New Extraction Methods for Actinides in Urine at SRS

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New Extraction Methods for Actinides in Urine at
SRS

• Sherrod L. Maxwell III and David Fauth
• Savannah River Site

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Recent Applications

• New Column Extraction Applications at SRS
• UTEVA method for Pu/U removal for Pu/U oxides
  (Impurity assay)
• New UTEVA method for Pu and U-Isotope Dilution
  Mass spectrometry in mixed oxides (strip Pu
  separately using 3M HNO3-0.2MHF)
• Actinides in soil using Diphonix Resin-microwave
  digestion
• Sequential column extraction in Bioassay Lab for
  Pu, Np, Am, U plus enhanced Sr method using
  cartridge technology
• Pu, Am in fecal samples using Diphonix
  Resin-microwave digestion and TEVATRU Resin

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Actinides in Urine

• Current Urine Methods
• Pu-acidified 500 mL samples/evaporated -anion
  resin
• U-acidified 50 mL samples/evaporated -anion resin
• Pu/Am/Sr- 500 mL calcium phosphate/ TRU SR
  Resin
• Need more efficient, consistent, sequential
  methods with better Th-228 removal larger
  aliquots for special urine samples

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Bioassay Urine Methods

• New Methods
• Expand use of calcium phosphate precipitation
  (500 ml to 1000 mL)
• Improve Th-228 removal
• Enhance vacuum column extraction with cartridge
  work
• Pu (Np when Pu-236 tracer used) on TEVA Resin
• Pu, Np, U, Am using TEVA/TRU column or cartridge
  technology
• Pu, Np, U, Am, Sr using TEVA/TRU SR columns or
  cartridge technology

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Bioassay Application

• Advantages
• Faster, more consistency, less acid waste (0.9 L
  vs. 6 L per batch) reduced labor costs
  sequential analysis better alpha peak resolution
  
• Better detection limit for uranium-500 mL sample
  (vs. current 50 mL sample size)
• Cartridge technology more efficient eliminates
  large sequential load solutions (evaporation
  steps)

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Bioassay Implementation

• Status
• Implementation over next 3 to 6 months
• Pu, Np-TEVA -implemented-10/99
• Pu, Np, Sr -TEVA /SR cartridge or column
• Pu, Np, Am -TEVATRU cartridge or column
• Pu, Np, Sr, U,Am -TEVATRU cart. SR column (add
  2nd small TEVA column to ensure complete Th-228
  removal)

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Challenges

• Optimize nitrate levels for Pu, Np on TEVA and Sr
  on SR Resin work using cartridges
• Achieve adequate Th-228 removal for Pu/U work
• successful with second 1 ml TEVA column
• Interface with current electroplating
  practices/evaluate cerium fluoride ppt
• Improved Pu stripping from TEVA Resin (NH4I or
  Ti3)
• Ensure adequate Pu, Np reduction w/o Fe2 to
  enable TRU cartridge below TEVA for urine samples

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Sample Preparation

• Tracer addition (Pu-242 or Pu-236, U-232, Am-243)
• Routine calcium phosphate precipitation
• 3 mmol Ca (120 mg ) 15 mmol (NH4)2HPO4
• Precipitate/centrifuge/redissolve/ash
• TEVATRU Pu, Np, Am, U, Sr
• Redissolve in 6 mL of 5M to 6M HNO3
• Add 6 mL of 2 to 2.5 M Al(NO3)3 -scrubbed using
  UTEVA
• after valance adj., no additional acidity
  adjustment needed
• TEVASR Pu, Np, Sr
• Redissolve in 5 mL of 5M HNO3
• Add 5 mL of 2 to 2.5 M Al(NO3)3 -scrubbed using
  UTEVA
• after valance adj., add 3 mL 16M HNO3 (adjust
  acidity to 4.5M )

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Sample Preparation (contd.)

