AN-1424

Rapid Determination of Pu, Am,and Cm in 80L Seawater Samples

Summary of Method Plutonium, Americium, and Curium are separated and concentrated from up to 80L samplesof seawater with a hydrous titanium oxide precipitation, enhanced with lanthanum and ferric iron. A second precipitation
with lanthanum fluoride removes additional matrix ions, and Pu and Am+Cm are separated from potentially interfering
radionuclides in the sample using stacked 2mL cartridges of Eichrom TEVA and DGA Resins. Isotopic Pu and Am+Cmare measured by alpha spectrometry following cerium fluoride microprecipitation onto Eichrom Resolve® Filters.
Chemical yields are determined by recovery of 243Am and 242Pu tracers. Recoveries of 243Am average 94 + 3%, while
242Pu average 86 + 4%. Measured values of 239Pu, 241Am, and 244Cm typically agree to within 10% of reference values.
A single operator can process batches of 12 samples through alpha source preparation in 6-8 hours. Alpha
spectrometry count times will vary depending on desired detection limit and data quality objectives.
Reagents
TEVA Resin, 2mL Cartridges (Eichrom TE-R50-S)
DGA Resin, 2mL Cartridges (Eichrom DN-R50-S)
Ammonium Hydroxide (listed as 28% NH3 or 56% NH4OH)
Nitric Acid (70%)
Hydrochloric Acid (37%)
Hydrofluoric Acid (49%) or Sodium Fluoride
Deionized Water
Iron Carrier (50mg/mL Fe, as ferric nitrate)
Lanthanum and Cerium Carriers (1mg/mL)
243Am and 242Pu tracers
10% (w:w) TiCl3
H2O2(30%)
2M Al(NO3)3
Boric acidSulfamic Acid
Ascorbic Acid
NaNO2
Denatured Ethanol
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 250-500mL Centrifuge Tubes
Centrifuge
Stainless Steel Planchets with adhesive tape
Alpha Spectrometry System
Analytical Balance
Vacuum Pump
Heat Lamp

Figure 1. Sample Preparation
1-80L Sample of Seawater.
Acidify to pH 2 with 70% HCl.
Add tracers. Mix well.
Add 15mg La, 50mg Fe/L sample and1mL 10% TiCl3/L sample. Mix well.
Add 2.5mL 56% NH4OH/L sample.
Mix well. Allow precipitate to settle.
Decant supernate to <1-2L.
Transfer remaining supernate and precipitate to250-500mL centrifuge tubes. Centrifuge
3000rpm for 10 minutes. Decant supernate.
Repeat until all sample processed.
Partially dissolve precipitate in 120mL 1M HCl.
Some solids will remain.
Add 15mL 10% TiCl3. Mix. Add 50mL 49% HF. Mix.
Wait 15 minutes. Centrifuge. Decant Supernate.
Dissolve precipitate with 10mL 3M HNO3-0.25M boric
acid, 12mL 2M Al(NO3)3 and 9mL 7M HNO3.
Load solution to valence adjustment
and TEVA-DGA separation.

Figure 2. TEVA-TRU Separation and Alpha Source Preparation(1) Adjust valence states of actinides
by adding the following reagents inthe order listed (mix between steps):-0.2mL 1.5M Sulfamic acid-0.01mL 50mg/mL Fe carrier-1.5mL 1M Ascorbic acid
-1mL 3.5M NaNO2(2) Precondition stacked 2mL TEVA +DGA cartridges with 5mL 3M HNO3.
(3) Load sample solution at ~1mL/min.
(4) Rinse sample tube with5mL 6M HNO3.* Add tube
rinse to cartridges.
(5) Rinse cartridges with
10mL 3M HNO3.

TEVA

DGA

(6) Separate TEVA andDGA cartridges.

(10) Rinse DGA with 15mL 3M HCl.
(22) Rinse filter funnel with 1-2mL(11) Rinse DGA with 4mL 1M HNO3.
100%ethanol.
(12) Rinse DGA w/ 30mL 0.05M HNO3. (23) Draw vacuum until filter is dry.
(13) Rinse DGA with 16mL 3M HNO3(24) Remove filter from funnel
0.25M HF.
assembly and mount filter on(14) Rinse DGA with 8mL 3M HCl.
stainless steel planchet with(15) Strip Am+Cm from DGA with 20mL
adhesive tape.
0.25M HCl. Add 0.2mL 30% H2O2.
(16) Add 50-100ug Ce carrier. Mix well.
Add 1mL 49% HF. Mix well. Wait
15-20 minutes.
(17) Set up Resolve® Filter Funnel
on vacuum box.
(18) Wet filter with 3mL 80% ethanol
followed by 3mLDI water.
(19) Filter sample.

(7) Rinse TEVA with 15mL 9M HCl.
(8) Rinse TEVA with 12mL 3M HNO3.
(9) Strip Pu and Np from TEVA with20mL 0.1M HCl-0.05M HF-0.01M
TiCl3. Add 0.5mL 30% H2O2.

(20) Rinse sample
tube with 5mL
DI water andadd to filter.
(21) Rinse filter funnel
with 3mL DI water.

(25) Dry filter under heat lamp for
3-5 minutes.
(26) Measure actinides by alphaspectrometry.

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

Analyte
239

Pu
239
Pu

Method Performance Pu, Am and Cm from Seawater% Tracer Analyte(mBq/L) Analyte(mBq/L)
Volume, L Replicates Tracer
Recovery
Reference
Measured242
16290 + 1
4.22
4.67 + 0.05
Pu
242
25
2
84.6 + 0.2
3.22
3.3 + 0.1
Pu% Bias
112.5

239

402

242

86 + 20.81

0.82 + 0.02

1.2239

Pu

80

2242

85 + 50.40

0.37 + 0.01

-7.5

241

Am
241
Am162

243

25
40

22

Pu

241

Am

Pu
Pu

Am
243
Am
243

Am

95 + 43.31

3.1 + 0.1-6.3

93.1 + 0.1
96 + 22.12
0.53

1.9 + 0.1
0.51 + 0.02

-10-3.8

241

Am80

2

243

93 + 40.27

0.25 + 0.01

-7.4244

Cm

162

243

95 + 42.16

2.1 + 0.2-2.8244

Cm244Cm

254022243

93.1 + 0.1
96 + 21.35
0.85

1.3 + 0.1
0.78 + 0.04

-3.7-8.2

244

80

2243

93 + 40.42

0.41 + 0.01

-2.3

Cm

AmAmAm
243AmAm

16 hour count times

References
1) Sherrod L. Maxwell, Brian K. Culligan, Jay B. Hutchinson, Robin C. Utsey, Daniel R. McAlister, “Rapid determinationof actinides in seawater samples,” J. Radioanal. Nucl. Chem., 300(3), 1175-1189 (2014).
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

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