SIST ISO 11704:2013
Water quality - Measurement of gross alpha and beta activity concentration in non-saline water - Liquid scintillation counting method
Water quality - Measurement of gross alpha and beta activity concentration in non-saline water - Liquid scintillation counting method
This International Standard specifies a method for the determination of gross alpha and gross beta activity in waters for radionuclides which are not volatile at 80 °C. Radon isotopes and their decay products of short half life are not included in the determination. The method is applicable to raw and potable waters with a dry residue less than 5 g/l and when no correction for colour quenching is necessary.
Qualité de l'eau - Mesurage des activités alpha globale et bêta globale des eaux non salines - Méthode de comptage par scintillation liquide
L'ISO 11704:2010 sp�cifie une m�thode de d�termination des activit�s alpha globale et b�ta globale dans les eaux, pour les radionucl�ides qui ne sont pas volatils � 80 �C. Les isotopes du radon et leurs produits de d�sint�gration � courte demi-vie ne sont pas inclus dans la d�termination.
La m�thode est applicable aux eaux brutes et potables ayant un r�sidu sec inf�rieur � 5 g/l et lorsque aucune correction n'est n�cessaire pour l'affaiblissement lumineux de couleur.
Kakovost vode - Merjenje skupne alfa in skupne beta koncentracije aktivnosti v neslanih vodah - Metoda štetja s tekočinskim scintilatorjem
Ta mednarodni standard opisuje metodo za določevanje skupne alfa in skupne beta aktivnosti v vodah za radionuklide, ki niso hlapni pri 80 °C. Izotopi radona in njihovi razpadni produkti s kratkim razpolovnim časom v določevanje niso vključeni. Metoda se uporablja za neobdelane in pitne vode s suhim ostankom, manjšim od 5 g/l, pri katerih ni potreben popravek za dušenje fluorescence.
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INTERNATIONAL ISO
STANDARD 11704
First edition
2010-07-01
Water quality — Measurement of gross
alpha and beta activity concentration in
non-saline water — Liquid scintillation
counting method
Qualité de l'eau — Mesurage des activités alpha globale et bêta globale
des eaux non salines — Méthode de comptage par scintillation liquide
Reference number
ISO 11704:2010(E)
©
ISO 2010
---------------------- Page: 1 ----------------------
ISO 11704:2010(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall 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. The ISO Central Secretariat
accepts no 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
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the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, 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.
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ii © ISO 2010 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 11704:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Symbols, definitions and units .2
4 Principle.2
5 Reagents and equipment.3
6 Sampling.4
7 Procedure.4
7.1 Direct counting .4
7.2 Thermal preconcentration.5
7.3 Sample preparation.5
7.4 Liquid scintillation measurement .5
8 Expression of results.7
8.1 Calculation of activity per unit of mass .7
8.2 Standard uncertainty.8
8.3 Decision threshold .8
8.4 Detection limit.9
8.5 Confidence limits.9
8.6 Quality control.10
9 Interference control.10
9.1 Contamination .10
9.2 Ingrowth of radon.10
9.3 Loss of polonium.10
10 Test report.10
Bibliography.12
© ISO 2010 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 11704:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11704 was prepared by Technical Committee ISO/TC 147, Water quality.
iv © ISO 2010 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 11704:2010(E)
Water quality — Measurement of gross alpha and beta activity
concentration in non-saline water — Liquid scintillation
counting method
WARNING — Persons using this International Standard should be familiar with normal laboratory
practice. This standard does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this International Standard
be carried out by suitably trained staff.
1 Scope
This International Standard specifies a method for the determination of gross alpha and gross beta activity in
waters for radionuclides which are not volatile at 80 °C. Radon isotopes and their decay products of short half
life are not included in the determination.
