Practice for use of calorimetric dosimetry systems for dose measurements and dosimetry system calibration in electron beams

This practice covers the preparation and use of semiadiabatic calorimetric dosimetry systems for measurement of absorbed dose and for calibration of routine dosimetry systems when irradiated with electrons for radiation processing applications. The calorimeters are either transported by a conveyor past a scanned electron beam or are stationary in a broadened beam. This document is one of a set of standards that provides recommendations for properly implementing dosimetry in radiation processing, and describes a means of achieving compliance with the requirements of ISO/ASTM Practice 52628 for a calorimetric dosimetry system. It is intended to be read in conjunction with ISO/ASTM Practice 52628. The calorimeters described in this practice are classified as Type II dosimeters on the basis of the complex effect of influence quantities. See ISO/ASTM Practice 52628. This practice applies to electron beams in the energy range from 1.5 to 12 MeV. The absorbed dose range depends on the calorimetric absorbing material and the irradiation and measurement conditions. Minimum dose is approximately 100 Gy and maximum dose is approximately 50 kGy. The average absorbed-dose rate range shall generally be greater than 10 Gy·s-1. The temperature range for use of these calorimetric dosimetry systems depends on the thermal resistance of the calorimetric materials, on the calibration range of the temperature sensor, and on the sensitivity of the measurement device. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Pratique de l'utilisation des systèmes dosimétriques calorimétriques pour pour des mesures de dose délivrée par un faisceau d'électrons et pour l'étalonnage de dosimètres

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Status
Published
Publication Date
24-Feb-2020
Current Stage
6060 - International Standard published
Start Date
25-Feb-2020
Due Date
03-Oct-2021
Completion Date
25-Feb-2020
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INTERNATIONAL ISO/ASTM
STANDARD 51631
Fourth edition
2020-02
Practice for use of calorimetric
dosimetry systems for dose
measurements and dosimetry system
calibration in electron beams
Pratique de l'utilisation des systèmes dosimétriques calorimétriques
pour pour des mesures de dose délivrée par un faisceau d'électrons et
pour l'étalonnage de dosimètres
Reference number
ISO/ASTM 51631:2020(E)
©
ISO/ASTM International 2020

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ISO/ASTM 51631:2020(E)

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© ISO/ASTM International 2020
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Published in Switzerland
ii © ISO/ASTM International 2020 – All rights reserved

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ISO/ASTM 51631:2020(E)
Contents Page
1 Scope. 1
2 Referenced Documents . 1
3 Terminology. 2
4 Significance and use. 2
5 Interferences . 3
6 Apparatus. 3
7 Calibration procedures. 4
8 Dose measurement procedures. 5
9 Calibration of other dosimetry systems . 6
10 Documentation. 7
11 Measurement uncertainty. 7
12 Keywords. 7
Annexes. 7
Figure 1 Example of a polystyrene calorimeter used for routine measurements at a 10-MeV
industrial electron accelerator. 3
Figure 2 Absorber (phantom) for irradiation at 10 MeV electron irradiation facility of routine and
transfer-standard dosimeters (10). Material: Polystyrene. 4
Figure 3 Example of measurements of temperature of a graphite calorimeter before and after
irradiation (7). 6
Figure 4 Example of on-line measurements of a graphite calorimeter (5). 6
Table 1 Measurement uncertainties of routine polystyrene calorimetric dosimetry systems from
Risø high dose reference laboratory (in percent, at k=2) (9). 7
Table A1.1 Results for alanine and calorimeter dose measurements. 8
Table A2.1 Thickness and size of several graphite calorimetric bodies designed at NIST for use
at specific electron energies . 8
iii
© ISO/ASTM International 2020 – All rights reserved

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ISO/ASTM 51631:2020(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is normally
carried out through ISO technical committees. Each member body interested in a subject for which a
technical committee has been established has the right to be represented on that committee.
International organizations, governmental and non‐governmental, in liaison with ISO, also take part in
the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted (see www.iso.org/directives).
ASTM International is one of the world’s largest voluntary standards development organizations with
global participation from affected stakeholders. ASTM technical committees follow rigorous due
process balloting procedures.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO and ASTM International shall not be held responsible for identifying any or all such
patent rights. Details of any patent rights identified during the development of the document will be in
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Any trade name used in this document is information given for the convenience of users and does not
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expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT),
see www.iso.org/iso/foreword.html.
This document was prepared by ASTM Committee E61, Radiation processing (as ASTM E1631‐94), and
drafted in accordance with its editorial rules. It was assigned to Technical Committee ISO/TC 85,
Nuclear energy, nuclear technologies and radiation protection, and adopted under the “fast‐track
procedure”.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv © ISO/ASTM International 2020 – All rights reserved

