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Rapid Actinide Analysis for Large Soil Samples Sherrod L. Maxwell, III Westinghouse Savannah River Company.

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Presentation on theme: "Rapid Actinide Analysis for Large Soil Samples Sherrod L. Maxwell, III Westinghouse Savannah River Company."— Presentation transcript:

1 Rapid Actinide Analysis for Large Soil Samples Sherrod L. Maxwell, III Westinghouse Savannah River Company

2 Background Need for improved analysis of large soil samples for actinides –large sample size - lower detection limits –total dissolution-refractory actinides –minimize problems with column load solutions –removal of soil matrix interferences –consistency in tracer recoveries –good alpha peak resolution

3 Recent Work Using Actinide Resin (Dipex) and Diphonix Resin Actinide Resin and Diphonex Resin –W.C. Burnett et al, "Preconcentration of Actinide Elements from Soils and Large Volume Water Samples Using Extraction Chromatography". Journal of Radioanalytical & Nuclear Chemistry. Vol. 226, (May 1997), –W.C. Burnett et al, Efficient Preconcentration and Separation of Actinide Elements from Large Soil and Sediment Samples, Analytical Chemistry, Vol. 72, pp (2000) Diphonex Resin –S.L. Maxwell and S. Nichols, “Actinide Recovery Method for Large Soil Samples”, Radioactivity and Radiochemistry Journal (January, 2001)

4 Actinide Resin/Diphonix Resin-Soil Eliminated soil matrix but still had some disadvantages: –Actinide Resin/Diphonix Resin (Burnett) high phosphate -HEDPA solvent destruction (Fenton’s Reagent)- large TRU column Fe in Fenton’s reagent -can’t stack TEVA+TRU cartridges –Diphonix (Maxwell)-requires microwave dissolution of resin microwave work takes time/ can be tedious using HEDPA strip instead of microwave on fecal samples Pre-concentration steps take time and can have losses Need a simple, user-friendly, effective approach

5 New Soil Method Cerium fluoride precipitation for soil matrix removal CeF3 used for high iron water samples M. Schultz et al, “Analysis of Am, Pu and Th in Large Volume Water Samples in the presence of High Concentrations of Iron”, International Radiochemical Analysis Conference, Maidstone, Kent, UK, Sept Rapid elimination of soil matrix problems Rare earth removal for large soil samples anyway-no extra separation time

6 Benefits Faster –After drying, blending, overnight furnace: –1 day sample preparation + 1 day column extraction –Previous method 4-5 days Total dissolution (5-10 grams) High recoveries/clean spectra Eliminates interferences (Ex. Th, Po) –Th-228 on Pu-238, Am-241, etc –Po-210 affecting U-232

7 Soil Sample Preparation Total dissolution and matrix removal (1 day) –After drying and blending, heat at 550C –Ash with nitric acid/HF to remove silicon, then fusion –Fusion in zirconium crucibles for 20 minutes at 700C 10 grams sodium peroxide + 5 grams sodium hydroxide (or as needed for larger samples) –Hydroxide precipitation Iron carrier with TiCl3 reductant Barium to eliminate carbonate interference Additional Ce carrier sometimes added here for very sandy samples to enhance precipitation

8 Soil Sample Preparation, contd. –Redissolve in dilute HCl and perform cerium fluoride precipitation (1 mg to ~5 mg Ce) with TiCl3 present –Rinse precipitate with 0.25M HCl- 6MHF with 0.02M rongalite present –Soil load solution: 5 mLs 3M HNO3-0.25M boric acid 6 mL 7M HNO3 7.5 mL 2M AL(NO3)3

9 Transfer to crucible after silicon removal

10 10 grams sodium peroxide + 5 grams sodium hydroxide 700C for 20 minutes

11 Just add water after cooling briefly

12 Dilute to 1 liter with water with iron carrier, TiCl3, and barium present

13 After centrifuging, acidify and add TiCl3, Ce and HF.

14 Place on ice, then centrifuge

15 Rinse with dilute HCl, HF with rongalite present

16 Redissolve in acid, boric acid and aluminum nitrate

17 TEVA +TRU Resin-Stacked Cartridges

18 Actinides in Soil Rinse Beaker rinse: 3mL 5MHN0 3 Separate cartridges: TEVA: 5 mL 3MHN0 3 Collect/acidify - with 2 mL16M HN0 3 then to TRU TEVA:10 mL5M HNO 3 8 mL3M HN0 3 Th Elution 20mL 9MHCI Pu (and/or Np) Elution 20mL 0.10MHCl MHF M TiCl3 1)Redissolve in 18.5 mL 3M HN M Al(NO 3 ) M boric acid 2)Add 0.5 mL 1.5M Sulfamic Acid mL 1.5M Ascorbic Acid 3)Add 1 mL 3 M Sodium Nitrite Remove TRU cartridge: 1) Elute Am with 15mL 4M HCI 2) Add 3M HNO3 rinse from TEVA 3) 10 mL 6M HNO3 -remove any Po-210 4) 15 mL 4M HCl-0.2M HF-remove Th 5)Elute U with 15mL 0.1M ammonium bioxalate 2mL TEVA Resin ( um) 2.0mL TRU-Resin (3mL if needed) ( um) Cerium fluoride / Alpha spectrometry Alpha spectrometry Cerium fluoride Add 0.5 mL 30 wt% H2O2

19 Am/RE Removal on TEVA Rinse Beaker rinse: 3mL 4M NH 4 SCN, warm 10 mL 1.5 M NH 4 SCN to column Am Elution 25 mL 1M HCl (warm and rinse original beaker) 1)Evaporate 4M HCl with 5mL con.HNO3, 50 uL of 1.8M H2SO4, then ash with nitric acid and hydrogen peroxide 2)Redissolve in 5 mL of 4M NH 4 SCN, warm gently. 2mL TEVA Resin ( um) Alpha spectrometry Cerium fluoride

20 Final Am Clean-up on TEVA

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24 QAP 0309-SOIL SRSEMLRatio Pu Pu Am U U Results in Bq/kg 5 gram sample analyzed

25 QAP 0403-SOIL SRSEMLRatio Pu Pu Am U U Results in Bq/kg 5 gram sample analyzed

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28 Summary Large sample size Total dissolution –fast fusion, multiple samples Removal of soil matrix interferences –Cerium fluoride precipitation Reduced sample preparation time by 2 days Good tracer recoveries and alpha peak resolution Reduced spectral interferences


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