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Rapid Extraction Methods for the Process Laboratory. S. L. Maxwell, III V. D. Jones S. T. Nichols J. Satkowski M. A. Bernard Westinghouse Savannah River Site. Improvements In Column Extraction . 1990s: Need to upgrade radiochemistry methods at SRS Methods developed and implemented

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Rapid Extraction Methods for the Process Laboratory

S. L. Maxwell, III

V. D. Jones

S. T. Nichols

J. Satkowski

M. A. Bernard

Westinghouse Savannah River Site


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Improvements In Column Extraction

  • 1990s: Need to upgrade radiochemistry methods at SRS

  • Methods developed and implemented

  • Rapid Column Extraction Applications at SRS

    • Pu, Np, U, Am, Th, Sr, Tc-99 for waste and process solutions at SRS (tandem methods)

      • E. Philip Horwitz, S.L. Maxwell et al., Analytica Chimica Acta, 310, 63, (1995).

        • TEVA+ UTEVA+ TRU sequential methods

        • Applied primarily to waste tank samples


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Improvements In Column Extraction

  • Upgraded process laboratory methods in 1996

    • Pu and Np by alpha spectrometry

    • U by laser phosphorescence

    • Pu and U actinide isotopics—TIMS

  • S.L. Maxwell III, “Rapid Actinide-Separation Methods”, Radioactivity and Radiochemistry, 8, No 4, 36, (1997)

    • Pu-TEVA (valence-ferrous sulfate/sodium nitrite)

    • Np-TEVA (valence-ferrous sulfamate + ascorbic acid)

    • U on UTEVA (valence-ferrous sulfamate)

    • Dual column TEVA+ UTEVA cartridge (valence-ferrous sulfate/sodium nitrite)


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Improvements In Column Extraction

  • Expanded to characterization of metals/oxides:

    • UTEVA method for Pu/U oxides (Impurity assay in mixed oxide or actinide process solutions—1998-1999)

    • Trace actinides in mixed oxide materials (Np, Th, Am extraction for ICP-MS using TEVA, UTEVA—1998-1999)

    • New UTEVA method for Pu and U-Isotope Dilution Mass spectrometry in mixed oxides (strip Pu separately using 3M HNO3-0.2MHF) -(2000)


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UTEVA Pu/U Separation for IDMS Assay by TIMS

  • Currently: Pu isotopics on TEVA; U on UTEVA

  • For mixed U/Pu solutions requiring assay/isotopics, combine on UTEVA

  • Approach:

    • Load on UTEVA

    • Strip Pu first using 3M HNO3-0.2M HF, then strip U with 0.02M HNO3-0.005M HF.

    • Reduces labor costs and improves productivity


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UTEVA Pu/U Separation for IDMS Assay by TIMS

  • 1 mL UTEVA resin

  • U-233 (140 ug) and Pu-244 (0.7 ug) spiked samples

  • Load solution: 5 mL 2.5 M HNO3-0.5M Al (NO3) 3

  • Valence adjustment to Pu (IV) with ferrous sulfate/nitrite

  • Column rinse: 13 mL 3M HNO3

  • Pu strip: 5 mls 3M HNO3 -0.2M HF (ash well to remove F)

  • U strip: 5 mL 0.02M HNO3 -0.005M HF


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Np, Th in Mixed Oxide by ICP-MS

  • Material dissolution by microwave

  • Dilution in glove box; separation in radiohood

  • Np and Th on 1 mL TEVA resin

    • Load solution 2.5M HNO3-0.5M Al(NO3) 3

    • Reduce Pu to Pu+3: ferrous sulfamate + ascorbic acid

    • 3M HNO3 rinse

    • Pu +3 / U +6 not retained on TEVA

    • Strip Np+Th together using 5 mL 0.02M HNO3-0.005M HF

  • Use 2nd TEVA column to remove nearly all U+Pu

  • Dilute and analyze by ICP-MS

  • 95%+ recovery


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UTEVA Pu/U Removal for Metals Assay

