR Treatment Technologies (TTT) FBSR process of destroying organics in the Tank 48 waste simulant and generating a solid carbonate product was successfully demonstrated on the pilot scale level in 2006. Pilot scale tests were completed in 2008 (Phase 1) and in 2009 (Phase 2) that further demonstrated the TTT FBSR process ability to destroy organics in the Tank 48 simulant and produce a transportable solid carbonate waste form. The final Phase 3 pilot scale testing will demonstrate the integrated TTT FBSR process capability to process the Tank 48 simulant from a slurry feed into a greater than 99% organic free and primarily dissolved carbonate FBSR product slurry. The final Phase 3 analytical results will be compared with prior 2008 and 2006 pilot scale results in terms of organic, nitrite, and nitrate destruction.

This presentation describes the Bench-scale Steam Reformer (BSR) that produces the solid and gas phase reactions of a THOR Treatment Technologies Fluidized Bed Steam Reformer (FBSR), but which is small enough to fit into a radioactive cell and can be operated using cell manipulators. It compares the results between the FBSR and BSR as well as the results between the simulant and actual waste. Sodium tetraphenylborate (Na-TPB) was added to approximately 240,000 gallons of salt waste in Tank 48H in order to remove the cesium as Cs-TPB by cross-flow filtration. However, the DOE decided to discontinue the process due to excessive benzene off-gassing from the solution. The original process included an acid hydrolysis step to breakdown the TPB into benzene which would be disposed of by incineration. The DOE now wishes to remove the organics from the solution without the need for incineration. One candidate technology for organic removal is fluidized bed steam reforming. Fluidized bed steam reforming destroys organics by the water gas shift reactions at temperatures above 600oC. Any carbon bearing species is converted to CO and CO2 as H2O becomes H2. C(s) + H2O(g) -> CO(g) + H2(g) H2O(g) + CO(g) -> H2(g) + CO2 In addition to destroying the organics, the CO and H2 rich atmosphere then promote the de-nitration of the salt solution. CO + NO2 -> CO2 + NO 2CO + 2NO -> 2CO2 + N2 H2 + NO2 -> H2O + NO 2H2 + 2NO -> 2H2O + N2 Typically, the H2 concentration was controlled to about 2% on a dry basis. It was controlled by adding air to create steam and heat. 2H2 (g) + O2(g) -> 2H2O(g) + heat Off-gases from the steam reformer still included some organics so a second reactor operated at 925oC with excess air to oxidize the remaining organics fully to CO2. The steam reformer creates a solid carbonate product which is readily soluble in water for further processing. One representative carbonation reaction is the conversion of sodium nitrate to sodium carbonate. 5C + 4NaNO3 -> 3CO2 + 2Na2CO3 + 2 N2 Note that these reactions represent the overall chemistry, but are not all inclusive. Full scale steam reforming is performed in a Fluidized Bed Steam Reformer(FBSR). Tests performed in the pilot scale FBSR at the Hazen Facility in Golden, Colorado proved the technology using simulants. With the technology proven on simulants, the DOE then requested SRNL to prove the technology on actual Tank 48 waste. Due to the radioactivity of the actual waste, the demonstration had to be performed in the SRNL high level cells. The dimension of the smallest proven FBSR far exceeds the space available within the cells, so an alternative approach had to be taken. Thus the Bench-scale Steam Reformer (BSR) was created. The BSR is a two reactor system that produces the solid and gas phase reactions of a FBSR and the secondary off-gas oxidizer. The complete reaction unit, which is located inside the radioactive cell, fits on a 4'x 3' pan and requires less than 5' of head space above the pan surface. The control and data acquisition system fits on a 30" x 45" table outside of the cell and two mass spectrometers used for measuring off-gases fit into a 6' x 2' hood behind the cell. The same simulant used in the Hazen FBSR was run in the BSR. The BSR also ran the actual tank 48 waste. Comparisons are made between the FBSR and the BSR using simulant. Comparisons are made between the actual waste and the simulant waste in the BSR.

The U.S. Department of Energy's Office of River Protection (ORP) is responsible for the retrieval, treatment, immobilization, and disposal of Hanford's tank waste. Currently there are approximately 56 million gallons of highly radioactive mixed wastes awaiting treatment. A key aspect of the River Protection Project (RPP) cleanup mission is to construct and operate the Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the RPP mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA), i.e. December 31, 2047. Therefore, Supplemental Treatment is required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. In addition, the WTP LAW vitrification facility off-gas condensate known as WTP Secondary Waste (WTP-SW) will be generated and enriched in volatile components such as ¹³Cs, ¹²I, Tc, Cl, F, and SO that volatilize at the vitrification temperature of 1150 C in the absence of a continuous cold cap (that could minimize volatilization). The current waste disposal path for the WTP-SW is to process it through the Effluent Treatment Facility (ETF). Fluidized Bed Steam Reforming (FBSR) is being considered for immobilization of the ETF concentrate that would be generated by processing the WTP-SW. The focus of this current report is the WTP-SW. FBSR offers a moderate temperature (700-750 C) continuous method by which WTP-SW wastes can be processed irrespective of whether they contain organics, nitrates, sulfates/sulfides, chlorides, fluorides, volatile radionuclides or other aqueous components. The FBSR technology can process these wastes into a crystalline ceramic (mineral) waste form. The mineral waste form that is produced by co-processing waste with kaolin clay in an FBSR process has been shown to be as durable as LAW glass. Monolithing of the granular FBSR product is being investigated to prevent dispersion during transport or burial/storage, but is not necessary for performance. A Benchscale Steam Reformer (BSR) was designed and constructed at the SRNL to treat actual radioactive wastes to confirm the findings of the non-radioactive FBSR pilot scale tests and to qualify the waste form for applications at Hanford. BSR testing with WTP SW waste surrogates and associated analytical analyses and tests of granular products (GP) and monoliths began in the Fall of 2009, and then was continued from the Fall of 2010 through the Spring of 2011. Radioactive testing commenced in 2010 with a demonstration of Hanford's WTP-SW where Savannah River Site (SRS) High Level Waste (HLW) secondary waste from the Defense Waste Processing Facility (DWPF) was shimmed with a mixture of ¹²¹²I and Tc to chemically resemble WTP-SW. Prior to these radioactive feed tests, non-radioactive simulants were also processed. Ninety six grams of radioactive granular product were made for testing and comparison to the non-radioactive pilot scale tests. The same mineral phases were found in the radioactive and non-radioactive testing.