International Radiation Protection Association11th International Congress
Madrid, Spain - May 23-28, 2004
Keynote Lecture 3aActive Methods & Instruments for Personal Dosimetry
of External Radiation in EuropePresented by Teresa Bolognese-MilsztajnCo-authors: M.Ginjaume and F.Vanhavere
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Contents
INTRODUCTION Recommendations and legal requirementsCalibrations and Standards
INSTRUMENTS AND METHODSDetectors Calibration and testing Measured quantitiesAPD (Active personal dosemeter) use in workplaces APD problems and advantages for usersIntercomparisons
CONCLUSIONS AND FUTURE NEEDS
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Legal requirements in europeancountries
The 96/29 EU directive is widely spread in Europe for external radiation:
Individual monitoring is practiced in most countries for category A workers Individual monitoring systems are delivered by accredited servicesIndividual monitoring record: passive dosemeters are mostly used.Optimisation of doses: APD are considered better tools for day-to-day, job-to-job processing data
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The 96/29 European Union directive is based on ICRP recommendations
Directive does not specify type of dosemeters for individual monitoring
butIn several european countries APD are considered better tools for optimisation of ALARA principlebecause of:
Instant direct reading Daily dose recording Data transfer to and from computer network Lower dose sensitivityAlarms
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APD USE IN EUROPE
In most EU countries passive dosemeters are obligatory and used for dose recordingIn some countries the legislations do not specify the type of dosemeter to be usedAPDs are mosty required in particularsituations:
Licence conditions in some workplacesObligatory for potential high dose level situationsItinerant workers Obligatory in France together with passives
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Calibrations and Standards
Calibration and testing specified by memberstates ISO Standard 17025 is progressively being applied in EuropeIEC Standards for APD are less well known and national calibration and testing are applied Progress still to be done to harmonise standards practices (EURADOS)
2004 May the 24th IRPA 11 Keynote Lecture 3a 7
IEC 61283 series.
IEC 1283: Radiation Protection Instrumentation – Direct reading personal dose equivalent (rate) monitors – X, gamma and high-energy beta radiation. IEC 61283 (1995)
IEC 1525: Radiation protection instrumentation – X, gamma, high energy beta and neutron radiations – Direct reading personal dose equivalent and/or dose equivalent rate monitors. IEC 1525, 1996
IEC: Radiation Protection Instrumentation. Measurement of Personal Dose Equivalent Hp (10) and Hp (0.07) for X, Gamma and Beta radiation: Direct Reading Personal Dose Equivalent and/or Dose Equivalent Rate Dosemeters. IEC 61526 (1998)
IEC1323
IEC 1323: Radiation Protection Instrumentation – Neutron radiation - Direct reading personal dose equivalent and/or dose equivalent rate monitors IEC-1323 (1995)
IAEA IAEA Safety Series: Safety Guide: Assessment of occupational exposures to external sources of radiation RS-G-1.3, 1999
Table 1 standards relevant for APDs
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Detectors
APDs commercially available are based on:Geiger-Müller
Pulse type ion chambers , electrons collected apply a constant electric field, low efficiency
Silicon diodesIonisation process and charge collection ~10 times more
efficient than for GM type detectors Direct ion storage (DIS)
Ionisation chamber combined with MOSFET data storage device ( active and passive device)
(Bubble detectors)Passive device but direct reading
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DIS
Figure 1 a Photon sensitive ion chamber Wall Material: Graphite or Teflon
Figure 1b Neutron/photon sensitive ion chamber Wall Material: A-150/PE containing 6Li or 10B
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EURADOS consortiumWorking group: Harmonization of individual monitoring in Europe
Report on APD in preparationTo be published in RPD
Status of implementation of direct reading devices in EU countriesAPD catalogue of gamma and betaAPD catalogue for neutronsAPD problems and advantages for users
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APDsγ−β from EURADOS catalogue
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APD catalogue for gamma and beta measurements
Overview of the main characteristics of some APDs used in Europe. A set of 22 dosemeters produced by 15 manufacturers was selected.
General information: manufacturer and type, year introduced, type of application, type of detector.
Radiological performance: measured quantities, type of radiation measured and energy response, range, angular response.
Physical characteristics: dimensions, weight, battery type and life-timefor typical use.
Environmental performance: electromagnetic fields sensitivity. Mechanical performance: acoustic sensitivity and shock resistance.Dose recording procedure: manual reading, reading equipment,
software.Type test: lab that conducted the type testing, standard followed or
approval.
