direct meassurement with xrf-sampling but no sample preparation
TRANSCRIPT
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Direct measurement with XRF –
sampling but no sample preparation?
Bertil Magnusson
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Content
an overview of direct XRF measurement will be
presented using standard wavelength dispersive and
energy dispersive instruments as well as handheld
instrument
• What we all know about XRF
• Direct measurement versus normal analysis in laboratory
• Elemental range
• Systematic effects
• Application of direct measurements
1. Quality control in nuclear power plant
2. Analysis of sediment and wood cores
3. Determination of thickness of coating
Direct measurement with XRF 2
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We all know that XRF
can be regarded as a non-destructive
technique
but in most cases in order to get more
reliable results with a lower
measurement uncertainty a sample
preparation step is performed for solid
samples. The preparation can e.g. be
homogenizing and subsequent
briquetting or fusion into a bead.
For liquid samples with no particles direct
measurement is possible with reliable
results
Direct measurement with XRF 3
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We also know that XRF analysis….
can be performed directly on many samples
with additional benefits such as
• less sample handling
• no sample transport to laboratory
• better spatial resolution
• lower response time
• higher sample throughput
Direct measurement with XRF 4
But in most cases with a
drawback of much higher
measurement uncertainty
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Direct measurement versus ”normal” analysis
”normal” analysis
Direct
measurement
”Normal” analysis
Atmosphere Air/He Vacuum or
helium
Sample
preparation
Normally not Yes
Sample size Few restrictions < 5 cm
Spatial resolution Yes No
Direct measurement with XRF 5
Drawbacks with measurement in air
and no sample preparation…
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Today light elements possible in air with short
pathlengt – example handheld XRF
6 Direct measurement with XRF
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XRF measurement with no sample preparation
Measuring depth is dependent on energy of analytical line and
mean atomic number in the matrix. With prepared sample that
are homogeneous - no systematic effect
7 Direct measurement with XRF
Direct measurement without sample preparation:
Systematic effects for inhomogeneous samples!
Sn Ka
Zn Ka
S Ka
Si Ka
Na Ka
Measuring
depth
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Measurement cycle
Client Issue
Client
Define issue
Decision on
measurement
Client
Sampling
Analysis
Measuring scientist
Interface Report on
measurement
Decision on result
Evaluation
Data presentation
Measuring
scientist
Direct measurement with XRF 8
Can i sell this
product?
Does the
product fulfil
the
regulations?
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Direct measurement - building materials
9 Direct measurement with XRF
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Direct measurement – consumer goods
10 Direct measurement with XRF
Metals in
• Plastics
• toys EU Toy directive (last March 2012)
• Presence of flame retardants e.g Br, Cl, Sb
• Electronics – ROHS directive Cd, Cr(VI), Ni, Hg, Pb
and org Br
• Jewellery e.g. Ni, Cd, Cr, Pb Co
• Textiles
• Isolation material
• Impregnated wood e.g As. Cr
Today these tests are performed routinely at SP
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Applications presented here
• Quality control in nuclear power plant -
Analysis of deposits (crud) on nuclear
fuel rods – sampling on a filter.
• Analysis of sediment and wood cores
– XRF footprint along the core
• Determination of thickness of coating
on welding wire – direct measurement
Direct measurement with XRF 11
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Measurement cycle – nuclear power plant
Client Issue
Client
Define issue
Decision on
measurement
Client
Sampling
Analysis
Measuring scientist
Interface Report on
measurement
Decision on result
Evaluation
Data presentation
Measuring
scientist
Direct measurement with XRF 12
Corrosion situation
and…..?