The method is applicable to raw and potable waters with a dry residue less than 5 g/l and when no correction
for colour quenching is necessary.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5667-3, Water quality — Sampling — Part 3: Guidance on the preservation and handling of water
samples
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
© ISO 2010 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 11704:2010(E)
3 Symbols, definitions and units
For the purposes of this document, the definitions, symbols and abbreviations defined in ISO 80000-10, as
well as the following symbols, definitions and units, apply.
−1
a , a Alpha and beta activity per mass Bq g
α β
−1
a* Decision threshold Bq g
#
−1
a Detection limit Bq g
−1
aa, Lower and upper limits of the confidence interval Bq g
A , A Activity of the alpha and beta emitter certified reference solution used for the Bq
α β
α and β calibration sources
m Mass of the test sample g
m Mass of initial sample subject to heating or possibly concentration g
1
m Mass of heated or concentrated sample g
2
m Mass of heated or concentrated sample transferred in the vial g
3
m , m Mass of alpha and beta emitters certified reference solutions, respectively g
Sα Sβ
−1
r , r Sample gross count rate, from the alpha and beta windows, respectively s
gα gβ
−1
r , r , r Blank count rate, from the alpha, beta and total windows, respectively s
0α 0β 0T
−1
r , r , r Count rate of the alpha calibration source in the alpha, beta and total window s
Sα,α Sα,β Sα,T
−1
r , r , r Count rate of the beta calibration source in the alpha, beta and total window s
Sβ,α Sβ,β Sβ,T
t Sample counting time s
g
t Blank counting time s
0
t , t Counting time of α and β calibration sources s
sα sβ
−1
u (a) Standard uncertainty associated with the measurement result Bq g
−1
U Expanded uncertainty, calculated from U = ku (a), where k = 1, 2 … Bq g
−1
ua() Standard uncertainty of a as a function of its true value Bq g
α α
ε , ε Counting efficiency for alpha and beta, respectively —
α β
α→β
τχ() Alpha interference — Fraction of counts observed in the beta window with —
α
respect to the total number of counts measured by the counter when an
alpha emitter is measured
β→α
τχ() Beta interference — Fraction of counts observed in the alpha window with —
β
respect to the total number of counts measured by the counter when a beta
emitter is measured
4 Principle
Gross alpha and beta activity concentrations are determined by using liquid scintillation counting of a water
sample mixed with a scintillation cocktail.
Gross alpha and beta determinations are not absolute determinations of the sample radioactive contents, but
relative determinations referred to a specific alpha or beta emitter which constitutes the standard calibration
sources. These types of determinations are also known as the alpha and beta index.
2 © ISO 2010 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 11704:2010(E)
The aqueous sample is acidified using nitric acid and heated. Subsequently, water with low salt content can
be thermally concentrated by slow evaporation to improve the method sensitivity. An aliquot of sample is
transferred into a liquid scintillation vial with scintillation cocktail; scintillations from the vial are then counted by
equipment with an alpha and beta discrimination device.
The counter is previously optimized with respect to an alpha and beta discriminator setting and then calibrated
against alpha and beta emitter certified reference solutions. In data evaluation, no correction for chemical
quenching is applied, since the procedure is designed to provide samples with a constant quenching level.
222 3 14
The method does not account for Rn and its daughters of short half life and it is not suitable for H and C
measurement.
When suspended matter is present in significant quantities, a filtration step is required before acidification.
5 Reagents and equipment
All reagents shall be of recognized analytical grade, except for the scintillation cocktail, and shall not contain
any detectable alpha and beta activity, except for the radioactive certified reference solutions.
5.1 Nitric acid, c(HNO ) = 15,8 mol/l, ρ = 1,42 g/ml, mass fraction w(HNO ) = 70 %.
3 3
[1]
5.2 Water, ISO 3696 , grade 3.
222
Deionized water can contain detectable amounts of Rn and short half-life decay products. It is therefore
strongly recommended to boil water under vigorous stirring and let it stand for one day before use.
Alternatively, use nitrogen flushing for about 1 h for a 2 l sample.
