Presentation on theme: "Ra in Water using MnO2 Resin: New Developments Sherrod L. Maxwell, III Westinghouse Savannah River Company."— Presentation transcript:
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 –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)
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
Ra-226 and Ra-228 in Water Initial testing Strip MnO2 with 20 mL 2M HCL-1% H 2 O 2 –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% H 2 O 2 and use…….
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
Slide- E. P. Horwitz, May, 2004 Users Meeting
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
Column Fully Stripped Collect 4M HCL-0.15% H2O2 and load to DGA
TRU/DGA Resin Separation
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.
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 spk95%99.0% River smp spk100%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 20 mL/min.
Ra-226/228 Recoveries % Recovery % Recovery % Recovery Ba-133Ra-226Ra-228 LCS (spiked DI H2O)60%106.2%108.6% River smp 108%N/AN/A River smp spk95%102.7%110.2% River smp spk100%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
Spiked river water sample-1500 mLRa-226 and Ra-228 daughters