Study crud
deposits
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Quality control – analysis of deposits, crud
• Crud sampling
• Direct measurement with XRF
• XRF analysis on active samples
• Validation with synthetic samples and active
test samples
13 Direct measurement with XRF
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Crud* sampling
The crud is scraped or brushed from a defined
area
of the fuel rod
The crud is collected on a filter membrane
The crud/filter sample is analysed to determine:
• Quantity (g/m2) - XRF
• Elemental composition (g/m2): XRF
Fe, Co, Cr, Mn, Ni, Cu, Zn, Pt Sampling from fuel rod?- measurement of Zr
• Gamma activity of radioactive nuclides: Co-
60 …
*deposits on the nuclear rod
This application is presented
courtesy to
Eva Fredriksson & Pentti
Hietala, Westinghouse
Zircalloy
ZrO2
crud
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Crud* sampling
SP 1
SP 2
SP 3
SP 4
SP 5
SP 6
2
3
4
1
BC
AD
A B C D E F GH I J
876
910
4321
5
4
1
2
3
A
D
B
Marking
Marking
2
3
4
1Channel Center
Side OrientationX
Subbundle OrientationX
SP Spacer
C
Sampling
level
Fuel crud is
sampled between
the spacers -
normally 5 or 6
levels
Water reference
samples are taken
both before and
after each
assembly
3
2
5
4
1
6
7 Top plate
Spacer 1
Spacer 2
Spacer 3
Spacer 4
Spacer 5
Spacer 6
HOW
Direct measurement with XRF 15
*deposits on the nuclear rod
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Crud sampling
HOW
The fuel
crud
sampling
equipment
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Crud sampling process in a nuclear power plant
1. Sampling under water on a filter (Millipore)
2. Removing water by pressing air throught
the filter
3. Removal with tool the upper part of filter
holder
4. Mounting av cup with mylar film on top of
filter
5. XRF-analysis using either
• Uniquant semiquantitative software
or
• a calibration based on active standards
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Analysis of crud in a nuclear power plant
XRF-
container
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ARL Optim’X in a container
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XRF measurement on radioactive samples
Issues with radioactive samples
The radioactivity of the sample can lead to:
• Sample excitation resulting in XRF signal for
several elements.
• Here we test X-ray tube off
• Higher background – especially for lighter
elements
• Samples in sample changer increasing
background for measured sample
20 Direct measurement with XRF
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Sample excitation from active samples
ED-XRF with X-ray tube on&off?
Spectrum presented courtesy to Kari Moum and Torill Solheim
Institutt for Energiteknikk/Halden Reaktor Prosjektet
Direct measurement with XRF 21
Tube off
Tube on
Sample is a filter.
Sampling 10 l water
from primary cooling
circuit in a nuclear
power plant. Activity 25
µS/cm close
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ED-XRF - tube off
we see Cr Mn Fe Ni but no Co Cu and Zn
Cr Mn Fe Co Ni Cu Zn
Direct measurement with XRF 22
Tube off
Tube on
Iron
background
≈ 2 µg/cm2
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WD-XRF with X-ray tube off&on
Direct measurement with XRF 23
Tube off Samples are crud from a nuclear
power plant
Tube on
NOTE:
log
scale
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WD-XRF with X-ray tube off
Direct measurement with XRF 24
Tube off Samples are crud from a nuclear
power plant
Tube on
Cr Ka Mn Ka
Green is ca
30 ug/cm2
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Background increase with more crud
25 Direct measurement with XRF
Red 20 mg crud or 5 mg/cm2
Blue 6 mg crud or 1.5 mg/cm2
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The background mystery
2009 was the first time we used XRF an a nuclear powr plant
For a water blank sample we got very much higher background
especially for Al & Si.
A scan showed low background???
Direct measurement with XRF 26
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New scan of water blank with samples and
without samples in sample changer
27 Direct measurement with XRF
With no samples in sample changer less than 0.3 kcps
No radioactive samples in sample changer
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Validation
Instrument calibrated with standardless software
1. Validation with synthetic crud samples prepared from pure
metals – Low ”recovery” - < 80 %
2. Validation with synthetic crud samples grinded further –
”recovery ” close to 100 %
3. Validation with active samples analysed with ICP-MS –
”recovery” close to 100 % for most elements
28 Direct measurement with XRF
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Validation with synthetic crud samples
Fe, Co, Cr, Mn, Ni, Cu, Zn, Pt
29 Direct measurement with XRF
Figure 1 Particle size distribution for crud 1. Surface weighted mean 3 µm
Figure 2 Particle size distribution for crud 1 after sample was further grinded. Surface weighted mean 1.2 µm
Low Recovery < 80 %
Recovery close to 100 %
1 µm
Particle
size
distribution
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Validation Fe up to 1 000 µg or 250 µg/cm2
XRF vs ICP-MS on active samples
2010-08-17 30 crud samples
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Validation Zn up to 600 µg or 150 µg/cm2
– XRF vs synthetic crud
2010-08-17 31 crud samples
Residuals
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Validation Zn up to 100 µg or 25 µg/cm2
XRF vs ICP-MS on active samples year 2009
2010-08-17 32 crud samples
-50
0
50
100
150
0 20 40 60 80 100 120Res
iid
ua
l u
g
Similar results were obtained 2010 –
Decision to use active crud samples for calibration
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Conclusions
Systematic effects – yes.
• Validation with synthetic standards - The sample
particles were finer than the synthetic crud standards
(before further grinding)
• Validation with active test samples
• For most elements the ”recovery” was close to 100
% comparing XRF Uniquant with ICP-MS results
• The Zn gave 150 % ”recovery” when comparing
with ICP-MS. No understanding of this effect so
far. The ICP-MS were validated with synesthetic
crud and gave excellent results
33 Direct measurement with XRF
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Conclusions
• New calibration performed with active crud samples,
analysed with ICP-MS, to minimise systematic
effects.
