Evidence for dawsonite in Hanford high-level nuclear waste tanks

Reynolds, Jacob G.; Cooke, Gary A.; Herting, D.L.; Warrant, R.W.

doi:10.1016/j.jhazmat.2012.01.018

Cited by 39 publications

(33 citation statements)

References 16 publications

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“…Solid phase characterization identified dawsonite as the largest crystals in the original composite with laths of 10 x 2 micron. This is in accordance with earlier sample analyses (see Evidence for dawsonite in Hanford high-level nuclear waste tanks, Reynolds et al, 2012). XRD identified dawsonite in the water leached solids, but could not detect it in the caustic leached samples, while SEM did not confirm dawsonite in either leach sample.…”

Section: Comparison Of Acid Digest and Koh Fusion Digest Resultssupporting

confidence: 91%

“…The newly formed gibbsite in turn will then dissolve together with the original gibbsite to water soluble sodium aluminate. The following equations are part of the detailed discussion on dawsonite dissolution in Hanford tank environments by Reynolds et al (2012). The amount of free hydroxide present in the original sample and the added hydroxide from the inhibited water seem to have been sufficient for the first reaction to happen during the water leach:…”

Section: Comparison Of Acid Digest and Koh Fusion Digest Resultsmentioning

confidence: 99%

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Laboratory Report on Performance Evaluation of Key Constituents during Pre-Treatment of High Level Waste Direct Feed

Huber¹

2013

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Section: Comparison Of Acid Digest and Koh Fusion Digest Resultssupporting

confidence: 91%

Section: Comparison Of Acid Digest and Koh Fusion Digest Resultsmentioning

confidence: 99%

Laboratory Report on Performance Evaluation of Key Constituents during Pre-Treatment of High Level Waste Direct Feed

Huber¹

2013

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“…The latter likely arises from reaction of NaOH with CO 2 in the atmosphere when drying. Although hydroxycancrinite was matched in the library, dawsonite, NaAl(OH) 2 CO 3 has been identified in other high carbonate aluminum sludges, [35] and cannot be ruled out. In subsequent Tests, all solids were dried in a vacuum oven.…”

Section: Small Scale Survey Testsmentioning

confidence: 96%

Aluminum Target Dissolution in Support of the Pu-238 Program

McFarlane¹,

Benker²,

DePaoli³

et al. 2014

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Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

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“…Furthermore, by increasing the carbonate concentration in the waste and decreasing hydroxide concentration, conditions are created favoring precipitation of the sodium aluminum carbonate hydroxide salt dawsonite, NaAlCO 3 (OH) 2 (Reynolds et al 2012). Finally, blending of wastes can precipitate aluminum as gibbsite, dawsonite, or sodium aluminosilicates such as cancrinite (see Section 2.1.2).…”

Section: Op7 -Aluminum Precipitation Carries Down Dissolved Plutoniummentioning

confidence: 99%

Effects Influencing Plutonium-Absorber Interactions and Distributions in Routine and Upset Waste Treatment Plant Operations

Delegard

Sinkov

Fiskum

2015

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Permanganate Effects -The solubilities of (hydr)oxide compounds of aluminum, cadmium, chromium, iron, and uranium (but not manganese and nickel), and of plutonium itself, increase with alkaline concentration and thus help preserve the plutonium/absorber ratio in solution. However, the ratio may be altered in permanganate oxidative dissolution of discrete plutonium phases such as PuO 2 ,PuO 2 •xH 2 O, or other low-solubility tetravalent plutonium because of oxidation to more soluble pentavalent or hexavalent plutonium. The ratio also may be altered because of oxidative leaching of Cr(III) phases while compounds of other absorber elements (e.g., aluminum, iron, nickel) are largely redox-indifferent. Plutonium dissolution from genuine washed sludge with permanganate is significantly enhanced by an increase in NaOH concentration, increasing by an average factor of 70 when permanganate oxidative leaching is undertaken at 3 M NaOH as compared with 0.1 or 0.25 M NaOH. The increase is likely due to plutonium being more readily oxidized to the more soluble hexavalent state. Dissolved plutonium species in alkaline solution, irrespective of oxidation state, are anionic so they are not expected to sorb onto the cation-sorbing resin used for 137 Cs removal. Indeed, such sorption is observed to be negligible. Excess permanganate does not appear to have an appreciable effect on the distribution of plutonium to solution based on oxidative leaching of REDOX Process sludge simulants and genuine Cr(III)-bearing Hanford tank sludges. In lab testing, intentional over-dosage of permanganate did not lead to enhanced plutonium leaching at lower alkalinity (0.09 to 0.25 M NaOH), while at higher alkalinity (3 M NaOH), the plutonium concentration increase to ~0.00036 g Pu/L was relatively low and could be mitigated by adding Cr(III) nitrate to the permanganate/manganate-bearing slurry to eliminate excess oxidant, form MnO 2 , and remove ~95% of the solubilized plutonium by coprecipitation. Separate testing showed that plutonium dissolution in the presence of excess permanganate at 2 to 4 M NaOH also can be mitigated by addition of hydrogen peroxide, removing ~75% of the solubilized plutonium. In treatment with Sr/Mn(VII) for 90 Sr and transuranic element removal from Envelope C supernates, both coprecipitated plutonium that remains undissolved and the residual soluble plutonium, should be protected with 100 to 1000 times higher neutron absorber concentrations based on AN-102 supernate studies. Although experimental data on 239 Pu decontamination from AN-107 supernates are lacking, it is likely that plutonium decontamination by Sr/Mn(VII) treatment was similar to that of AN-102 supernates based on solution composition and total alpha analyses. Decontamination of tank SY-101 from dissolved plutonium by permanganate treatment also is found. Overall, treatment of Envelope C wastes by Sr/Mn(VII) should improve criticality safety by carrying plutonium into the solid phase in the presence of co-precipitated iron and especially manganese.Cerium an...

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Evidence for dawsonite in Hanford high-level nuclear waste tanks

Cited by 39 publications

References 16 publications

Laboratory Report on Performance Evaluation of Key Constituents during Pre-Treatment of High Level Waste Direct Feed

Laboratory Report on Performance Evaluation of Key Constituents during Pre-Treatment of High Level Waste Direct Feed

Aluminum Target Dissolution in Support of the Pu-238 Program

Effects Influencing Plutonium-Absorber Interactions and Distributions in Routine and Upset Waste Treatment Plant Operations

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