Recent Improvements in Rapid Column Separation Methods at SRS

S. L. Maxwell, III, D. J. Fauth, R. C. Henderson, J. J. Smiley, S. R. Johnson

Westinghouse Savannah River Site

Recent Improvements

• SRS Environmental Monitoring lab– faster water and air filter analysis for actinides

– improved soil-fecal sludge analyses (wastewater treatment plant samples)

• SRS Bioassay lab– improved Pu-Np column extraction for urine (better Pu

stripping/less volume)

– faster fecal analysis method (no microwave)

• Central Laboratory (process lab)– improved Pu, Np in HEU and LEU samples

– TEVA + Pu-236 tracer

SRS Environmental Monitoring Lab• Vacuum box systems and stacked cartridges

• Significant cost and time savings vs. gravity flow

• Tested both stacked UTEVA+ TRU and TEVA+TRU methods– both methods work very well; much faster than gravity flow

– eliminated evaporation of Am fraction: use 5 mL con HF

– use 50 ug cerium instead of 100 ug to improve peak resolution

SRS Environmental Monitoring Lab

• Showed stacked TEVA+TRU can be used on water samples – just like urine method- no iron interference – may have some advantages for air filters (Po-210 interference)

• Po-210 can interfere with U-232 on UTEVA

– allows Pu AND Np together on TEVA

– use Ti (III) reductant in Pu strip from TEVA when performing cerium fluoride microprecipitation

Pu, Np/Am, U, Sr on TEVA/TRU RESIN (Water/Air filters)

Rinse20 mL 3M HN03

Th Removal3mL 9M HCI/25mL

8MHCI

Pu Elution20mL

0.10M HCl - 0.05MHF - 0.03M TiCl3

1) Redissolve in 10 mL 3M HN03 - 0.5M Al(NO3)3

2) Add 0.5 mL 1.5M Sulfamic Acid + 1 mL 1.5M Ascorbic Acid3) Add 1 mL 3.5M Sodium Nitrite

Remove TRU cartridge:1) Elute Am with

15mL 4M HCI2) Elute U with

10mL 0.1M ammoniumbioxalate

2mL TEVA Resin(50-100 um)

2.0mL TRU-Resin(50-100 um)

Collect, evaporate, dissolve in 6M HNO3Sr Resin

Alpha spectrometry

Cerium fluoride

Add 0.5 mL 3M sodium nitrite

Pu-242 Tracer Recoveries

1000 mL water samples/ Pu-242 tracer= 4.40 dpm

Calcium phosphate precipitation

% Pu242 Recovery % Pu242 Recovery

UTEVA+TRU Method TEVA+TRU Method

1) 101 1) 99.3

2) 106 2) 105

3) 106 3) 105

4) 108 4) 109

5) 98.6

6) 102

Avg. = 105% (2.8% @1s) Avg. = 103% ( 3.8% @1s)

Am-243 Tracer Recoveries

1000 mL water samples/ Am-243 tracer= 3.84 dpm

Calcium phosphate precipitation

% Am-243 Recovery % Am-243 Recovery

UTEVA+TRU Method TEVA+TRU Method

1) 105 1) 98.4

2) 100 2) 99.0

3) 91.5 3) 107

4) 98.7 4) 100

5) 102 5) 106

6) 106 6) 105

Avg. = 101% (5.2% @1s) Avg. = 103% ( 3.8% @1s)

U-232 Tracer Recoveries1000 mL water samples/ U-232 tracer= 5.45 dpm

Calcium phosphate precipitation

% U-232 Recovery % U-232 Recovery

UTEVA+TRU Method TEVA+TRU Method

1) 92.9 1) 87.5

2) 98.2 2) 93.5

3) 96.2 3) 97.4

4) 94.9 4) 92.4

5) 91.6 5) 94.0

6) 93.2

Avg. = 94.5% (2.6% @1s) Avg. = 93.0% ( 3.8 % @1s)

SRS Environmental Monitoring Lab

• Actinides in soil-fecal samples – dissolution and column flow problems with current method

– need total dissolution/eliminate flow problems & low uranium

– use Diphonix resin technology as in bioassay lab• Initial testing encouraging

• Use sodium peroxide/sodium hydroxide fusion (Zr crucibles)

• Precipitate actinides as hydroxides; redissolve in HCL-HF/also boric acid fraction

• 4 mLs Diphonix Resin + small volume HEDPA strip (15-20 mLs)

• Faster HEDPA destruction method (no microwave)– modified Fenton’s Reagent method

• Routine size Eichrom columns

Diphonix Stripping-HEDPA

0.5M HEDPA % Pu242 % U232

Strip Volume Tracer Tracer

1) 3 mL resin 15 mL 104 96

2) 4 mL resin 15 mL 99 97

3) 4 mL resin 20 mL 105 84

4) Direct -HEDPA 20 mL 113 113

Avg= 105 % 98 %

Redissolve in 10 mLs 6M HNO3 and 10 mls 2.5M aluminum nitrate (to avoid

phosphate interference), then TEVA+ TRU Column extraction

Soil-Fecal Sludge Samples

Pu-242 Pu-238 Pu-239/240

% Recovery pCi/g pCi/g

1) 101% 0.435 2.18

2) 69 % 0.484 2.33

3) 84% 0.442 2.07

4) 49 % 0.448 2.39

Avg= 76% 0.452 (4.8% @1s) 2.24 (6.5% @1s)

