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 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)

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

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

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

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

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

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

Column Loading

Column Stripping Strip with 4M HCL-0.15% H2O2 Wait 36 hours and load to Ln/DGA

Ln/DGA Resin Separation

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

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

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.

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

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

Spiked Groundwater sample-1 liter FWHM=81.6

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

Summary Ra-226 and Ra 228 using MnO2 resin Vacuum Box method Benefits 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