---------------------- Page: 4 ----------------------
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ISO/ASTM 51631:2020(E)
Standard Practice for
Use of Calorimetric Dosimetry Systems for Dose
Measurements and Routine Dosimetry System Calibration in
1
Electron Beams
This standard is issued under the fixed designation ISO/ASTM 51631; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This practice covers the preparation and use of semi-
1.9 This international standard was developed in accor-
adiabatic calorimetric dosimetry systems for measurement of
dance with internationally recognized principles on standard-
absorbeddoseandforcalibrationofroutinedosimetrysystems
ization established in the Decision on Principles for the
when irradiated with electrons for radiation processing appli-
Development of International Standards, Guides and Recom-
cations. The calorimeters are either transported by a conveyor
mendations issued by the World Trade Organization Technical
past a scanned electron beam or are stationary in a broadened
Barriers to Trade (TBT) Committee.
beam.
1.2 This document is one of a set of standards that provides 2. Referenced Documents
recommendations for properly implementing dosimetry in 2
2.1 ASTM Standards:
radiation processing, and describes a means of achieving
E666Practice for CalculatingAbsorbed Dose From Gamma
compliance with the requirements of ISO/ASTM Practice
or X Radiation
52628 for a calorimetric dosimetry system. It is intended to be
E668 Practice for Application of Thermoluminescence-
read in conjunction with ISO/ASTM Practice 52628.
Dosimetry (TLD) Systems for Determining Absorbed
1.3 The calorimeters described in this practice are classified DoseinRadiation-HardnessTestingofElectronicDevices
as Type II dosimeters on the basis of the complex effect of
E3083Terminology Relating to Radiation Processing: Do-
influence quantities. See ISO/ASTM Practice 52628. simetry and Applications
2
2.2 ISO/ASTM Standards:
1.4 This practice applies to electron beams in the energy
51261Practice for Calibration of Routine Dosimetry Sys-
range from 1.5 to 12 MeV.
tems for Radiation Processing
1.5 The absorbed dose range depends on the calorimetric
51649Practice for Dosimetry in an Electron Beam Facility
absorbing material and the irradiation and measurement con-
for Radiation Processing at Energies Between 300 keV
ditions. Minimum dose is approximately 100 Gy and maxi-
and 25 MeV
mum dose is approximately 50 kGy.
51707Guide for Estimating Uncertainties in Dosimetry for
1.6 Theaverageabsorbed-doseraterangeshallgenerallybe Radiation Processing
-1
greater than 10 Gy·s . 52628Practice for Dosimetry in Radiation Processing
2.3 International Commission on Radiation Units and Mea-
1.7 The temperature range for use of these calorimetric
3
surements (ICRU) Reports:
dosimetry systems depends on the thermal resistance of the
ICRU Report 34The Dosimetry of Pulsed Radiation
calorimetric materials, on the calibration range of the tempera-
ICRU Report 35Radiation Dosimetry: Electron Beams with
ture sensor, and on the sensitivity of the measurement device.
Energies Between 1 and 50 MeV
1.8 This standard does not purport to address all of the
ICRU Report 80Dosimetry Systems for use in Radiation
safety concerns, if any, associated with its use. It is the
Processing
responsibility of the user of this standard to establish appro-
ICRU Report 85aFundamental Quantities and Units for
Ionizing Radiation
1
This practice is under the jurisdiction of ASTM Committee E61 on Radiation
Processing and is the direct responsibility of Subcommittee E61.02 on Dosimetry 2
For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
Systems, and is also under the jurisdiction of ISO/TC 85/WG 3. www.astm.org, or contact ASTM Customer Service at service@astm.org. For
Current edition approved by ASTM May 15, 2019. Published February 2020. Annual Book of ASTM Standards volume information, refer to the standard’s
Originally published as E1631–94. The present Fourth Edition of Document Summary page on the ASTM website.
3
International Standard ISO/ASTM 51631:2020(E) is a minor revision of the Third Available from the Commission on Radiation Units and Measurements, 7910
Edition of ISO/ASTM 51631–2013(E). Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A.
© ISO/ASTM International 2020 – All rights reserved
1