5.3 Scintillation cocktail. Commercially available scintillation cocktails suitable for alpha and beta
discrimination (e.g. diisopropylnaphthalene-based cocktails).
5.4 Volatile organic solvents. Methanol or ethanol.
5.5 Certified reference solutions. A calibration laboratory establishes traceability of its own calibration
sources and measuring instruments to the International System of Units (SI) by means of an unbroken chain
of calibrations or comparisons linking them to relevant certified reference solutions of the SI units of
measurement. The link to the SI units may be achieved with respect to national certified reference materials.
These may be primary realizations of the SI units, or agreed representations of SI units based on fundamental
physical constants, or they may be secondary materials which are materials certified by another national
metrology institute. When using external calibration services, traceability of measurement shall be assured by
the use of calibration services from laboratories that can demonstrate competence, measurement capability,
and traceability. The calibration certificates issued by these laboratories shall contain the measurement results,
including the measurement uncertainty and/or statement of compliance with an identified metrological
specification.
NOTE Calibration laboratories fulfilling the requirements of this International Standard are considered to be
competent. A calibration certificate bearing an accreditation body logo from a calibration laboratory accredited to this
International Standard, for the calibration concerned, is sufficient evidence of traceability of the calibration data reported.
In general, the experimental parameters (efficiency, alpha and beta optimum discrimination) depend on alpha
and beta energies, thus the choice of alpha and beta emitter certified reference solutions will depend on
knowledge of the type of radioactive contaminant likely to be present in the waters being tested (see
[4]
ISO 9696 and Reference [11]).
5.5.1 Alpha emitter certified reference solution. The alpha emitter certified reference solution shall not
contain any unexpected detectable alpha and beta activity.
© ISO 2010 – All rights reserved 3
---------------------- Page: 7 ----------------------
ISO 11704:2010(E)
236
NOTE U is a convenient choice when waters are checked for their natural radioactivity content, as its energy is
226
close to the most widespread natural radionuclides (e.g. uranium and thorium isotopes, Ra) and it is commercially
available without decay products of short half life. The supplier can supply details of the absence of any decay product.
241 239
Am is commonly used when artificial radionuclide contamination is suspected. Pu can be used as well in such
circumstances.
5.5.2 Beta emitter certified reference solution. The beta emitter certified reference solution shall not
contain alpha-emitting radioisotopes.
90 90 40
NOTE A Sr and Y mixture or K are commonly used. A potassium solution for atomic absorption spectrometry
has one arguable advantage, in that its specific activity can be calculated from established physical constants and isotopic
abundance data which are independent of the calibration procedures of a particular organization.
5.6 Equipment.
5.6.1 Analytical balance.
5.6.2 Hot plate with magnetic stirrer and stirring bar.
5.6.3 pH meter.
5.6.4 Wide-mouth HDPE sample bottles, capacities between 100 ml and 500 ml.
5.6.5 Liquid scintillation counter, with α and β discrimination option, preferably an ultra low level counter
to achieve better detection limits.
5.6.6 Polyethylene scintillation vials, capacity 20 ml, such as PET vials, low diffusion PET vials or PTFE-
coated polyethylene vials.
PTFE-coated polyethylene vials are the best choice since they prevent both the diffusion of the cocktail into
the wall of the vial and the absorption of radon from the outer environment. Glass vials generally worsen α
and β discrimination.
6 Sampling
Collect 0,1 l to 1 l of water in a plastic bottle (5.6.4) in accordance with ISO 5667-3. If necessary, filter
immediately on collection and before acidification. If possible, acidify immediately with nitric acid (5.1) to a
value not lower than pH 1,7 ± 0,2 (7.1) or pH 2,7 ± 0,2 if preconcentration is desired (7.2). Verify by pH meter.
NOTE Acidification of the water sample minimizes the loss of radioactive material from solution by adsorption. If
carried out before filtration, it desorbs radioactive material already adsorbed on to the particulate material.
