ISO/ASTM 51538:2009
(Main)Practice for use of the ethanol-chlorobenzene dosimetry system
Practice for use of the ethanol-chlorobenzene dosimetry system
ISO 51538:2009 covers the procedure for preparation, handling, testing, and use of the ethanol-chlorobenzene (ECB) dosimetry system to determine absorbed dose (in terms of absorbed dose to water) in materials irradiated by photons (gamma radiation or X-radiation/bremsstrahlung) or high energy electrons. The system consists of a dosimeter and appropriate analytical instrumentation. It is classified as a reference-standard dosimetry system and is also used as a routine dosimetry system. ISO 51538:2009 describes the mercurimetric titration analysis as a standard readout procedure for the ECB dosimeter when used as a reference standard dosimetry system. Other readout methods (spectrophotometric, oscillometric) that are applicable when the ECB system is used as a routine dosimetry system are described. ISO 51538:2009 applies provided the following conditions are satisfied. The absorbed dose range is between 10 Gy and 2 MGy for gamma radiation and between 10 Gy and 200 kGy for high current electron accelerators.The absorbed-dose rate is less than 106 Gy s−1.For radionuclide gamma-ray sources, the initial photon energy is greater than 0,6 MeV. For bremsstrahlung photons, the 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 equal to or greater than 4 MeV. The ECB system may be used at energies of incident electrons lower than 4 MeV by employing thinner (in the beam direction) dosimeters. The ECB system may also be used at X-ray energies as low as 120 kVp. However, in this range of photon energies the effect caused by the ampoule wall is considerable. The irradiation temperature of the dosimeter is within the range from −40°C to 80°C. The effects of size and shape of the dosimeter on the response of the dosimeter can adequately be taken into account by performing the appropriate calculations using cavity theory.
Pratique de l'utilisation d'un système dosimétrique à l'éthanol chlorobenzène
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO/ASTM
STANDARD 51538
Second edition
2009-06-15
Practice for use of the ethanol-
chlorobenzene dosimetry system
Pratique de l’utilisation d’un système dosimétrique à l’éthanol
chlorobenzène
Reference number
ISO/ASTM 51538:2009(E)
© ISO/ASTM International 2009
---------------------- Page: 1 ----------------------
ISO/ASTM 51538:2009(E)
PDF disclaimer
ThisPDFfilemaycontainembeddedtypefaces.InaccordancewithAdobe’slicensingpolicy,thisfilemaybeprintedorviewedbutshall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe’s licensing policy. Neither the ISO Central
Secretariat nor ASTM International accepts any liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies
and ASTM members. In the unlikely event that a problem relating to it is found, please inform the ISO Central Secretariat or ASTM
International at the addresses given below.
© ISO/ASTM International 2009
Allrightsreserved.Unlessotherwisespecified,nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,
including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s member body in the country of the
requester. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTMInternational,100BarrHarborDrive,POBoxC700,
Case postale 56 • CH-1211 Geneva 20 West Conshohocken, PA 19428-2959, USA
Tel. +41 22 749 01 11 Tel. +610 832 9634
Fax +41 22 749 09 47 Fax +610 832 9635
E-mail copyright@iso.org E-mail khooper@astm.org
Web www.iso.org Web www.astm.org
Published in the United States
ii © ISO/ASTM International 2009 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/ASTM 51538:2009(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 . 4
8 Preparation of dosimeters . 4
9 Calibration of the mercuric nitrate solution . 4
10 Calibration of the dosimetry system . 4
11 Application of dosimetry system . 5
12 Minimum documentation requirements . 5
13 Measurement Uncertainty . 6
14 Keywords . 6
Annexes . 7
Bibliography . 10
Table 1 Typical ECB solution formulations . 3
−1
Table 2 Temperature coefficients k (°C) for typical ECB solution formulations . 3
Table A3.1 Characteristics of some applicable methods . 9
Table A3.2 Some suppliers of readout instruments suitable for use with Ethanol-Chlorobenzene
(ECB) dosimetry . 10
Table A3.3 Some suppliers of Ethanol-Chlorobenzene (ECB) dosimeters . 10
© ISO/ASTM International 2009 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/ASTM 51538:2009(E)
Foreword
ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies
(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,
Radiation Processing: Dosimetry and Applications, 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 51538 was developed byASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear energy.