• For elements not found in crud synthetic samples
were used.
• Interference from active samples
• Increased background with radioactive samples.
• No characteristic peaks found with WD-XRF
• Fitness for intended purpose
34 Direct measurement with XRF
Direct analysis now possible for
elemental composition and amount
using XRF for elements of interest
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Measurement cycle – Increasing depth in harbour area
Client Issue
Client
Define issue
Decision on
measurement
Client
Sampling
Analysis
Measuring scientist
Interface Report on
measurement
Decision on result
Evaluation
Data presentation
Measuring
scientist
Direct measurement with XRF 35
Can we dredge in
the harbour area?
Will there be
an
environmental
impact?
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Analysis of sediment and wood cores
Shale (norsk: skifer) sample was scanned with steps of 0.2
millimeters at 10 seconds using XRF. On top of the optical image is
superimposed Si and Fe graphs.
Si (blue) Fe (red)
50 mm
Applications
This
application is
presented
courtesy to
Anders
Rindby
Direct measurement with XRF 36
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Combined m-XRF, radiography and optical scanning
The Core Scanner moves the sample in steps.
Sample is irradiated with an X-ray tube with a
well-defined beam. The fluorescence (XRF) and
absorption (radiography) are measured.
An camera system provides sample images.
Direct measurement with XRF 37
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Combined m-XRF, radiography and optical scanning
XRF
detector
profiler
Camera
Sample
Direct measurement with XRF 38
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K profile Ti profile Fe profile
As profile
Br profile
Average atomic number
Sample with courtesy of Dr. Bernard Dennielou, Ifremer, France
820 mm
XRF scan examples
Direct measurement with XRF 39
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Illustrations/graphs area
Determination of thickness of coating on welding wire
This application is presented
courtesy to
Göran Säwemark, ESAB
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Determination of thickness of coating on welding wire
Client Issue
Client
Define issue
Decision on
measurement
Client
Sampling
Analysis
Measuring scientist
Interface Report on
measurement
Decision on result
Evaluation
Data presentation
Measuring
scientist
Client need
reporting in
mg/dm2
Production
need direct
reporting
Direct measurement with XRF 41
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Application of surface additives
Lubricant
•MoS2 - thickness on wire 0.001-0.01µm ( up to 0,3 mg/dm2)
•Ca (soap) 0,07 mg/dm2
Wet Chemical Analysis
Analysis of Mo and Ca
4 m sample is leached in acetone in an ultrasonic bath to remove
the MoS2 powder.
The acetone is evaporated and the MoS2 is dissolved in aqua regia
and Mo is determined by ICP.
Determination of thickness of coating on welding wire
Direct measurement with XRF 42
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Illustrations/graphs area
Sample Preparation of wires for XRF
Sample holder on the insert Sample ready for XRF-analysis
Opening: 27 mm
Analysed wire: 0.4-0.5 m
Wire diameter: 1.0 -1.2 mm
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Illustrations/graphs area
Mo and S scan WD-XRF Intensity versus 2
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Illustrations/graphs area
Calibration curve Mo Lb Intensity versus Mo (mg/dm2)
Mo (mg/dm2) measured with ICP
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Illustrations/graphs area
Calibration curve Ca Intensity versus Ca (mg/dm2)
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Illustrations/graphs area
ED-XRF
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Illustrations/graphs area
Mo and S scan ED-XRF Intensity versus energy (channel number) 1.6 to 7.5 keV
We measure S k alfa + partly Mo L alfa
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Illustrations/graphs area
Handheld XRF for screening
Using a general metal calibration
The apparent sulfur concentration
is used for screening if the
product fulfils the specification
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Illustrations/graphs area
Production control before respooling
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Conclusions - Application welding wire
At factory no wet chemical analysis
XRF is a fast tool for deposited amount on the surface of MoS2
and Ca on welding wires
For accurate analysis: Separate calibration curves / diameter
• WDXRF: Can separate Mo and S
• EDXRF: Analysis of S (Mo overlap)
• Handheld XRF: Analysis of S (Mo overlap)
Fast production control on line Pass/Fail
Direct measurement with XRF 51
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Direct measurement with XRF –
sampling but no sample preparation?
YES
when we know our analytical
technique
&
when we can demonstrate fitness for
intended purpose
Bertil Magnusson
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And I also would like to pay homage to Wilhelm
Conrad Röntgen
53 Direct measurement with XRF