ISO/ASTM 51401:2003
(Main)Practice for use of a dichromate dosimetry system
Practice for use of a dichromate dosimetry system
ISO/ASTM 51401:2003 covers the preparation, testing, and procedure for using the acidic aqueous silver dichromate dosimetry system to measure absorbed dose in water when exposed to ionizing radiation. The system consists of a dosimeter and appropriate analytical instrumentation. For simplicity, the system will be referred to as the dichromate system. It is classified as a reference standard dosimetry system. ISO/ASTM 51401:2003 describes the spectrophotometric analysis procedures for the dichromate system.
Pratique de l'utilisation d'un système dosimétrique au dichromate
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Standards Content (Sample)
INTERNATIONAL ISO/ASTM
STANDARD 51401
Second edition
2003-07-15
Practice for use of a dichromate
dosimetry system
Pratique de l’utilisation d’un système dosimétrique au dichromate
Reference number
ISO/ASTM 51401:2003(E)
© ISO/ASTM International 2003
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ISO/ASTM 51401:2003(E)
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ii © ISO/ASTM International 2003 – All rights reserved
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ISO/ASTM 51401:2003(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 2
4 Significance and use . 2
5 Interferences . 2
6 Apparatus . 2
7 Reagents . 3
8 Preparation of dosimeters . 3
9 Calibration of the dosimetry system . 3
10 Application of dosimetry system . 5
11 Minimum documentation requirements . 5
12 Measurement uncertainty . 5
13 Keywords . 6
Bibliography . 6
Figure 1 Relative response of dichromate dosimeter as a function of irradiation temperature. . 2
Figure 2 Response of high-range dosimeter in terms of DA as a function of absorbed dose in
water. . 5
Figure 3 Response of the low-range dosimeter in terms of DA as a function of absorbed dose in
water. . 5
Table 1 Effect of irradiation temperature on dosimeter response . 2
Table 2 Typical dichromate calibration data . 4
© ISO/ASTM International 2003 – All rights reserved iii
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ISO/ASTM 51401:2003(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 project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this 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 document 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 51401 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
iv © ISO/ASTM International 2003 – All rights reserved
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ISO/ASTM 51401 – 2003(E)
Standard Practice for
1
Use of a Dichromate Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51401; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
determination of the temperature coefficient.
1. Scope
1.5 This standard does not purport to address all of the
1.1 This practice covers the preparation, testing, and proce-
dure for using the acidic aqueous silver dichromate dosimetry safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
system to measure absorbed dose in water when exposed to
ionizing radiation. The system consists of a dosimeter and priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific precau-
appropriate analytical instrumentation. For simplicity, the sys-
tem will be referred to as the dichromate system. It is classified tionary statements are given in 8.3.
as a reference standard dosimetry system (see ISO/ASTM
2. Referenced documents
Guide 51261).
2.1 ASTM Standards:
1.2 This practice describes the spectrophotometric analysis
C 912 Practice for Designing a Process for Cleaning Tech-
procedures for the dichromate system.
3
nical Glasses
1.3 This practice applies only to g-rays, x-rays/
E 170 Terminology Relating to Radiation Measurements
bremsstrahlung, and high energy electrons.
4
and Dosimetry
1.4 This practice applies provided the following conditions
5
E 178 Practice for Dealing with Outlying Observations
are satisfied:
3 4
E 275 Practice for Describing and Measuring Performance
1.4.1 The absorbed dose range is from 2 3 10 to 5 3 10
of Ultraviolet, Visible and Near Infrared Spectrophotom-
Gy.
6
eters
1.4.2 The absorbed dose rate does not exceed 600 Gy/pulse
E 666 Practice for Calculating Absorbed Dose from Gamma
(12.5 pulses per second), or does not exceed an equivalent dose
4
2
or X-Radiation
rate of 7.5 kGy/s from continuous sources (1).
E 668 Practice for Application of Thermoluminescence Do-
1.4.3 For radionuclide gamma-ray sources, the initial pho-
simetry (TLD) Systems for Determining Absorbed Dose in
ton energy shall be greater than 0.6 MeV. For bremsstrahlung
4
Radiation-Hardness Testing of Electronic Devices
photons, the initial energy of the electrons used to produce the
E 925 Practice for the Periodic Calibration of Narrow Band-
bremsstrahlung photons shall be equal to or greater than 2
6
Pass Spectrophotometers
MeV. For electron beams, the initial electron energy shall be
E 958 Practice for Measuring Practical Spectral Bandwidth
greater than 8 MeV.