The relatively low acidification of the sample does not ensure long-term preservation. Prepare the sample
withi
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Qualité de l'eau - Mesurage des activités alpha globale et bêta globale des eaux non salines - Méthode de comptage par scintillation liquideWater quality - Measurement of gross alpha and beta activity concentration in non-saline water - Liquid scintillation counting method17.240Merjenje sevanjaRadiation measurements13.060.60Preiskava fizikalnih lastnosti vodeExamination of physical properties of waterICS:Ta slovenski standard je istoveten z:ISO 11704:2010SIST ISO 11704:2013en,fr01-januar-2013SIST ISO 11704:2013SLOVENSKI
STANDARD
SIST ISO 11704:2013
Reference numberISO 11704:2010(E)© ISO 2010
INTERNATIONAL STANDARD ISO11704First edition2010-07-01Water quality — Measurement of gross alpha and beta activity concentration in non-saline water — Liquid scintillation counting method Qualité de l'eau — Mesurage des activités alpha globale et bêta globale des eaux non salines — Méthode de comptage par scintillation liquide
SIST ISO 11704:2013
ISO 11704:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall 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. The ISO Central Secretariat accepts no 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. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
©
ISO 2010 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, 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. ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel.
+ 41 22 749 01 11 Fax
+ 41 22 749 09 47 E-mail
copyright@iso.org Web
www.iso.org Published in Switzerland
ii © ISO 2010 – All rights reserved
SIST ISO 11704:2013
ISO 11704:2010(E) © ISO 2010 – All rights reserved iii Contents Page Foreword.iv 1 Scope.1 2 Normative references.1 3 Symbols, definitions and units.2 4 Principle.2 5 Reagents and equipment.3 6 Sampling.4 7 Procedure.4 7.1 Direct counting.4 7.2 Thermal preconcentration.5 7.3 Sample preparation.5 7.4 Liquid scintillation measurement.5 8 Expression of results.7 8.1 Calculation of activity per unit of mass.7 8.2 Standard uncertainty.8 8.3 Decision threshold.8 8.4 Detection limit.9 8.5 Confidence limits.9 8.6 Quality control.10 9 Interference control.10 9.1 Contamination.10 9.2 Ingrowth of radon.10 9.3 Loss of polonium.10 10 Test report.10 Bibliography.12
SIST ISO 11704:2013
ISO 11704:2010(E) iv © ISO 2010 – All rights reserved 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. 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. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 11704 was prepared by Technical Committee ISO/TC 147, Water quality. SIST ISO 11704:2013
INTERNATIONAL STANDARD ISO 11704:2010(E) © ISO 2010 – All rights reserved 1 Water quality — Measurement of gross alpha and beta activity concentration in non-saline water — Liquid scintillation counting method WARNING — Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. IMPORTANT — It is absolutely essential that tests conducted according to this International Standard be carried out by suitably trained staff. 1 Scope This International Standard specifies a method for the determination of gross alpha and gross beta activity in waters for radionuclides which are not volatile at 80 °C. Radon isotopes and their decay products of short half life are not included in the determination. The method is applicable to raw and potable waters with a dry residue less than 5 g/l and when no correction for colour quenching is necessary. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5667-3, Water quality — Sampling — Part 3: Guidance on the preservation and handling of water samples ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics SIST ISO 11704:2013
ISO 11704:2010(E) 2 © ISO 2010 – All rights reserved 3 Symbols, definitions and units For the purposes of this document, the definitions, symbols and abbreviations defined in ISO 80000-10, as well as the following symbols, definitions and units, apply. aα, aβ Alpha and beta activity per mass Bq g−1 a* Decision threshold Bq g−1 #a Detection limit Bq g−1 ,aa Lower and upper limits of the confidence interval Bq g−1 Aα, Aβ Activity of the alpha and beta emitter certified reference solution used for the α and β calibration sources Bq m Mass of the test sample g m1 Mass of initial sample subject to heating or possibly concentration g m2 Mass of heated or concentrated sample g m3 Mass of heated or concentrated sample transferred in the vial g mSα, mSβ Mass of alpha and beta emitters certified reference solutions, respectively g rgα, rgβ Sample gross count rate, from the alpha and beta windows, respectively
