Methylmercury and Ethylmercury Analytical Performance in SRR Samples Measured by SRNL and Eurofins Frontier Global Sciences

Boggess, Andrew J.; Bannochie, C. J.; White, Thomas L.; Jones, Mark; Edwards, T. B.

doi:10.2172/1557972

Cited by 5 publications

(5 citation statements)

References 8 publications

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“…Methylmercury and ethyl mercury were measured by Cold Vapor Atomic Fluorescence Spectroscopy (CVAFS). 14 Soluble elemental mercury (Hg 0 ) was measured by ACSM using a Purge & Trap, Thermal Desorption, CVAFS (P&T-TD-CVAFS) method. 15 A variation of this method was also developed by ACSM to analyze for inorganic mercury (Hg(I/II)).…”

Section: Table 2-2 Interpretation and Assumptions For Converting Icp-...mentioning

confidence: 99%

Radioactive Waste Sludge Washing and Demonstration of the Nitric-Glycolic Acid Flowsheet for Sludge Batch 10 Qualification

MARTINO¹,

Siegfried²,

Pareizs³

et al. 2022

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For each sludge batch that is processed in the Defense Waste Processing Facility (DWPF), the Savannah River National Laboratory (SRNL) performs qualification testing to demonstrate that the sludge batch (SB) is processible. During processing of SB9, DWPF will be transitioning from the Nitric-Formic Acid (NFA) flowsheet to the Nitric-Glycolic Acid (NGA) flowsheet. Thus, the qualification of SB10 was requested to only be performed using the NGA flowsheet.In order to qualify the batch for the NGA flowsheet, Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles, designated SC-19, were performed using SB10 Tank 51 sample material. SRNL received Tank 51 material in the midst of Tank Farm washing. SRNL continued the washing in the SRNL Shielded Cells. The SRNL process included the addition of Sodium Reactor Experiment (SRE) material from H Canyon, simulating the transfer of SRE from H Canyon to Tank 51 during Tank Farm washing. The washed SB10 Tank 51 material, with SRE, was characterized prior to flowsheet qualification testing.The Chemical Process Cell demonstration with the NGA flowsheet utilized an acid stoichiometry of 107% Koopman Minimum Acid basis (102% Hsu basis). The qualification was performed on the "batch", which is representative of the Tank 51 material that will be transferred to Tank 40, rather than the "blend", which is representative of the Tank 40 material that will be fed to DWPF. Thus, specifics for the DWPF processing of the Tank 40 blend may differ in varying degrees from this qualification test. Additionally, the qualification did not include Salt Waste Processing Facility (SWPF) feeds (Monosodium Titanate (MST)/Sludge Solids and Strip Effluent), which would contribute soluble salts and the MST solids, which could influence the acid addition and the product rheology, respectively. For these reasons, the results of this qualification testing demonstration are used in conjunction with simulant testing to inform the processing of the Tank 40 blend with inclusion of SWPF feeds.Highlights of the testing results are summarized in the paragraphs below.Prior to the addition of antifoam, foaming was encountered in the SRAT cycle during the addition of nitric acid to the extent that sludge foamed over into the off-gas system. Based on observations from simulant testing, during which foaming was not noted during nitric acid addition, the plan involved addition of Momentive TM Y-17112 antifoam after the completion of nitric acid addition and prior to glycolic acid addition. The foaming during nitric acid addition was likely due to the release of carbon dioxide from the acid reacting with carbonate. After a time out (3 weeks), the SRAT cycle was resumed with an antifoam addition prior to resumption of nitric acid addition. Foaming was successfully mitigated during the remainder of the SRAT and SME cycles.Total dried solids measurements of the SRAT and SME Products were 20.1 and 48.1 weight percent (wt%), respectively. Calcined solids measured 11.3 wt% in the SRAT Receipt and SRAT Pr...

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Section: Table 2-2 Interpretation and Assumptions For Converting Icp-...mentioning

confidence: 99%

Radioactive Waste Sludge Washing and Demonstration of the Nitric-Glycolic Acid Flowsheet for Sludge Batch 10 Qualification

MARTINO¹,

Siegfried²,

Pareizs³

et al. 2022

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show abstract

“…Both the GC/AFS method for MeHg and the DMA method (EPA Method 7473) for total Hg have been recently described in SRNL AR&D reports that are available on the U. S. Department of Energy Information Bridge internet site, the Office of Scientific and Technical Information (OSTI.GOV). 12,13 These analyses were completed within four weeks of leachate collection. It was expected that measuring only total mercury and MeHg would give adequate information for the mercury concentrations in the TCLP leachates (i.e., the difference in leachate total mercury and MeHg can be attributed to inorganic mercury in the leachates which could derive from the ionic Hg added in the initial simulant salt solutions).…”

