Rapid Determination of Np/Pu/Am
in 10-20g Soil Samples

AN-1607-10
Summary of Method Plutonium, Neptunium, and Americium are separated and concentrated from 10 gram soilsamples. Samples are fused in zirconium crucibles with 40g NaOH to facilitate complete dissolution. Actinides areseparated from matrix using an iron/titanium hydroxide precipitate. A second precipitate with Ca/La-fluoride is used toremove additional matrix, particularly silicates, and decrease the volume of precipitate. Actinides are separated frompotential radiometric impurities using 2mL cartridges of TEVA and DGA Resins. Am/Cm fractions may require additional
purification using TEVA-NH4SCN to remove native rare earths which can degrade alpha spectra. Pu/Np and Am/Cm are
prepared for alpha spectrometry measurement via CeF3
Figure 1. Sample Preparation
microprecipitation onto Resolve® Filters. To further lower
Dry soil at 110°C. Blend and Crush to fine powder.
detection limits, two 10g soil aliquots can be fused
separately, combined following the Fe/Ti hydroxide
precipitate, and then processed through theremaining steps of the method.
Reagents
TEVA Resin, 2mL Cartridges (Eichrom TE-R50-S)
DGA Resin, Normal, 2mL Cartridges (Eichrom DN-R50-S)
Iron carrier (50mg/mL Fe, as ferric iron nitrate)
242Pu (or 236Pu if Np Measured) tracer
243Am tracer
La carrier (10mg/mL)
Ce Carrier (10mg/mL) 1.25M Ca(NO3)2
Deionized Water
2M Al(NO3)3
10% (w:w) TiCl3
HNO3 (70%)
HCl (37%)
NaOH
HF (49%) or NaF
Boric acid
NaNO2
Sulfamic Acid
Ascorbic Acid
30% H2O2
NH4SCN (rare earth separation)
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 with funnel (Eichrom RF-DF25-25PP01)
250mL Zirconium Crucibles with lids
50mL and 500mL Centrifuge Tubes
Alpha Spectrometry System
Stainless Steel Planchets with double sided tapeCentrifuge
Hot Plate
Analytical Balance
Vacuum Pump
Muffle Furnace

Aliquot 10g sample to Zr crucible. Add 242Pu(236Pu)/243Am.
Dry on Hotplate. Place in Muffle furnace at 250oC.
Ramp to 600oC. Heat 2 hrs to destroy organics.
Remove from furnace. Add 40g NaOH.
Fuse at 600oC for 30 minutes.
Transfer to 500mL centrifuge tube with water.
Add 125mg Fe, 100mg Ca, 10mg La, 10mL 10% TiCl3.
Dilute to 450 mL. Mix. Cool to room temp. in ice bath.
Centrifuge 10 min. Discard Supernate.
Rinse ppt with 150 mL pH ~9 NaOH.
Centrifuge 10min. Decant Supernate.
Partially dissolve in 200mL 1.5M HCl.
Solids will remain. Dilute to 250mL.
Add 6mL 10% TiCl3 and 40mL 49% HF.
Mix. Place in ice bath for 10min.
Centrifuge 10min. Decant supernate.
Dissolve solids in 10mL 3M HNO3-0.25M H3BO3, 6mL
7M HNO3, 8mL 2M Al(NO3)3 and 3mL 3M HNO3.
Warming samples can improve dissolution.
Cool to room temperature.
Adjust valence with 1mg Fe, 1.5mL
1M Ascorbic acid. Mix. Add 1mL 3.5M NaNO2.

Figure 2. Actinide Separation on TEVA - DGA(1) Precondition 2mL TEVA + DGA
cartridges with 5mL 8M HNO3.
(2) Load Sample.

Optional: Rare Earth Removal Steps(10) Add 3mL 3M HNO3 and 3mL 30%
H2O2 to Am/Cm fraction.

(3) Rinse centrifuge tube
with 5mL 6M HNO3. Addto TEVA + DGA.*(4) Rinse TEVA + DGA with
10mL 3M HNO3.
(5) Separate TEVA and DGA.

(11) Wet ash on hotplate to dryness.

TEVADGA(6) Rinse TEVA with
-15mL 3M HNO3
-20mL 9M HCl (Th)-5mL 3M HNO3(12) Dissolve in 10mL 1.5M NH4SCN.
(13) Precondition 2mL TEVA with
5mL 1.5M NH4SCN.
(14) Load Am/Cm fraction.
(15) Rinse beaker with 5mL 1.5M
NH4SCN. Add to TEVA.
(16) Rinse TEVA with 5mL 1.5M
NH4SCN.

(23) Rinse filter
funnel with 3mL
DI water and 2mL
100% ethanol.
(24) Draw vacuum
until filter is dry.
(25) Remove filter fromfunnel assembly andmount filter on stainlesssteel planchet with 2-sided tape.

(17) Strip Am/Cm with 20mL 1M HCl.

(7) Strip Pu/Np from TEVA with 20mL
0.1M HCl-0.05M HF-0.01M TiCl3.

(8) Rinse DGA with:-10mL 3M HCl (Ca)-3mL 1M HNO3
-15mL 0.1M HNO3 (La, Ca)-25mL 3M HNO3-0.25M HF (Th)-5mL 4M HCl(9) Strip Am/Cm with 12mL 0.25M HCl.

(18) Add 50ug Ce carrier and 0.5mL
30% H2O2 to all samples. Mix well. Add
1mL 49% HF. Mix well. Wait 15-20minutes.
(19) Set up Resolve® Filter Funnel onvacuum box.
(20) Wet filter with 3mL 80% ethanol
followed by 3mL DI water.
(21) Filter sample.
(22) Rinse sample tube with 5mL DI
water and add to filter.

(26) Dry filter under heat lamp for
3-5 minutes.
(27) Measure actinides by alpha
spectrometry.

*Adding 50uL of 30% H2O2 to the 6M HNO3 tube rinse can further improve uranium decontamination factors.
Method PerformanceSample
10g Soil
10g Soilreplicates10610g Soil

11

analyte239/240
Pu
237
Np

tracer
236
Pu
236
Pu

241

243

AmAm% tracer
recovery85 + 882 + 4mBq/greference
3.43
3.99

mBq/g
measured
3.41 + 0.22
4.19 + 0.16

% bias+5+689 + 4

2.14

2.07 + 0.16

+6References
1) Maxwell, Culligan, Hutchinson, McAlister, “Rapid Fusion Method for the Determination of Pu, Np, and Am in Large
Soil Samples,” J. Radioanal. Nucl. Chem. 305 : 599-608 (2015).
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