ISO/ASTM 51205:2002

Practice for use of a ceric-cerous sulfate dosimetry system

ISO/ASTM 51205 covers the preparation, testing and procedure for using the ceric-cerous sulfate dosimetry system to measure absorbed doses in water when exposed to ionizing radiation. The system consists of a dosimeter and appropriate analytical instrumentation. For simplicity, the system is referred to as the ceric-cerous system. It is classified as a reference standard dosimetry system. Ceric-cerous dosimeters are also used as transfer standard dosimeters or routine dosimeters. ISO/ASTM 51205 describes both the spectrophotometric and the potentiometric read-out procedures for the ceric-cerous systems. The practice described applies only to gamma rays, X rays and high energy electrons and is applicable provided the following are satisfied: the absorbed-dose range is between 5 times 102 and 5 times 10 4 Gy; the absorbed-dose rate is less than 106 Gy/s; for radionuclide gamma-ray sources, the initial photon energy is greater than 0,6 MeV; for bremsstrahlung photons, the initial energy of the electrons used to produce the bremsstrahlung photons is equal to or greater than 2 MeV; for electron beams, the initial electron energy is greater than 8 MeV.

Pratique de l'utilisation d'un système dosimétrique au sulfate cérique-céreux

General Information

• Status: Withdrawn
• Publication Date: 17-Apr-2002
• Withdrawal Date: 17-Apr-2002
• ICS: 17.240 - Radiation measurements
• Technical Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Drafting Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 07-Jul-2009

Relations

• Revised: ISO/ASTM 51205:2009 - Practice for use of a ceric-cerous sulfate dosimetry system
• Effective Date: 15-Apr-2008
• Revises: ISO 15555:1998 - Practice for use of a ceric-cerous sulfate dosimetry system
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51205
First edition
2002-03-15
Practice for use of a ceric-cerous sulfate
dosimetry system
Pratique de l’utilisation d’un système dosimétrique au sulfate
cérique-céreux
Reference number
ISO/ASTM 51205:2002(E)
© ISO/ASTM International 2002

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ISO/ASTM 51205:2002(E)
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ii © ISO/ASTM International 2002 – All rights reserved

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ISO/ASTM 51205:2002(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 Reagents . 3
8 Preparation of the dosimetric solution . 3
9 Analytical instrument performance . 4
10 Calibration of the dosimetry system . 4
11 Application of dosimetry system . 6
12 Minimum documentation requirements . 7
13 Measurement uncertainty . 7
14 Keywords . 7
Annexes . 7
Bibliography . 11
Figure A1.1 Electrochemical cell . 8
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ISO/ASTM 51205:2002(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.
Draft International Standards adopted by the technical committees are circulated to the member bodies for
voting. Publication as an International Standard requires approval by at least 75% of the member bodies
casting a vote.
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.
A pilot project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this pilot project, ASTM Subcommittee E10.01,
Dosimetry for Radiation Processing, is responsible for the development and maintenance of these dosimetry
standards with unrestricted participation and input from appropriate ISO member bodies.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. Neither ISO nor ASTM International shall be held responsible for identifying any or all such
patent rights.
International Standard ISO/ASTM 51205 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
Annexes A1, A2 and A3 of this International Standard are for information only.
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ISO/ASTM 51205:2002(E)
Standard Practice for
1
Use of a Ceric-Cerous Sulfate Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51205; 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 safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.1 This practice covers the preparation, testing, and proce-
priate safety and health practices and determine the applica-
dure for using the ceric-cerous sulfate dosimetry system to
bility of regulatory limitations prior to use.
measure absorbed dose in water when exposed to ionizing
radiation. The system consists of a dosimeter and appropriate
2. Referenced Documents
analytical instrumentation. For simplicity, the system will be
2.1 ASTM Standards:
referred to as the ceric-cerous system. It is classified as a
C 912 Practice for Designing a Process for Cleaning Tech-
reference standard dosimetry system (see ISO/ASTM Guide
3
nical Glasses
51261). Ceric-cerous dosimeters are also used as transfer–stan-
D 941 Test Method for Density and Relative Density (Spe-
dard dosimeters or routine dosimeters.
cific Gravity) of Liquids by Lipkin Bicapillary Pycnom-
1.2 This practice describes both the spectrophotometric and
4
eter
the potentiometric readout procedures for the ceric-cerous
5
D 1193 Specification for Reagent Water
systems.
