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New Fecal Method for Plutonium and Americium at SRS

New Fecal Method for Plutonium and Americium at SRS. Sherrod L. Maxwell III and David Fauth Savannah River Site. Background. SRS Incident in FB-Line Need for Improved Fecal Analysis for Pu and Am Complete dissolution of any plutonium oxide present Effective Th-228 removal. New Approach.

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New Fecal Method for Plutonium and Americium at SRS

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  1. New Fecal Method for Plutonium and Americium at SRS Sherrod L. Maxwell III and David Fauth Savannah River Site

  2. Background • SRS Incident in FB-Line • Need for Improved Fecal Analysis for Pu and Am • Complete dissolution of any plutonium oxide present • Effective Th-228 removal

  3. New Approach • Old method: • residual undissolved solids in final nitric acid solution • solids contained some activity • New approach: • Continue to use HNO3-HF dissolution/multiple digestion • Apply Diphonix Resin technology • Used successfully for large soil samples • Allows loading from HCl-HF solutions • Digest Diphonix using SRS microwave method • Apply Eichrom sequential column method

  4. Method Details • Fecal sample preparation • Dry/weigh/flame/ash overnight • Weigh ash in glass beaker • Wet ash with HNO3, then H2O2, then HCl, then HNO3, then H2O2 • Wet ash with HNO3, then H2O2 until white or lavender • Dissolve in 10 mL 1MHCL-0.2M HF • Centrifuge, decant solution • Add 10 mL 0.5M HCL:-0.1M H3BO3 to solids, heat in teflon beaker • Centrifuge, decant solution-separate H3BO3 fraction

  5. Method Details • Fecal sample preparation, contd. • Heat in HNO3 +HCl+HF+ H2O2 /go to near dryness • Dissolve in 5 mL1M HCl-0.1M HF • Centrifuge, decant solution • Heat in HNO3 +HF+ H2O2 / go to near dryness • Dissolve in 5 mL 1M HCl-0.1M HF • Centrifuge, decant solution • Heat in HNO3 +HF/ go to near dryness • Centrifuge, decant solution • Repeat HNO3 +HF / and dissolve in 1M HCl-0.1M HF until completely dissolved. • Combine clear HCl-HF fractions. Keep separate clear H3BO3 fraction.

  6. Method Details • Actinide Preconcentration on Diphonix Resin • Add ascorbic acid to HCL-HF and boric acid sample solutions • Load HCl-HF sample aliquot to 2.4 ml Diphonix resin • Load boric acid sample aliquot to same Diphonix column • Rinse column with 10 mL 0.5M HCL-0.25M HF • Rinse column with 5 mL 0.5M HCl • Rinse column with 20 mL water

  7. Method Details • Microwave Digestion of Diphonix Resin • Microwave to 190C for 20 minutes in 10 mL 16M HNO3 • Vent & microwave to 22O C for 35 minutes in 10 mL 16M HNO3 • Add 3.5 mL 30wt% H2O2 & microwave to 21O C for 20 minutes in 10 ml 16M HNO3 • Final wet ashing of Resin • Ash with 30wt% H2O2 four times • Ash with HNO3 + H2O2 two times, or until does not get any whiter

  8. Method Details • Preparation for Pu, Am column separation • Dissolve in 6 mLs of 5M to 6M HNO3 • Add 6 mLs 2 to 2.5M aluminum nitrate • Solution ready for TEVA + TRU Resin column extraction • Preparation for Pu, Am column separation • Valence adjustment for Pu 1) Add 1 mL 1.5M ferrous sulfate + 1 mL 1.5M ascorbic acid, wait 3 min. 2) Add 1 mL 3.5M to 4M sodium nitrite

  9. Method Details • Separate Pu using TEVA column • Th removal 9M HCl+8M HCl • Use 2nd 1 mL TEVA column to remove all Th-228 • High retention/good clean-up • Separate Am using TRU column • Collect load plus rinse from 1st TEVA column • Evaporate to dryness • Redissolve in 15 mls 3 M HNO3 • Add 2 mLs 1.5M sulfamic acid + 2.5 to 3 mls 1.5M ascorbic acid • Load to TRU resin

  10. Pu, Am ON TEVA + TRU RESIN (FECAL METHOD)

  11. TEVA+TRU Pu/Am Tracer Recoveries Fecal samples : 1.5-4 grams ash/ Pu-242 spike= 1.26 dpm TEVA column+ 2nd 1 mL TEVA column %Pu-242 Recovery %Am-243 Recovery Fecal blank 1A 75.3 91.5 Fecal blank 1B 68.5 103.1 Fecal blank 2 72.1 81.5 Fecal blank 3 A 75.6 89.2 Fecal blank 3 B 79.3 95.8 Fecal blank 4 78.4100.8 Avg. 74.9 93.7 Column Reagent blank 74.4 90.8 Column Reagent blank 82.889.8 Avg. 78.6 90.3

  12. Method Validation • Analysis of multiple sample blanks • Complete dissolution • High tracer recovery • Good Th-228 removal • Analysis of artificial fecal sample spiked with Pu oxide from RESL-Idaho • Test plan to validate versus known Pu levels

  13. Summary • New fecal method dissolves Pu oxide using HNO3 -HF • Enables column loading from HCl-HF sample solutions with no visible solids • High recovery/good Th-228 removal • Diphonix technology compatible with fusion preparation as well (as demostrated with soil fusions)

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