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Optimizing Radiochemical Methods at SRS

Optimizing Radiochemical Methods at SRS. Sherrod L. Maxwell, III Westinghouse Savannah River Company. Recent Improvements. SRS Environmental Monitoring lab new actinide methods for water, air filters, soil, sediments, sanitary sludge SRS Bioassay lab (with Dave Fauth)

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Optimizing Radiochemical Methods at SRS

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  1. Optimizing Radiochemical Methods at SRS Sherrod L. Maxwell, III Westinghouse Savannah River Company

  2. Recent Improvements • SRS Environmental Monitoring lab • new actinide methods for water, air filters, soil, sediments, sanitary sludge • SRS Bioassay lab (with Dave Fauth) • increased Pu-Np recoveries • faster fecal method (HEDPA-no microwave) • F/H Laboratory (Process lab) • faster single column separation for Pu/Np in high U samples (U-234 removal of 1E6)

  3. SRS Environmental Monitoring Lab • Stacked TEVA + TRU cartridges for all matrices • Replaced UTEVA+TRU • water samples • air filter samples • soil, sediments (up to 10 grams) • sanitary waste sludge (5 grams) • vegetation (10 grams) • fruit (100 grams)

  4. Advantages of TEVA+TRU • Pu, Np, Am, Cm, U (Th) in a single stacked column • Allows Pu and Np together on TEVA (Pu-236 tracer) • High retention of Pu, Np on TEVA • Higher retention of U on TRU vs. UTEVA • Better Po-210 removal (interferes with U-232) and Th removal • Removal of TEVA/removal on TRU if any residual

  5. Pu, Np, Am, Cm,U, Sr on TEVA/TRU RESIN (Water/Air filters) 1) Redissolve in 10-15 mL 3M HN03 - 0.5M to 1M Al(NO3)3 2) Add 0.5 mL 1.5M Sulfamic Acid + 1 mL 1.5M Ascorbic Acid 3) Add 1 mL 3 M Sodium Nitrite Th Elution 20mL 9MHCI Rinse 20 mL 3MHN03 Pu, Np Elution 20mL 0.10MHC1 - 0.05MHF - 0.03M TiCl3 Add 0.5 mL 30 wt% H2O2 2mL TEVA Resin (50-100 um) Cerium fluoride Remove TRU cartridge: 1) Elute Am with 15mL 4M HCI 2) 10 mL 4MHCL-0.2M HF to remove any Th 2) Elute U with 15mL 0.1M ammonium bioxalate Alpha spectrometry 2.0mL TRU-Resin (50-100 um) Collect, evaporate, dissolve in 8M HNO3 Sr Resin

  6. Alpha Resolution Improvements • Strong HCL can cause extractant bleed-off • TEVA: 5 mL 3M HNO3 rinse after 9M HCL Th removal rinse prior to stripping Pu and Np • TRU: • 4M HCL extractant bleed-off affects resolution (worse with 9M) • We have gone back to evaporating 4M HCl with con HNO3 and 100 uL of 1.8M H2SO4, then ash with con HNO3 and H2O2, redissolve in 0.5M HCL • 3M HNO3 rinse after 4M HCl-0.2M HF rinse • UTEVA/TRU: • Using 9M HCl with UTEVA or TRU can affect bleed-off and peak resolution/not needed

  7. Total DissolutionSoil, Sediments, Sludge • Actinides in soil, sediment and sanitary sludge samples • 5 to 10 gram soil • 5 gram sanitary sludge • Replaced fusion method which had poor recoveries, load solution problems, and Po-210 problems • Total Dissolution • sodium peroxide/sodium hydroxide fusion (15-20 minutes) • multiple samples fused at once in furnace • inexpensive zirconium crucibles

  8. Total DissolutionSoil, Sediments, Sludge, contd. • Total Dissolution and matrix removal (1 day) • soils: heat at 550C, then nitric acid/HF silicon removal first, then fusion • sanitary sludge: heat at 550C, then fusion • fusion in zirconium crucibles for 20 minutes at 700C • 10 grams sodium peroxide/5 grams sodium hydroxide • Hydroxide precipitation with TiCl3 reductant and barium present to eliminate carbonate interference

  9. Total DissolutionSoil, Sediments, Sludge, contd. • Redissolve in dilute HCl and perform cerium fluoride precipitation (500 ug to 2 mg Ce) with TiCl3 present • Rinse precipitate with 0.25M HCl- 6MHF with 0.02M rongalite present • Soil load solution: 5 mLs 3M HNO3-0.25M boric acid, 6 mL 7M HNO3, 7.5 mL 2M AL(NO3)3

