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 HNO 3 -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 HNO 3, then H 2 O 2, then HCl, then HNO 3, then H 2 O 2 Wet ash with HNO 3, then H 2 O 2 until white or lavender –Dissolve in 10 mL 1MHCL-0.2M HF Centrifuge, decant solution –Add 10 mL 0.5M HCL:-0.1M H 3 BO 3 to solids, heat in teflon beaker Centrifuge, decant solution-separate H 3 BO 3 fraction

Method Details Fecal sample preparation, contd. –Heat in HNO 3 +HCl+HF+ H 2 O 2 /go to near dryness –Dissolve in 5 mL1M HCl-0.1M HF Centrifuge, decant solution –Heat in HNO 3 +HF+ H 2 O 2 / go to near dryness –Dissolve in 5 mL 1M HCl-0.1M HF Centrifuge, decant solution –Heat in HNO 3 +HF/ go to near dryness Centrifuge, decant solution –Repeat HNO 3 +HF / and dissolve in 1M HCl-0.1M HF until completely dissolved. Combine clear HCl-HF fractions. Keep separate clear H 3 BO 3 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 HNO 3 –Vent & microwave to 22O C for 35 minutes in 10 mL 16M HNO 3 –Add 3.5 mL 30wt% H 2 O 2 & microwave to 21O C for 20 minutes in 10 ml 16M HNO 3 Final wet ashing of Resin –Ash with 30wt% H 2 O 2 four times –Ash with HNO 3 + H 2 O 2 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 HNO 3 –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 HNO 3 –Add 2 mLs 1.5M sulfamic acid 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 : grams ash/ Pu-242 spike= 1.26 dpm TEVA column+ 2nd 1 mL TEVA column %Pu-242 Recovery%Am-243 Recovery Fecal blank 1A Fecal blank 1B Fecal blank Fecal blank 3 A Fecal blank 3 B Fecal blank Avg Column Reagent blank Column Reagent blank Avg

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 HNO 3 -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)