E 170 Terminology Relating to Radiation Measurements
1.3 This practice applies only to g rays, X rays, and high
6
and Dosimetry
energy electrons.
E 177 Practice for Use of the Terms Precision and Bias in
1.4 This practice applies provided the following are satis-
7
ASTM Test Methods
fied:
7
2
E 178 Practice for Dealing with Outlying Observations
1.4.1 The absorbed-dose range shall be between 5 3 10
4 2
E 275 Practice for Describing and Measuring Performance
and 5 3 10 Gy (1).
6
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
1.4.2 The absorbed-dose rate shall be less than 10 Gy/s (1).
8
eters
1.4.3 For radionuclide gamma-ray sources, the initial pho-
7
E 456 Terminology Relating to Quality and Statistics
ton energy shall be greater than 0.6 MeV. For bremsstrahlung
E 666 Practice for Calculating Absorbed Dose from Gamma
photons, the initial energy of the electrons used to produce the
6
or X Radiation
bremsstrahlung photons shall be equal to or greater than 2
E 668 Practice for Application of Thermoluminescence-
MeV. For electron beams, the initial electron energy shall be
Dosimetry (TLD) Systems for Determining Absorbed Dose
greater than 8 MeV.
6
in Radiation-Hardness Testing of Electronic Devices
NOTE 1—The lower energy limits are appropriate for a cylindrical
E 925 Practice for the Periodic Calibration of Narrow Band-
dosimeter ampoule of 12-mm diameter. Corrections for dose gradients
8
Pass Spectrophotometers
across an ampoule of that diameter or less are not required for photons, but
E 958 Practice for Measuring Practical Spectral Bandwidth
may be required for electron beams (2). The ceric-cerous system may be
8
of Ultraviolet-Visible Spectrophotometers
used at lower energies by employing thinner (in the beam direction)
E 1026 Practice for Using the Fricke Reference Standard
dosimeter containers (see ICRU Report 35).
6
Dosimetry System
1.4.4 The irradiation temperature of the dosimeter shall be
2.2 ISO/ASTM Standards:
between 0 and 62°C (3).
51261 Guide for Selection and Calibration of Dosimetry
6
NOTE 2—The temperature coefficient of dosimeter response is known
Systems for Radiation Processing
only in this range. For use outside this range, the dosimetry system should
51400 Practice for Characterization and Performance of a
be calibrated for the required range of irradiation temperatures.
High-Dose Gamma Radiation Dosimetry Calibration
6
1.5 This standard does not purport to address all of the
Laboratory
6
51401 Practice for Use of a Dichromate Dosimetry System
51607 Practice for Use of the Alanine-EPR Dosimetry
1
This guide is under the jurisdiction of ASTM Committee E10 on Nuclear
6
System
Technology and Applications and is the direct responsibility of Subcommittee
51707 Guide for Estimating Uncertainties in Dosimetry for
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
ISO/TC 85/WG 3.
Current edition approved Jan. 22, 2002. Published March 15, 2002. Originally
3
published as ASTM E 1205–88. Last previous ASTM edition E 1205–99. ASTM E Annual Book of ASTM Standards, Vol 15.02.
4
1205–93 was adopted by ISO in 1998 with the intermediate designation ISO Discontinued; see 1993 Annual Book of ASTM Standards, Vol 05.01.
5
15555:1998(E). The present International Standard ISO/ASTM 51205:2002(E) is a Annual Book of ASTM Standards, Vol 11.01.
6
revision of ISO 15555. Annual Book of ASTM Standards, Vol 12.02.
2 7
The boldface numbers in parentheses refer to the bibliography at the end of this Annual Book of ASTM Standards, Vol 14.02.
8
standard. Annual Book of ASTM Standards, Vol 03.06.
© ISO/ASTM International 2002 – All rights reserved
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ISO/ASTM 51205:2002(E)
6
Radiation Processing continuing basis that the overall uncertainty meets the require-
2.3 International Commission on Radiation Units and ments of the specific application. This plan requires traceability
9
Measurements (ICRU) Reports: to, and consistency with, nationally or internationally recog-
ICRU Report 14 Radiation Dosimetry: X-Rays and Gamma nized standards.
