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 (9/1/99) Need for Improved Fecal Analysis for Pu and Am –Complete dissolution of any plutonium oxide present –Effective Th-228 removal Completed FB-Line incident samples Successful routine operation

New Approach Old method: –residual undissolved solids in final nitric acid solution –solids contained some activity New approach: –Use HNO 3 -HF dissolution/multiple digestions –Apply Diphonix Resin technology used successfully for large soil samples –Digest Diphonix using SRS microwave method –Apply Eichrom sequential column method

Actinide Retention on Diphonix Resin Ref: E. Philip Horwitz et al., Separation Science and Technology, 32, 1, (1977)

Performance on Large Soil Samples

Pu, Am on DIPHONIX RESIN Redissolve in 0.5M to1M HCL-0.1M to 0.2M HF Redissolve any solids that precipitate in 0.5M HCL-O.25M H 3 BO 3 Add 1.5M Ascorbic Acid (Reduce Fe) Load HCl-HF and HCl- H 3 BO 3 fractions separately Rinse 2 10mL 0.5MHCL Rinse 1 20mL 0.5MHCL-0.25M HF Rinse 3 20mL water 2.4 mL Diphonix Resin

Method Digestion Details Microwave Digestion of Diphonix Resin –Microwave to 190C for 15 minutes in 10 mL 16M HNO 3 –Change disk/microwave to 200C for 20 minutes in 10 mL 16M HNO 3 –Change disk/ microwave to 215 C for 25 minutes in 10 mL 16M HNO 3 –Add 3.5 mL 30wt% H 2 O 2 & microwave to 21O C for 10 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 one time, or until does not get any whiter

Pu, Am Column Separation 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

Pu, Am Column Separation 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 + 5 mls 1.5M ascorbic acid –Load to TRU resin

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

Pu on TEVA RESIN (2nd Column to Remove all Th-228) Redissolve in 7.5mL 3M HN mL 2.5M Al(NO 3 ) 3 Add 0.5mL 1.5M Ferrous Sulfate + 1mL 1.5M Ascorbic Acid Add 1mL 3.5M Sodium Nitrite Add 1mL 16M Nitric Acid Th Removal 2mL 9MHCI/8mL 8MHCI Rinse 10mL 3MHN0 3 Pu Elution 15mL 0.10MHC MHF - 0.1M NH 4 l 1mL TEVA Resin

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 DOE RESL-Idaho –Test plan to validate versus known Pu levels

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

Assay of of DOE-RESL Fecal Standards RESL RESL SRS Measured Bias vs. RESL % Std. Dev. Stds. Ref. ValuesValues Values Bewteen Dups. PicocuriesPicocuries 1 std. dev SR-194 # % # % SR-194Pu Avg %1.0% # % # % SR-194Am Avg %10.1% SR-234 # % # % SR-234Pu Avg %3.9% # % # % SR-234Am Avg %7.7% DOELAP Bias Criteria: -25% to +50% DOELAP Standard Deviation Criteria:<40%

Sr in Fecal Samples Approach Collect rinses from Diphonix columns Evaporate/Dissolve in 8M HNO3 Separate on Sr-Resin Preliminary Results 90% recovery on spiked samples Good precision on DOELAP samples

DOELAP SR RESULTS SamplesBlanks Spike Spike Spike AddedMeasuredRecovery (pCi) (pCi) (pCi) (pCi)(%) 1) ) ) ) )254 6)253 Avg Stdev6.9%41.6%0.11%

Summary New fecal method dissolves Pu oxide using HNO 3 -HF Column loading from HCl-HF sample solutions with no visible solids High recovery/accurate results/good Th-228 removal Sr-90 can also be assayed