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: mg NiO Ni-63 in Water Evaporation Sample loading Load complete, Ni complex color at bottom of column During column rising: Ni complex bleed-off caught on prefilter cartridge Ni column stripping Evaporate/ash NiO Ni Cartridge Option Ni Resin cartridges instead of columns + disposable reservoirs 10 mg Ni carrier Ni-63 Method Data LCS SMP-1 SMP-2 DUP SMP-3 MS SMP-4 SMP-5 MS SMP-6 SMP-7 MS BLK 300 mL groundwater samples Ni-63 Spk= 50 pCi Ni carrier = mg NiO NiO Recovery 99.9 % 98.9 % 97.9 % 101.9% 99.9 % 97.4 % 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, 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 AddedMeasured LCS =16.7 pCi/L15.5 pCi/L MS = 16.7 pCi/L16.0 pCi/L % Recovery LCS93% % Recovery MS96% TEVA-TRU Separations (Pu, Np, Am, Cm, U) Alpha Resolution Improvements Resolve filters-Eichrom reduced FWHM, from about keV to about 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 Resolution with Filters from Bad Lot Resolution with RESOLVE Filters Resolve Filters-No Ashing Summary Ni Resin Ni capacity expanded using prefilter resin gravimetric carrier I-129 method-vacuum box reduced loading times TEVA-TRU Separations for all matrices Eliminated cerium fluoride filter problems Am/Cm and Th alpha resolution-no ashing/prefilter cartridge