Thissecondeditioncancelsandreplacesthefirstedition(ISO/ASTM51538:2002),whichhasbeentechnically
revised.
iv © ISO/ASTM International 2009 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/ASTM 51538:2009(E)
Standard Practice for
1
Use of the Ethanol-Chlorobenzene Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51538; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
dose gradients across an ampoule of that diameter or less are not required.
1. Scope
The ECB system may be used at energies of incident electrons lower than
1.1 This practice covers the procedure for preparation,
4 MeV by employing thinner (in the beam direction) dosimeters. The ECB
handling, testing, and use of the ethanol-chlorobenzene (ECB)
system may also be used at X-ray energies as low as 120 kVp (5).
dosimetry system to determine absorbed dose (in terms of
However, in this range of photon energies the effect caused by the
absorbed dose to water) in materials irradiated by photons ampoule wall is considerable.
(gamma radiation or X-radiation/bremsstrahlung) or high en-
1.3.4 The irradiation temperature of the dosimeter is within
ergy electrons. The system consists of a dosimeter and appro-
the range from −40°C to 80°C.
priate analytical instrumentation. For simplicity, the system
NOTE 2—The temperature dependence of dosimeter response is known
will be referred to as the ECB system. It is classified as a
only in this range (see 4.3). For use outside this range, the dosimetry
reference-standard dosimetry system and is also used as a
system should be calibrated for the required range of irradiation tempera-
routine dosimetry system (see ISO/ASTM Guide 51261).
tures.
1.2 This practice describes the mercurimetric titration
1.4 The effects of size and shape of the dosimeter on the
analysis as a standard readout procedure for the ECB dosimeter
response of the dosimeter can adequately be taken into account
when used as a reference standard dosimetry system. Other
by performing the appropriate calculations using cavity theory
readout methods (spectrophotometric, oscillometric) that are
(6).
applicable when the ECB system is used as a routine dosimetry
1.5 This standard does not purport to address all of the
system are described in Annex A1 and Annex A2.
safety concerns, if any, associated with its use. It is the
1.3 This practice applies provided the following conditions
responsibility of the user of this standard to establish appro-
are satisfied:
priate safety and health practices and determine the applica-
1.3.1 The absorbed dose range is between 10 Gy and 2 MGy
bility of regulatory limitations prior to use. Specific warnings
for gamma radiation and between 10 Gy and 200 kGy for high
are given in 8.2 and 9.2.
2
current electron accelerators (1,2). (Warning—the boiling
point of ethanol chlorobenzene solutions is approximately
2. Referenced documents
80°C. Ampoules may explode if the temperature during irra-
3
2.1 ASTM Standards:
diation exceeds the boiling point. This boiling point may be
C 912 Practice for Designing a Process for Cleaning Tech-
exceeded if an absorbed dose greater than 200 kGy is given in
nical Glasses
a short period of time.)
6 −1 D 1193 Specification for Reagent Water
1.3.2 The absorbed-dose rate is less than 10 Gy s (2).
E 170 Terminology Relating to Radiation Measurements
1.3.3 For radionuclide gamma-ray sources, the initial pho-
and Dosimetry
ton energy is greater than 0.6 MeV. For bremsstrahlung
E 275 Practice for Describing and Measuring Performance
photons, the energy of the electrons used to produce the
of Ultraviolet and Visible Spectrophotometers
bremsstrahlung photons is equal to or greater than 2 MeV. For
E 666 Practice for Calculating Absorbed Dose From
electron beams, the initial electron energy is equal to or greater
Gamma or X Radiation
than 4 MeV (3) (see ICRU Reports 34 and 35).
E 668 Practice for Application of Thermoluminescence-
60
NOTE 1—The same response relative to Co gamma radiation was
Dosimetry (TLD) Systems for Determining Absorbed Dose
obtained in high-power bremsstrahlung irradiation produced bya5MeV
in Radiation-Hardness Testing of Electronic Devices
electron accelerator (4). The lower limits of energy given are appropriate
E 925 Practice for Monitoring the Calibration of
for a cylindrical dosimeter ampoule of 12-mm diameter. Corrections for
Ultraviolet-Visible Spectrophotometers whose Spectral
Slit Width does not Exceed 2 nm
E 958 Practice for Measuring Practical Spectral Bandwidth
1
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
of Ultraviolet-Visible Spectrophotometers
Technology and Applications and is the direct responsibility of Subcommittee
3
2.2 ISO/ASTM Standards:
E10.01 on Radiation Processing: Dosimetry and Applications, and is also under the
jurisdiction of ISO/TC 85/WG 3. 51261 Guide for Selection and Calibration of Dosimetry
Current edition approved June 18, 2008. Published June 2009. Originally
published as ASTM E 1538-93. Last previous ASTM edition E 1538–99. ASTM E
1538–93 was adopted by ISO in 1998 with the intermediate designation ISO
3
15563:1998(E). The present International Standard ISO/ASTM 51538:2009 (E) is a For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
major revision of ISO/ASTM 51538:2002(E), which replaced ISO 15563. www.astm.org, or contact ASTM Customer Service at service@astm.org. For
2
The boldface numbers in parentheses refer to the bibliography at the end of this Annual Book of ASTM Standards volume information, refer to the standard’s
practice. Document Summary page on the ASTM website.
