radiotracer inradiotracer in prozess investigation · 33 outside (probe) measurement 4.3.3. 5.1....
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Radiotracer inRadiotracer inProzess Investigation
Fraunhofer Institute forFraunhofer Institute for Nondestructive Testing Dresden
D t h bil Alb t Z
Fraunhofer IZFP-D
Dr. rer. nat. habil. Albert Zeuner
Maria-Reiche-Straße 2D-01109 Dresden
+49(0)351 / 888 15-611 (Laboratory)
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( ) ( y)[email protected]. deand(0351) 268 7784 / (0172) 372 8894 1( ) ( )[email protected]
VeranstaltungOrt, Termin
Function and Purposes of IzfP-D
• The Fraunhofer Institute for Nondestructive Testing (IZFP) was founded in 1972 and is situated in Saarbrücken.
• The Dresden branch (IZFP-D) was founded in 1992.
Purposes of the IZFP-D:
• Improvement of the product quality• Lowering of the Quality costsIZFP D:• Confirmation of the technical safety for devices, machines and plants as
condition of their use
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ContentContent
1 I t d ti 4 E l ti f d l1. Introduction 4. Evaluation of measured values
2. Labelling2 1 G l P bl
4.1. General4.2. Residence time investigations4 2 1 Mean residence time2.1. General Problems
2.2. Addition of labelled material2.3. Radionuclides as labelling agent2 4 Labelling possibilities
4.2.1. Mean residence time4.2.2. Mixing behaviour4.2.3. Vessel number4 3 Mixing investigations
3 Measuring technique
2.4. Labelling possibilities2.5. Amount of labelling agent
4.3. Mixing investigations4.3.1. Batch processing4.3.2. Continuous operation4 3 3 Other homogeneity terms3. Measuring technique5. Investigated subjects3.1. General
3.2. Sample measurement3 3 Outside (probe) measurement
4.3.3. Other homogeneity terms
5.1. Residence time
6. Radiation protection aspects
3.3. Outside (probe) measurement 5.2. Mixing investigations5.3. Other activities
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p p
7. Summary
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some basics of radionuclides1.1. IntroductionIntroduction
sealedsources
solidmaterial
openradionuclides = „radiotracer“
use of ionizing radiation itselfwhere is the radioacti e material?wherein what concentration
is the radioactive material?the actual (radio-)tracer technique- RNT -
• potassium content in the potash industry
• estimation of radionuclides in human body („Body counter“)
ions
:
• soil analysis (gamma spectrometry)
chemical investigations (equilibria)
• investigation of residence time and mixing processes
appl
icat
i
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• chemical investigations (equilibria)
• nuclear medicine
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• residence time and mixing investigations2.2. LabellingLabelling
The radioactve material has the function of „labelled atoms“ and allows conclusions with regard to the origin of the radiation
application:nuclear medicine
t h i
in nuclear medicine - scintigraphyin continuously working technical devices• residence time analysis
technique• mixing investigations
principle: • addition of a (radioactive) indicator what indicator?how much?
measuring technique• measurement of the indicator
concentration
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justified?• conclusion about the behaviour of the
interesting material
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some remarks to labelling of material (with radionuclides):
2.2. LabellingLabellingro
blem
1:
but the properties of labelled material must not differ from those of the original
to label something (by an indicator)means to change its properties
pr material.
m 2
: well detectibilitybut large change of propertiesmuch labelling agent
prob
lem
small change of propertiesbut bad detectibility
little labelling agent
labelling paradox“
99mTc : 0.1 GBq108 Bq
3 x 1012 atomsexample for calculation:
Let‘s ass me a„labelling paradox“
nsw
er:
use ofradionuclides !
