Pyrosulfate fusion vs. TEVA / TRU forcing the issue

1
Pyrosulfate fusion vs. TEVA / TRUforcing the
issue

• Shane Knockemus
• U.S. EPA / NAREL
• Montgomery, AL
• November 11, 2002

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Advantages / disadvantage / goal

• Advantages of fusion
• Achieves total sample dissolution (including
  refractory material) of nearly any type of
  sample.
• Rapid and vigorous.
• Not many reagents consumed.
• Insures homogeneity between tracer and sample.

• Disadvantage of fusion
• Introduces large amount of sulfate ions into
  sample matrix, which may effect some separation
  processes.

Goal To achieve a reliable separation process
for Am, Pu, Th, and U when analyzing a sample
put into solution by pyrosulfate fusion.
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Potassium fluoride / pyrosulfate fusion

• 0.5-1.0 gram soil in Pt dish
• 1 g KF, 1.3 g KHF2.FUSE
• 3 mL 18 M H2SO4, 2 g Na2SO4.FUSE

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TEVA / TRU Separation Scheme

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Experiment 1 flowchart

cake
HNO3 / Al(NO3)3
TEVA / TRU
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Poor Pu / Th separation (exp.1)
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Experiment 1 Results
Analysis Resolution / separation Tracer Yield Analyte Yield
Am Good Good Good
U Good Good Good
Pu Poor Poor NA
Th NA Poor NA
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Experiment 2 flowchart
cake
16 M HNO3
HNO3 / Al(NO3)3
TEVA / TRU
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Pu spectrum with Th contamination (exp. 2)

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Experiment 2 Results
Analysis Resolution / separation Tracer yield Analyte yield
Am Poor Poor NA
U Good Good Good
Pu Poor Poor NA
Th NA Poor NA
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Influence of Matrix Constituents on TEVA
Find a way to eliminate the SO4-2 introduced
during the fusion before the sample is loaded
onto TEVA / TRU.
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Experiment 3 flowchart
cake
TEVA / TRU
HCl
Calcium phosphate pptn
HNO3 / Al(NO3)3
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Am and U spectra (exp. 3)
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Experiment 3 Results
Analysis Resolution / Separation Tracer yield Analyte yield
Am Good Good Good
U Good Good Good
Pu Poor Poor NA
Th NA Poor NA
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Experiment 4 flowchart
cake
TEVA / TRU
HCl
BaSO4 pptn
HNO3 / Al(NO3)3
Titanous hydroxide pptn
KEDTA
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Th spectra (exp. 4)
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Clean Pu spectrum (exp. 4)
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Experiment 4 Results
Analysis Resolution / separation Tracer Yield Analyte yield
Am NA Poor NA
U NA NA NA
Pu Good Good Good
Th Good Good Good
Uranium recovery was 0 because there was no
valence adjustment prior to BaSO4 coprecipitation
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Experiment 5

• This experiment was carried out the same as
  experiment 4, but instead of a titanous hydroxide
  precipitation, a calcium phosphate precipitation
  was used.
• Prior to the BaSO4 precipitation U6 was reduced
  to U4 with hydrazine and TiCl3

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Spectra experiment 5
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Experiment 5 Results
Analysis Resolution/ separation Tracer Yield Analyte Yield
Am NA Poor NA
U Good Good Good
Pu Good Good Good
Th Good Good Good
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Experiment 6 flowchart
cake
HCl / HF
TEVA / TRU
diphonix
destroy resin
HNO3 / Al(NO3)3
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Usefulness of diphonix

• Diphonix will help separate the sample from
  certain matrix constituents introduced to the
  sample as part of the digestion process.
• Sample loaded in 1 M HCl / 0.5 M HF. Actinides
  stick, while troublesome ions not be sorbed by
  the resin.

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Loading of sample on diphonix

• 0.3 g of diphonix resin packed into column
• Resin charged with 5 mL 1 M HCl
• Cake dissolved in 30 mL 1 M HCl / 0.5 M HF
• Sample loaded onto column
• Column rinsed with 5 mL 1 M HCl
• Resin destroyed by charring with H2SO4 and HNO3,
  followed by oxidation of organics with HClO4

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Spectra of experiment 6
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Experiment 6 Results
Analysis Resolution / separation Tracer Yield Analyte Yield
Am Good Good Good
U Good Good Good
Pu Good Good Good
Th Good Better NA
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Evaluation of data for exp. 6
Nuclide MAPEP value(pCi/g) Measured activity Measured / known
Am-241 1.65 1.57 0.95
Pu-239 2.01 1.96 0.98
U-234 2.44 2.31 0.95
U-238 2.51 2.61 1.04
MAPEP did not have certified values for Th
nuclides
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Final tally of experiments (hit or miss)
Exp. Am Pu U Th
1 HIT MISS HIT MISS
2 MISS MISS HIT MISS
3 HIT MISS HIT MISS
4 MISS HIT NA HIT
5 MISS HIT HIT HIT
6 HIT HIT HIT HIT