© ISO/ASTM International 2009 – All rights reserved
1
---------------------- Page: 5 ----------------------
ISO/ASTM 51538:2009(E)
Systems for Radiation Processing absorbing molecular species at a given wavelength, l, per unit
pathlength, d, to the molar concentration, c, of that species in
51400 Practice for Characterization and Performance of a
solution:
High-Dose Gamma-Radiation Dosimetry Calibration
Laboratory
A
l
´ 5 (1)
m
51707 Guide for Estimating Uncertainties in Dosimetry for d 3 c
2 −1
Radiation Processing
(SI unit: m mol )
2.3 International Commission on Radiation Units and
3.1.6.1 Discussion—It is sometimes expressed in units of L
4
−1 −1
Measurements (ICRU) Reports:
mol cm .
ICRU Report 14 Radiation Dosimetry: X-Rays and Gamma
3.1.7 radiation chemical yield G(x)—quotient of n(x) by ´¯
Rays with Maximum Photon Energies Between 0.6 and 60
where n(x) is the mean amount of a specified entity, x,
MeV
produced, destroyed, or changed by the mean energy, ´¯
ICRU Report 17 Radiation Dosimetry: X-Rays Generated
imparted to the matter.
at Potentials of 5 to 150 kV
G~x! 5 n~x! / ´¯ (2)
ICRU Report 34 The Dosimetry of Pulsed Radiation
−1
(SI unit: mol J )
ICRU Report 35 Radiation Dosimetry: Electrons with
3.1.8 reference-standard dosimeter—dosimeter of high
Initial Energies Between 1 and 50 MeV
metrological quality used as a standard to provide measure-
ICRU Report 37 Stopping Powers for Electrons and
ments traceable to measurements made using primary-standard
Positrons
dosimeters.
ICRU Report 60 Fundamental Quantities and Units for
3.1.9 response function—mathematical representation of
Ionizing Radiation
the relationship between dosimeter response and absorbed
dose, for a given dosimetry system.
3. Terminology
3.1.10 routine dosimeter—dosimeter calibrated against a
3.1 Definitions: primary-, reference-, or transfer-standard dosimeter and used
3.1.1 calibration—set of operations under specified condi- for routine absorbed-dose measurements.
tions, which establishes the relationship between values indi- 3.1.11 traceability—property of the result of a measurement
cated by a measuring instrument or measuring system, and the
or the value of a standard whereby it can be related to stated
corresponding values realised by standards traceable to a references, usually national or international standards, through
nationally or internationally recognized laboratory. an unbroken chain of comparisons all having stated uncertain-
3.1.1.1 Discussion—Calibration conditions include envi- ties.
ronmental and irradiation conditions present during irradiation,
3.2 Definitions of Terms Specific to This Standard:
storage and measurement of the dosimeters that are used for the
3.2.1 conductometry—analytical method based on the mea-
generation of a calibration curve. To achieve stable environ-
surement of conductivity of solutions.
mental conditions, it may be necessary to condition the
3.2.1.1 Discussion—The conductivity of a solution depends
dosimeters before performing the calibration procedure.
on the concentration of free ions in the solution.
3.1.2 calibration curve—graphical representation of the
3.2.2 oscillometry—electroanalytical method of conductiv-
dosimetry system’s response function.
ity measurements, when high-frequency (1 to 600 MHz)
3.1.3 dosimetry system—system used for determining ab-
alternating current is applied to measure or follow changes in
sorbed dose, consisting of dosimeters, measurement instru-
the composition of chemical systems.
ments and their associated reference standards, and procedures
3.3 Definitions of other terms used in this standard that
for the system’s use.
pertain to radiation measurement and dosimetry may be found
3.1.4 ethanol-chlorobenzene dosimeter—partly deoxygen-
in ASTM Terminology Standard E 170. Definitions in ASTM
ated solution of chlorobenzene (CB) in 96 volume % ethanol in
E 170 are compatible with ICRU 60; that document, therefore,
an appropriate container, such as a flame-sealed glass ampoule,
may be used as an alternative reference.
used to indicate absorbed dose by measurement of the amount
of HCl formed under irradiation.