• extremely little material = practicallyno change of the properties
t l ll d t tibilit
Let‘s assume a100-fold spillover:
10-9 molesca. 10-13 g
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an radionuclides ! • extremely well detectibilityin addition: • decay of the radioactivity
gless than each other imputity
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process analysis versus radionuclide technique
connections between
2.2. LabellingLabelling
connections between
result(product)
process parameters
pressurestemperatures
of materials
use of radionuclides allows to estimate:(p )
qualityamount
cs yield p
amounts andconcentrations
and energies
depending ontime and placehn
ical
onom
icar
acte
risti yield
conversion degreecosts of material
energyi flow rates
balances
p
this results in:investigation possibilities:
tech
eco
cha equipment
• singular investigation at constant
residence timereaction time
elapsed timevelocity
• singular investigation at constant parameters actual state
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mixinghomogeneity
yfilling degree• repeated investigation with parameter
variation correlations
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scheme of radiotracer application3.3. MeasuringMeasuring techniquetechnique
process section in investigationradionuclides
propertiesnuclear physicalphysical
economicresults
yield
technicalphysical conditionsh i lphysical
chemicalavailabilitycosts
yieldconversion
energy inputcosts
chemicalradioactive contamination
of the environment
control
outs
ide
prob
es
ampl
es
ctio
nev
icechoise of a
radionuclide
processinterpretation
o p sa
inje
c dedi ti
activityestimation
transition-function
measuringvalues (incl.correction)in
put
sign
alradioactivelabelling of
a sample of the material
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labelling measurement evaluation
material
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outside (probe) measurement3.3. MeasuringMeasuring techniquetechnique
scintillation detector
…inserted into a cooling jacket
20 O2
120O
61… and in an collimator (lead, tungsten)
920160 9160
3.3. MeasuringMeasuring techniquetechnique sample measurement
samplebeaker h3
h4
beakerabove thedetector h1
h2
theoretical
th l d itthe pulse densitydepends on the sample mass(sample high)
realmeasurement
(sample high)
for this reason a calibration is necessary,due to the self-absorption of
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measurementdue to the self absorption ofradiation inside the sample
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material transport4.4. EvaluationEvaluation
uni
ts
different shapesof residence timedistributions,d di
rel.depending on n
l e n0 t 0 t
t sig
nal
c pu
lse
wer
sig
naen
ce ti
me
strib
utio
n0 t 0 t
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normalized mean residence timeinpu
tD
irac
answ
resi
de dis
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4.4. EvaluationEvaluation material transport
than: mean residence time first step: density function1. initial moment
most important parametermost important parametermean residence time :
derived: elapsed time between 2 (detector) positions, 1 und 2
• material velocity between 2 (detector) positions
• material amount between 2 (detector) positions( ) p
• filling degree
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• filling degree
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4.4. EvaluationEvaluation material transport
third step: plug flow or mixer?
∞
( )∫∞
⋅−=0
22 )()()( dttwtEttZ2. central momentthe variance around the mean value characterizes the uniformity of the material transport vessel ( ))( 2tEnp vessel
number( )
)()(2tZ
n =n
1→n - mixer behaviour
∞→n - plug flow
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batch mixer
4.4. EvaluationEvaluation mixing investigation
batch mixer • labelled substance is added at one point of the mixer volume
• samples are taken at different moments (after stopping the mixer)
• mean value standard deviation and variance are calculatedmean value, standard deviation, and variance are calculated
• the variance is plottet against time
• the optimal mixing time is at the minimum of the variance
continuously working mixers
• labelled substance is continuously added at the mixer inlet
• one or more detectors
• puls rate is plotted as function of time
• in case of homogeneous mixing, the pulse rate at each detector is
t t
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constant
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4.4. EvaluationEvaluation mixing investigation
xx x
xσσ ,,
al tim
eop
tima
mix
ing
decomposition practice
theory
batch operation:At different moments, the mixer is stopped samples are taken;
y
stopped, samples are taken;
mean value, standard deviation, and variance are calculated
i i t i i ti
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variance against mixing time(mixing of two sorts of sand)
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4.4. EvaluationEvaluation mixing investigation, other homogeneity terms
1. homogeneity degree H: H=1-ν...only usable when the measured values are near to a Gauss or Poisson distribution.In practice, the variance may be greater than 1, so a negative homogeneity degree would arise.