6
of Ultraviolet-Visible Spectrophotometers
NOTE 1—The lower energy limits given are appropriate for a cylindri-
E 1026 Practice for Using the Fricke Reference Standard
cal dosimeter ampoule of 12 mm diameter. Corrections for displacement
4
Dosimetry System
effects and dose gradient across the ampoule may be required for electron
2.2 ISO/ASTM Standards:
beams (2). The dichromate system may be used at lower energies by
employing thinner (in the beam direction) dosimeter containers (see ICRU 51261 Guide for Selection and Calibration of Dosimetry
4
Report 35).
Systems for Radiation Processing
51400 Practice for Characterization and Performance of a
1.4.4 The irradiation temperature of the dosimeter shall be
4
High-Dose Radiation Dosimetry Calibration Laboratory
above 0°C and should be below 80°C.
51707 Guide for Estimating Uncertainties in Dosimetry for
NOTE 2—The temperature coefficient of dosimeter response is known 4
Radiation Processing
only in the range of 5° to 50°C (see 4.3). Use outside this range requires
2.3 International Commission on Radiation Units and
7
Measurements (ICRU) Reports:
1
ICRU Report 35 Radiation Dosimetry: Electrons With Ini-
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee
tial Energies Between 1 and 50 MeV
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
ISO/TC 85/WG 3.
Current edition approved Feb. 27, 2003. Published July 15, 2003. Originally
e1 3
published as ASTM E 1401 – 91. ASTM E 1401 – 96 was adopted by ISO in 1998 Annual Book of ASTM Standards, Vol 15.02.
4
with the intermediate designation ISO 15561:1998(E). The present International Annual Book of ASTM Standards, Vol 12.02.
5
Standard ISO/ASTM 51401:2003(E) replaces ISO 15561 and is a minor revision of Annual Book of ASTM Standards, Vol 14.02.
6
the last previous edition ISO/ASTM 51401:2002(E). Annual Book of ASTM Standards, Vol 03.06.
2 7
The boldface numbers in parentheses refer to the bibliography at the end of this Available from the International Commission on Radiation Units and Measure-
practice. ments (ICRU), 7910 Woodmont Ave., Bethesda, MD 20814, U.S.A.
© ISO/ASTM International 2003 – All rights reserved
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ISO/ASTM 51401 – 2003(E)
TABLE 1 Effect of irradiation temperature on dosimeter
response
Temperature, °C Relative Response Temperature, °C Relative Response
5 1.020 30 0.992
10 1.017 35 0.983
15 1.013 40 0.972
20 1.007 45 0.960
25 1.000 50 0.948
ICRU Report 60 Fundamental Quantities and Units for
Ionizing Radiation
3. Terminology
3.1 Definitions:
3.1.1 net absorbance, (DA)—change in measured optical
absorbance at a selected wavelength determined as the absolute
FIG. 1 Relative response of dichromate dosimeter as a function
difference between the pre-irradiation absorbance, A , and the
0
of irradiation temperature. A fit of the data using Eq 2 yields fit
−5
post-irradiation absorbance, A, as follows:
parameters as follows: b = 1.021; b = −6.259 3 10 ; b = 1.806.
0 1 2
DA 5 ?A 2 A ? (1)
0
4.4 No effect of ambient light (even direct sunlight) has
3.1.2 reference–standard dosimeter—dosimeter of high
been observed on dichromate solutions in glass ampoules (6).
metrological quality, used as a standard to provide measure-
4.5 For calibration with photons, the dichromate dosimeter
ments traceable to and consistent with measurements made
shall be irradiated under conditions that approximate electron
using primary-standard dosimeters.
equilibrium.
3.2 Definitions of other terms used in this practice that
4.6 The absorbed dose in materials other than water irradi-
pertain to radiation measurement and dosimetry may be found
ated under equivalent conditions may be calculated using the
in ASTM Terminology E 170. Definitions in E 170 are com-
procedures given in ASTM Practices E 666, E 668 and ISO/
patible with ICRU 60; that document, therefore, may be used
ASTM Guide 51261.
as an alternative reference.
4.7 The dosimeter response is dependent on the type and
energy of the radiation employed. For example, the response in
4. Significance and use
high energy (10 MeV) electron beams is reported to be
4.1 The dichromate system provides a reliable means for
approximately 3 % lower than the response in cobalt-60
measuring absorbed dose in water. It is based on a process of
radiation (2). The dosimeter shall be calibrated in a radiation
reduction of dichromate ions to chromic ions in acidic aqueous
field of the same type and energy as that in which it is to be
solution by ionizing radiation.
used.
