spectroscopic on-line monitoring of radiochemical …
TRANSCRIPT
SPECTROSCOPIC ON-LINE MONITORING OF
RADIOCHEMICAL STREAMS
NEET Review
September 17, 2014
Sam Bryan, Tatiana Levitskaia, and Amanda
Casella
Pacific Northwest National Laboratory
Process Monitoring Can Be Achieved
Throughout the Flowsheet
Global vision:
Process monitoring/control
at various points in
flowsheet
Every flowsheet contains
Raman and/or UV-vis-NIR
active species
Coriolis and conductivity
instruments can be used on
all process streams
Monitoring Is Not Flowsheet Specific
CoDECON
dissolved fuel
TRUEX
TALSPEAK
rare earths
U, Pu, Np
Tc
FPs
Am/Cm
Monitoring of
strong acid
or pH desired
U
Approach:
Online Spectroscopic Measurements
Raman measurements of
– Actinide oxide ions
– Organics: solvent components and complexants
– Inorganic oxo-anions (NO3-, CO3
2-, OH-, SO42-, etc)
– Water, strong acid (H+), strong base (OH-)
– pH – weak acid/base buffer systems
UV-vis-NIR measurements of
– trivalent and tetravalent actinide and lanthanide ions
Potential Uses
– Process monitoring for safeguards verification (IAEA)
– Process control (operator)
Previous Experience: Hanford Site including deployments
– Real-time, online monitoring of high-level nuclear waste in tanks and to the waste
pretreatment process
Future – Cost share demonstration of performance in an actual processing plant
and enable comparison to existing methods
– In discussions with SRS H Canyon
Np(VI)
Np(V)
relative
Methodology for on-line process monitor
development: from proof-of-concept to
final output
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
450 550 650 750 850 950
wavelength, nm
Ab
so
rba
nc
e
Pu chemometric model
PLS model for Pu(IV) using UV-vis data
y = 0.9997x + 0.0006
R2 = 0.9999
0
2
4
6
8
10
12
0 2 4 6 8 10 12
Pu(IV), mM
Pu
(IV
), m
M p
red
icte
d[P
u(I
V)]
, m
M,
mo
de
l
Static measurements:
Model training database Chemometric model
development On-line model verification
and translation
Integrated software for data collection,
processing, storage and archiving
Real-time on-line concentration data display
Np titration into Simple Feed
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
550 650 750 850 950 1050
wavelength, nm
ab
so
rban
ce
0.05
0.10
0.15
0.20
0.24
0.29
0.34
0.38
0.43
0.48
0.57
0.65
0.74
0.83
0.91
1.11
1.30
1.49
1.67
2.00
2.31
2.59
2.86
3.10
3.33
Np, mM
Np(V)
Np titration into Simple Feed
y = 0.0588x - 0.0023
R2 = 0.9938
y = 0.0508x - 0.0012
R2 = 0.9937
y = 0.0088x - 0.0003
R2 = 0.9808
0
0.05
0.1
0.15
0.2
0.25
0.00 1.00 2.00 3.00 4.00
Np concentration in Simple Feed, mM
Ab
so
rban
ce
614 nm
982 nm
996 nm
Vis-NIR measurements for Pu and Np
model development
Pu(IV) concentration variable 0.1 to 10 mM
Np(V) concentration, variable 0.05 to 3.3 mM
Feed composition: 1.3 M UO2(NO3)2 in 0.8 M HNO3
UO2(NO3)2 does not interfere with Pu(IV) measurements
5
Pu and Np concentration can be quantified over wide range of process chemistry conditions
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
450 550 650 750 850 950
wavelength, nm
Ab
so
rba
nc
e
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12
Pu(IV) added, mM
Ab
so
rba
nc
e
542 nm
659 nm
797 nm
854 nm
R2 = 0.998
R2 = 0.999
R2 = 0.998
R2 = 0.997
Pu(IV)
Proof-of-Concept : Applicability of
spectroscopic methods for commercial
BWR ATM-109 fuel measurements
Commercial fuel: ATM-109, BWR, Quad Cities I reactor; 70 MWd/kg; high burnup
Fuel dissolved in HNO3
Performed batch contact on each aqueous feed with 30 vol% TBP-dodecane
Feed, Organic, Raffinate phases
successfully measured by
– Raman, Vis-NIR
Excellent Agreement of spectroscopic
determination with ORIGEN code and
ICP measurement
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Bryan et al. Radiochim. Acta, 2011.
