Flowsheet Evaluation for the Dissolving and Neutralization of Sodium Reactor Experiment Used Nuclear Fuel

Daniel, William E.; Hansen, E. K.; Shehee, T. C.

doi:10.2172/1054282

Cited by 3 publications

(9 citation statements)

References 6 publications

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“…The Al and HNO 3 concentrations throughout the experiments are estimated based on the actual initial concentrations and the assumption that 3.75 moles of HNO 3 are used per mole of Al dissolved, as discussed in prior work 10 and shown below:…”

Section: Baseline Aluminum Dissolution Rates For Al-1100mentioning

confidence: 99%

“…SRNL-STI-2014-00228 Revision 0 3.7 Evaluation of L-Bundle Alloy Dissolution Representative of SRE SRE fuel meat is comprised of a Th-U alloy, and its reactivity and off-gas behavior were measured in previous work. 10 The L-Bundle serves as the outer container for the fuel and Al tubes and confinement can for dissolution. L-bundle off-gas rate and H 2 concentration data were collected for use as input for flammability calculations applicable to SRE fuel to be dissolved in L-Bundles.…”

Section: Dissolution Experiments With Other Al-containing Alloysmentioning

confidence: 99%

“…The off-gas rates and H 2 concentrations measured for Experiment 36 were used to simulate the dissolution of the L-Bundle containing the SRE fuel since the L-Bundle material has to be dissolved first and has the largest surface area and off-gas generation compared to the SRE fuel. 10 The off-gas rates and H 2 concentrations measured for Experiment 41 are from the dissolution of a 30 wt % U-Al alloy. The off-gas generation data from Experiment 41 were similar to data from the dissolution of the L-Bundle material; therefore, the data from Experiment 41 were used to represent the dissolution of the L-Bundle containing the DR-3 fuel assemblies.…”

Section: Off-gas Ratementioning

confidence: 99%

“…The dissolution of SRE fuels was covered by prior research which indicated that the limiting factor in processing the Th fuel (associated with H 2 gas generation) was the L-Bundle (Al-6061/6063) alloy containing the Th fuel slugs. 10 The basic conditions for the SRE/DR-3 flowsheet recommendations for the H-Canyon dissolver for Batches 5 and 6 are: The higher Hg concentration of 0.012-0.015 M is being recommended to handle the case of maximum contaminants from the recycle of the AFS-2 HNO 3 stream from anion exchange. The Hg should be added slowly to the dissolver over a six-hour time period after charging fuel using the same procedures as currently used for the SRE/DR-3 campaign.…”

Section: Recommendationsmentioning

confidence: 99%

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Flowsheet Modification for Sodium Reactor Experiment and Denmark Reactor-3 Used Nuclear Fuel Processing

Almond¹,

Daniel²,

Rudisill³

2014

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Flowsheet parameters for the dissolution of SRE/DR-3 fuel include the following. The Hg catalyst is added gradually after the dissolver has reached temperature to achieve a maximum catalyst concentration of 0.012-0.015 M. The initial nitric acid concentration is in the range of 6-7 M and dependent on the amount of Al, Th, and U to be dissolved, targeting a final nitric acid concentration of 0.5-1.0 M after completion of the dissolution of the last charge. Boric acid (H 3 BO 3) or gadolinium nitrate (Gd(NO 3) 3) may be used as a nuclear safety poison. Concentrations of up to 2 g/L of B or Gd in surrogate dissolver solutions have been observed to be stable from precipitation. Hydrogen flammability calculations were performed using the experimental data to determine the conditions that H-Canyon can safely dissolve SRE/DR-3 fuel in L-Bundles with respect to the H 2 levels during the projected peak off-gas rates. To stay under the 60% LFL for H 2 , the charges of L-Bundles containing SRE shall be limited to four, where the Hg concentration is added to the recommended 0.012-0.015 M. In order to process the L-Bundles of DR-3 fuel, a minimum of 0.17 M Al must be in solution. This minimum dissolved Al could be reached by first dissolving SRE fuel or by adding Al(NO 3) 3 to the dissolver solution. The number of L-Bundles of DR-3 fuel that could be charged successively to the H-Canyon dissolver is dependent on the concentration of U in the U-Al alloy and the dissolved Al concentration. The number of bundles increases as the Al concentration increases in the dissolving solution. Instructions and limitations regarding the use of this document are provided in the transmittal letter.

