New Fecal Method for Plutonium and Americium at

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. 5 M to 1 M HCL-0. 1 M to 0. 2 M HF • Redissolve any solids that precipitate in 0. 5 M HCL-O. 25 M H 3 BO 3 • Add 1. 5 M Ascorbic Acid (Reduce Fe) • Load HCl-HF and HCl- H 3 BO 3 fractions separately Rinse 1 20 m. L 0. 5 MHCL-0. 25 M HF Rinse 2 10 m. L 0. 5 MHCL Rinse 3 20 m. L water 2. 4 m. L Diphonix Resin

Method Digestion Details • Microwave Digestion of Diphonix Resin – Microwave to 190 C for 15 minutes in 10 m. L 16 M HNO 3 – Change disk/microwave to 200 C for 20 minutes in 10 m. L 16 M HNO 3 – Change disk/ microwave to 215 C for 25 minutes in 10 m. L 16 M HNO 3 – Add 3. 5 m. L 30 wt% H 2 O 2 & microwave to 21 O C for 10 minutes in 10 ml 16 M HNO 3 • Final wet ashing of Resin – Ash with 30 wt% 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 m. Ls of 5 M to 6 M HNO 3 – Add 6 m. Ls 2 to 2. 5 M aluminum nitrate – Solution ready for TEVA + TRU Resin column extraction • Preparation for Pu, Am column separation – Valence adjustment for Pu 1) Add 1 m. L 1. 5 M ferrous sulfate + 1 m. L 1. 5 M ascorbic acid, wait 3 min. 2) Add 1 m. L 3. 5 M to 4 M sodium nitrite

Pu, Am Column Separation • Separate Pu using TEVA column – Th removal 9 M HCl+8 M HCl – Use 2 nd 1 m. L TEVA column to remove all Th-228 – High retention/good clean-up • Separate Am using TRU column – – – Collect load plus rinse from 1 st TEVA column Evaporate to dryness Redissolve in 15 mls 3 M HNO 3 Add 2 m. Ls 1. 5 M sulfamic acid + 5 mls 1. 5 M ascorbic acid Load to TRU resin

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

Pu on TEVA RESIN (2 nd Column to Remove all Th-228) • Redissolve in 7. 5 m. L 3 M HN 03 + 1 m. L 2. 5 M Al(NO 3)3 • Add 0. 5 m. L 1. 5 M Ferrous Sulfate + 1 m. L 1. 5 M Ascorbic Acid • Add 1 m. L 3. 5 M Sodium Nitrite • Add 1 m. L 16 M Nitric Acid Rinse 10 m. L 3 MHN 03 Th Removal 2 m. L 9 MHCI/8 m. L 8 MHCI Pu Elution 15 m. L 0. 10 MHC 1 - 0. 05 MHF - 0. 1 M NH 4 l 1 m. L 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 : 1. 5 -4 grams ash/ Pu-242 spike= 1. 26 dpm TEVA column+ 2 nd 1 m. L TEVA column %Pu-242 Recovery Fecal blank 1 A Fecal blank 1 B Fecal blank 2 Fecal blank 3 A Fecal blank 3 B Fecal blank 4 Avg. Column Reagent blank Avg. %Am-243 Recovery 75. 3 68. 5 72. 1 75. 6 79. 3 78. 4 74. 9 91. 5 103. 1 81. 5 89. 2 95. 8 100. 8 93. 7 74. 4 82. 8 78. 6 90. 8 89. 8 90. 3

Assay of of DOE-RESL Fecal Standards RESL Stds. Picocuries RESL Ref. Values Picocuries SRS Measured Values 1 std. dev Bias vs. RESL Bewteen Dups. SR-194 SR-234 Pu-239 #1 #2 2. 18 1. 860 1. 841 Avg -14. 7% -15. 6% 1. 850 -15. 1% 1. 0% Am-241 #1 #2 2. 76 2. 405 2. 608 Avg -12. 8% -5. 5% 2. 507 -9. 2% 10. 1% Pu-239 SR-234 #1 #2 2. 13 2. 062 2. 139 Avg -3. 2% 0. 4% 2. 101 -1. 4% 3. 9% Am-241 #1 #2 2. 70 2. 488 2. 335 Avg -7. 8% -13. 5% 2. 411 -10. 7% 7. 7% DOELAP Bias Criteria: -25% to +50% DOELAP Standard Deviation Criteria: <40% % Std. Dev.

Sr in Fecal Samples Approach • Collect rinses from Diphonix columns • Evaporate/Dissolve in 8 M HNO 3 • Separate on Sr-Resin Preliminary Results • 90% recovery on spiked samples • Good precision on DOELAP samples

DOELAP SR RESULTS Samples Blanks Spike Added Measured Recovery (p. Ci) 1) 2) 3) 4) 5) 6) 258 285 287 244 253 Avg. Stdev 0. 98 0. 78 1. 32 0. 44 263 6. 9% (p. Ci) 194. 5 178. 7 91. 8 91. 9 0. 88 41. 6% 178. 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