Transcript Technical Updates on UTEVA Resin and TEVA Resin Denver May 2, 2002

Technical Updates on UTEVA Resin
and TEVA Resin
Denver
May 2, 2002
Topics
• UTEVA Resin:
– Decontamination of Po-210
– U-232 yields
• TEVA Resin:
– Decontamination of U-nat/Th in Tc-99 region
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 Ferrous
210Pb/210Po
spike (1100 pCi)
Method
Activity in U
Region (dpm)
Ferrous
230
No ferrous
3.5
Effect of Additional 3M HNO3 Rinse
210Pb/210Po
Additional Rinse
(mL)
0
spike
Activity in Uranium Region (dpm)
92 pCi spike
1080 pCi spike
no ferrous
ferrous
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 Strip
Solution
0.01M HCl
No ferrous
ferrous
3.5
230
0.1M HCl
1.3
--
1M HCl
0.16
1.84
Additional Rinse/1M HCl Strip Combo
Method
Original procedure
Activity in Uranium Region
(dpm)
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 0.1 HNO3
• Extrude resin in LSC vial
• Added 15 ml of cocktail and count
BWXT’s ProcedureTest Results
Rinse volume used=25 mL
TEVA Lot #
0.1M HNO3
(CPM)
72
0.5M HF
/0.02M HNO3
(CPM)
14.84
1M NaF
/0.02M HNO3
(CPM)
Not tested
TEA06309
TE0K
18.9
13.1
15.36
TEVA Clform
Blank
24.5
15.36
15.0
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