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Section: Baseline Aluminum Dissolution Rates For Al-1100mentioning

confidence: 99%

Section: Dissolution Experiments With Other Al-containing Alloysmentioning

confidence: 99%

Section: Off-gas Ratementioning

confidence: 99%

Section: Recommendationsmentioning

confidence: 99%

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Flowsheet Modification for Sodium Reactor Experiment and Denmark Reactor-3 Used Nuclear Fuel Processing

Almond¹,

Daniel²,

Rudisill³

2014

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“…The L-Bundles have the largest surface area and off-gas generation compared to fuels similar to Missouri University Research Reactor (MURR) fuel. 10 Although, most research reactor fuel assemblies are fabricated from multiple plates, the spacing between plates is sufficiently close that fresh dissolving solution cannot continuously fill the small void between adjacent surfaces and dissolve Al. The offgas generation from the dissolution of Al would also hinder the flow of fresh solution to the close surfaces.…”

Section: Flammable Gas Generationmentioning

confidence: 99%

Dissolution of Material and Test reactor Fuel in an H-Canyon Dissolver

Daniel

Rudisill

O'Rourke

2017

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In an amended record of decision for the management of spent nuclear fuel (SNF) at the Savannah River Site, the US Department of Energy has authorized the dissolution and recovery of U from 1000 bundles of Al-clad SNF. The SNF is fuel from domestic and foreign research reactors and is typically referred to as Material Test Reactor (MTR) fuel. Bundles of MTR fuel containing assemblies fabricated from U-Al alloys (or other U compounds) are currently dissolved using a Hg-catalyzed HNO 3 flowsheet. Since the development of the existing flowsheet, improved experimental methods have been developed to more accurately characterize the offgas composition and generation rate during laboratory dissolutions. Recently, these new techniques were successfully used to develop a flowsheet for the dissolution of High Flux Isotope Reactor (HFIR) fuel. Using the data from the HFIR dissolution flowsheet development and necessary laboratory experiments, the Savannah River National Laboratory (SRNL) was requested to define flowsheet conditions for the dissolution of MTR fuels. With improved offgas characterization techniques, SRNL will be able define the number of bundles of fuel which can be charged to an H-Canyon dissolver with much less conservatism.Laboratory-scale experiments were performed to evaluate the dissolution of MTR fuels using both Al 1100 and 30 wt % U-Al alloys. The Al 1100 alloy was considered a representative surrogate since it provided an upper bound on the generation of flammable (i.e., H 2 ) gas during the dissolution process. The dissolution of the 30 wt % U-Al alloy proceeded at a slower rate than the Al 1100 alloy and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentrations. Raman spectroscopy was used to provide continuous monitoring of the concentration of H 2 and other permanent gases in the dissolution offgas allowing the development of H 2 generation rate profiles. The H 2 generation rates were subsequently used to evaluate how many L-Bundles could be dissolved in an H-Canyon dissolver without exceeding 60% of the calculated lower flammability limit (LFL) for H 2 at a given Hg concentration.Complete dissolution of the Al 1100 and 30 wt % U-Al alloys up to a final Al concentration of 2 M was obtained using a HNO 3 solution containing a 0.002 M Hg catalyst. However, following the dissolutions, solids were observed in the solutions. Analysis of the solids generally showed amorphous material or Si and SiO 2 which likely originated from the Si present in the alloys. No crystalline materials, such as UO 2 (NO 3 ) 2 or Al(NO3)3 were observed. Amorphous and silicon-containing solids from the dissolution of MTR fuels should be easily removed by the Head End centrifuge using the standard gelatin strike process. In experiments performed to develop the HFIR fuel dissolution flowsheet, the H 2 generation data showed that delaying the addition of Hg once the HNO 3 solution reached the boiling point can reduce the total offgas and H 2 generation rates. The delay...

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Dissolution of used nuclear fuel using recycled nitric acid

Almond

Daniel

Rudisill

2017

Separation Science and Technology

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SRNL evaluated the feasibility of using HB-Line anion exchange column waste streams from AFS-2 processing for the dissolver solution for Used Nuclear Fuel (UNF) processing. The targeted UNF for dissolution using recycled solution are fuels similar to the University of Missouri Research Reactor (MURR) fuel. The objectives of this experimental program were to validate the feasibility of using impure dissolver solutions with the MURR dissolution flowsheet to verify they would not significantly affect dissolution of the UNF in a detrimental manner.Initial dissolution experiments were unsuccessful in dissolving Al alloy sufficiently using 0.002 M Hg in solutions containing impurities in the concentration ranges expected to originate from AFS-2 processing. These impurities included F, Fe, Cr, Ni, Mn, Al, Cl, B, and Gd.Solutions with these impurities dramatically slowed or stopped the dissolution. Through this work, it was discovered that increasing the concentration of the Hg catalyst could overcome the deleterious effects of these impurities together. Experiments were subsequently performed with individual impurities to identify those that are problematic and to determine the amount of Hg required to overcome their effects. Iron was identified as the impurity that most significantly impacted the dissolution rates. The Hg catalyst concentration was increased from 0.002 M to 0.012 M to dissolve Al in the presence of all the impurities at their maximum concentrations (including Fe at 10 g/L).

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Flowsheet Evaluation for the Dissolving and Neutralization of Sodium Reactor Experiment Used Nuclear Fuel

Cited by 3 publications

References 6 publications

Flowsheet Modification for Sodium Reactor Experiment and Denmark Reactor-3 Used Nuclear Fuel Processing

Flowsheet Modification for Sodium Reactor Experiment and Denmark Reactor-3 Used Nuclear Fuel Processing

Dissolution of Material and Test reactor Fuel in an H-Canyon Dissolver

Dissolution of used nuclear fuel using recycled nitric acid

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