1 / 19

Ra in Water using MnO2 Resin: Update

Ra in Water using MnO2 Resin: Update. 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

Jims
Download Presentation

Ra in Water using MnO2 Resin: Update

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ra in Water using MnO2 Resin: Update 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 (1L) 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 • 1.25 g MnO2 Resin (Eichrom) • 1 liter samples + Ba-133 tracer • pH adjustment to 6-7 / add 25 mg Ca • Flow rate ~15 mL/min • Vacuum box loading with inner liner • ~ 1-2 hour loading • speed & ability to deal with slow samples • Strip MnO2 with 12 mL 4M HCL-1.5% H2O2 • Wait 36 hours if analyzing Ra-228

  4. Ac-228 on DGA Resin • Ln Resin (2 mL) + DGA-Normal (2mL) stacked • Ln resin (U,Th removal) and DGA (Ac-228 retention) • loaded 12 mL strip solution from MnO2 resin on LN-DGA • collect load + 5 mL 4M HCL rinse for Ra-226 • 10 mL 4M HCL rinse-discard • Save LN Resin • Strip Ac-228 from DGA with 10 mL 0.5M HCl • 100 uL Ce and 1 mL con. HF

  5. Improvements • Use Ln -DGA Resin instead of TRU-DGA • better alpha resolution and consistency • even with large groundwater sample size • combines Ra-226 and Ra-228 sample preparation • Ac-228 on DGA (Ln Resin removes Th,U) • Ra-226 after repass through Ln-Resin at low acid

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

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

  8. Ra-226 in Water • Evaporate load + rinse solutions from Ln-DGA • Redissolve in 0.1M HCl • Pass solution through same Ln cartridges to better remove alpha resolution interferences • Precipitate Ra-226 (Ra-224) using Ba sulfate • 100 uL of 0.70 mg/mL Ba + 5 mL 30% sodium sulfate 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 Strip with 4M HCL-0.15% H2O2 Wait 36 hours and load to Ln/DGA

  11. Ln/DGA Resin Separation

  12. 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

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

  14. 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.

  15. Spiked Groundwater sample-500 mL Passed through TRU-DGA at 4M HCL evaporate and precipitate

  16. Better alpha resolution with repass through Ln-Resin after lowering acid to 0.1M HCL Spiked LCS-1 liter

  17. Spiked Groundwater sample-1 liter FWHM=81.6

  18. Ra-226 and Ra-228 in Groundwater % Recovery % Recovery % Recovery Ba-133 Ra-226 Ra-228 BLK 90% N/A N/A LCS (spiked DI H2O) 95% 99.2% 99.7% GRNDWATER smp 100% N/A N/A GRNDWATER smp 89% N/A N/A GRNDWATER smp 97% N/A N/A GRNDWATER SPK 95% 96.5% 101.2% Avg = 94% 97.8% 100.4% 1 L samples Ba-133=1040 pCi; Ra-226 spk= 5 pCi: Ra-228 spk= 20 pCi waited 36 hr/used Ln-DGA

  19. Summary • Ra-226 and Ra 228 using MnO2 resin • Ln/DGA Resin -Ra-228 via Ac-228 • Ra-226 using barium sulfate micro-precipitation • Speed and selectivity • Vacuum Box method • 1L loaded and stripped ~ 1.5-2 hours • Benefits • Fast, easy separation for both Ra-226, 228 • Short count for Ra-226 with large aliquot • Better alpha resolution

More Related