ulrika nygren, june 2002 determination of actinides in emergency preparedness using diphonix or...

Ulrika Nygren, June 2002

Determination of actinides in emergency preparedness using Diphonix or Actinide resin

in combination with gamma spectrometry

Ulrika Nygren and Daniela Stricklin


Emergency Preparedness

• To protect the Swedish population from exposure to ionising radiation produced in the decay of radioactive nuclides– Fallout from nuclear power plant accidents

– Fallout from nuclear weapons explosions

– Terrorism

• Designated laboratory for the Swedish Radiation Protection Authority (SSI)


Transfer of radioactive debris to the environment

Radioactive Cloud

wet deposition

transfer: vegetation to forest floor

root uptake

migration

dry deposition

inhalation

plantproduction

animalproduction

externalradiation

reindeer

fish

radioactive cloud

wet deposition

transfer: vegetation to forest floor

root uptake

migration

dry deposition

inhalation

plantproduction

animalproduction

externalradiation

reindeer

fish

Fast determination of fall-out composition critical


Mobile Measurement Techniques

Backpack

NaI-detector, GPS

Fieldgamma Spectrometry

HPGe

Measurement Vehicle

HPGe, NaI for thyroid measurements

Primarily determination of deposited gamma emitting fission products – actinides and pure beta emitters not determined


Dry, homogenise

LiB-fusionWet ashing

Si-removal

Oxalate precipitation

UTEVA

TRUElectrodep. andα-spectrometry

U

Pu

Standard radioanalytical procedure for actinide determination at FOI- identification of time consuming procedures

VegetationSoil Water

Am (Cm)


– fast preconcentration and partial separation of the actinides

– good spectral resolution provides qualitative and quantitative information

– geometry well suited for gamma spectrometry, facilitates calibration

Issues?– sensitivity– retention of actinides on resin

Determination of actinides by the use of actinide specific resins and low-energy gamma spectrometry


LiB-fusion1100°C, 10 min

5% HNO3, 20 min

Microwave digestionHNO3 and H2O2, 15 min

Surry with resin0.7 g, 1 h.

vegetationsoil

Low-energy γ-spectrometry

water

Adjustment of acid concentration

Elektrodep. andα-spectrometry

Digestion of extractant

Extraction chromatography

Analytical procedure – emergency preparedness


Retention of nuclides from rainwater on Actinide resin

0

20

40

60

80

100

Am-241 Cd-109 Co-57 Ce-139 Sn-113 Sr-85 Cs-137 Mn-54 Y-88 Zn-65 Co-60

No Acid

pH 1.5

5% Nitric Acid


Retention of nuclides from rainwater on Diphonix

0

20

40

60

80

100


No Acid

pH 1.5

5% Nitric Acid


Retention of nuclides from vegetation on Actinide resin

5% Nitric Acid99.24

2.57 0.19

79.0274.63

6.78

0.124.73

75.48

0.31 0.140

20

40

60

80

100


% R

eten

tion


Separation of 241Am from soil

The sample-solutions were adjusted to 1M HF and 0.125M AA prior to the addition of the resins

97.40 95.8191.50

71.76

0

20

40

60

80

100

Actinide Resin Diphonix

% R

eten

tion

2.5% Nitric Acid

5% Nitric Acid


Detection limits for 241Am

1 Based on 100 min counting time and 95% conf. interval according to L. A. Currie, Anal. Chem., 40 (1968)

2 N. Green, ”An evaluation of rapid methods of radionuclide analysis for use in the aftermath of an accident”, Sci. Total Environ., 130/131 (1993)

Minimum detectable activity concentration

Sample amount

Limiting Activity

Concentration2

Rainwater (Bq / l) 0.6 200 ml 3.7x105

Vegetation (Bq / kg) 65 2 g 3.7x105

Soil (Bq / kg) 130 1 g 1.3x104


Time of analysis

The analysis times are based on a counting time of 100 min

1 N. Green, G. Ham, S. Shaw, Rapid Radioactivity Measurements in Emergency

and Routine Situations, Proceedings, NPL, Teddington, UK, (1997)

Conventional

methods1Lowenergy-

methodConventional

methods1Lowenergy-

method

Rainwater 24 3 29 11Vegetation 24 3.5 31 11.5Soil 24 4 34 12

Total analysis time for 1 sample (h) Total analysis time for 6 samples


Nuclide Energy Intensity Theoretical Detection Limits

(keV) % Water (Bq/l) Grass (Bq/kg) Soil (Bq/kg)

234U 53.1 10.4 1.5 150 300

235U 185.7 54 0.44 44 88

238U 48.0 0.075 210 21000 43000

239Np 103.7 24 0.7 70 140

237Np 86.5 13.1 1.5 150 290

241Am 59.5 36.3 0.65 65 130

238Pu 43.5 0.038 410 41000 83000

239Pu 51.6 0.021 820 82000 160000

240Pu 45.2 0.045 350 35000 71000

241Pu 98.4 0.0022 7500 750000 1500000

242Cm 44.0 0.033 490 49000 99000

244Cm 42.8 0.025 610 61000 120000

Theoretical detection limits for other actinides- complete retention on resin assumed

Based on 100 min counting time and 95% conf. interval according to L. A. Currie, Anal. Chem., 40 (1968)


Destruction of resin/extractant for further separation and analysis

Actinide resin• Removal of extractant with

actinides from resin by isopropanol

• Evaporation till dryness in Ni-crucible

• Fusion with Na2O2 (550ºC, 10 min)

• Leaching of melt by H2O followed by dilute HNO3

Diphonix• 30 ml HNO3 (conc.) added

to resin and evaporated to near dryness at 200ºC

• 10 ml H2O2, ev. to near dryness

• 15 ml H2O2 and 0.35 g FeSO4*7H2O, ev. to near dryness

• 6 ml H2O2, ev. to dryness


Chemical yields in alpha spectrometric analysisDestruction of extractant:

•Fentons reagent for Diphonix

•Na2O2 fusion for Actinide resin

0

10

20

30

40

50

60

70

80

90

100

U Pu Am

yie

ld (

%) Diphonix

Actinide resin


Determination of actinides by the use of actinide-specific resins and low-energy gamma spectrometry-

Conclusions

• The method shows good capacity for the separation and determination of 241Am in water, vegetation and soil

• Analysis time is dramatically reduced compared to conventional methods

• The method provides sufficient sensitivity for the determination of several actinide-nuclides in emergency preparedness

• The retention of 241Am is good on both resins, although the Actinide resin is somewhat more selective and provides higher retention at higher acid concentrations

• Possible to process resins for further analysis based on e.g. alpha spectrometry

D. L. Stricklin, Å. Tjärnhage, U. Nygren, J. Radioanal. Nucl. Chem., 251 (2002) 69

ulrika nygren, june 2002 determination of actinides in emergency preparedness using diphonix or...

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