  10. Transfer to crucible after silicon removal

  11. 10 grams sodium peroxide + 5 grams sodium hydroxide 700C for 20 minutes

  12. Just add water after cooling briefly

  13. Dilute to 1 liter with water with iron carrier, TiCl3, and barium present

  14. After centrifuging, acidify and add TiCl3, Ce and HF.

  15. Place on ice, then centrifuge

  16. Rinse with dilute HCl, HF with rongalite present

  17. Redissolve in acid, boric acid and aluminum nitrate

  18. Actinides in SOIL 1) Redissolve in 18.5 mL 3M HN03 - 0.8M Al(NO3)3- 0.07M boric acid 2) Add 0.5 mL 1.5M Sulfamic Acid + 1.25 mL 1.5M Ascorbic Acid 3) Add 1 mL 3 M Sodium Nitrite Rinse Beaker rinse: 3mL 5MHN03 Separate cartridges: TEVA: 5 mL 3MHN03 Collect/acidify - with 2 mL16M HN03 then to TRU TEVA:10 mL5M HNO3 8 mL3M HN03 Th Elution 20mL 9MHCI Pu Elution 20mL 0.10MHC1 - 0.05MHF - 0.03M TiCl3 Remove TRU cartridge: 1) Elute Am with 15mL 4M HCI 2) Add 3M HNO3 rinse from TEVA 3) 10 mL 6M HNO3 -remove any Po-210 4) 15 mL 4M HCl-0.2M HF-remove Th 5) Elute U with 15mL 0.1M ammonium bioxalate Add 0.5 mL 30 wt% H2O2 2mL TEVA Resin (50-100 um) Cerium fluoride Alpha spectrometry 2.0mL TRU-Resin (50-100 um) Cerium fluoride / Alpha spectrometry

  19. Am/RE Removal on TEVA 1) Evaporate 4M HCl with 5mL con.HNO3, 50 uL of 1.8M H2SO4, then ash with nitric acid and hydrogen peroxide 2) Redissolve in 5 mL of 4M NH4SCN, warm gently. Rinse Beaker rinse: 3mL 4M NH4SCN, warm 10 mL 1.5 M NH4SCN to column Am Elution 25 mL 1M HCl (warm and rinse original beaker) 2mL TEVA Resin (50-100 um) Cerium fluoride Alpha spectrometry

  20. Final Am Clean-up on TEVA

  21. QAP 0903-SOIL SRS EML Ratio Pu-238 14.9 14.6 1.021 Pu-239 31.6 30.4 1.039 Am-241 18.3 18.4 0.995 U-234 117.7 127.3 0.925 U-238 119.9 127.1 0.943 Results in Bq/kg 5 gram sample analyzed

  22. Bioassay Lab Improvements • Actinides and Sr-90 in urine • stacked TEVA+TRU Resin cartridges with vacuum boxes • Pu-236 tracer for Pu and Np at same time • Pu, Np (TEVA) and U, Am (TRU) • Sr (Sr Resin) • Pu stripping improvement: • Increased rongalite to 0.04M (sodium formaldehyde sulfoxylate) - • compatible with electroplating • adjust bisulfate added for sulfate added from rongalite decomposition (2.0 mLs 10 % bisulfate instead of 3 mLs)

  23. Bioassay Lab Urine MethodTracer Recoveries 2002 2003 2004 Pu 77.5 86.1 95.1 EU 80.6 83.4 87.4 Sr 82.7 80.1 82.2 Am 83.5 84.3 80.5 Np 76.6 87.1 94.4

  24. Recent Improvements in Fecal Method • HEDPA strip of Diphonix instead of microwave destruction (18 mL 0.5M HEDPA) • 45 minute hot plate destruction • 30 mL of 30 wt% H2O2 • Add 200 uL of 1.5M ferrous sulfate • 1 mL of concentrated HNO3 • Ash to dryness • Add 5 mL concentrated HNO3, ash to dryness • Add 5 mL 30 wt% H2O2, ash to dryness. Repeat 3 more times. • Faster than microwave, but requires more aluminum in load solution due to higher phosphate

  25. Process Lab Improvements • Process samples to support HEU Blenddown processing • Pu and Np are key product specification measurements • Pu-236 tracer for Pu and Np on TEVA resin in HEU and LEU process solutions • Improvements: • Single cartridge instead of two column method • use Ti (III) reductant in Pu strip from TEVA • Using 0.5mL 30wt% H2O2 instead of nitrite, much better oxidation of U+4 to U+6 • 1000 x removal of residual U in cerium fluoride precipitation • $100K savings-labor and materials

  26. Summary • SRS Environmental Monitoring lab work • TEVA+TRU for all matrices • Cerium fluoride matrix elimination • Bioassay lab • Improved Pu stripping using rongalite (95% recoveries) • HEDPA to eliminate microwave in fecal analysis (save 1-2 days) • Process lab • Single cartridge separation for Pu, Np in process lab on high uranium samples (cost/time savings) • Future work • Ra on MnO2 resin

  27. MnO2 Resin

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