4. Significance and use
3.1.5 measurement quality assurance plan—documented
4.1 The ECB dosimetry system provides a reliable means of
program for the measurement process that ensures that the
measuring absorbed dose in materials. It is based on a process
expanded uncertainty consistently meets the requirements of
of radiolytic formation of hydrochloric acid (HCl) in aqueous
the specific application. This plan requires traceability to
ethanolic solutions of chlorobenzene by ionizing radiation (7,
nationally or internationally recognized standards.
8).
3.1.6 molar linear absorption coeffıcient ´ —constant re-
m
4.2 The dosimeters are partly deoxygenated solutions of
lating the spectrophotometric absorbance, A , of an optically
l
chlorobenzene (CB) in 96 volume % ethanol in an appropriate
container, such as a flame-sealed glass ampoule. The irradiated
solutions indicate absorbed dose by the amount of HCl formed.
4 A number of analytical methods are available for measuring the
Available from the Commission on Radiation Units and Measurements, 7910
Woodmont Ave., Suite 800, Bethesda, MD 20814, USA. amount of HCl in ethanol (9).
© ISO/ASTM International 2009 – All rights reserved
2
---------------------- Page: 6 ----------------------
ISO/ASTM 51538:2009(E)
4.3 Effect of Irradiation Temperature: Procedures for making such calculations are given in ASTM
4.3.1 The temperature dependence of dosimeter response is Practices E 666 and E 668 and ISO/ASTM Guide 51261.
a complex function of dose and temperature for each concen-
NOTE 3—For a comprehensive discussion of various dosimetry meth-
tration of chlorobenzene (that is, for each formulation). The
ods applicable to the radiation types and energies discussed in this
analysis of the published data (10) shows that the temperature
practice, see ICRU Reports 14, 17, 34, 35, and 37.
dependence between 20°C and 80°C at any chlorobenzene
4.6 The ECB dosimetry system may be used with other
concentration can be described by a simple exponential expres-
radiation types, such as neutrons (18), and protons (19).
sion:
Meaningful dosimetry of any radiation types and energies
G 5 G exp[k~t 2 20!# (3)
t 0 novel to the system’s use requires that the respective radiation
chemical responses applicable under the circumstances be
where:
−1 established in advance.
G = the radiation chemical yield in µmol J at a given
t
temperature t in °C,
5. Interferences
−1
G = the radiation chemical yield in µmol J at 20°C (G
0 0
5.1 The ECB dosimetric solution response is not particu-
for different ECB solutions are given in Table 1), and
larly sensitive to impurities which occur in commercially
−1
k = the temperature coefficient in (°C) applicable at a
available components, chlorobenzene and ethanol of the ana-
given dose.
lytical reagent (AR) grade purity or equivalent (pro analysi,
4.3.2 The values of k are given in Table 2.
p.a., and puriss). For high-accuracy results, organic materials
of technical grade purity (or purum) can be purified by
TABLE 1 Typical ECB solution formulations
distillation.
Radiation Chemical Yields
5.2 Care should be exercised in filling ampoules to avoid
B −1
at 20°C (µmol· J )
Concentration Density at 20°C Ratio of depositing solution in the ampoule neck. Subsequent heating
60
−3 A
Co 4to10MeV
of CB, vol % kg · m Coefficients
during sealing of the ampoule may cause an undesirable
Gamma Electrons (3)
chemical change in the dosimetric solution remaining inside
Rays (11)
C the ampoule’s neck. Test tubes with ground-glass stoppers are
4 819 0.989 0.42
10 839 0.995 0.52 therefore preferred to sealed ampoules for measuring doses
20 869 1.006 0.59
below 100 Gy. For the same reason, care should be given to
D
24 880 1.011 0.60 0.57
avoid heating the body of the ampoule during sealing.
40 925 1.027 0.63
5.3 The dosimetric solution is somewhat sensitive to ultra-
A
The ratio of the mass energy-absorption coefficients for water and the
60
dosimeter solution at Co gamma ray energy: violet light and should be kept in the dark for long-term
~µ /r!
en w storage. No special precautions are required during routine
f 5
~µ /r!
en D
handling under normal laboratory lighting conditions, but
B
Radiation chemical yields of HCl in the dose range from 100 Gy to 100 kGy.