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Table 2: Main Characteristics of a set of 22 photon APD(information provided by manufacturers)
Energy range (keV) APD Reference M in Max % 137Cs
Angular response % 137Cs
W eight (g)
Volume (cm 3)
AEA Tech. DoseGuard S10 60 3000 80 115.0 Aloka PDM 112 40 1000 50 52.2
Automess ADOS 70 3000 0º-45º 20% 190 133.9 Canberra Dosicard 50 2000 15% 0º-90º 25% (Co-60) 65 83.3
Comet APD (P anasonic Ind. Eur.) 20 1600 0º-60º 20% 109 93.5 Dositec L36 60 6200 25% 77 57.1
Fuji E lectric NRY 20001 50 6000 25% 0º-60º 20% 100 85.0 Graetz ED 150 50 2000 160 92.5
M GP DMC 2000S 50 6000 20% IEC 61283 70 70.6 M GP DMC 2000X 20 6000 30% IEC 61283 70 70.6
M GP DM C 2000XB 20 6000 30% IEC 61526 70 70.6 M GP SOR/R 50 6000 IEC 61283 55 37.0
M ini Instruments 6100 30 1000 20% 125 118.8 Polimaster PM 1203 60 1500 25% 90 126.0
Rados D IS-1 15 9000 30% 0º-60º 20% 20 16.2 Rados RAD-51/51T 60 3000 25/35% IEC 61283 90 115.0 Rados RAD-60/62 60 3000 25% IEC 61283 80 115.0
Rados RDD-20/RDR-20 50 1500 30% IEC 61283 24 14.0 Saic PD-2i/PD-3i 55 6000 25% 90 58.8
Saphydose Gam m a 50 1300 30% IEC 61283 165 167.3 Siemens EPD1, EPD2 (M k1) 20 10000 20% IEC 61526 170 162.3
Siemens Mk2 15 7000 20% IEC 61526 95 101.7
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1 10 10 0 10 0 0 10 0 0 0
A E A T e c h. D o s e G ua rd S 10A lo ka P D M 112
A ut o me s s A D O SC a nb e r ra D o s ic a rd
C o me t A P D (P a na s o nic Ind . E ur .)D o s it e c L3 6
F uji E le c t r ic N R Y 2 0 0 0 1G ra e t z E D 150
M G P D M C 2 0 0 0 SM G P D M C 2 0 0 0 X
M G P D M C 2 0 0 0 X BM G P S O R / R
M ini Ins t rume nt s 6 10 0P o lima s t e r P M 12 0 3
R a d o s D IS -1R a d o s R A D -51/ 51TR a d o s R A D -6 0 / 6 2
R a d o s R D D -2 0 / R D R -2 0S a ic P D -2 i/ P D -3 i
S a p hyd o s e G a mmaS ie me ns E P D 1, E P D 2 (M k1)
S ie me ns M k2
Ph o to n e n e r g y (k e V )Low er limit( IEC
Low er limit
Upper limit
APD Energy range from constructors
Figure 4.3: Energy range within a +/- 30 % of 137Cs response
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New developments
For high doses Detectors based on industrial diamonds
Biological tissues equivalent, resistant to high doses but low detection efficiency compared to siliconSuitable for measurements in radiotherapy
Low doses CCD coupled with Caesium iodine detectors and MOS detectors
Down to µSv region Extremity
Small sensors coupled with pocket size readout unit Few data publishedNo specific standards yet
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APDs for neutrons
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APD catalogue for neutrons
10-8 10-3 10-1 1010,01
0,1
1
10
100
GSF PTB DOS-2002 Pisa SDD RADOS DIS-N Munich amira
Hp,
m(1
0)/H
p,c(1
0)
En / MeV
Figure 5.2 Response as a function of the energy of APD prototypes
Figure 5.1 Response as a function of the energy for some commercial APDs
10-8 10-3 10-1 1010,01
0,1
1
10
100
SIEMENS EPD-N SIEMENS EPD-N2 ALOKA PDM-313 FUJI ELECTRIC NRNO BTI BD-PND BTI BDT Saphydose-n
Hp,
m(1
0)/H
p,c(1
0)
En / MeV
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The Saphydose-n individual electronic dosemeter for neutrons
Poster section 3h35 ID 288
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E. C. project November 2002 – April 2005Oral section 3a-347 H. Schuhmacher et. al.
