Alternative and Enhanced Chemical Cleaning: Corrosion Studies Results: Fy2010

Wiersma, Bruce J.

doi:10.2172/990341

Cited by 5 publications

(9 citation statements)

References 12 publications

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“…Previous testing in oxalic/nitric acid mixtures suggested that the corrosion rate for carbon steel in dilute acid mixtures (i.e., 0.3 M nitric acid) would result in a "manageable" amount of degradation over a short period of time (Wiersma, 2002). These expectations were confirmed during recent corrosion evaluations performed in support of the EM-31 chemical cleaning program (Wiersma, 2010). Corrosion studies conducted with acid mixtures containing 1 wt.…”

Section: Background and Introductionmentioning

confidence: 65%

“…Based on the results, optimized conditions for hematite dissolution in oxalic acid were selected using nitric or sulfuric acid as a supplemental proton source. Electrochemical corrosion studies were also conducted (reported separately; Wiersma, 2010) with oxalic/mineral acid mixtures to evaluate the effects of these solutions on waste tank integrity.…”

Section: Discussionmentioning

confidence: 99%

“…Mixtures of nitric and sulfuric acids with oxalic acid proved to be suitable solutions to promote optimal dissolution of iron phases. The oxalic and mineral acid concentrations required to give acceptable and manageable carbon steel corrosion rates were determined separately (Wiersma, 2010). Based on the combined dissolution and corrosion test results, conditions for real waste dissolution testing using oxalic/nitric acid mixtures were recommended (King, 2010c).…”

Section: Discussionmentioning

confidence: 99%

“…% oxalic acid has recently been shown to promote very high carbon steel corrosion rates (Wiersma, 2010). Based on these results, it will likely be necessary to use an oxalic acid concentration between 0.5 and 1 wt.…”

Section: Hematite Solubility Versus Phmentioning

confidence: 99%

“…The latest dissolution test results are the subject of this report. The corrosion test results are provided in a separate report (Wiersma, 2010).…”

Section: Background and Introductionmentioning

confidence: 99%

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Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

King¹,

Hay²

2011

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Section: Background and Introductionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Hematite Solubility Versus Phmentioning

confidence: 99%

“…The latest dissolution test results are the subject of this report. The corrosion test results are provided in a separate report (Wiersma, 2010).…”

Section: Background and Introductionmentioning

confidence: 99%

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Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

King¹,

Hay²

2011

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Enhanced Chemical Cleaning of SRS Waste Tanks to Improve Actinide Solubility

Rudisill¹,

Thompson²

2011

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Revision 0 iv EXECUTIVE SUMMARYProcesses for the removal of residual sludge from SRS waste tanks have historically used solutions containing up to 0.9 M oxalic acid to dissolve the remaining material following sludge removal. The selection of this process was based on a comparison of a number of studies performed to evaluate the dissolution of residual sludge. [1] In contrast, the dissolution of the actinide mass, which represents a very small fraction of the waste, has not been extensively studied. The Pu, Np, and Am in the sludge is reported to be present as hydrated and crystalline oxides. [2][3][4] To identify aqueous solutions which have the potential to increase the solubility of the actinides, the alkaline and mildly acidic test solutions shown below were selected as candidates for use in a series of solubility experiments. 8 wt % (0.9 M) oxalic acid 2 wt % (0.22 M) oxalic acid 1.8 wt % (0.2 M) oxalic acid/0.1 M citric acid 0.18 M HNO 3 /0.5 wt % (0.056 M) oxalic acid 0.18 M HNO 3 /0.2 M NaMnO 4 0.18 M HNO 3 10 M NaOH 10 M NaOH/0.2 M NaMnO 4 1 M NaHCO 3 /Na 2 CO 3 at pH 9.5 1 M NaHCO 3 /Na 2 CO 3 /0.2 M NaMnO 4 at pH 9.5 0.05 M DTPA at pH 2-4 0.18 M HNO 3 blank 10.0 M NaOH blank 1 M NaHCO 3 /Na 2 CO 3 at pH 9.5 blank The efficiency of the solutions in solubilizing the actinides was evaluated using a simulated sludge prepared by neutralizing a HNO 3 solution containing Pu, Np, and Am. The hydroxide concentration was adjusted to a 1.2 M excess and the solids were allowed to age for several weeks prior to starting the experiments. The sludge was washed with 0.01 M NaOH to prepare the solids for use. Following the addition of an equal portion of the solids to each test solution, the concentrations of Pu, Np, and Am were measured as a function of time over a 792 h (33 day) period to provide a direct comparison of the efficiency of each solution in solubilizing the actinide elements. Although the composition of the sludge was limited to the hydrated actinide oxides (and did not contain other components of demonstrated importance), the results of the study provides guidance for the selection of solutions which should be evaluated in subsequent tests with a more realistic surrogate sludge and actual tank waste.The results from the solubility experiments showed that the test solutions containing 0.2 M NaMnO 4 were highly effective in solubilizing the Pu. The order of the solutions from the highest to the lowest concentrations achieved was as follows: 0.18 M HNO 3 /0.2 M NaMnO 4 , > 10 M NaOH/0.2 M NaMnO 4 , > 1 M NaHCO 3 /Na 2 CO 3 /0.2 M NaMnO 4 . SRNL-STI-2011-00521Revision 0 v The concentrations after 792 h (33 days) fell in the range of 0.4-2.0E-02 mol/L (1.0-4.8 g/L); although, the Pu in each solution was at or near its maximum concentration after 168 h (1 week). The concentrations of Pu in these solutions were higher than the concentration measured in the baseline 0.9 M oxalic acid solution at the conclusion of the experiments (5.2E-03 mol/L or 1.2 g/L) except for the concentration in NaHCO 3 /Na 2 CO 3 /NaMn...

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Alternative Chemical Cleaning Methods for High Level Waste Tanks: Simulant Studies

Rudisill

King

Hay

et al. 2015

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We gratefully acknowledge the assistance of Holly Hall in the movement of equipment, supplies, samples, and chemicals between laboratories during testing. The efforts of Whitney Riley in analyzing most of the non-radioactive test samples are appreciated. SRNL-STI-2015-00517 Revision 0 vi SRNL-STI-2015-00517 Revision 0 vii oxalic/nitric acid reagent. Following treatment using the baseline oxalic acid reagent, detectable levels of actinide removal were achieved using the acidic permanganate cleaning method. Based on the results observed with non-radioactive and radioactive simulants, actual waste testing of both alternative cleaning technologies (optimized oxalic acid cleaning using supplementary nitric acid and permanganate-based cleaning under both acidic and basic conditions) is recommended.

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Alternative and Enhanced Chemical Cleaning: Corrosion Studies Results: Fy2010

Cited by 5 publications

References 12 publications

Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

Enhanced Chemical Cleaning of SRS Waste Tanks to Improve Actinide Solubility

Alternative Chemical Cleaning Methods for High Level Waste Tanks: Simulant Studies

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