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Radiotracer forProcessInvestigation

the authors:Albert Zeuner Peter Krüger

Fraunhofer Institut für zerstörungsfreie Prüfverfahren, Institutsteil DresdenMaria-Reiche-Straße 2, D-01109 Dresdenwww.izfp-d.fraunhofer.de

VeranstaltungOrt, Termin

4th International Freiberg Conference on IGCC & XtL Technologies

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Process investigation - Radionuclides ?

Process investigation seeks correlations between

pressurestemperatures

amounts andconcentrations

flowsbalancies

of materialsand energies

depending ondepending on-- time andtime and-- location in the reactorlocation in the reactor

investigation options:• unique investigation at constant

parameters

• repeated investigation with variation of parameters

actual conditiongives

interrelationsgives

derived from this:

elapsed timefilling degreebetween different

reactor sectionsmaterial velocity

residence timereaction timemixinghomogeneity

process parametersresult(product) and

RADIONUCLIDES may be useful in the following fields:qualityquantity

tech

nica

l and

econ

omic

para

met

ers yield

degree of reactioncosts of material

energyplant

of product

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measurement ofinherent radioactivity

use of„open“ radionuclides

What can you do with radioactivity ?

• own radioactivity for non-destructice material analysis• potassium determination in potassium salts

• potassium (raw) salt is a mixture from about 80 % of NaCl and only 20 % KCl. Because natural potassium contains a radioactive isotop (K-40), it is possible to estimate the potassium content during the process by measuring the radioactivity

• radionuclide measuremtent in human body• „Body counter“

• earth and water analysis• gammaspectrometry

• localisation („labelled atoms“) – also non-destructice• tracing of fertilizers in plants• nuclear medicine (incl. emission tomography)• residence time measurement in technical equipment• mixing investigation

• use of interaction (between radiation and material) – also non-destructice• measurement of fill level, thickness, density, grammage• compound analysis• structur analysis• (transmission) tomography

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application:nuclear medicine

technics

principle: • addition of a (radioactive) indicatorwhichever indicator?how much?

„labelled atoms“ allow

• residence time (and mixing) investigation

• szintigraphy in nuclear medicine:• residence time analysis in continously

working technical equipment• mixing investigation

• conclusions about the radiation origin

justifiable?• conclusion about the behaviour of the

material of interest

measuring technique• measurement of the indicator concentration

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labelling of material (with radionuclides)

but properties must be not different from the original material.

prob

lem

2:

„labelling paradoxon“

solu

tion:

radiotracer:

• extremely low concentration= practically no change of properties• extremely good detectibility

in addition: • decay of radioactivity enablesfurther use of the product

some remarks to:

to label something (by an indicator)leads to a change of properties

good detectabilitybut big change of propertiesexcessive indicator

low change of propertiesbut bad detectibility

insufficient indicator

prob

lem

1:

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radiotracer application scheme

process section of interest improvement ofprocess regime

yieldconversion

energy consumptioncosts

transferfunction

process-interpretation

process control

labelling measurement interpretation

outs

ide

dete

ctor

s

taki

ngsa

mpl

es

radiationmeasurementand correction

inpu

tsi

gnal

feed

er fo

rla

belle

dm

ater

ial

technicalphysical conditionschemical

(radioactive) contaminationof environment

radionuclides

propertiesnuclear physicsphysicschemistry

availabilitycost

radioactivelabelling

of a material sample

choice ofradionuclide

activity estimation

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important relations:

labelled substance= source of radiation

activity is defined bydecrease of atom quantity

time unit

radiation

radiation emission =quants (resp. particles)

time unit

detector (measurement)

produceselektrical pulses

time unit(puls density / puls rate)

specific activity ∼

concentration

some transformations:

A A e t= ⋅ −0λ

A N= ⋅λ division by V

A

puls rate at the detector

radiation intensityproportional

activity / activity concentrationproportional

indicator concentrationproportional

conclusion

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radiation measurement under technical conditions

scintillation detector,

if required: (measurement at hot plants) inserted into an

cooling jacket (water, air)

20°

120

Ø

20160

61

cooling jacket with detector may be inserted into an collimator (e.g. lead, tungsten), so that the

detector receives radiation only from a desired solid angle

some remarks to:

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modular (from single slices) tungsten collimators allow in connection with a sandwich plate more sensitive radiation measurements

modulartungsten collimator

with scintillation detector

sandwich plate

possibility for for four detectors

example 1: special equipment for measurement at an extruder

labelled with Tc-99m, half-life 6 h

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residence time distributions in an extruder along the transport path

5 residence time distributions *

*

* time scale with regard to tracer injection („zero“)

5 detectors (or groups of detectors)

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equipment in investigation:

•vertical tube reactor

•high-velocity gas stream

example 2: special equipment for measurement at an gas reactor

©© TU Bergakademie FreibergTU Bergakademie Freiberg

•

multiple detector planes,each collimated by some layersof lead bricks(5 x 10 x 15 cm³)

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layers of lead bricks(collimation for detectors)

flexible tubefor cooling water

©© TU Bergakademie FreibergTU Bergakademie Freiberg

special detector assembly:some detectors in one plane= addition of detector pulses

special equipment for measurement at an gas reactor

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, half-life only 109 min, noble gas4118Ar

special equipment: measurement at an gas reactor

• half-life is short with regard to transport by car

• for that reason

radionuclide:i.e. no chemical reactions = transport of the gas phase

• is produced by (n,γ) activation in the research reactor of the HMI in Berlin

• half-life is long enough for measurements in gas streams

• emits high energy γ-radiation (1.293 MeV), suitable to penetrate metal walls

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gas reactor: measured residence time distributions

0.040.060.080.100.120.140.160.180.200.220.24

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Normalised residence time t/tm0

Signal: Upp. free space (2)Signal: Outlet (6)Approx. by convolution

0.000.02

0.0

Prob

abili

ty d

ensi

ty E

(t)

catalystcatalystlayerlayer

6

2

natural gas +oxygen + steam

synthesis gas

Source: Zeißler et al., CIT 2006, 78, No. 1-2

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• Radionuclides in sealed and open Form are very suitable for process control and analysis and for investigation of chemical and medical problemes

• sometimes there is no alternative to radioactivity(thickness of tubes, filling level, γ-defectoscopy; nuclear medizine, reactions under high

pressure or vacuum)

• open radionuclides have some advantages in the investigation of material transport and mixing processes• (practically) no pollution of the product• no samples needed• contactless measurement through the walls of the plant• information about the tracer concentration at many positions• on-line measurement• after decay the products are usable without limitations

• measurements by working groups with special measuring technique• we have a legal permission and work - of course - in accordance with radiation

protection specifications

Summary 1

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We have used open radionuclides in the followingfields of investigation

Summary 2

residence time investigation•

gas: natural gas conversion

•

liquids: organic matter, water balance, sewage plants, filtrationoil consumption of combustion engines

•

fluidized bed: particle growth in a granulation fluidized bed

•

solids: conveyors, dryers, rotary kilnsmillssynthetic fibres, polymers, extruders

homogeneity•distribution of binding agent in rock wool

single particles•CARPT (Computer Aided Radioactive Particle Tracking) in a screw conveyor

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We thank youfor

yourattention

Albert ZeunerAlbert.Zeuner@web.de

Peter Krügerpeter.krueger@izfp-

d.fraunhofer.de

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