Rays with Maximum Photon Energies Between 0.6 and 60 3.1.5 measurement traceability—the ability to demonstrate
MeV by means of an unbroken chain of comparisons that a mea-
ICRU Report 34 The Dosimetry of Pulsed Radiation surement is in agreement within acceptable limits of uncer-
ICRU Report 35 Radiation Dosimetry: Electrons with tainty with comparable nationally or internationally recognized
Initial Energies Between 1 and 50 MeV standards.
ICRU Report 37 Stopping Powers for Electrons and 3.1.6 molar linear absorption coeffıcient, e —a constant
m
Positrons relating the spectrophotometric absorbance, A , of an optically
l
ICRU Report 60 Radiation Quantities and Units absorbing molecular species at a given wavelength, l, per unit
pathlength, d, to the molar concentration, c, of that species in
3. Terminology
solution:
3.1 Definitions:
A
l
3.1.1 absorbed dose, D—quantity of ionizing radiation
e 5 (3)
m
d · c
energy imparted per unit mass of a specified material. The SI
2 −1
SI unit: m mol
unit of absorbed dose is the gray (Gy), where 1 Gy is
3.1.6.1 Discussion—The measurement is sometimes ex-
equivalent to the absorption of 1 J/kg of the specified material
−1 −1
pressed in units of L mol cm .
(1 Gy = 1 J/kg). The mathematical relationship is the quotient
3.1.7 net absorbance, DA—change in measured optical
of de by dm, where de is the mean incremental energy imparted
absorbance at a selected wavelength determined as the absolute
by ionizing radiation to matter of incremental mass dm (see
difference between the pre-irradiation absorbance, A , and the
ICRU 60). o
post-irradiation absorbance, A, as follows:
de¯
D 5
(1)
DA 5 |A2A | (4)
dm o
3.1.8 radiation chemical yield, G(x)—the quotient of n(x)
3.1.1.1 Discussion—The discontinued unit for absorbed
by e¯, where n(x) is the mean amount of a specified entity, x,
dose is the rad (1 rad = 100 erg/g = 0.01 Gy). Absorbed dose
produced, or changed by the mean energy, e¯, imparted to the
is sometimes referred to simply as dose. For a photon source
matter.
under conditions of charged particle equilibrium, the absorbed
dose, D, may be expressed as:
n~x!
G~x! 5 (5)
e¯
μ
en
D5f·E· (2)
−1
r
SI unit: mol J
3.1.9 reference–standard dosimeter—a dosimeter of high-
where:
2 metrological quality, used as a standard to provide measure-
f = particle fluence (particles/m ),
ments traceable to, and consistent with, measurements made
E = energy of the ionizing radiation (J), and
2
using primary–standard dosimeters.
μ /r = mass energy absorption coefficient (m /kg). If
en
3.1.10 transfer–standard dosimeter—a dosimeter, often a
bremsstrahlung production within the specified
reference–standard dosimeter suitable for transport between
material is negligible, the mass energy absorption
different locations, used to compare absorbed-dose measure-
coefficient (μ /r) is equal to the mass energy
en
ments.
transfer coefficient (μ /r), and absorbed dose is
tr
3.2 For definitions of other terms used in this practice that
equal to kerma if, in addition, charged particle
pertain to radiation measurement and dosimetry, refer to
equilibrium exists.
ASTM Terminology E 170. Definitions in ASTM Terminology
3.1.2 calibration facility—combination of an ionizing radia-
E 170 are compatible with ICRU 60; that document, therefore,
tion source and its associated instrumentation that provides a
may be used as an alternative reference.
uniform and reproducible absorbed dose, or absorbed-dose rate
traceable to national or international standards at a specified
4. Significance and Use
location and within a specific material, and that may be used to
4.1 The ceric-cerous system provides a reliable means for
derive the dosimetry system’s response function or calibration
curve. measuring absorbed dose in water. It is based on a process of
reduction of ceric ions to cerous ions in acidic aqueous solution
3.1.3 electropotential—difference in potential, E, between
irradiated and unirradiated solutions in an electrochemical cell, by ionizing radiation (1, 4).
4.2 The dosimeter is a solution of ceric sulfate and cerous
measured in millivolts.
3.1.4 measurement quality assurance plan—a documented sulfate in sulfuric acid in an appropriate container such as a
flame-sealed glass ampoule. The solution indicates a level of
program for the measurement process that ensures on a
absorbed dose by a change (decrease) in optical absorbance at
9 a specified wavelength in the ultraviolet region, or a change
Available from International Commission on Radiation Units and Measure-
(increase) in electropotential. A calibrated spectrophotometer is
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA.