4.2 The dosimeter is a solution containing silver and dichro-
4.8 Provided the dosimeter solution is prepared as described
mate ions in perchloric acid in an appropriate container such as
in this document, and steps are taken to avoid contamination,
a sealed glass ampoule. The solution indicates absorbed dose
the dosimeter solution stored or sealed in glass vessels (for
by a change (decrease) in optical absorbance at a specified
example, ampoules) is stable before and after irradiation.
wavelength(s) (3). A calibrated spectrophotometer is used to
measure the absorbance. 5. Interferences
4.3 Effect of Irradiation Temperature:
5.1 The dichromate dosimetric solution response is sensitive
4.3.1 The dosimeter response has a temperature dependence
to impurities, particularly organic impurities. Even in trace
during irradiation that is approximately equal to −0.2 % per
quantities, impurities can cause a detectable change in the
degree Celsius between 25 and 50°C. At temperatures below
observed response (6). For high accuracy results, organic
25°C, the dependence is smaller. The dosimeter response
materials shall not be used for any component in contact with
between 5 and 50°C is shown in Table 1, where the response at
the solution, unless it has been demonstrated that the materials
a given temperature is tabulated relative to the response at
do not affect dosimeter response. The effect of trace impurities
25°C (4,5).
may be minimized by pre-irradiation of the bulk dichromate
4.3.2 The data in Table 1 may be fitted with an appropriate
solution (see Ref (6) and 8.4).
formula for convenience of interpolation as follows:
5.2 Undesirable chemical changes in the dosimetric solution
b
2
can occur if care is not taken during sealing of ampoules (see
R 5 b 1 b t (2)
t 0 1
8.6).
where:
6. Apparatus
R = dosimeter response at temperature t relative to that at
t
25°C.
6.1 High-Precision Spectrophotometer—For the analysis of
the dosimetric solution, use a high-precision spectrophotom-
The curve generated from the fitted data is shown in Fig. 1. eter capable of measuring absorbance values up to 2 with an
© ISO/ASTM International 2003 – All rights reserved
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ISO/ASTM 51401 – 2003(E)
uncertainty of no more than 61 % in the region of 350 to 440 8.2 Air saturate both solutions before use. Shaking of the
nm. Use a quartz cuvette with 5 or 10 mm path length for solution is normally sufficient to achieve this.
spectrophotometric measurements of the solution. The cuvette
8.3 Silver dichromate dissolves slowly and normally re-
capacity must be small enough to allow it to be thoroughly
quires at least 18 h to dissolve completely. For the high range
rinsed by the dosimeter solution and still leave an adequate
dosimeter, it is preferable to dissolve the silver dichromate
amount of that solution to fill the cuvette to the appropriate
before adding the potassium dichromate. (Warning—
level for the absorbance measurement. For dosimeter ampoules
Concentrated perchloric acid is a strong oxidizer and dichro-
of less than 2 mL, this may require the use of micro-capacity
mate salts are skin irritants. Appropriate precautions should be
cuvettes. Other solution handling techniques, such as the use of
exercised in handling these materials.)
micro-capacity flow cells, may be employed provided precau-
NOTE 5—Dichromate dosimeters of other formulations have been
tions are taken to avoid cross-contamination. Control the
described (8, 9).
temperature of the dosimetric solution during measurement at
25 6 1°C. If this is not possible, determine the solution
8.4 If appropriate, irradiate the bulk solution to minimize
temperature during the spectrophotometric analysis and correct
the effects of impurities.
the measured absorbance to 25°C. The temperature coefficient
8.4.1 The exact dose is not critical, but a dose of approxi-
during measurement is −0.1 % per degree Celsius within the
mately 1.0 kGy is recommended (6). The size of the container
range of 20 to 30°C (6).
for this bulk solution irradiation should be such that the dose
variation to the solution is less than 610 %. Mix the solution
NOTE 3—The dosimetric ampoule commonly used has a capacity of
thoroughly after irradiation.
about 2 mL.
8.5 Rinse the dosimeter ampoules or other containers as
6.2 Glassware—Use borosilicate glass or equivalent chemi-
prepared in 6.2 at least once with the dosimeter solution before
cally resistant glass to store the reagents and the prepared
filling them for irradiation.
dosimetric solution. Clean all apparatus used in the preparation
of the solution, as well as the glass ampoules or other 8.6 Exercise
...
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