• Valence options to adjust Pu and Np for TEVA
• A. 1) Add 1 mL 1.5M ferrous sulfate 1 mL 1.5M
  ascorbic acid, wait 3 min.
• 2) Add 1 mL 3.5M to 4M sodium nitrite
• For TRU cartridge below TEVA (no iron added)
• B. 1) Add 0.5 mL 1.5M sulfamic acid , 2mL 1.5M
  ascorbic acid, wait 3 to 5 min.
• 2) 2 mL 4 M sodium nitrite, ensuring excess
  nitrite

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Pu, Np on TEVA RESIN (URINE)
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TEVA Pu Tracer Recoveries

• 500 mL urine sample/ Pu-242 tracer 1.25 dpm /
  One TEVA Column FeAA/NO2
• Recovery (CeF3 microprecipitation)
  Recovery (Electroplating )
• 1) 110 1) 84.4
• 2) 93.3 2) 72.4
• 3) 92.6 3) 69.3
• 4) 95.2 4) 69.6
• 5) 101.5 5) 79.8
• 6) 99.3 6) 84.5
• 7) 97.7 7) 79.1
• 8) 115.4 8) 85.5
• 9) 107.9 9) 84.8
• 10) 106.8 10) 77.0
• 11) 101.6 11) 82.5
• 12) 102.6
• Avg. 102.0 Avg. 79.0
• Add 4 mL 0.02M H2SO4 to enhance F removal during
  solution cleanup for plating

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TEVA- Np Spike Recoveries

• 500 mL urine sample/ Np-237 spike 1.40 dpm
• Single TEVA column Valence adj.
  FeAA/NO2
• Np-237 Recovery (electroplating)
• 1) 101.6
• 2) 99.5
• 3) 71.3 4) 104.5
• 5) 85.8
• 6) 78.3
• 7) 85.9 8) 81.3
• 9) 77.8
• 10) 75.3 11) 91.9
• 12) 105.3
• Avg. 88.2

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Pu, Np/Am, U, Sr on TEVA/TRU RESIN (URINE)
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Pu on TEVA RESIN (URINE or FECAL) (2nd Column to
Remove all Th-228)
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TEVA (w/ 2nd Col.) -Pu Tracer Recoveries

• 500 mL urine sample/ Pu-242 tracer 1.25 dpm
• With 2nd 1 mL TEVA Column to ensure complete
  Th-228 removal when U-232 added
• 12 FeAA/NO2
• 3-7 SAAA/NO2
• Recovery (CeF3 microprecipitation)
  Recovery (Electroplating )
• 1) 93.2 1) 66.0
• 2) 90.0 2) 75.4
• 3) 84.1 3) 72.7
• 4) 90.0 4) 71.0
• 5) 86.0
• Avg. 89.3 6) 80.9
• 7) 73.0
• Avg. 75.0

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TRU Resin -Am Tracer Recoveries

• 500 mL urine sample/ Am-243 tracer 1.55 dpm /
  TRU cartridge after TEVA
• SAAA/NO2 / load TEVA and TRU at same
  time/remove TRU cart./elute Am
• Am-243 Recovery (Electroplating )
• 1) 93.2
• 2) 92.1
• 3) 107.4
• 4) 70.3
• 5) 102.4
• 6) 103.0
• 7) 100.2
• 8) 103.3
• 9) 102.6
• 10) 94.7
• Avg. 96.9

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TRU Resin-U Tracer Recoveries

• 500 mL urine sample/ U-232 tracer 0.554 dpm /
  TRU cartridge after TEVA
• SAAA/NO2 / load TEVA and TRU at same
  time/remove TRU cart./elute U
• U-232 Recovery (Electroplating )
• 1) 97.9
• 2) 74.1
• 3) 85.6
• 4) 102.9
• 5) 90.6
• 6) 83.1
• 7) 57.7
• 8) 81.0
• 9) 80.4
• 10) 93.3
• Avg. 84.7

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Pu/Sr On TEVA/SR RESIN (URINE)
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TEVA-Pu/Sr Cartridge Recoveries

• 500 mL urine sample Sr-90 spiked in samples 206
  dpm
• Measured dpm Sr-90 Spike Recovery
• 171 83.0
• 172 83.5
• 155 75.2
• 160 77.7
• 173 84.0
• 160 77.7
• 159 77.2
• Avg 164.3 79.8
• Sr-90 Spiked after precipitation
• Measured dpm Sr-90 Spike Recovery
• 184 89.3
• 188 91.3
• Avg 186 90.3

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Summary

• New implementation of rapid column methods in
  bioassay lab will result in significant time/cost
  savings
• Pu and Np together with Pu-236 tracer
• Better Th-228 removal using 2nd 1 mL TEVA col.
  when U-232 tracer added
• Pu, Np and Sr on TEVASr cartridge
• Pu, Np and Am, U on single two stage TEVA-TRU
  column with Sr-90 on SR Resin after evaporation