C
strong ultraviolet (UV) sources such as sunlight should be
Upper dose range 20 kGy.
D
Lowerdoserange1kGy.Thisformulationalsocontained0.04%acetoneand
avoided (20).
0.04 % benzene.
6. Apparatus
4.3.3 Between −30°C and 50°C the temperature coefficient 6.1 This practice describes mercurimetric titration of radi-
−
0.015 kGy/°C applies at 30 kGy dose (12). Information on the olytically formed Cl ions as a standard readout procedure for
temperature dependence of dosimeter response during irradia- the ECB system when used as a reference-standard dosimetry
tion between 20 and 80°C is found in Ref (10), and between system.
−40 and 20°C in Ref (13). 6.2 For the analysis of the dosimetric solution, use a
4.4 The concentration of chlorobenzene in the solution can precision burette capable of measuring volumes with 0.01 mL
be varied so as to simulate a number of materials in terms of resolution. If necessary, check the original calibration of
the photon mass energy-absorption coefficients (µ /r) for X- volumetric glassware and, if necessary, recalibrate to attain
en
and gamma radiation, and electron mass collision stopping 0.1 % relative uncertainty. Control the temperature of all
−2
powers (S/r), over a broad energy range from 10 to 100 MeV solutions during handling at 20 6 2°C.
(14-17). 6.3 Use borosilicate glass or equivalent chemically resistant
4.5 The absorbed dose that is determined is the dose glass to store the reagents and the prepared dosimetric solution,
absorbed in the water. Absorbed dose in other materials and to perform the titration. Clean all apparatus thoroughly
irradiated under equivalent conditions may be calculated. before use (see ASTM Practice C 912).
−1
TABLE 2 Temperature coefficients k (°C) for typical ECB solution formulations
Concentration of CB, Vol % 2.5 kGy 5 kGy 10 kGy 15 kGy 20 kGy 25 kGy
4 −0.0002 −0.0004 −0.0007 −0.0011 −0.0015 −0.0019
10 0.0018 0.0014 0.0009 0.0002 0.0 0.0
20, 25, 40 0.0037 0.0031 0.0020 0.0013 0.0008 0.0
NOTE 1—For intermediate doses interpolation should be made.
© ISO/ASTM International 2009 – All rights reserved
3
---------------------- Page: 7 ----------------------
ISO/ASTM 51538:2009(E)
composition before the bubbling of the dosimeter ampoules.
6.4 Use a sealed glass ampoule or other appropriate glass
container to hold the dosimetric solution during irradiation. For
9. Calibration of the mercuric nitrate solution
photons, surround the container with material of thickness
sufficient to produce approximate electron equilibrium condi-
9.1 The dosimeter measurement procedure is based on the
tions during calibration irradiations. For measurement of ab-
titration of chloride ions formed by irradiation. Free chloride is
sorbed dose in water, use materials that have radiation-
precipitated with mercuric ions as insoluble HgCl , where-
2
absorption properties essentially equivalent to water, for 2+
upon the excess of Hg ions gives a violet-red coloration with
example, polystyrene and polyethylene. The appropriate thick-
the indicator diphenylcarbazone in acid medium (21).
ness of such material depends on the energy of the photon (see
−4 −3
9.2 Prepare approximately 5 3 10 mol dm Hg(NO ) in
3 2
ASTM Practices E 666 and E 668).
acidic aqueous ethanol. First dissolve an appropriate amount of
NOTE 4—The dosimetric ampoule commonly used has a capacity of
Hg(NO ) in water acidified with sufficient HNO to attain the
3 2 3
about 5 mL. Quick-break, glass ampoules or “Type 1 glass” colorbreak
−3
concentration of the acid in the final solution, 0.05 mol dm .
ampoules or equivalent containers, may be used. Commercially available
(Warning—Mercuric (II) nitrate is highly toxic. Acute expo-
pharmaceutical ampoules have been found to give reproducible results
without requiring additional cleaning.
sure of skin and mucous membranes produces violent corrosive
effects. Chronic exposure causes many pathological changes.
7. Reagents
Appropriate precautions should be exercised in handling it.
7.1 Analytical reagent grade chemicals shall be used in this
Used solutions should be disposed of as hazardous waste.
5
practice for preparing all solutions.