Poster ID 730 V. Lacoste et al., Neutron spectrometry in workplaces of european nuclear industryPoster ID 956 F. Vanhavere, M. Coeck,Improvements of the Neutron Shielding around the VENUS Reactor Facility at the Belgian Nuclear Research Centre Session: 3b. External exposurePoster ID 670 M. Reginatto et al., Dose Equivalent Response Of Neutron Dosemeters Determined Using Unfolding MethodsPoster ID 288 T.Lahaye et al., Individual electronic neutron dosimetry in workplaces of european power plants and fuel processing facilities
EvaluationEvaluation of of Individual DosimetryIndividual Dosimetry ininMixed Neutron Mixed Neutron andand Photon Radiation FieldsPhoton Radiation Fields
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IM 2005European workshop on individualmonitoring of ionising radiation
April 11 - 15, 2005Renaissance Penta Hotel
Vienna / Austria
organised by theARC Seibersdorf research GmbH
Health Physics Division
in co-operation withthe European Radiation Dosimetry Group
EURADOS and IAEA
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Calibration and testing
ISO 4037 and IEC-61526 standards for γ and βReference radiation quality recommended :
Filtered X -radiation in the range 12 to 300 keV Gamma sources 137Cs(662 keV) and 60Co(1.25 MeV)
Calibration on ISO 4037-3 defined phantoms (table)For neutrons IEC-13233 standard
Reference radiation quality recommended : Thermal Mono-energetic up to 15 MeV
For both : environmental tests :Electromagnetic compatibility, humidity, temperature, drop test, etc...
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From EURADOS reportCalibration and testing from users
questionaire
0
1
2
3
4
5
6
7
NPP Fuel Cycle Research Industrial Medical
No periodic calibration
periodic internal radiological test
periodic external calibration
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Measured quantities
Ambient Dosemeter
H*
The ambient dose equivalent is an isotropic quantity
The personal dose equivalent is a directional quantity
Hp
Hp (10) = dose equivalent at 10 mm in the body at the location where the personal dosemeter is worn ( chest )
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ICRP60 recommends the effective dose E for radiological protection
E is not measurable but can be approximated, for individual monitoring, by the operational quantity Hp(10)
Hp = ∫ ∫ hp(Ε, α) ΦΕ,αdΕ dα
hp(E, α) is defined between 0° and 75°; new coefficients calculations are in progress for higher angles
Hp accurately estimates E only for certain geometries end energy field distributions see fig (5)
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Hp/E
FIG 5 Ratio personal dose equivalent Hp to effective dose equivalent as a
function of the energy for photons at AP,ROT and PA field geometry
104 105 106 107
Photon Energy / eV
0
5
10
15
20
25
Rat
io
H*(10)/E(AP)
H*(10)/E(ISO)H*(10)/E(ROT)
10-2 10-1 100 101 102 103 104 105 106 107 108
Energy (eV)
0
1
2
Rat
io
Hp(10,AP) / E(AP)Hp(10,ROT) / E(ROT)Hp(10,ISO) / E(ISO)
FIG 5 Ratio personal dose equivalent Hp to effective dose
equivalent as a function of the energy for neutrons at AP, ROT and PA field
geometry
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Accuracy of Hp measurements with personal dosemeters
Dosemeter reading should be tested in workpaces conditions Spectrometric measurement at workplacesTest on phantoms
Difficulties:Workplace field conditions are sometimes difficult to reproduce
Simulated workplaces fieldsIso phantoms represents only average workers, i.e. : workers
morphology is not taken into accountInstrumented antropomorphic phantoms
Hp accuracy in laboratory conditions may be ~10 to 20% (95%CL)
In workplaces:Hp measured/ Hp reference � 1.5for low doses and for neutrons
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10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 1010.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Proton recoil spectrometers Bonner spheres (Average) New MCNP
∆Φ(E
)/∆ln
(E) (
cm-2/ N
DA)
Neutron Energy (MeV)
10-2 10-1 1000.00
0.05
0.10
0.15
0.20
Proton recoil spectrometers Bonner spheres (Average) New MCNP
∆Φ(E
)/∆ln
(E) (
cm-2/ N
DA)
Neutron Energy (MeV)
CANEL/T400New geometry
To be published
water lens
depleted Unat
polyethylene
iron
end cap of the accelerator beam line and TiD target water lens
depleted Unat
polyethylene
iron
end cap of the accelerator beam line and TiD target
See Poster ID 730Neutron spectrometry in workplaces
of european nuclear industry
ISO 12789-1, Reference neutron radiations: Characteristics and methods of production of simulated workplace neutron fields (2001)
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Neutron fluence energy distribution for different directional intervals from 0o to 50o at theCANEL/T400 calibration area.
