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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

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Rapid extraction methods for the process laboratory l.jpg

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

Ag92 Hf84 Se101

Al99 Hg69 Si151

As90 K87Ta69

B100La100V98

Ba100Li97W106

Be98Mg105Zn101

Ca94Mo98Zr63

Cd96Na105

Ce103Nb99

Cr102Ni101

Cu 98P161

Fe106Pb84

Ga104S97

Element% Recovery Element % RecoveryElement% Recovery


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Average Column Spike RecoveriesICP-MS

Ag106Hf90 Se87

Al101Hg77 Si132

As88K102Ta84

B89La108V104

Ba106Li101W113

Be90Mg103Zn91

CaNAMo101Zr63

Cd94Na98

Ce108Nb98

Cr103Ni103

Cu106P154

Fe106Pb99

Ga101SNA

Element% Recovery Element% Recovery Element % Recovery


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Analysis of CRM-124 Uranium Oxide Standards

Al102105 (81-120)-3%

Be11.612.5 (10-17)-7%

Cr55.4 52 (50-64)+6%

Mg52.4 51 (37-86)+3%

Mo53.7 50 (30-50)+7%

Na230 200 (189-252)+15%

Ni 106102 (92-158)+4%

V 24.2 25 (23-30)-3%

W105 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

MeasuredRef. 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


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