Hazards of mercury poisoning can be avoided by using some of
7.2 Use of triply distilled water from coupled all-glass stills
the alternative readout methods described in Annex A2 and
is recommended. Type II reagent water as specified in ASTM
Table A3.1 in Annex A3.)
Specification D 1193 is also considered to be of sufficient
9.2.1 Prepare standard solutions of NaCl in water. Make
quality for use in preparing solutions and 96 volume % ethanol.
several concentrations to enable cross-checking. Suitable con-
−3 −2 −2
NOTE 5—High-purity water is commercially available from some
centrations are 5 3 10 , 1.0 3 10 , 1.5 3 10 , and 2.0 3
suppliers. Such water, labelled HPLC (high-pressure liquid chromatogra-
−2 −3
10 mol dm . If kept properly in ground-glass stoppered
phy) grade, is usually sufficiently free of impurities to be used in this
bottles, these solutions are stable for years. Avoid contamina-
practice.
tion of the standard solutions by using for daily work small
8. Preparation of dosimeters
portions of these solutions kept in small ground-glass stop-
8.1 Dosimetric solutions may contain any concentration of
pered flasks. Replenish standard solutions in the small flasks as
CB. For practical reasons, only a few characteristic formula-
necessary.
tions have been thoroughly characterized. Table 1 lists these −3
9.2.2 Prepare 0.2 mol dm HNO in ethanol and 1 %
3
typical formulations in terms of CB concentrations and radia-
ethanolic solutions of diphenylcarbazone (DPC).
tion chemical yields pertaining to these concentrations.
9.3 Distribute technical grade ethanol to beakers for titra-
8.2 Prepare 96 volume % aqueous ethanol first by adding
tion, 10 mL into each. Pipet standard NaCl solution quantita-
absolute ethanol into a volumetric flask containing the appro-
−3
tively to beakers with ethanol. Add 1 mL of 0.2 mol dm
priate amount of water. (Warning—Ethanol is flammable.)
HNO and 7 drops of 1 % DPC and shake. Titrate with
3
Use this aqueous ethanol for making the dosimetric solutions
Hg(NO ) solution from the burette. The solution in the beaker,
of the desired concentrations by adding it into volumetric flasks 3 2
which is initially yellow-orange, turns to reddish-violet at the
containing appropriate amounts of CB. Store the dosimetric
end point.
solution in the dark. (Warning—Chlorobenzene is toxic and a
skin irritant. Appropriate precaution should be taken to avoid 9.4 Construct or calculate the best straight line through the
contact with the solution during preparation and analysis of the
points: (consumption of Hg(NO ) ) versus (milliequivalents of
3 2
dosimeters. Used solutions should be disposed of as hazardous
NaCl). The small positive intercept represents the blank;
waste.)
inverse slope gives concentration of Hg(NO ) solution.
3 2
8.3 Fill the dosimeter ampoules with the dosimetric solu-
NOTE 7—Volumes of the standard NaCl solutions should be such that
tion. Bubble the solution in the ampoule with nitrogen for
the consumptions of the titrant solution on calibration are similar to the
about 1 min at about 1 bubble per second through a 1-mm
consumptions when analyzing irradiated dosimetric solutions. Take two
capillary. Flame-seal immediately after bubbling. Exercise care
different volumes of each standard solution to enable cross-checking. The
to avoid depositing solution in the ampoule neck. Store
concentration of mercuric nitrate solution should be calibrated daily.
dosimeters in the dark.
NOTE 6—To minimize the removal of the vapor above the dosimetic 10. Calibration of the dosimetry system
solution in the ampoules, the nitrogen is saturated with the vapors of the
10.1 The dosimetry system shall be calibrated prior to use
dosimetric solution by passing it through ECB solution of the same
and at intervals thereafter in accordance with the user’s
documented procedure that specifies details of the calibration
5
process and quality assurance requirements. Calibration re-
Reagent specifications are available from the American Chemical Society, 1115
16th Street, NW, Washington, DC 20036, USA. quirements are given in ISO/ASTM Guide 51261.
© ISO/ASTM International 2009 – All rights reserved
4
---------------------- Page: 8 ----------------------
ISO/ASTM 51538:2009(E)
−
10.2 Calibration Irradiation of Dosimeters—Irradiation is a 10.5.2 Obtain a response function for [Cl ] as a function of
critical component of the calibration of the dosimetry system. the absorbed dose, D. Fit the data by means of a least-squares
Calibration irradiations shall be performed at a national or method with an appropriate analytical form that best fits the
accredited
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.