Th, Pu & U Separation Using TEVA and UTEVA Resin

Eichrom Workshop at RRMC12 November, 2002

Knoxville, TN

Objective

To develop a quick method for the separation of

Th, Pu and U in water samples

Tracers

• U232 tracer cleanup required to remove daughter Th228

• Followed David Sill (NAREL)’s BaSO4 procedure

• Pu242 and Th229 used for plutonium and thorium

• Pu236 better choice if Np measurement is required

Sample Preparation

• 1 liter aliquots of acidified water samples were spiked with Th229, Pu242 and U232 tracers

• Samples were heated to near boiling for 2 hours

• A Ca3(PO4)2 precipitation was performed

• Decant supernatant, centrifuge and collect the precipitate

Load Solution

• Dissolve precipitate in 3M HNO3/1M Al(NO3)3 solution

• Add ferrous sulfamate and NaNO2

• Load on TEVA and UTEVA Resin cartridge in tandem

Proposed Procedure

1) Attach TEVA resin and UTEVA resin cartridges in tandem

2) Load 10 ml of 3M HNO3/1M Al(N03)3. with 2 mL of 0.6M Ferrous sulfamate followed with 1 ml of 3M NaNO2

3) Rinse sample beaker with 5 mL of 3M HNO3

4) Rinse cartridge with 5 mL of 3M HNO3

5) Separate TEVA and UTEVA cartridges

Proposed Procedure continued

TEVA cartridge

1) Rinse with 30 ml of 3M HNO3

2) Elute Th with 20 ml of 9M HCl and 5 ml of 6M HCl

3) Elute Pu with 20 ml of 0.02M TiCl3/0.05M HCl/0.05M HF (Np eluted in this fraction)

Proposed Procedure continued

UTEVA Cartridge

1) Rinse with 5 ml of 9M HCl

2) Elute U with 15 ml of 1M HCl

Direct Spike Results(Proposed Procedure)

Actinide% Recoveries

(n=6)

Th 100 + 1

Pu 74 + 9

U 69 + 5

U fraction contaminated with Pu

Improvements Needed

• Possible Pu valence adjustment for better recoveries

• U recoveries need to be higher

• Better decontamination for U fraction

Possible Solutions for Improvements

1) Use 2 ml of ferrous sulfamate + 0.5 ml of NaNO2

2) Use 1 ml of ferrous sulfamate + 1 ml of NaNO2

3) Increase U and Pu strip volumes

4) Add oxalic acid rinse on UTEVA

Direct Spike Results(2 ml of Ferrous+0.5ml of NaNO2 )

Actinide% Recoveries

(n=6)

Th 98.6 + 3

Pu* 66.3 + 12

U** 88 + 8

* With 25 ml of Pu strip volume

**With 20 ml of U strip volume & oxalic acid rinse

Direct Spike Results(1 ml of Ferrous + 1ml of NaNO2)

Actinide% Recoveries

(n=6)

Th 97.2 + 11

Pu* 99.7 + 2

U** 91.0 + 6

*With 25 ml of Pu strip volume

**With 20 ml of U strip volume & oxalic acid rinse

Revised Procedure

1) Load sample on TEVA resin and UTEVA resin cartridges in tandem with 10 ml of 3M HNO3/1M Al(N03)3. with 1.0 mL of 0.6M ferrous sulfamate and 1 ml of 3M NaNO2

2) Rinse sample beaker with 5 mL of 3M HNO3

3) Rinse cartridge with 5 mL of 3M HNO3

4) Separate TEVA and UTEVA cartridges

ACW13 continued

TEVA cartridge

1) Rinse with 5 ml of 3M HNO3

2) Rinse with 30 ml of 3M HNO3

3) Elute Th with 20 ml of 9M HCl and 5 ml of 6M HCl

4) Elute Pu with 25 ml of 0.02M TiCl3/0.05M HCl/0.05M HF (Np will be present in this fraction)

Revised ACW13 continued

UTEVA Cartridge

1) Rinse with 5 ml of 3M HNO3

2) Rinse with 5 ml of 9M HCl

3) Rinse with 20 ml of 5M HCl/0.05M oxalic acid

4) Elute U with 20 ml of 1M HCl

Decontamination Test

• ~100 pCi of Am, Np, Th, Pu and U were added to the load solution

• Solution was processed following ACW13

Decontamination Factors

Actinide DF in Thfraction

DF in Pufraction

DF in Ufraction

Uranium >800 13,000 N/A

Plutonium >1500 N/A 20,000

Amercium >800 21,000 >2200

Thorium N/A >3600 >2000

Neptunium >3000 N/A 4600

DI Water

Actinide % Recoveries(n=6)

Th 87.2 + 7

Pu 90.8 + 6

U 80.3 + 3

Th229 Spectrum

U232 Spectrum

Pu242 Spectrum

Tap Water

Actinide % Recoveries(n=6)

Th 102 + 4

Pu 103 + 5

U 87.2 + 7

Summary

• Benefits– A quick method with consistent, reproducible

recoveries

– Rugged enough to provide good decontamination from other actinides

• Drawbacks

– Th228 cleanup required

– Pu236 tracer required if Np237 measured