On-line Actinide Quantification with Extractive Scintillating Resins

Timothy A. DeVol, James E. Roane, Lara D. Hughes

Clemson University

Eichrom Users’ Group Workshop

May 4, 2004

Need for Monitoring Method

• Radionuclide contamination in natural waters– natural– anthropogenic

• Radionuclide specific and gross alpha analyses – primarily laboratory based– can be time intensive and costly

• Need for in-situ and on-line monitoring – site assessment before, during and following remedial action

Sample SamplePrep

Concentration

Separation

Detection

Data

Sample SamplePrep

ConcentrationSeparation Detection Data

Dual FunctionalitySimultaneous Concentration and Detection

Heimbuch, et al., 1964

Li and Schlenoff, 1994DeVol, et al., 1997Campi, et al., 1998Link and Synovec, 1999Egorov, et al., 1999Headrick, et al., 2000

Extractive Scintillating Resin

Inert polystyrene chromatographic supports

(100 - 150 m particle size, ~700 m2/g)

Resin Fluor Extractant

TRU ES PPO/DM-POPOP CMPO/TBP

Actinide ES -NPO Dipex®

Experimental- Flow cell procedure• Flow cell

– resin dry packed into FEP Teflon tubing – placed in front of PMT(s)

• Test procedure– conditioning, loading and washing steps with appropriate reagents– collecting on-line data during flow – pulse height spectra before and after load– aliquots of effluent analyzed off-line (mass balance)

• Radioactivity– spiked solutions of 241Am, 239Pu and 233U– Anthropogenic samples– natural groundwater containing U

Extractive Scintillator in

Flow-cellRadiation Detector

Computer

Effluent

Sam

ple

Load

ing

Sol

utio

n

Elu

ant

LSC

Simultaneous Separation and Detection

Manually controlled pump

Flow-Cell Detection Systems

Ultraviolet Illumination

Coincidence System for TRU ESModified Hidex Triathler for Actinide ESModified Eberline E-600 for Tc ES II

TRU ES Loading Profile

0

2

4

6

8

10

12

0 500 1000 1500 2000

Gro

ss C

ou

nt R

ate

(cp

s)

Time (sec)

I II III

I Condition w/ 2 M HNO3

II Load 239Pu in 2 M HNO3

III Rinse w/ 2 M HNO3

0

10

20

30

40

50

60

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 100 200 300 400 500

239

Pu

Gro

ss C

oun

tsB

ackg

rou

nd

Co

unts

Channel Number

TRU ES Pulse Height Spectra

239PuBackground

0

20

40

60

80

100

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 1000 2000 3000 4000 5000On-

Line

Gro

ss C

oun

t Rat

e (c

ps) O

ff-Line N

et Co

unt Rate (cp

s)

Free Column Volumes (FCV)

off-line 3H

on-line 233U off-line 233U

Chromatographic capacity of the ES TRU resin as illustrated by the loading and elution of 233U

k’ ~ 3000

Sequential Elution of 241Am, 239Pu and 233U from TRU ES Resin

Off-Line Counting

On-Line Counting

Sample Load in 2-M HNO3

4-M HCl

4-M HCl + 0.02-M TiCl32-M HCl0.1-M Ammonium Bioxalate

0

50

100

150

200

250

300

350

400

450

500

0 2000 4000 6000 8000 10000Time (s)

Net

Cou

nt R

ate

(cps

)

241Am 239Pu 233U

0

5

10

15

20

25

30

0 2000 4000 6000 8000 10000Time (s)

Gro

ss C

ount

Rat

e (c

ps)

239Pu,233U

241Am, 239Pu, 233U

233U

Analysis of SRTC High Level Waste Sludge

Plot of average activity (n=3) with 1 standard deviation

100

101

102

103

Gross An3+ Pu4+ U6+

On-line avg.Off-line avg

Con

cen

trat

ion

(Bq

mL-1

)

0.00

0.25

0.50

0.75

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Gro

ss C

oun

t Rat

e (c

ps)

Volume (L)

On-Line Monitoring233U in Synthetic Groundwater

CR(cps) = 0.151 + 0.650*V(L) R= 0.95

CR(cps) = 0.165 + 4.631*V(L) R= 0.99

CR(cps) = 0.159 + 2.729*V(L) R= 0.97

8.62 Bq L-1

4.92 Bq L-1

1.74 Bq L-1

0.00

0.25

0.00 0.02 0.04 0.06 0.08 0.10

Gro

ss C

ou

nt R

ate

(cps

)

Volume (L)

Background

Monitoring Natural Uranium in Water

0.00

0.10

0.20

0.30

0.40

0.50

0.00 0.02 0.04 0.06 0.08 0.10 0.12

Gro

ss C

oun

t Ra

te (

cps)

Volume (L)

CR (cps) = 0.153 + 4.884*V(L) R=0.96Expected 7.48 Bq/LMeasured 9.6 Bq/L from slope of first 50 mL

125 mL sample acidified to 0.5 M HCl

Actinide ES Resin

0

2

4

6

8

10

12

14

0 200 400 600 800 1000

y = 1.1842 + 0.011822x R= 0.99584

Gro

ss C

ount

Rat

e (c

ps)

Volume (mL)

685 g U/L17.4 Bq/L

Actinide ES Resin

1

1.5

2

0 200 400 600 800 1000

Background 1.96 backgroundNPO 30 mg/L

y = 0.99462 + 0.00083531x R= 0.90612 G

ros

s C

ou

nt

Ra

te (

cp

s)

Volume (mL)

30 g uranium/L (0.76 Bq/L)

Natural Uranium in Groundwater acidified to pH 1

Summary of Results

Resin Detector Background Count Rate (cps)

Detection Efficiency

TRU ES Coincidence system

0.14 51% (nat. U) 97% (241Am)

Actinide ES Modified Hidex Triathler

0.75 52% (nat. U) 65% (241Am)

Conclusions• Extractive scintillating resins are selective dual-purpose

media– High

– Transparent to scintillation light

• Chromatographic property of ES resin is similar to non-scintillating commercially available resin

• Quantification has been demonstrated on-line• Applicable toward environmental screening applications.

Continuing to work on solving the stability, sensitivity, benign sample matrix, and reusability issues

FUTURE WORK

• Solve the problems that affect the results, such as,– Chemical luminescence– Dark adaptation time– Signal variation with radionuclide position in flow-cell

• Optimize flow-cell geometry for maximum sensitivity

• Develop ruggedize field instrument and demonstrate in the field

• Off-line evaluation procedures

Acknowledgments

Dr. James Harvey, Dr. Jonathon Duffey, and Joel Williamson at Eichrom Technologies, Inc.

NSF SBIR Phase I contract # NSF/SBIR-9760934

DOE Office of Science (BER) grant DE-FG07-99ER62888