Technical Updates on UTEVA, TEVA and TRU Resins Anil Thakkar & Michael Fern Eichrom...

Technical Updates on UTEVA, TEVA and TRU Resins

Anil Thakkar & Michael Fern

Eichrom Technologies, Inc.

Paris

May 14, 2002

Topics

• UTEVA Resin: – Decontamination of Po-210 – U-232 yields

• TEVA Resin: – Decontamination of U-nat/Th in Tc-99 region

• TRU Resin: – Am recoveries

U-232 Yields

• Unrealistic high U-232 yields reported with UTEVA resin in samples with high in Pb-210

Current Procedure

1) Load sample on UTEVA resin with 10 ml of 3M HNO3/1M Al(NO3)3. with 2 mL of 0.6M Ferrous sulfamate and 200 mg of ascorbic acid.

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

3) Rinse column with 5 mL of 3M HNO3

4) Rinse column with 5 mL of 9M HCl

5) Rinse column with 20 mL of 5M HCl/0.05M Oxalic

6) Elute U with 15 mL of 0.01M HCl

Effect of Ferrous210Pb/210Po spike (1100 pCi)

Method Activity in URegion (dpm)

Ferrous 230

No ferrous 3.5

Effect of Additional 3M HNO3 Rinse 210Pb/210Po spike

Activity in Uranium Region (dpm)Additional Rinse

(mL)92 pCi spike

no ferrous1080 pCi spike

ferrous

0 3.0 230

10 1.6 --

20 0.23 --

30 -- 28

Effect of Uranium Strip Solution no ferrous added

210Pb/210Po spike (1100 pCi)

Activity in Uranium Region (dpm)

Uranium StripSolution

No ferrous ferrous

0.01M HCl 3.5 230

0.1M HCl 1.3 --

1M HCl 0.16 1.84

Additional Rinse/1M HCl Strip Combo

Method Activity in Uranium Region(dpm)

Original procedure 230

30 mL HNO3 Rinse only 28

1M HCl Strip only 1.84

30mL rinse + 1M Strip <background

Revised Procedure

1) Load sample on UTEVA with 10 ml of 3M HNO3/1M Al(N03)3 with 2 mL of 0.6M Ferrous sulfamate and 200 mg of ascorbic acid

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

3) Rinse column with 5 mL of 3M HNO3

4) Rinse column with 10 mL of 3M HNO3 (3x)

5) Rinse column with 5 mL of 9M HCl

6) Rinse column with 20 mL of 5M HCl/0.05M Oxalic

7) Elute U with 15 mL of 1M HCl

Summary

A good decontamination of Po-210 in U-232 region can be

achieved by additional 3M HNO3 rinse on UTEVA and

eluting uranium selectively with 1M HCl

TEVA Column: Tc-99 Issues

• Problem reported by Darrin Mann (BWXT, Oak Ridge, Tn) with bias high Tc-99 recoveries in samples with natural uranium.

• Th-234 interference was detected in Tc-99 region.

BWXT’s Tc-99 Procedure

• Solid samples are digested and dissolved finally in 20 ml of 0.1M HNO3

• Load sample on TEVA column

• Rinse column with 25 ml of 0.1M HNO3

• Extrude resin from the column in a LSC vial.

• Add cocktail and count on LSC.

BWXT’s Procedure tested at Eichrom

• Spiked 20 ml of 0.01M HNO3 with ~2000 dpm of U-234/238

• Load on TEVA Resin column

• Rinse with 25 ml of 0.1M HNO3

• Extrude resin in LSC vial

• Added 15 ml of cocktail and count

Possible Solutions for Decontamination

• Use of fluoride to complex the residual Th-234 on the column

• Two fluoride solutions tested:

– Hydrofluoric acid – Sodium fluoride

Decontamination of Th-234

• Spiked 20 ml of 0.01HNO3 with ~2000 dpm of U-234/238

• Load on TEVA Resin column

• Rinse with 5 ml of 0.1M HNO3

• Rinse with 25 ml of 0.5M HF/0.02M HNO3 OR with 25 ml of 1M NaF/0.02 HNO3

• Rinse with 5 ml of 0.1M HNO3

• Extrude resin in LSC vial

• Added 15 ml of cocktail and count

BWXT’s ProcedureTest ResultsRinse volume used=25 mL

TEVA Lot # 0.1M HNO3

(CPM)0.5M HF

/0.02M HNO3

(CPM)

1M NaF/0.02M HNO3

(CPM)

TEA06309 72 14.84 Not tested

TE0K 18.9 13.1 15.36

TEVA Cl-

form24.5 15.36 15.0

Blank 14.7 + 0.9 14.7 + 0.9 14.7 + 0.9

Conclusion

• Decontamination of Th-234 in Tc-99 region can be accomplished with additional fluoride rinse on the TEVA Resin columns

• Fluoride in the form of 1M NaF or 0.5M HF solutions could be used to remove the residual amounts of Th-234

TRU Resin: History

• Historical problems with Am recoveries from TRU Resin (HCl strip.)

• Suspected Extractant Leaching handled with wet ashing of HCl Strip Solution

TRU Resin Cartridges

1) TRU Resin

2) TRU Resin with a ‘post’ Prefilter layer

Am-243 Spike Test

1) Spike 10 ml of 3M HNO3 with 6.52 dpm of Am-243

2) Load solution on TRU cartridges (assisted with VBS, flow rate 1ml/min)

3) Rinse with 10 ml of 3M HNO3

4) Rinse with 5ml of 0.5M HNO3

5) Strip Am with 9M + 4M HCl

Cerium Fluoride Precipitation

Four different preparation prior to CeF3 ppt.

– 1) Digested with Aqua-regia

– 2) Undigested

– 3) Changed molarity (~0.5 M HCl)

– 4) Digested with 10% H2SO4

Am-243 recoveries (n=4)

Resin Type Am Strip Solution

Digested with Aqua-

regia

No digestion Changed molarity

Digested with H2SO4

TRU 9M HCl + 4M HCl

89 % + 3% 48 % + 3% 97 % + 7% 84 % + 6%

TRU with prefilter layer

9M HCl + 4M HCl

89 % + 5% 62 % + 5% 97 % + 3% 82 % + 23%

RETEST: Am-243 recoveries (n=4)

Resin Type Am StripSolution

Changedmolarity-First Run

Changedmolarity-RERUN

TRU 9M HCl +4M HCl

97 % + 7% 93 % + 10%

TRU withprefilter layer

9M HCl +4M HCl

97 % + 3% 95 % + 4%

ACW03 tested for Am

• 0.5 L of Eichrom tap water spiked with Am-243

• Precipitated Am with calcium phosphate

• Scavenge ppt. and dissolve in the load solution

• Followed ACW03 procedure using UTEVA/TRU cartridges

• Collect Am fraction

ACW03…continued

6) Evaporate Am fraction to dryness

7) Add 0.5 ml of conc. HCl and dilute to 15 ml of DI water

8) Perform CeF3 ppt.

Tap Water: Am-243 recoveries(n=5)

Resin Type Am StripSolution

Changedmolarity

UTEVA / TRU 9M HCl +4M HCl

89 % + 10%

UTEVA / TRU withprefilter layer

9M HCl +4M HCl

89 % + 11%

Conclusion

• Am recoveries improved by changing the concentration on HCl prior to CeF3

• TRU resin cartridge performed well once the HCl concentration was changed