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ISO/ASTM 51631:2020(E)
3.2.9 thermistor—electrical resistor with a well-defined re-
2.4 Joint Committee for Guides in Metrology (JCGM)
Reports: lationship between resistance and temperature of the thermis-
JCGM 100:2008, GUM 1995, with minor corrections, tor.
Evaluation of measurement data – Guide to the Expres-
3.2.10 thermocouple—junction of two metals producing an
4
sion of Uncertainty in Measurement
electrical voltage with a well-defined relationship to junction
JCGM 200:2012, VIMInternational vocabulary of metrol-
temperature.
5
ogy – Basic general concepts and general terms
3.3 Definitions of other terms used in this standard that
pertain to radiation measurement and dosimetry may be found
3. Terminology
in ASTM Terminology E3083. Definitions in E3083 are
3.1 Definitions:
compatible with ICRU Report 85a; that document, therefore,
3.1.1 primary-standard dosimetry system—dosimetry sys-
may be used as an alternative reference.
tem that is designated or widely acknowledged as having the
4. Significance and use
highest metrological qualities and whose value is accepted
without reference to other standards of the same quantity.
4.1 This practice is applicable to the use of calorimetric
dosimetry systems for the measurement of absorbed dose in
3.1.2 reference standard dosimetry system—dosimetry
electron beams, the qualification of electron irradiation
system, generally having the highest metrological quality
facilities, periodic checks of operating parameters of electron
available at a given location or in a given organization, from
irradiationfacilities,andcalibrationofotherdosimetrysystems
which measurements made there are derived.
in electron beams. Calorimetric dosimetry systems are most
3.1.3 transfer standard dosimetry system—dosimetry sys-
suitable for dose measurement at electron irradiation facilities
tem used as an intermediary to calibrate other dosimetry
utilizing conveyor systems for transport of product during
systems.
irradiation.
NOTE 1—For additional information on calorimetric dosimetry system
3.1.4 type II dosimeter—dosimeter,theresponseofwhichis
operation and use, see ICRU Report 80. For additional information on the
affected by influence quantities in a complex way that cannot
use of dosimetry in electron accelerator facilities, see ISO/ASTM 51649,
practically be expressed in terms of independent correction
6
and ICRU Reports 34 and 35, and Refs (1-3).
factors.
4.2 The calorimetric dosimetry systems described in this
3.2 Definitions of Terms Specific to This Standard:
practice are not primary standard dosimetry systems. The
3.2.1 adiabatic—no heat exchange with the surroundings.
calorimeters are classified as Type II dosimeters (ISO/ASTM
52628).Theymightbeusedasinternalstandardsatanelectron
3.2.2 calorimeter—assembly consisting of calorimetric
beam irradiation facility, including being used as transfer
body (absorber), thermal insulation, and temperature sensor
standard dosimetry systems for calibration of other dosimetry
with wiring that, when irradiated, exhibits increase in the
systems, or they might be used as routine dosimeters. The
absorbertemperaturethatcanberelatedtoabsorbeddose.This
calorimetric dosimetry systems are calibrated by comparison
language parallels that of dosimeter.
with transfer standard dosimeters.
3.2.3 calorimetric body—mass of material absorbing radia-
4.3 The dose measurement is based on the measurement of
tion energy and whose temperature is measured.
the temperature rise (dosimeter response) in an absorber
3.2.4 calorimetric dosimetry system—dosimetry system
(calorimetric body) irradiated by an electron beam. Different
consisting of calorimeter, measurement instruments and their
absorbing materials are used, but the response is usually
associatedreferencestandards,andproceduresforthesystem’s
defined in terms of dose to water.
use.
NOTE 2—The calorimetric bodies of the calorimeters described in this
practice are made from low atomic number materials. The electron
3.2.5 endothermic reaction—chemical reaction that con-
fluenceswithinthesecalorimetricbodiesarealmostindependentofenergy
sumes energy.
when irradiated with electron beams of 1.5 MeV or higher, and the mass
collision stopping powers are approximately the same for these materials.
3.2.6 exothermic reaction—chemical reaction that releases
energy.
4.4 The absorbed dose in other materials irradiated under
equivalentconditionscanbecalculated.Proceduresformaking
3.2.7 heat defect (thermal defect)—amount of energy re-
suchcalculationsaregiveninASTMPracticesE666andE668,
leased or consumed by chemical reactions caused by the
and Ref (1).
absorption of radiation energy.
4.4.1 Calorimeters for use at industrial electron accelerators
3.2.8 specific heat capacity—amount of energy required to
have been constructed using graphite, polystyrene or a Petri
raise 1 kg of material by the temperature of 1 K.
dish filled with water as the calorimetric body (4-10). The
thicknessofthecalorimetricbodyshouldbelessthantherange
of the incident electrons.
4
Document produced byWorking Group 1 of the Joint Committee for Guides in
4.4.2 Polymeric materials other than polystyrene might also
Metrology (JCGM/WG 1). Available free of charge at the BIPM website (http://
be used for calorimetric measurements. Polystyrene is used
www.bipm.org).
5
Document produced byWorking Group 2 of the Joint Committee for Guides in
6