© ISO/ASTM International 2002 – All rights reserved
2

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ISO/ASTM 51205:2002(E)
used to determine the change in absorbance and a potentiom- using chromic acid solution or an equivalent cleaning agent
eter, with a specially designed cell, is used to determine the (see ASTM Practice C 912). Rinse at least three times with
change in potential in millivolts. double-distilled water. Dry thoroughly and store under condi-
4.3 The dosimeter response has a temperature dependence tions that will minimize exposure to dust.
during irradiation that is approximately equal to −0.2 % per 6.4 Glass Ampoules—If required, clean glass ampoules in
degree Celsius between 0 and 62°C (3, 5, 6). boiling double-distilled water. Rinse twice with double-
4.4 For calibration with photons, the ceric-cerous dosimeter distilled water and oven dry.
shall be irradiated under conditions that approximate electron
NOTE 5—The dosimetric ampoule normally used has a capacity of
equilibrium.
approximately 2 mL. Quick-break glass ampoules, or Type 1 glass
4.5 The absorbed dose in other materials irradiated under
colorbreak ampoules or equivalent containers, are commonly used.
equivalent conditions may be calculated. Procedures for mak-
Commercially available ampoules have been found to give reproducible
results without requiring additional cleaning.
ing such calculations are given in ASTM Practices E 666 and
E 668 and ISO/ASTM Guide 51261.
7. Reagents
NOTE 3—For a comprehensive discussion of various dosimetry meth-
7.1 Analytical reagent grade (or better) chemicals shall be
ods applicable to the radiation types and energies discussed in this
10
used for preparing all solutions.
practice, see ICRU Reports 14, 34, 35, and 37.
7.2 Use of double-distilled water from coupled all-glass and
5. Interferences silica stills is recommended for high-range dosimeters. For
low-range stock solutions, use triply-distilled water. Water
5.1 The ceric-cerous dosimetric solution response is sensi-
purity is very important since it is the major component of the
tive to impurities, particularly organic impurities. Even in trace
dosimetric solutions, and therefore may be the prime source of
quantities, impurities can cause a detectable change in the
contamination. Use of deionized water is not recommended.
observed response (7). For high-accuracy results, organic
Type III reagent water as specified in ASTM Specification
materials shall not be used for any component in contact with
D 1193 is considered to be of sufficient quality for use in
the solution. The effect of trace impurities is minimized by the
preparing all solutions.
addition of cerous ions to the solution (8, 9)
5.2 Undesirable chemical changes in the dosimetric solution
NOTE 6—Double-distilled water distilled from an alkaline potassium
can occur if care is not taken during flame-sealing of the
permanganate (KMnO ) solution (2 g KMnO plus 5 g sodium hydroxide
4 4
(NaOH) pellets in 2 L of distilled water) has been found to be adequate for
ampoules (see 8.7).
routine preparation of the dosimetric solution. High-purity water is
commercially available from some suppliers. Such water labeled HPLC
6. Apparatus
(high-pressure liquid chromatographic) grade is usually sufficiently free
6.1 Spectrophotometric Method—For the analysis of the
from organics to be used in this practice.
dosimetric solution, use a high-precision spectrophotometer
7.3 Do not store purified water used in this practice in
capable of measuring absorbance values up to two with an
plastic containers or in containers with plastic caps or plastic
uncertainty of no more than 61 % in the region from 254 to
cap liners.
320 nm. Use quartz cuvettes with 10-mm path length for
spectrophotometric measurements of absorbance of the solu-
8. Preparation of the Dosimetric Solution
tion.
8.1 The recommended concentrations for the ceric-cerous
6.2 Potentiometric Method—Use an electrochemical cell,
dosimeter to measure absorbed doses from about 5 to 50 kGy
similar to that in Annex A1 (see Fig. A1.1). Measure the
(high-range dosimeter) are 0.015-M ceric sulfate [Ce(SO ) ·
4 2
electropotential across the cell with a high-precision digital
4H O] and 0.015-M cerous sulfate [Ce (SO ) ·8H O]. For
2 2 4 3 2
potentiometer that is capable of measuring d-c potentials in the
measurement of absorbed doses from about 0.5 to 10 kGy
range from 1 to 100 mV within an uncertainty of 61%.
