Rapid Determination ofActinides in Soil Samples

AN-1430
Summary of Method
Actinides are separated and measured from 1-2g samples of soil. Soil samples arefused in zirconium crucibles with sodium hydroxide. Sequential precipitations remove matrix prior to separation ofactinides on 2mL cartridges of Eichrom TRU and DGA resins. Actinides are measured by alpha spectrometry following
cerium fluoride microprecipitation onto Eichrom Resolve® Filters. Chemical recoveries averaged 97+9%, 96+7%, and91+4%, respectively, for 242Pu, 243Am and 232U tracers. Measured values typically agreed to within 3% of reference
values. Batches of 12 samples can be prepared for measurement in as little as 4 hours.

Reagents
TRU Resin, 2mL Cartridges (Eichrom TR-R50-S)
DGA Resin, 2mL Cartridges (Eichrom DN-R50-S)
Iron carrier (50mg/mL Fe, as ferric iron nitrate)
242Pu (or 236Pu if meas. Np), 243Am and 232U tracers
Oxalic acid/Ammonium oxalate
La carrier (10mg/mL)
Ce carrier (1mg/mL)
Deionized Water
1.25M Ca(NO3)2
3.2M (NH4)2HPO42M Al(NO3)3
10% (w:w) TiCl3
HNO3 (70%)
HCl (37%)
NaOH
HF (49%) or NaF
Boric acid
H2O2 (30%)
NaNO2Denatured ethanol
Sulfamic Acid
Ascorbic Acid
Equipment
Vacuum Box (Eichrom AR-24-BOX or AR-12-BOX)
Cartridge Reservoir, 20mL (Eichrom AR-200-RV20)
Inner Support Tubes-PE (Eichrom AR-1000-TUBE-PE)
Yellow Outer Tips (Eichrom AR-1000-OT)
Resolve Filters in Funnel (Eichrom RF-DF25-25PP01)
50mL and 250mL Centrifuge Tubes
Centrifuge
Muffle Furnace
Analytical Balance
250mL Zirconium crucibles with zirconium lids
Stainless Steel Planchets with adhesive tapeAlpha Spectrometry System
Vacuum Pump
Heat Lamp

Figure 1. Sample Preparation
1-2g finely ground soil + tracers in 250mL Zr-crucible
Fuse samples with 15g NaOH at 600°C for 15 minutes.
Dissolve fusion cake with H2O. Transfer to 250mL c-tube.
Add 10mL 3M HNO3 to crucible. Heat to dissolve
residue. Add to same c-tube.
Add 125mg Fe and 5mg La to c-tube. Dilute to 180mL.
Add 2mL 1.25M Ca(NO3)2, 5mL 3.2M (NH4)2HPO4,10mL 10% TiCl3. Mix. Cool in ice bath for 10min.
Centrifuge at 3500rpm. Decant Supernate.
Partially dissolve precipitate in 60-80mL 1.5M HCl.*
Dilute to 170mL with 0.01M HCl.
Add 1mg La and 5mL 10% TiCl3. Mix.
Add 20mL 49% HF. Mix. Wait 10 min.
*The entire precipitate will not dissolve in HCl.
Dissolution will be completed with the HF addition.
Centrifuge at 3500rpm. Decant Supernate.
Dissolve precipitate in 5mL 3M HNO3-0.25M Boricacid, 7mL 70% HNO3, and 7mL 2M Al(NO3)3.
Fix valence states. Mix between each addition of: 0.5mL
1.5M sulfamic acid, 10uL 50mg/mL Fe, 1.5mL 1M
ascorbic acid, 1mL 3.5M NaNO2, 1.5mL 70% HNO3.

Figure 2. Actinide Separation on TRU/DGA and Source Preparation(1) Precondition TRU/DGAresin with 5mL 8M HNO3.
(2) Load samples.
TRU(3) Rinse sample tube with
5mL 8M HNO3, and addtube rinse to TRU/DGA.*
DGA(4) Rinse TRU/DGA with:-10mL 10M HNO3
-15mL 4M HCl(5) Separate TRU and DGA.
(6) Strip Pu from TRU w/ 15mL 3M
HCl-0.02M TiCl3. Add 0.5mL 30%
H2O2.

(10) Rinse DGA with 5mL 3M HCl.
(11) Strip Am/Cm from DGA with 12mL
0.25M HCl. Add 0.2mL 30% H2O2.
(12) Add 50-ug Ce carrier to eachsample. Mix well. Add 1mL 49% HF.
Mix well. Wait 15-20 minutes.

(19) Draw vacuum until filter is dry.
(20) Remove filter from funnel
assembly and mount filter on
stainless steel planchet withadhesive tape.

(13) Set up Resolve® Filter Funnel
on vacuum box.
(14) Wet filter with 3mL 80% ethanol
followed by 3mL DI water.
(15) Filter sample.

(7) Rinse TRU with:-5mL 8M HNO3 + 50uL 30% H2O2
-10mL 4M HCl-0.2M HF-10mL 4M HCl-0.2M HF-2mM TiCl3-3mL 8M HNO3(16) Rinse sample
tube with 5mL
DI water andadd to filter.

(8) Strip U from TRU with 15mL 0.1M
ammonium bioxalate. Add 0.5mL
TiCl3 for CeF3 ppt.
(9) Rinse DGA with:-12mL 3M HCl-20mL 0.05M HNO3
-12mL 3M HNO3-0.25M HF(17) Rinse filter funnel
with 3mL DI water.

(21) Dry filter under heat lamp for3-5 minutes.
(22) Measure actinides by alphaspectrometry.

(18) Rinse filter funnel
with 2mL 100% ethanol.

*Adding 50uL of 30% H2O2 to tube rinse can improve U recoveries and decontamination in Pu(Np) fractions.

AnalyteMethod Performance
Analyte% Tracer Reference
TracerRecovery(mBq/g)242
97 + 998.0
Pu

Pu

Replicates
7Am

7243

7232

239
241

238

U
16 hour counts

AmU

AnalyteMeasured(mBq/g)95 + 3% Bias-3.1

96 + 761.1

59 + 4-3.4

91 + 4184

183 + 6-0.5

References
1) Sherrod L. Maxwell, Brian K. Culligan, Jay B. Hutchinson, “Rapid determination of actinides and in asphalt samples,”J. Radioanal. Nucl. Chem., 299(3), 1891-1901 (2014).
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

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