Metrology (JCGM/WG 2). Available free of charge at the BIPM website (http:// Theboldfacenumbersinparenthesesrefertothebibliographyattheendofthis
www.bipm.org). practice.
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ISO/ASTM 51631:2020(E)
becauseitisknowntoberesistanttoradiation(11)andbecause inside the disc. Some typical examples of graphite disc
almost no exo- or endothermic reactions take place (12). thicknesses and masses are listed in Annex A2 (2).
6.2 A Typical Water Calorimeter is a sealed polystyrene
5. Interferences
Petri dish filled with water and placed in thermally insulating
5.1 Extrapolation—The calorimetric dosimetry systems de-
foamed plastic (4). A calibrated temperature sensor (thermis-
scribed in this practice are not adiabatic, because of the
tor) is placed through the side of the dish into the water. The
exchange of heat with the surroundings or within the calorim-
shape and size of the water calorimeter can be similar to the
eter assembly. The maximum temperature reached by the
shape and size of the polystyrene calorimeter (see 6.3).
calorimetric body is different from the temperature that would
6.3 A Typical Polystyrene Calorimeter is a polystyrene disc
have been reached in the absence of that heat exchange. The
placed in thermally insulating foamed plastic. A calibrated
temperature drifts before and after irradiation should be ex-
thermistor or thermocouple is imbedded inside the disc. The
trapolated to the midpoint of the irradiation period in order to
dimension of the polystyrene disc might be similar to that of
determine the true temperature increase due to the absorbed
the graphite and water calorimeters (9). See Fig. 1 as an
dose.
example of a polystyrene calorimeter designed for use at 10
5.2 Heat Defect—Chemical reactions in irradiated material
MeV electron irradiation (13).
(resulting in what is called the heat defect or thermal defect)
6.4 The thickness of the calorimetric body should be less
might be endo- or exothermic and might lead to measurable
than the range of the irradiating electrons, typically not
temperature changes (3).
1
exceeding ⁄3 of the range of the incident electrons. This will
5.3 Specific Heat Capacity—The specific heat capacity of
limit the effects of variation of the dose gradients within the
some materials used as a calorimetric body might change with
calorimetric body.
accumulated absorbed dose, thereby affecting the response of
6.5 Radiation-resistant components should be used for the
the calorimeters.This is notably the case for polymers, such as
parts of the calorimeter that are exposed to the electron beam.
polystyrene, and it will therefore be necessary to recalibrate
This also applies to insulation of electrical wires.
calorimetric dosimetry systems at intervals that will depend on
the total accumulated dose. 6.6 Good thermal contact must exist between the tempera-
NOTE 3—For calorimeters using polystyrene as material for the calori-
ture sensor and the calorimetric body. For graphite and
metric body, the change in specific heat capacity might be in the order of
polystyrenecalorimeters,thiscanbeassuredbyaddingasmall
1 % per accumulated dose of 1 MGy. It can therefore be useful to track
amount of heat-conducting compound when mounting the
accumulated dose for polystyrene calorimeters.
temperature sensor.
5.4 Influence Quantities—The response of the calorimetric
6.7 Measurement—The response of the calorimeters is the
dosimetry systems to absorbed dose does not depend on
temperatureriseofthecalorimetricbody.Thistemperaturerise
ambient relative humidity and temperature.
is usually registered by thermistors or thermocouples.
5.5 Temperature Effects from Accelerator Structure—The
6.7.1 Thermistor—Ahigh-precision ohm-meter can be used
calorimetersareoftenirradiatedonaconveyorusedforpassing
for measurement of thermistor resistance. The meter should
products and samples through the irradiation zone. Recogniz-
have a reproducibility of better than 60.1% (k=1) and a
ing that the thermal insulation around the calorimetric body is
combined uncertainty of better than 60.2% (k=1). It should
not perfect, there is possibility that, for example, radiated heat
preferably be equipped for four-wire type resistance
from the mechanical structures of the irradiation facility and
from the conveyor might contribute to the measured tempera-
ture increase in the calorimeters.
5.6 Thermal Equilibrium—The most reproducible results
are obtained when the calorimeters are in thermal equilibrium
with their surroundings before irradiation.
5.7 Foreign Materials—Thetemperaturesensors,wires,etc.
of the calorimeter represent foreign materials, which might
influence the temperature rise of the calorimetric body. These
components should be as small as possible.
5.8 Dose Gradients—Dose gradients will exist within the
calorimetric body when it is irradiated with electrons. These
gradients must be taken into account, for example, when other
dosimeters are calibrated by comparison with calorimetric
dosimetry systems.
6. Apparatus
6.1 A Typical Graphite Calorimeter is a disc of graphite
Courtesy of Risø High Dose Reference Laboratory.
placed in a thermally insulating material such as foamed plastic
FIG. 1 Example of a polystyrene calorimeter used for routine
(4-6). A calibrated thermistor or thermocouple is embedded measurements at a 10-MeV industrial electron accelerator
© ISO/ASTM International 2020 – All rights reserved
3

