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