optimizing radiochemical methods at srs (ni-63, i-129, actinides)
DESCRIPTION
Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides). Sherrod L. Maxwell, III Westinghouse Savannah River Company. Recent Improvements. Ni-63 in water method increase Ni Resin capacity for gravimetric recovery I-129 in water method adapt to vacuum box for rapid flow - PowerPoint PPT PresentationTRANSCRIPT
Optimizing Radiochemical Methods at SRS (Ni-63, I-129, Actinides)
Sherrod L. Maxwell, III
Westinghouse Savannah River Company
Recent Improvements
• Ni-63 in water method– increase Ni Resin capacity for gravimetric recovery
• I-129 in water method– adapt to vacuum box for rapid flow
• Actinides– TEVA+ TRU for waters, air filters, vegetation, soils
• Pu+Np in same fraction
• Less Th and Po-210 problems
• New soil method
– Alpha resolution: Am/Cm and Th w/o ashing
Ni-63 in Water• Ni resin columns limited in Ni capacity (3 mg )
– Need more Ni capacity for reliable gravimetric carrier recovery
– Ni carrier limited to ICP levels
– Ni-dimethylglyoxime complex bleeds off resin
• Adjust pH to 10 instead of 8-9 for higher retention
• Added prefilter cartridge to catch bleed-off
• Can use up to ~10 mg Ni carrier
• Used 8 mg Ni carrier: 10.21 mg NiO
Load complete, Ni complex color at bottom of column
During column rising:Ni complex bleed-off caught on prefilter cartridge
Ni-63 Method Data
LCSSMP-1SMP-2 DUPSMP-3 MSSMP-4SMP-5 MSSMP-6SMP-7 MSBLK
300 mL groundwater samplesNi-63 Spk= 50 pCi Ni carrier = 10.21 mg NiO NiO
Recovery
99.9 %98.9 %98.9 %97.9 %101.9%99.9 %97.4 %98.9 %98.9 %
Ni-63 Spk Recovery
92.0 %
97.2 %
89.5%
90.4 %
avg = 92.3 % (3.4% rsd)
I-129 Method
• 1 pCi/L MDA; 1.5 liter samples• pH adjust /reduce to iodide ion with NaHSO3• Anion exchange-1X8, 100-200 mesh• Flow rate ~25 mL/min• Vacuum box loading with inner liner
– ~ 1 to 1.5 hour loading
– speed & ability to deal with slow samples
• Resin to petri dish• Low energy x-ray
I-129 Method Data
Typical batch of 1.5L samples
I-129 Standard Added Measured
LCS =16.7 pCi/L 15.5 pCi/L
MS = 16.7 pCi/L 16.0 pCi/L
% Recovery LCS 93%
% Recovery MS 96%
Alpha Resolution Improvements
• Resolve™ filters-Eichrom– reduced FWHM, from about 50-60 keV to about 40-50 keV– eliminated a lot of filter problems and rework from “bad” lots of
filters from other suppliers
• Strong HCl causes more extractant bleed-off– added small, 3M nitric rinse after strong HCL Th removal and
before Pu strip from TEVA– added small, 3M nitric rinse after strong HCL Th removal and
before U strip from TRU Resin
• What about Am-Cm and Th strong HCl solutions containing organic?– Had tried Am/Cm micro-precipitation from 4M HCL with extra
HF and no ashing but too often had poor resolution/rework
Alpha Resolution Improvements
• Am/Cm and Th HCL strip solutions contain organic bleed-off that can affect alpha peak resolution
• Ashing takes time– Th samples (3-4 hrs) and Am/Cm samples (2-3 hrs)– Prolongs sample preparation
• Solution:– Use prefilter cartridges when stripping Th or Am/Cm– No ashing required– Dilute Am/Cm to 30 mL with water + 3mL con HF– Dilute Th to 45 mL + 5 mL con HF