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ISO/ASTM 51631:2020(E)
measurements, especially if the thermistor resistance is less that specifies details of the calibration process and quality
than 10 kΩ. With the four-wire measurement technique, the
assurance requirements. This calibration process shall be
effects of resistance in the measurement wires and electrical
repeated at regular intervals to ensure that the accuracy of the
contacts are minimized.
absorbed dose measurement is maintained within required
6.7.2 Other appropriate instrumentation may be used for the
limits. Calibration methods are described in ISO/ASTM Guide
thermistor resistance measurement, for example, a resistance
51261.
bridge or commercially calibrated thermistor readers (5). It is
7.2 Graphite, water or polystyrene calorimetric dosimetry
important for both ohm-meters and resistance bridge measure-
systems should be calibrated by comparison with transfer
ments to minimize the dissipated power in the thermistor,
standard dosimetry systems from an accredited calibration
preferably below 0.1 mW, in order to avoid self-heating of the
thermistor during measurement. laboratory by irradiating the calorimeter(s) and transfer-
6.7.3 Thermocouple—A high-precision digital voltmeter, or standard dosimeters sequentially (or simultaneously) at an
other dedicated instrument (2), can be used for the measure-
electron irradiation facility. The radiation field over the cross-
ment. The reproducibility of the voltmeter should be better
sectional area of the calorimetric body shall be uniform over
than 0.1 µV (k=1), and a combined uncertainty of better than
the time required to irradiate the calorimeters and the transfer-
60.2 % (k=1).
standard dosimeters.Any non-uniformity should be taken into
6.7.4 Suppliers—Some commercial suppliers of calorimet-
account when evaluating and comparing dose to calorimeter
ric dosimetry systems are listed in Annex A3.
and dose to transfer-standard dosimeter.
7. Calibration procedures
7.3 It must be assured that the transfer-standard dosimeters
and the calorimeters are irradiated to the same dose. Specially
7.1 Prior to use, the calorimetric dosimetry system (consist-
designedabsorbers(phantoms)areneededforirradiationofthe
ing of calorimeter and measurement instruments) shall be
calibratedinaccordancewiththeuser’sdocumentedprocedure transfer-standard dosimeters, see for example Fig. 2.
NOTE 1—All dimensions are in mm. Alanine transfer standard dosimeters in cylindrical flat holders (diameter 25 mm, thickness 6 mm) to be placed
intheroundcut-outs.Routinedosimeters(thinfilmdosimeters)tobeplacedinrectangularcut-outs.Thecentresofbothdosimetersareplacedinthesame
depth in the absorber.
FIG. 2 Absorber (phantom) for irradiation at 10 MeV electron irradiation facility of routine and transfer-standard dosimeters (10). Mate-
rial: Polystyrene
© ISO/ASTM International 2020 – All rights reserved
4