Section: Tclp Testsmentioning

confidence: 99%

Tank 50 Simulant Grout and Toxicity Characteristic Leaching Procedure (TCLP) Results for Methyl Mercury Waste Acceptance Criteria (WAC) Limit

Crawford

Hill

2021

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Preliminary non-baseline studies were recently performed by the Savannah River National Laboratory (SRNL) to investigate the effects of various concentrations of mercury in saltstone on the Toxicity Characteristic Leaching Procedure (TCLP). Tank 50 salt solution simulants were prepared containing both chromium and ionic mercury (Hg(II)) in addition to elevated concentrations of methylmercury (MeHg). These simulants were used to make saltstone samples that cured for 28 days and were evaluated using the TCLP. Saltstone samples containing the full premix constituents of slag, fly ash and cement at the mass ratios of 45,45,10 wt% were prepared with total Hg concentrations between 147 mgHg/L to 372 mgHg/L containing primarily MeHg. Total Hg mercury concentrations in the corresponding TCLP leachates ranged from 0.035 mg/L to 0.095 mg/L and were compared to the reference Total Hg leachate TCLP limit of 0.2 mg/L. Consequently, at these leached mercury concentrations, saltstone did not exhibit the characteristic of mercury toxicity.Cement-free saltstone formulation containing 60 wt% slag and 40 wt% fly ash prepared with similar total Hg concentrations between 147 mg/L to 372 mg/L resulted in TCLP total Hg leachate values for this formulation that were 9% to 18% lower than the total Hg leachate values shown above for the full premix samples. An explanation for this result is that sulfide in slag is responsible for stabilizing mercury as mercury sulfide, which has very low solubility. Additionally, replacing the cement with slag could influence the overall saltstone reaction products, hydration gel chemistry and pore structure, all of which might impact Hg retention via encapsulation and adsorption.The saltstone particle size used in these TCLP tests ranged from 4.760 mm (0.1874 inches) to 9.525 mm (0.375 inches), which is the same size range used for quarterly Tank 50 saltstone regulatory testing. Test results presented in this report on nonradioactive saltstone suggest that the current waste acceptance criteria (WAC) limits for total Hg (325 mg/L) and MeHg (350 mg/L) will support production of saltstone that does not exhibit the characteristics of mercury toxicity (TCLP leachate for total Hg limit of less than 0.2 mg/L). These results could be confirmed for saltstone made with Tank 50 solution spiked with these higher concentrations of MeHg in proposed future studies.These simulant exploratory tests suggest that the current WAC limits on total Hg (325 mg/L) and MeHg (350 mg/L) are adequate for protecting the TCLP Hg limit of 0.2 mg/L. Further testing with more replicates at current and higher concentrations of Hg spikes, as well as similar testing with Hg-spiked radioactive Tank 50 solutions could provide further insight into the Hg behavior/retention in saltstone samples. Initial tests for the direct analysis of total Hg in saltstone yield results similar to those expected from the calculated Hg in saltstone based on the simulant Hg analysis and the batching amounts used to prepare the saltstone.

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“…Mercury analyses performed at SRNL by AR&D included Total mercury using the Direct Mercury Analyzer (DMA) method 14 and monomethyl mercury and ethyl mercury by Cold Vapor Atomic Fluorescence Spectroscopy (CVAFS). 15 Soluble elemental mercury (Hg(0)) was measured by AR&D using a Purge & Trap, Thermal Desorption, CVAFS (P&T-TD-CVAFS) method. 16 A variation of this method was also developed by AR&D to analyze for inorganic mercury (Hg(I/II).…”

Section: Introductionmentioning

confidence: 99%

Results for the First Quarter Calendar Year 2021 Tank 50 Salt Solution Sample

Crawford

2021

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Methylmercury and Ethylmercury Analytical Performance in SRR Samples Measured by SRNL and Eurofins Frontier Global Sciences

Cited by 5 publications

References 8 publications

Radioactive Waste Sludge Washing and Demonstration of the Nitric-Glycolic Acid Flowsheet for Sludge Batch 10 Qualification

Radioactive Waste Sludge Washing and Demonstration of the Nitric-Glycolic Acid Flowsheet for Sludge Batch 10 Qualification

Tank 50 Simulant Grout and Toxicity Characteristic Leaching Procedure (TCLP) Results for Methyl Mercury Waste Acceptance Criteria (WAC) Limit

Results for the First Quarter Calendar Year 2021 Tank 50 Salt Solution Sample

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