  • Background

  • AG MP-1 Anion resin for Pu removal prior to ICP-AES/MS of impurities in metal/oxides to removal spectral interference:

    • Problem: at least partial retention of Au, Ag, Pt, Ir, Pd, Nb, Tl, La, Ce and Ta on anion resin

    • Increased need to analyze mixed Pu/U materials requiring Pu/U removal

  • UTEVA resin offers improved impurity recovery and removes both Pu and U


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UTEVA Pu/U Removal Method

  • UTEVA resin (diamylamylphosphonate)

    • Recovers all impurities except Au*

    • Zr, Ta, Hf, Nb require dilute HF in column load (and/or rinse) solution

    • Handles Pu, U or Pu/U mixtures

    • Large 10 mL columns remove 200 mg or more of Pu/U

      * Au done by dilute HCL-HF cation method


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UTEVA Pu/U Removal Method for Impurities Assay

  • Glove box separation for Pu materials

  • Load solution: 10 mL 8 M HNO3-0.04M HF

  • Column rinse: 14-19 mLs 8M HNO3 (optional with HF)

  • Adjust to 25 or 30 mL in graduated tube

  • Pu/U recovery from resin: 20 mL 0.1M HCl-0.05M HF

    Note:

    • No HF in rinse to enhance Pu retention; still adequate recovery of Zr, Ta, Hf, Nb

    • May increase HF with U only to increase Ta, etc., but minimize to minimize Si background at ICP-torch due to HF

    • Load solution can be larger

    • HF in rinse may be necessary if HF is less in load solution


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Average Column Spike RecoveriesICP-AES

Ag 92 Hf 84 Se 101

Al 99 Hg 69 Si 151

As 90 K 87 Ta 69

B 100 La 100 V 98

Ba 100 Li 97 W 106

Be 98 Mg 105 Zn 101

Ca 94 Mo 98 Zr 63

Cd 96 Na 105

Ce 103 Nb 99

Cr 102 Ni 101

Cu 98 P 161

Fe 106 Pb 84

Ga 104 S 97

Element % Recovery Element % Recovery Element % Recovery


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Average Column Spike RecoveriesICP-MS

Ag 106 Hf 90 Se 87

Al 101 Hg 77 Si 132

As 88 K 102 Ta 84

B 89 La 108 V 104

Ba 106 Li 101 W 113

Be 90 Mg 103 Zn 91

Ca NA Mo 101 Zr 63

Cd 94 Na 98

Ce 108 Nb 98

Cr 103 Ni 103

Cu 106 P 154

Fe 106 Pb 99

Ga 101 S NA

Element % Recovery Element % Recovery Element % Recovery


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Analysis of CRM-124 Uranium Oxide Standards

Al 102 105 (81-120) -3%

Be 11.6 12.5 (10-17) -7%

Cr 55.4 52 (50-64) +6%

Mg 52.4 51 (37-86) +3%

Mo 53.7 50 (30-50) +7%

Na 230 200 (189-252) +15%

Ni 106 102 (92-158) +4%

V 24.2 25 (23-30) -3%

W 105 100 (86-95) +5%

Zn 110 102 (75-115) +8%

Zr 108 100 (67-100) +8%

measured = single solution analyzed once by ICP-AES and ICP-MS

Measured Ref. Prepared Value/

Element (ppm) dc arc range (ppm)%Difference


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Am in Mixed Oxide by ICP-MS

  • Use solution (8M HNO3) from initial UTEVA resin separation (10 ml resin) for metal impurities

    • No retention of Am on UTEVA resin

  • Remove traces of uranium and plutonium using 2 ml UTEVA column

    • 2 mL aliquot

    • 8 mL 8M HNO3 column rinse

  • Dilute to low acid

  • Analyze by ICP-MS


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Summary

  • Process column methods

    • Faster and more rugged

    • Reduced labor costs

    • Better accuracy and precision

    • Reduced rework

    • No mixed waste solvents