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ISO/ASTM 51631:2020(E)
7.4 The specific heat capacities of polystyrene and of 7.7 Calorimetric dosimetry systems can be calibrated by
graphite are functions of temperature, while the specific heat irradiation at a calibration laboratory. The calibration obtained
in this way must be verified by irradiation of the calorimeters
capacity of water is almost constant within the temperature
range normally employed in electron beam calorimetry. The and transfer-standard dosimeters together at the user’s facility.
NOTE 8—Calibration curves provided by manufacturers of calorimeters
calibration curves of the calorimetric dosimetry systems are
are typically not obtained by irradiation at the user’s facility. Such
therefore expected to be functions of the average temperature
calibration curves should be verified by irradiation at the user’s facility.
of the calorimetric body (see Note 4).
7.8 An example of a calibration verification of a calorimet-
7.4.1 For graphite calorimetric dosimetry systems, the cali-
ric dosimetry system is given in Annex A1.
bration curve might take the following form:
7.9 Measurement Instrument Calibration and Performance
Dose 5 T 2 T 2 T ·c · S /ρ w/ S /ρ ·k
~ ! ~ ! ~ !
2 1 a G el el G
Verification—For the calibration of the measuring instruments,
where:
and for the verification of instrument performance between
T = temperature before irradiation,
calibrations, see ISO/ASTM Guide 51261 or instrument-
1
T = temperature after irradiation,
2 specific operating manuals, or both.
T = temperature rise from irradiation facility
a
components,
8. Dose measurement procedures
c = specific heat capacity of graphite,
G
8.1 Conveyor Irradiation Off-Line Measurements—For
(S /ρ)w = electronic mass stopping power of water,
el
calorimeters carried on conveyors through scanned electron
(S /ρ) = electronic mass stopping power of graphite, and
el G
beams, the calorimeter is usually disconnected from the tem-
k = calibration constant to be determined during cali-
perature measurement system just prior to placing the calorim-
bration verification.
eterontheconveyorandreconnectedformeasurementassoon
NOTE 4—Repeated measurements of specific heat of various types of
as practical after irradiation (7).
graphite have been carried out over the range of 0 to 50°C, indicating a
-1 -1
value for the specific heat capacity of graphite c (J·kg ·°C ) = 644.2 8.1.1 Before irradiation, the temperature of the calorimetric
G
+2.86 T,where Tisthemeantemperature(°C)ofthegraphite.Thisvalue
body is measured. It should remain stable, typically less than
must, however, not be considered a universal value (6).
0.1°C change over a period of at least 10 min.
7.4.2 For polystyrene calorimetric dosimetry systems, the
NOTE 9—It is recommended to store calorimeters in close proximity to
calibration curve might take the following form:
the irradiation area, so that the calorimeters are in approximate thermal
equilibrium with the conditions of the irradiation area prior to use.
Dose 5 T 2 T 2 T ·F T ·k
~ ! ~ !
2 1 a
where: 8.1.2 The measurement wires are disconnected and the
calorimeter is placed on the conveyor for transport through the
T = temperature before irradiation,
1
irradiation zone.
T = temperature after irradiation,
2
8.1.3 The calorimeter is transported through the irradiation
T = temperature rise from irradiation facility
a
zone on the conveyor system.
components,
8.1.4 The time of irradiation, and the irradiation parameters
F(T) = function representing specific heat capacity of
(for example, electron energy, electron current, scanned beam
polystyrene, and
width
...

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