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 MnO g MnO2
81% 94%
85% 90%
87% 90%
95% 92%
Avg. 87% 91%
Ba-133=1040 pCi in 1.5 L groundwater 20 mL/min.

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

15. Ra-226/228 Recoveries % Recovery % Recovery % Recovery
Ba-133 Ra-226 Ra-228
LCS (spiked DI H2O) 60% % %
River smp 108% N/A N/A
River smp spk 95% % %
River smp spk 100% % 93.7% Avg = % %
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 % N/A
Grndwater smp spk 88.6% %
Grndwater smp % N/A
Grndwater smp spk 92.7% %
Tapwater smp % N/A
Tapwater smp spk 91.2% %
Avg.= 89.0% Avg = 93.8% ±6.9%
Ba-133= 1040 pCi, 500 mL sample, 5 pCi Ra mg 15 mL/ min.

18. Spiked Groundwater sample-500 mL

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