Soil-Fecal Sludge Samples

U-232 U-234 U-235 U-238

% Recovery pCi/g pCi/g pCi/g

1) 56% 6.16 0.355 5.56

2) 75 % 5.44 0.351 4.76

3) 74% 5.28 0.346 5.04

4) 98 % 4.44 0.253 3.98

Avg= 76% 5.33 (13% @1s) 0.326 (15% @1s) 4.84 (14% @1s)

Soil-Fecal Sludge Samples

Am-243 Am-241 Cm-244

% Recovery pCi/g pCi/g

1) 73% 0.746 0.506

2) 53 % 0.684 0.506

3) 64% 0.620 0.462

4) 38 % 0.670 0.378

Avg=57% 0.679 (7.6% @1s) 0.464 (13% @1s)

Bioassay Lab Improvements

• Actinides and Sr-90 in urine– stacked TEVA+TRU Resin cartridges with vacuum boxes

– Pu-236 tracer for Pu and Np at same time

– Pu, Np (TEVA) and U, Am (TRU)

– Sr (Sr Resin)

• Pu stripping improvement:– improved Pu stripping with rongalite instead of iodide in strip

solution (less volume/faster flow rate)

– rongalite (sodium formaldehyde sulfoxylate)

– compatible with electroplating

– adjust bisulfate added for sulfate added from rongalite decomposition (2.5 mLs 10 % bisulfate instead of 3 mLs)

Urine Batch: Calcium Phosphate Precipitation

Pu, Np/Am, U, Sr on TEVA/TRU RESIN (URINE)

Rinse20 mL 3MHN03

Th Removal5mL 9M HCI/25mL 8M HCI

Pu Elution20mL

0.10M HCl - 0.05M HF - 0.015M Rongalite

1) Redissolve in 12 mLs of 3M HN03 - 1M Al(NO3)3

2) Add 0.5 mL 1.5M Sulfamic Acid + 2 mls 1.5M Ascorbic Acid3) Add 2 mLs 4M Sodium Nitrite

Remove TRU cartridge:1) Elute Am with

15mL 4M HCI2) Elute U with

20mL 0.1M ammoniumbioxalate

2mL TEVA Resin(50-100 um)

2.0mL TRU-Resin(50-100 um)

Collect, evaporate, dissolve in 6M HNO3Sr Resin

Electrodeposition

4mls 0.02M H2SO4 + 3mls 16M HN03

Evaporate/ash

TEVA+ TRU Stacked Column: Pu, Np, U, Am

TRU Cartridge: U, Am Stripping

SR Cartridge: Sr-90 Separation

Pu-236 Recoveries-UrineUsing TEVA/Rongalite

Pu-236=0.426 dpm500 mL urineAvg Recovery=99%

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Spiked Urine Samples: Rongalite Test

Known values: Avg. measured: Pu-238 =0.110 dpm/L Pu-238 =0.143 dpm/LPu-239 =0.857 dpm/L Pu-239 =0.848 dpm/LNp-237=0.535 dpm/L Np-237=0.508 dpm/L

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Pu-238

Np-237

Pu-239

Bioassay Lab Improvements• Bioassay: fecal method

– wet ashing and dissolution in HCL-HF

– Diphonix Resin

– TEVA+TRU Resin

– cartridges not stacked due to possible iron

– previously evaporated load plus rinse from TEVA then redissolved, added reductant and loaded onto TRU

– Pu, Np (TEVA) and U, Am (TRU)

– Sr (Sr Resin)

Recent Improvements in Fecal Method

• Improvements:– no evaporation of load solution from TEVA to save time

• collect load plus minimal rinse from TEVA

• add sulfamic acid + ascorbic acid and load to TRU resin

– improved Pu stripping with rongalite instead of iodide in strip solution

– Also testing:• use of HEDPA strip of Diphonix instead of microwave (minimize

HEDPA to minimize phosphate and increase Al in final load solution)

• Use sodium peroxide/sodium hydroxide fusion instead of wet ashing

Microwave Digestion of Diphonix: Fecal Method

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Testing using 15 mL strip with 0.04M Rongalite; acidify to 3M HNO3, add Al(NO3)3 and nitrite and load to second TEVA column

Collect load and small rinseONLY: Eliminated evaporation

Pu on TEVA Resin-Fecal(2nd Column to Remove all Th-228)

• Adjust acidity of 15 mL strip solution to 3M HNO3 using 4 mLs 16M HNO3• Add 1 mL of 2.5M aluminum nitrate• Add 1mL 3.5 M Sodium Nitrite

Th Removal3mL 9MHCI/7mL

8MHCIRinse

10mL 3MHN03

Pu Elution20 mL

0.10MHC1 - 0.05MHF - 0.015M rongalite

1mL TEVA Resin

Process Lab Improvements

• Process samples to support HEU Blenddown processing

• Improvements:– Pu and Np are key product specification measurements

– Pu-236 tracer for Pu and Np on TEVA resin in HEU and LEU process solutions

– 1 mL TEVA cartridges to ensure total Th-228 removal (separated twice on TEVA)

– use Ti (III) reductant in Pu strip from TEVA

Summary

• SRS Environmental Monitoring lab work– Vacuum box technology reduced method time by about 50%

– Diphonix-HEDPA may help with difficult soil-fecal samples

• Bioassay lab– Improved Pu stripping using rongalite (85% to 99%)

– HEDPA to eliminate microwave in fecal analysis

• Process lab– Pu-236 tracer use for Pu, Np in process lab on high uranium

samples