B h d h d d d i i f h P i
2. relative inhomogeneity I
In practical investigations, the condition that the particles do not influence each other
Between the mean µ and the standard deviation σ of the Poissondistribution exists the relationship
is not fulfilled, this equation may be not valid.For these cases the connection between mean and standard deviation is assembled by the definition of the relative inhomogeneity I: I (relative inhomogeneity)g y
If I > 1 - the mixture is classified assubstochastic (inefficient mixing)
( g y)• allows to compare different
mixing investigations and• shows the difference of the
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If I < 1 - the mixture is hyperstochastic found homogeneity to the ideal value I = 1
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5.5. InvestigatedInvestigated subjectssubjects ((extractextract))
5 15 1 residenceresidence timetimeSolid:• material transport in a lot of drum dryers and rotary kilns in coal processing and in
cement and potash industry
5.1.5.1. residenceresidence timetime
cement and potash industry.radiotracer: 140La, eluated from a 140Ba/140La generator.
• transport of a single particle through a screw conveyor by the CARPT method.a small glass ball was activated The built radionuclide was 24Naa small glass ball was activated. The built radionuclide was 24Na.
Liquid:• In a pilot plant (two-phase system, 20 bar pressure) a benzene derivative was p p ( p y , p )
labelled with 82Br.7 detectors at different points along the plant.
GGaseous:• In a gas reactor the transport of the gaseous phase was investigated by addition of
41Ar.This work was referred already in the 4 IGCC&XtL in 2010
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This work was referred already in the 4. IGCC&XtL in 2010.• The air exchange in cabs of trucks was investigated by using 85Kr.
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5.5. InvestigatedInvestigated subjectssubjects ((extractextract))
5 25 2 mixingmixing5.2.5.2. mixingmixingsolid:• Optimization of mixing time for batch mixers by using 99mTc.
Th bi d di t ib ti i i l l l t i ti t d b diff t• The binder distribution in mineral wool plates was investigated by different radionuclides (140La, 99mTc, 32P) to study the influence of radiation from outside volume elements.
• In the same way the distribution of one reaction partner in polyurethane foam was• In the same way the distribution of one reaction partner in polyurethane foam was investigated (99mTc).
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5.5. InvestigatedInvestigated subjectssubjects ((extractextract))
5 35 3 otherother activitiesactivities5.3.5.3. otherother activitiesactivities• Isotope generators: Because radionuclides from isotope generators are very useful
also for technical application, a lot of investigations were done by these generator 113 99nuclides (113mIn, 99mTc).
As these radionuclides are not usable for investigation of processes at higher temperatures, a 140La generator was developed. 140La was used for a lot of i ti ti i t ti d i ll t hi h t tinvestigations in rotating drums, especially at higher temperatures.
• By labelling with 99mTc the grain growth in a fluid bed was investigated.I ti ith th l b lli f h d b i k th l bilit f L O• In connection with the labelling of crushed brick, the solubility of La2O3 was estimated.
i l i ti ti ith l dsome special investigations with sealed sources• very exact density estimation• determination of steam content in streaming hot water.
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6.6. Radiation Radiation protectionprotection aspectsaspects
• The IZFP (Institute for non-destructive testing) Dresden has a legal permission to apply radionuclides for investigations also outside the laboratory.
• The radioactively contaminated material is to collect and to store until its activity lies below the maximum permissible value, accordingly to the annex XVI of the German radiation protection ordinance.German radiation protection ordinance.
• Being compliant with these limitations is not an issue, especially in pilot plants.
• The radiation exposure for the involved personnel of the industrial partner can be neglegted.
• The radiation exposure of the staff of the institute is controlled by dosimeters and in no p ycase exceeded the limiting values.
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Radiotracers
7.7. SummarySummary
Radiotracers• offer some advantages in investigation of laboratory and technical processes:
- The amount of radiotracers is in the order of 10-6 moles/use. This is normally below the concentration of other impurities and does practically not influence the quality of the product,
- By using short lived radionuclides, the time until the activity is below the permitted limit is short. So, a temporary storage causes no issues, especially in investigation in laboratory or pilot plant scalepilot plant scale,
- By using short lived gamma radiation emitting radionuclides, the necessity of taking samples is omitted and probes can be positioned outside the walls of the plant.
- Results of the measurement are available shortly after the end of the experiment.
• can be used in investigation of material transport and mixing processes.
Results of the measurement are available shortly after the end of the experiment.
- vessel number n can be calculated only from the measured values
- Mixing investigations have been explained, as well as another interpretation of homogeneity.
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