s−1 r0α, r0β, r0T Blank count rate, from the alpha, beta and total windows, respectively s−1 rSα,α, rSα,β, rSα,T Count rate of the alpha calibration source in the alpha, beta and total window s−1 rSβ,α, rSβ,β, rSβ,T Count rate of the beta calibration source in the alpha, beta and total window s−1 tg Sample counting time s t0 Blank counting time s tsα, tsβ Counting time of α and β calibration sources s u (a) Standard uncertainty associated with the measurement result Bq g−1 U Expanded uncertainty, calculated from U = ku (a), where k = 1, 2 … Bq g−1 ()uaα Standard uncertainty of aα as a function of its true value Bq g−1 εα, εβ Counting efficiency for alpha and beta, respectively — ()τχαŽ Alpha interference — Fraction of counts observed in the beta window withrespect to the total number of counts measured by the counter when analpha emitter is measured — ()βτχŽ Beta interference — Fraction of counts observed in the alpha window withrespect to the total number of counts measured by the counter when a betaemitter is measured — 4 Principle Gross alpha and beta activity concentrations are determined by using liquid scintillation counting of a water sample mixed with a scintillation cocktail. Gross alpha and beta determinations are not absolute determinations of the sample radioactive contents, but relative determinations referred to a specific alpha or beta emitter which constitutes the standard calibration sources. These types of determinations are also known as the alpha and beta index. SIST ISO 11704:2013
ISO 11704:2010(E) © ISO 2010 – All rights reserved 3 The aqueous sample is acidified using nitric acid and heated. Subsequently, water with low salt content can be thermally concentrated by slow evaporation to improve the method sensitivity. An aliquot of sample is transferred into a liquid scintillation vial with scintillation cocktail; scintillations from the vial are then counted by equipment with an alpha and beta discrimination device. The counter is previously optimized with respect to an alpha and beta discriminator setting and then calibrated against alpha and beta emitter certified reference solutions. In data evaluation, no correction for chemical quenching is applied, since the procedure is designed to provide samples with a constant quenching level. The method does not account for 222Rn and its daughters of short half life and it is not suitable for 3H and 14C measurement. When suspended matter is present in significant quantities, a filtration step is required before acidification. 5 Reagents and equipment All reagents shall be of recognized analytical grade, except for the scintillation cocktail, and shall not contain any detectable alpha and beta activity, except for the radioactive certified reference solutions. 5.1 Nitric acid, c(HNO3) = 15,8 mol/l,
= 1,42 g/ml, mass fraction w(HNO3) = 70 %. 5.2 Water, ISO 3696[1], grade 3. Deionized water can contain detectable amounts of 222Rn and short half-life decay products. It is therefore strongly recommended to boil water under vigorous stirring and let it stand for one day before use. Alternatively, use nitrogen flushing for about 1 h for a 2 l sample. 5.3 Scintillation cocktail. Commercially available scintillation cocktails suitable for alpha and beta discrimination (e.g. diisopropylnaphthalene-based cocktails). 5.4 Volatile organic solvents. Methanol or ethanol. 5.5 Certified reference solutions. A calibration laboratory establishes traceability of its own calibration sources and measuring instruments to the International System of Units (SI) by means of an unbroken chain of calibrations or comparisons linking them to relevant certified reference solutions of the SI units of measurement. The link to the SI units may be achieved with respect to national certified reference materials. These may be primary realizations of the SI units, or agreed representations of SI units based on fundamental physical constants, or they may be secondary materials which are materials certified by another national metrology institute. When using external calibration services, traceability of measurement shall be