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Ra in Water using MnO2 Resin: New Developments

Ra in Water using MnO2 Resin: New Developments. Sherrod L. Maxwell, III Westinghouse Savannah River Company. Need for Improved Method for Ra-226, 228 in Groundwater Samples. Cation Resin experience slow flow-1 to 2 days load time potential calcium interference 1 pCi/L MDA required

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Ra in Water using MnO2 Resin: New Developments

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  1. Ra in Water using MnO2 Resin: New Developments Sherrod L. Maxwell, III Westinghouse Savannah River Company

  2. Need for Improved Method for Ra-226, 228 in Groundwater Samples • Cation Resin experience • slow flow-1 to 2 days load time • potential calcium interference • 1 pCi/L MDA required • need large sample aliquot (1.5L) for Ra-228 via Ac-228 (gas proportional counting) • Test MnO2 Resin developed by PGRF (Horwitz et al) and W. Burnett et al (FSU)

  3. Ra-226 and Ra-228 in Water • MnO2 Resin from Eichrom • 1.25 g MnO2 Resin • 1.5 liter samples + Ba-133 tracer • pH adjustment to 6-7 • Flow rate ~20 mL/min • Vacuum box loading with inner liner • ~ 1.5 hour loading • speed & ability to deal with slow samples

  4. Ra-226 and Ra-228 in Water • Initial testing • Strip MnO2 with 20 mL 2M HCL-1% H2O2 • evaporated and redissolved in 0.075M HCL • Hold >30 hrs for Ac-228 ingrowth • Ln-Resin tests • 10 mL 0.075M HCL load + 5 mL 0.075M beaker rinse • 10 mL 0.090M HCl Rinse • 15 mL 0.35M HNO3 strip • Had some inconsistencies that seemed related to Mn in load solution • Instead, strip MnO2 with 15 mL 4M HCL-1.5% H2O2 and use…….

  5. Ac-228 on DGA Resin • TRU (1 mL) + DGA-Normal (2mL) stacked • TRU (U,Th removal) and DGA (Ac-228 retention) • No impact from Mn on Ac-228 recovery • loaded 15 mL strip solution from MnO2 resin on TRU-DGA • collect load + 5 mL 4M HCL rinse for Ra-226 • 10 mL 4M HCL rinse-discard • Discard TRU Resin • Strip Ac-228 from DGA with 10 mL 0.5M HCl • 100 uL Ce and 1 mL con. HF • Consistent high recoveries of Ac-228

  6. Slide- E. P. Horwitz, May, 2004 User’s Meeting

  7. Slide- E. P. Horwitz, May, 2004 User’s Meeting

  8. Ra-226 and Ra-228 in Water • Evaporate load + rinse solutions from TRU-DGA • Redissolve in 0.075M HCl • Precipitate Ra-226 (Ra-224) using Ba sulfate • 100 uL of 0.70 mg/mL Ba + 3 mL 40% sodium sulfate + 4 drops 1:1 acetic acid/place on ice • 0.1 mL seeding suspension • Count Ra-226 (Ra-224) by alpha spectrometry • Count filter by gamma for Ba-133 tracer recovery

  9. Column Loading

  10. Column Stripping

  11. Column Fully Stripped Collect 4M HCL-0.15% H2O2 and load to DGA

  12. TRU/DGA Resin Separation

  13. Ba-133 Recovery on MnO2 Resin 1 g MnO2 1.25 g MnO2 81% 94% 85% 90% 87% 90% 95% 92% Avg. 87% 91% Ba-133=1040 pCi in 1.5 L groundwater samples @ 20 mL/min.

  14. Ra-228 by Ac-228 on DGA % Recovery % Recovery Ba-133 Ra-228 LCS (spiked DI H2O) 62% 98.0% River smp 108% N/A River smp spk 95% 99.0% River smp spk 100% 86.5% River smp 102% N/A River smp spk 106% 84.3% River smp spk 93% 107.9% Avg = 95.1%±10.1% Ba-133= 1040 pCi, 1.5L sample, 67.8 pCi Ra-228@ 20 mL/min.

  15. Ra-226/228 Recoveries % Recovery % Recovery % Recovery Ba-133 Ra-226 Ra-228 LCS (spiked DI H2O) 60% 106.2% 108.6% River smp 108% N/A N/A River smp spk 95% 102.7% 110.2% River smp spk 100% 103.1% 93.7% Avg = 104 % 104% 1.5 L samples Ba-133=1040 pCi Ra-226 spk= 5 pCi Ra-228 spk= 20 pCi Initial Ra-228/Ac-228 using Ln-Resin low/ waited 30 hr/used DGA

  16. Spiked river water sample-1500 mL Ra-226 and Ra-228 daughters

  17. Ra-226 in Groundwater % Recovery % Recovery Ba-133 Ra-226 Blank (DI H2O) 86.3% N/A LCS (spiked DI H2O) 88.6% 104% Grndwater smp 87.3% N/A Grndwater smp spk 88.6% 87.3% Grndwater smp 92.4% N/A Grndwater smp spk 92.7% 89.1% Tapwater smp 84.6% N/A Tapwater smp spk 91.2% 94.6% Avg.= 89.0% Avg = 93.8% ±6.9% • Ba-133= 1040 pCi, 500 mL sample, 5 pCi Ra-226 + 25 mg Ca, @ 15 mL/ min.

  18. Spiked Groundwater sample-500 mL

  19. Summary • Ra-226 and Ra 228 using MnO2 resin • Ra-226 using barium sulfate micro-precipitation • TRU/DGA Resin -Ra-228 via Ac-228 • Speed and selectivity • Vacuum Box method • Rapid flow rates • 1.5 L loaded and stripped < 2 hours • Benefits • Fast, easy separation (<1 hr loading for 500 mL groundwater sample) • Consistent • Increased productivity

  20. Acknowlegments • Eichrom-Larry Jassin and Anil Thakkar • W. Burnett et al, MnO2 Resin • PGRF- E.P. Horwitz et al • DGA and MnO2 • Joyce Ray, SRS, lab technician

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