(low-range dosimeter), the recommended concentrations are
NOTE 4—As shown in Fig. A1.1, the electrochemical cell has two
0.003-M [Ce(SO ) ·4H O] and 0.003-M [Ce (SO ) ·8H O].
4 2 2 2 4 3 2
compartments separated by a porous junction, such as a glass frit, a
8.2 The dosimeters specified in 8.1 may be formulated from
ceramic or kaolin junction, or a fibreglass wick. The inner compartment is
the following nominal stock solutions: (a) 0.4-M and 4-M
filled with unirradiated solution. The lower compartment is filled with
sulfuric acid (H SO ), (b) 0.1-M Ce(SO )·4H O, and (c)
2 4 4 2 2
solution transferred from an irradiated or unirradiated ampoule. The
0.1-M Ce (SO ) ·8H O. Procedures for preparing these solu-
potential difference, E, generated between the platinum electrodes in the 2 4 3 2
two compartments is measured by a digital potentiometer. tions are given in Annex A2.
6.3 Glassware—Use borosilicate glass or equivalent chemi-
cally resistant glass to store the reagents and the prepared 10
Reagent specifications are available from American Chemical Society, 1115
th
dosimetric solution. Clean all glassware, except ampoules, 16 St., Northwest, Washington, DC 20036, USA.
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ISO/ASTM 51205:2002(E)
8.3 Use the following equations to determine the volume in neck. Flame seal the ampoules, exercising care to avoid heating
millilitres of each stock solution necessary to prepare 1 L of the body of the ampoule during sealing.
dosimetric solution: 8.8 Store dosimeters in a dark place at room temperature (23
6 5°C).
High Range Low Range
9. Analytical Instrument Performance
V 0.015 V 0.003
1 1
5 5 (6)
1000 M 1000 M
1 1
9.1 Spectrophotometer Performance:
9.1.1 Check the wavelength scale of the spectrophotometer
V 0.015 V 0.003
2 2
5 5 (7)
1000 M 1000 M and establish its accuracy. The emission spectrum from a
2 2
low-pressure mercury arc lamp can be used for this purpose.
V 0.4 V 0.4
3 3
5 5 (8)
Such lamps may be obtained from the spectrophotometer
1000 2 V M 1000 2 V M
1 3 1 3
manufacturer or other scientific laboratory instrument suppli-
V 5 1000 2 V 2 V 2 V V 5 1000 2 V 2 V 2 V (9)
4 1 2 3 4 1 2 3
ers. Other appropriate wavelength standards are holmium-
oxide filters and solutions. For more details see ASTM Prac-
where: tices E 275, E 925, and E 958.
V = volume of nominal 0.1-M ceric-sulfate stock solu-
1
NOTE 8—For example, holmium-oxide solutions in sealed cuvettes are
tion,
available as certified wavelength standards (SRM 2034) for use in the
V = volume of nominal 0.1-M cerous-sulfate stock solu-
2
wavelength region from 240 to 650 nm (10).
tion,
9.1.2 Check the accuracy of the photometric (absorbance)
V = volume of nominal 4-M sulfuric-acid stock solution,
3
scale of the spectrophotometer. Certified absorbance standard
V = volume of distilled water,
4
filters or solutions are available for this purpose.
M = actual molarity of the ceric-sulfate stock solution,
1
M = actual molarity of the cerous-sulfate stock solution,
2 NOTE 9—Examples of absorbance standards are solutions of various
and
concentrations, such as SRM 931d (11) and SRM 935 (12), and metal-
M = actual molarity of the nominal 4-M sulfuric-acid on-quartz filters, such as SRM 2031 (13, 14).
3
stock solution.
9.1.3 Check the linearity of the absorbance scale of the
spectrophotometer as a function of the ceric-ion concentration.