10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
10-3
10-2
10-1
100
Total 20o - 30o
0o - 10o 30o - 40o
10o - 20o 40o - 50o
∆Φ(E
)/∆ln
(E) (
cm-2.N
DA-1
)
Neutron Energy (MeV)
Lacoste, V., Gressier, V., Monte-Carlo simulation of the IRSN CANEL/T400 realistic mixed neutron-photon field, RPD (in press) (2004)
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APD use in workplaces
APD should be adapted to the workplace field More reliable APD use in power plants
Centralize recordingIndividual use
In hospitalsEnergy range not always adaptedManual recording
In some power plants, systematic comparison with passives performed
Differences between 3 and 8%When > 10% differences are investigated
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Photon field measurements in workplaces from ref : [Burgess],
[d’Errico] [Ambrosi]
0.00
0.20
0.40
0.60
0.80
1.00
Photon energy (keV)
Spec
tral
dis
trib
utio
n (d
Hp(
10)/d
E ar
b.un
its) Hospital
TestingHotcellsNuclear power
10 20 40 100 200 400 1000
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APD energy response compared with photon spectra in nuclear industry (Janwillem van Dijk)
0.0%
0.1%
0.2%
0.3%
0.4%
0.5%
0.6%
0.7%
0.8%
0.9%
1.0%
Photon energy (keV)
Spec
tral
dis
trib
utio
n (d
Hp(
10)/d
E)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Response (H
p (10)m /Hp (10)true )
SWRPSWROSiemensDISRAD50MGP SOR/TTLD-Arnhem
20 40 100 200 400 100010
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APD energy response compared to hot cells spectra
0.0%
0.1%
0.2%
0.3%
0.4%
0.5%
0.6%
0.7%
0.8%
0.9%
1.0%
Photon energy (keV)
Spec
tral
dis
trib
utio
n (d
H p(1
0)/d
E)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Response (H
p (10)m /Hp (10)true )
HZCsHZPmVSQuHZJSiemensDISRAD50MGP SOR/TTLD-Arnhem
Bre
mss
tral
ung
147P
m
10 20 40 100 200 400 1000
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Comparison of X-ray spectral distribution in medical sector with some APD response as a
function of the energy
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
Photon energy (keV)
Spec
tral
dis
trib
utio
n (d
H p(1
0)/d
E)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Response (H
p (10)m /Hp (10)true )
AngioCbogHkathEndoSiemensDISEuroSysMGP SOR/TTLD-Arnhem
20 40 100 200 400
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Neutron spectra measurements EVIDOS
Bare fuel rodsFuel rods in a rack
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 1010
2
4
6
8
10
12
14
16
18
POINT 1 POINT 2a POINT 2b POINT 3
Neutron Energy (MeV)
E ∆
Φ/∆
E (c
m-2.s
-1)
0
10
20
30
40
50
60
70
E ∆Φ
/∆E (cm
-2.s-1)
Poster ID 730 V.Lacoste et al., Neutron spectrometry in workplaces of european nuclear industry
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APD problems and advantages for users ( from EURADOS report)
The ideal dosemeter for userscheaper dosemetersbetter environmental characteristicslonger battery lifebetter radiological response:
most end-users make the assumption that present dosemeters measure the radiation quantities adequately
NPP only wish for an electronic neutron dosemeterbetter mechanical characteristics were not
considered a high priority
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Intercomparisons
Several national intercomparisons were performedBased on standards
EURADOS-AIEA intercomparison projectObjectives :
Verify performance of the different APD types available on the marketHelp the participating APD suppliers/ Member States in achieving a sufficiently accurate dosimetry Provide guidelines for improvements .
No budget availableIrradiation time foreseen by some EURADOS standard laboratoriesAIEA organiserHope to have devices from constructors >
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ISO 4037 and IEC-61526 standards radiation tests
Reproducibility of the readingRepeatability of the readingDose equivalent rate dependenceRelative intrinsic errorResponse as a function of radiation energyResponse as a function of radiation angle of incidenceRetention of readingAccuracy of alarm levelsResponse time
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Intercomparisons
FIG 7 Measured [Tex] response as function of energy of some commercial APD
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EURADOS-AIEA intercomparison preliminary protocol
Energy responsePhoton
S-Co,S-CS,N-30,N-80,N-300
0.1 mSvper quality
Dose rate response. Photon
S-Cs 10 mSv(at 1Sv/h)
10 µSv(at 1 mSv/h)
Angular responsePhoton
S-CS(Horizontal rotation)
1 mSv(for each angle: 0o, 45o 60o)
Electromagnetic interference
Mobile phone Dose set to lower limit of effective range of
measurement
Mixed field Photons
N-30 + S-CS0o angle
1 mSv
ResponseBeta
To be defined0o
1 mSv
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CONCLUSIONS AND FUTURE NEEDS
APDs for γ/β as reliable or better than passivesExperience in power plants confirm the advantages of APDs over conventional dosimetry mainly because of alarm featuresand direct reading allowing betteroptimisation of practicesImprovements needed for extremity, lowdoses, high intensity and neutrons
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CONCLUSIONS AND FUTURE NEEDS
Improvements on effective dose assessmentby:
Angular and energy spectrometry in workplacesChoice of detectors and calibration practicesSimulated workplaces fields calibrations
Type testing and standardHarmonize practices in EuropeStandards for extremity needed
APD use for legal Record?