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Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides)

Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides). Sherrod L. Maxwell, III Westinghouse Savannah River Company. Recent Improvements. Ni-63 in water method increase Ni Resin capacity for gravimetric recovery I-129 in water method adapt to vacuum box for rapid flow

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Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides)

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  1. Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides) Sherrod L. Maxwell, III Westinghouse Savannah River Company

  2. Recent Improvements • Ni-63 in water method • increase Ni Resin capacity for gravimetric recovery • I-129 in water method • adapt to vacuum box for rapid flow • Actinides • TEVA+ TRU for waters, air filters, vegetation, soils • Pu+Np in same fraction • Less Th and Po-210 problems • New soil method • Alpha resolution: Am/Cm and Th w/o ashing

  3. Ni-63 in Water • Ni resin columns limited in Ni capacity (3 mg ) • Need more Ni capacity for reliable gravimetric carrier recovery • Ni carrier limited to ICP levels • Ni-dimethylglyoxime complex bleeds off resin • Adjust pH to 10 instead of 8-9 for higher retention • Added prefilter cartridge to catch bleed-off • Can use up to ~10 mg Ni carrier • Used 8 mg Ni carrier: 10.21 mg NiO

  4. Ni-63 in Water Evaporation Sample loading

  5. Load complete, Ni complex color at bottom of column During column rising: Ni complex bleed-off caught on prefilter cartridge

  6. Ni column stripping Evaporate/ash NiO

  7. Ni Cartridge Option Ni Resin cartridges instead of columns + disposable reservoirs

  8. 10 mg Ni carrier

  9. Ni-63 Method Data 300 mL groundwater samples Ni-63 Spk= 50 pCi Ni carrier = 10.21 mg NiO NiO Recovery 99.9 % 98.9 % 98.9 % 97.9 % 101.9% 99.9 % 97.4 % 98.9 % 98.9 % Ni-63 Spk Recovery 92.0 % 97.2 % 89.5% 90.4 % avg = 92.3 % (3.4% rsd) LCS SMP-1 SMP-2 DUP SMP-3 MS SMP-4 SMP-5 MS SMP-6 SMP-7 MS BLK

  10. I-129 Method • 1 pCi/L MDA; 1.5 liter samples • pH adjust /reduce to iodide ion with NaHSO3 • Anion exchange-1X8, 100-200 mesh • Flow rate ~25 mL/min • Vacuum box loading with inner liner • ~ 1 to 1.5 hour loading • speed & ability to deal with slow samples • Resin to petri dish • Low energy x-ray

  11. I-129 Method Data Typical batch of 1.5L samples I-129 Standard Added Measured LCS =16.7 pCi/L 15.5 pCi/L MS = 16.7 pCi/L 16.0 pCi/L % Recovery LCS 93% % Recovery MS 96%

  12. TEVA-TRU Separations(Pu, Np, Am, Cm, U)

  13. Alpha Resolution Improvements • Resolve™ filters-Eichrom • reduced FWHM, from about 50-60 keV to about 40-50 keV • eliminated a lot of filter problems and rework from “bad” lots of filters from other suppliers • Strong HCl causes more extractant bleed-off • added small, 3M nitric rinse after strong HCL Th removal and before Pu strip from TEVA • added small, 3M nitric rinse after strong HCL Th removal and before U strip from TRU Resin • What about Am-Cm and Th strong HCl solutions containing organic? • Had tried Am/Cm micro-precipitation from 4M HCL with extra HF and no ashing but too often had poor resolution/rework

  14. Alpha Resolution Improvements • Am/Cm and Th HCL strip solutions contain organic bleed-off that can affect alpha peak resolution • Ashing takes time • Th samples (3-4 hrs) and Am/Cm samples (2-3 hrs) • Prolongs sample preparation • Solution: • Use prefilter cartridges when stripping Th or Am/Cm • No ashing required • Dilute Am/Cm to 30 mL with water + 3mL con HF • Dilute Th to 45 mL + 5 mL con HF

  15. Resolution with Filters from “Bad” Lot

  16. Resolution with RESOLVE ™ Filters

  17. Resolve Filters-No Ashing

  18. Resolve Filters-No Ashing

  19. Summary • Ni Resin • Ni capacity expanded using prefilter resin • gravimetric carrier • I-129 method-vacuum box • reduced loading times • TEVA-TRU Separations for all matrices • Eliminated cerium fluoride filter problems • Am/Cm and Th alpha resolution-no ashing/prefilter cartridge

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