NOTE 7—If the nominal molarities of M = M = 0.1, and M = 4 are
1 2 3
This should be done at the peak of the absorbance spectrum for
assumed, then V = V = 150 mL for the high range and V = V =30mLfor
1 2 1 2
the ceric ion at 320 nm at a constant temperature, preferably
the low range; V = 85 mL for the high range and V = 97 mL for the low
3 3
25°C. The standardized ceric-sulfate stock solution (0.1-M
range. If the molarities of the various stock solutions are significantly
different from the nominal values, then use Eq 6-8 to determine the exact
nominal in 0.4-M H SO ), as described in A2.3, may be used
2 4
volumes. To prepare a volume of the dosimetric solution other than 1000
for this measurement. The plot of measured absorbance, A, per
mL, the result of these equations should be multiplied by the ratio of the
unit path length versus molar concentration shall be linear. The
desired volume in millilitres to 1000 mL.
slope of the line gives, e , the molar linear absorption
m
8.4 Determine all of the volumes given in 8.3 using a
coefficient.
calibrated graduated cylinder that can be read to within 60.5
2 −1
NOTE 10—A reference value for e is 561 m ·mol 6 0.4 % at 320 nm
m
mL.
(3).
8.5 Transfer the volume of each component of the dosim-
9.2 Potentiometer and Electrochemical Cell Performance:
etric solution into a 1-L or larger glass storage container. Rinse
9.2.1 For the potentiometer method, correct performance
the graduated cylinder used for measuring V , V , and V by
1 2 3
can be demonstrated by showing that the readings of dosim-
using some portion of the distilled water of V . Stopper the
4
eters given known absorbed doses are in agreement with the
container and shake well. Before use, allow the dosimetric
expected readings within the limits of the dosimetry system
solution to stand for at least five days in the dark.
uncertainty (see Section 13).
8.6 Quality control testing of the dosimetric solution prior to
NOTE 11—This method is only applicable for reference standard
ampouling can be performed by quantifying some of the
dosimetry systems where the long term stability of the response has been
dosimetric solution parameters, such as ceric-ion concentra-
demonstrated and documented.
tion, cerous-ion concentration, ceric-ion molar linear absorp-
10. Calibration of the Dosimetry System
tion coefficient, radiation chemical yield for the cerous ion, and
density. Procedures for performing these measurements are
10.1 Prior to use, the dosimetry system shall be calibrated in
given in Annex A3. Alternatively, quality control testing can be
accordance with the user’s documented procedure that speci-
performed following ampouling by comparing calibration data
fies details of the calibration process and quality assurance
with data obtained from previous batches (see 10.4.2).
requirements. This calibration procedure shall be repeated at
8.7 Prepare dosimeters by filling ampoules with ;2mL of regular intervals to ensure that the accuracy of the absorbed
dosimetric solution. Take care not to contaminate the dosim- dose measurement is maintained within required limits. De-
etric solution with impurities. Exercise care in filling ampoules tailed calibration procedures are provided in ISO/ASTM Guide
to avoid depositing solution in the ampoule neck. Subsequent 51261.
heating during sealing may cause an undesirable chemical 10.2 Calibration Irradiation of Dosimeters—Irradiation is a
change in the dosimetric solution remaining inside the ampoule critical component of the calibration of the dosimetry system.
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ISO/ASTM 51205:2002(E)
Calibration irradiations shall be performed by irradiating the trophotometric cuvette (sample cell) from the 25-mL volumet-
dosimeters using a calibration facility that provides an ab- ric flask.
sorbed dose or an absorbed-dose rate having measurement 10.3.6 Read the absorbance, A, in the spectrophotometer at
traceability to nationally or internationally recognized stan- 320 nm.
dards. 10.3.7 Calculate the mean absorbance of the unirradiated
¯
10.2.1 For the spectrophotometric measurement, separate
dosimeters, A (see 10.2.1). Calculate the net absorbance, DA,
o
five dosimeters from the remainder of the batch and do not for each irradiated dosimeter by subtracting its absorbance, A,
¯
¯
irradiate them. Use them in determining A (see 10.2.7).
from A as follows:
o o
10.2.2 Calibrate the dosimeters, using an irradiation facility
¯
DA 5 A 2 A (10)
o
that has a dose rate traceable to national standards and that
10.4 Potentiometric Measurement:
meets the requirements specified in ISO/ASTM Practice
10.4.1 Place contents of an unirradiated dosimeter (am-
51400. Use a reference or transfer dosimetry system to
poule) into both compartments of the electrochemical cell. See
establish this traceability (see ISO/ASTM Guide 51261 and
Annex A1 for a description of the electrochemical cell.
ASTM Practice E 1026).
10.4.2 Allow the unirradiated dosimetric solution to remain
10.2.3 Specify the calibration dose in te
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