ATM-109 U Pu Np Nd*
ICP-MS 0.721 8.99E-03 4.7E-04 8.40E-02
Spectroscopy 0.719 8.90E-03 4.7E-04 1.10E-02
Spectroscopic / ICP ratio 0.99 0.99 1.0 1.3
*concentrations in Molar units
Vis-NIR and Raman Multiplexer allows
for multiple, simultaneous sensor
locations on contactor system
September 2011 7
multiple fiber-optic cables
UV/Vis/NIR spectrometer
multiplexer
light source
multiple fiber-optic cables
Raman spectrometer
multiplexer
laser
Centrifugal contactor:
flow diversion experiment
test conditions •centrifugal contactors; 2-cm, 3600 rpm
•Aqueous phase: 11 mL/min
•Organic phase: 11 mL/min
•Diversion experiment
•3 mL/min of feed during flow test
•Spectroscopic probes and flow meters
attached to feed, raffinate, and organic
product streams
Raffinate
Solvent: 30 vol% TBP/DodecaneLoaded Organic
Feed
Feed diversion valve after process monitoring equipment
diverted feed solution
Loaded organic Solvent 30% vol%
TBP/dodecane
feed raffinate
Spectroscopic measurements for
diversion detection
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diversion of 3 ml/min started at 87 min
diversion stoppedat 134 min
diversion of 3 ml/min started at 87 min
diversion stoppedat 134 min
time (min) wavelength (nm)
ab
so
rban
ce
organic product (TBP/dodecane) phase raffinate (aqueous) phase
delta from in-process
Organic
Raffinate
Feed
Organic + Raffinate
delta from
in-process
delta from diversion
delta from diversion
Diversion quantification: mass flow plus
spectroscopic measurement
10
Excellent agreement between process
monitor and mass balance
measurements
2.9 x 10-3 mol Nd3+ diverted based on
mass balance
3.0 x 10-3 mol Nd3+ diverted based on
process monitor analysis
delta from diversion diversion start
diversion start, 87 min
Motivation for weak acid (pH 2 – 6)
measurements using spectroscopic
signatures
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• pH control is critical in TALSPEAK
separations
• spectroscopic determination of pH
desirable
• Simultaneous spectroscopic
determination of lanthanides also
desirable
• activities coordinated with Sigma
Team for Minor Actinide Separations
Aqueous phase: 1 M total NO3-, 1 mM total [Ln] + [Y],
1 M lactic acid, 0.05 M DTPA at various acidity.
Organic phase: 0.5 M HDEHP in 1,4-DIPB
Nilsson and Nash, Solv. Extr. Ion Exch., 27, 354-377, 2009
pH monitoring:
Weak Acid Measurements
TALSPEAK and Advanced-TALSPEAK as Model Systems
Raman Spectroscopic measurements for pH monitoring
Effects of lanthanides and stripping complexants in aqueous phase
– DTPA, 0.01 – 0.05 M
– HEDTA, 0.05 – 0.25 M
– [Ln]tot, ~ 20mM
Effects of complexants in organic phase
– HDEHP and HEH[EHP] / n-dodecane
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Citric acid system
• Citrate, 0.1 - 1.0 M
• Ionic Strength, 0.5 - 3.0 M
• pH = 1.2 – 6
Lactic acid system
• Lactate, 0.25 - 1.0 M
• Ionic Strength, 0.5 - 3.0 M
• pH = 1.2 - 5
Lactic acid buffer system
13
Carboxylate group modified by pH changes
free acid (-CO2H) to anion (-CO2- )
Bending of –COH
Can be used as spectroscopic probe of system pH
NaOH
pKa = 3.86
A-
HA
pH monitoring: Weak Acid Measurement
trend with increasing pH
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Carboxylate effects free acid (-CO2H) to anion (-CO2
- )
pKa = 3.86
600 800 1000 1200 1400 1600 1800 2000
0
100
200
300
400
500
600
700
800
wavenumber, cm-1
Ram
an
in
ten
sit
y
pH 1.7
pH 2.0
pH 2.2
pH 2.7
pH 3.1
pH 3.6
pH 4.1
pH 5.0
Increasing pH
1.5 2 2.5 3 3.5 4 4.5 5
1.5
2
2.5
3
3.5
4
4.5
5
5.5
measured pH
pre
dic
ted
pH
model data, 0 mM Nd3+
model data, 25 mM Nd3+
fit of data
95% conf. int.
Y = 0.9856*X + 0.04283; r2 = 0.9856
Y = 0.9856X + 0.0428
R2 = 0.9856
A B
pH Results based on Raman
Spectroscopy
October 1, 2014 15
Aqueous raffinate Raman
pH and Nd3+ successfully monitored
by Raman and vis-NIR spectroscopy
during flow contactor test
October 1, 2014 16
The change in Nd3+ extraction was successfully monitored in both raffinate and
organic product phases when the pH was modified with NaOH and HNO3 additions.
When pH was increased, the extraction of Nd3+ decreased, as predicted.
0 50 100 150 200 250 300
0
5
10
15
20
25
30
35
time (min)
Nd
, m
M,
sp
ectr
osco
pic
mo
del
Nd3+ organic product
Nd3+ raffinate
Nd, ICP confirmation
0 50 100 150 200 250 3002.5
3
3.5
4
4.5
time (min)
pH
, sp
ectr
osco
pic
mo
del
pH raffinate
pH confirmation
NaOH add’n
at 73 min NaOH add’n
at 73 min
HNO3 add’n
at 190 min
HNO3 add’n
at 190 min
low pH low pH high pH low pH low pH high pH
Conclusions
Using simulants and BWR Spent Fuel
– Demonstrated quantitative spectroscopic measurement on actual commercial fuel samples under fuel reprocessing conditions
• Raman for on-line monitoring of U(VI), nitrate, and HNO3 concentrations, for both aqueous and organic phases
• Vis/NIR for on-line monitoring of Np(V/VI), Pu(IV/VI), Nd(III)
Demonstrated mass balance in on-line contactor system using spectroscopic process monitoring
– During real-time centrifugal contactor TBP/dodecane extraction
– Diversion of feed was quantitatively detected within contactor system
– pH monitoring and simultaneous Ln (Nd3+) monitoring demonstrated with TALSPEAK system
Future plans for on-line process monitoring
– Collaborative demonstration on commercial (larger) scale :
• H-Canyon (SRS), others
Acknowledgements
U.S. Department of Energy (DOE)
– Fuel Cycle Research and Development (FCR&D), Separations
Campaign (NE)
– NNSA Office of Nonproliferation and International Security (NA-24)
PNNL’s Sustainable Nuclear Power Initiative (SNPI)
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