Rapid Determination ofPlutonium in Large Rice Samples

AN-1427
Summary of Method Plutonium is separated andmeasured from up to 1.5kg rice samples. Rice samples are
muffled and wet ashed to reduce volume and destroy organiccontent. The residue is then fused with sodium hydroxide.
Precipitation steps remove additional matrix and prepare
plutonium for separation on Eichrom TEVA resin. Plutonium
is measured by alpha spectrometry following cerium fluoride
microprecipitation onto Eichrom Resolve® Filters. Plutonium
recovery through the method, determined using 242Pu tracer,
was 87 + 4% for 1kg samples. Measured values for 239Pu
and 238Pu agreed within 6% of reference values, even when
refractory 239Pu was present in the sample. Sample
preparation can be completed in less than 48 hours.
Reagents
TEVA Resin, 2mL Cartridges (Eichrom TE-R50-S)
Iron carrier (50mg/mL Fe, as ferric iron nitrate)
La carrier (10mg/mL)
Ce carrier (1mg/mL)
Deionized Water
1.25M Ca(NO3)2
3.2M (NH4)2HPO4
2M Al(NO3)3
10% (w:w) TiCl3
HNO3 (70%)
HCl (37%)
NaOH
HF (49%) or NaF
Boric acidNaNO2
H2O2 (30%)
Denatured ethanol
Sulfamic Acid
242Pu tracer
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
250mL Zirconium crucibles with zirconium lids
Stainless Steel Planchets with adhesive tape
Alpha Spectrometry SystemCentrifuge
Heat Lamp
Muffle Furnace
Hot Plate
Analytical Balance
Vacuum Pump
600mL glass beakers

Figure 1. Sample Preparation
Rice Sample + tracers in 600mL glass beaker(s).
Multiple beakers may be needed for large samples.
Muffle for 5 hours at 350°C, then 550°C for 12 hours.
Carefully wet ash with enough 1:1 (v:v)
70% HNO3:30% H2O2 to cover sample.
Heat to dryness. Muffle 550°C for 6-12 hours.
Transfer residue to Zr crucible. Rinse beaker with
70% HNO3. Add rinse to crucible. Wet ash with 1:1
70% HNO3:30% H2O2. Heat to dryness.
Repeat wet ash until no black char remains(violet residue common).
Fuse samples with 15g NaOH at 600°C for 20-30 minutes.
Dissolve fusion cake with H2O. Transfer to 250mL c-tube.
Add 10mL 3M HNO3 to crucible. Heat to dissolve residue.
Transfer to same 25mL c-tube.
Add 125mg Fe and 10mg La to c-tube. Dilute to 180mL.
Add 2mL 1.25M Ca(NO3)2, 1mL 3.2M (NH4)2HPO4,6mL 10% TiCl3. Mix. Cool in ice bath for 10min.
Centrifuge at 3500rpm. Decant Supernate.
Partially dissolve precipitate in 100mL 1.5M HCl.
Some solids will remain. Dilute to 170mL.
Add 5mL 10% TiCl3 and 22mL 49% HF. Mix.
Centrifuge at 3500rpm. Decant Supernate.
Dissolve precipitate in 5mL 3M HNO3-0.25M Boric acid, 7mL
6M HNO3, and 7mL 2M Al(NO3)3. Cool to room temperature.
Fix valence states. Mix between each addition of:
0.5mL 1.5M sulfamic acid, 40uL 50mg/mL Fe,
1.5mL 1M ascorbic acid, 1mL 3.5M NaNO2.

Figure 2. Plutonium Separation on TEVA Resin and Source Preparation(1) Precondition 2mL TEVA,5mL 3M HNO3.
(2) Load sample solution.

TEVA(7) Add 50ug Ce carrier to all samples.
Mix well.
(8) Add 1mL 49% HF. Mix well.
Wait 15-20 minutes.

(3) Rinse sample tube
with 5mL 3M HNO3.* Addtube rinse to cartridges.

(9) Set up Resolve® Filter Funnel onvacuum box.
(4) Rinse TEVA cartridge with:(10) Wet filter with
-15mL 3M HNO3
3mL 80%-20mL 9M HCl (Th removal)
ethanol followed-5mL 3M HNO3
by 3mL DI(5) Strip Pu from TEVA cartridge withwater.
20mL 0.1M HCl-0.05MHF-0.01M(11) Filter sample.
TiCl3 .
-If measuring Pu by ICP-MS, Pu may
be stripped from TEVA with 20mL of (12) Rinse sample
tube with 5mL DI
0.05M HCl-0.025M HF-0.02M
water and add tohydroxylamine-HCl.
filter.
-If preparing Pu sources for alpha
spectrometry by electrodeposition,(13) Rinse filter funnel with 3mL DI
strip Pu with 20mL 0.1M HCl-0.025M
water and 2mL 100% ethanol.
HF-0.02M rongalite (sodiumhydroxymethanesulfinate).
(14) Draw vacuum until filter is dry.
(6) Add 0.5mL 30% H2O2 for Uranium
decontamination in rare earth fluoride
precipitation alpha source(15) Remove filter from funnel
assembly and mount filter on
stainless steel planchet with
2-sided tape.

(16) Dry filter under heat lamp for
3-5 minutes.
(17) Measure plutonium by alpha
spectrometry.

*Adding 50uL of 30% H2O2 to tube rinse can improve Uranium decontamination.

Method Performance
242

Pu
TracerSample (kg)
1.0

Replicates
8% Yield
87 + 4

Reference (mBq/kg)

Measured (mBq/kg)

239

239

Pu

12.5
MDA for 1 kg sample, 30hours count time, 0.37uBq/kg

238

Pu

10.6% Bias

Pu238

Pu

239

238

11.8 + 1.0

10.5 + 0.7-5.6-0.7

Pu

Pu

References1) Sherrod L. Maxwell, Brian K. Culligan, Jay B. Hutchinson, “Rapid fusion method for determination of plutonium
isotopes in large rice samples,” J. Radioanal. Nucl. Chem., 298(2), 1367-1374 (2013).
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

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