assured by the use of calibration services from laboratories that can demonstrate competence, measurement capability, and traceability. The calibration certificates issued by these laboratories shall contain the measurement results, including the measurement uncertainty and/or statement of compliance with an identified metrological specification. NOTE Calibration laboratories fulfilling the requirements of this International Standard are considered to be competent. A calibration certificate bearing an accreditation body logo from a calibration laboratory accredited to this International Standard, for the calibration concerned, is sufficient evidence of traceability of the calibration data reported. In general, the experimental parameters (efficiency, alpha and beta optimum discrimination) depend on alpha and beta energies, thus the choice of alpha and beta emitter certified reference solutions will depend on knowledge of the type of radioactive contaminant likely to be present in the waters being tested (see ISO 9696[4] and Reference [11]). 5.5.1 Alpha emitter certified reference solution. The alpha emitter certified reference solution shall not contain any unexpected detectable alpha and beta activity. SIST ISO 11704:2013
ISO 11704:2010(E) 4 © ISO 2010 – All rights reserved NOTE 236U is a convenient choice when waters are checked for their natural radioactivity content, as its energy is close to the most widespread natural radionuclides (e.g. uranium and thorium isotopes, 226Ra) and it is commercially available without decay products of short half life. The supplier can supply details of the absence of any decay product. 241Am is commonly used when artificial radionuclide contamination is suspected. 239Pu can be used as well in such circumstances. 5.5.2 Beta emitter certified reference solution. The beta emitter certified reference solution shall not contain alpha-emitting radioisotopes. NOTE A 90Sr and 90Y mixture or 40K are commonly used. A potassium solution for atomic absorption spectrometry has one arguable advantage, in that its specific activity can be calculated from established physical constants and isotopic abundance data which are independent of the calibration procedures of a particular organization. 5.6 Equipment. 5.6.1 Analytical balance. 5.6.2 Hot plate with magnetic stirrer and stirring bar. 5.6.3 pH meter. 5.6.4 Wide-mouth HDPE sample bottles, capacities between 100 ml and 500 ml. 5.6.5 Liquid scintillation counter, with α and β discrimination option, preferably an ultra low level counter to achieve better detection limits. 5.6.6 Polyethylene scintillation vials, capacity 20 ml, such as PET vials, low diffusion PET vials or PTFE-coated polyethylene vials. PTFE-coated polyethylene vials are the best choice since they prevent both the diffusion of the cocktail into the wall of the vial and the absorption of radon from the outer environment. Glass vials generally worsen α and β discrimination. 6 Sampling Collect 0,1 l to 1 l of water in a plastic bottle (5.6.4) in accordance with ISO 5667-3. If
...
NORME ISO
INTERNATIONALE 11704
Première édition
2010-07-01
Qualité de l'eau — Mesurage des activités
alpha globale et bêta globale des eaux
non salines — Méthode de comptage par
scintillation liquide
Water quality — Measurement of gross alpha and beta activity
concentration in non-saline water — Liquid scintillation counting method
Numéro de référence
ISO 11704:2010(F)
©
ISO 2010
---------------------- Page: 1 ----------------------
ISO 11704:2010(F)
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Case postale 56 • CH-1211 Geneva 20
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Web www.iso.org
Publié en Suisse
ii © ISO 2010 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 11704:2010(F)
Sommaire Page
Avant-propos .iv
1 Domaine d'application .1
2 Références normatives.1
3 Symboles, définitions et unités .2
4 Principe.2
5 Réactifs et matériel.3
6 Prélèvement .4
7 Mode opératoire.5
7.1 Comptage direct .5
7.2 Préconcentration thermique.5
7.3 Préparation de l'échantillon .5
7.4 Mesurage par scintillation liquide .6
8 Expression des résultats.8
8.1 Calcul de l'activité par unité de masse.8
8.2 Incertitude-type.8
8.3 Seuil de décision .9
8.4 Limite de détection.9
8.5 Limites de l'intervalle de confiance.10
8.6 Contrôle de la qualité .10
9 Contrôle de l'interférence .10
9.1 Contamination .10
9.2 Accroissement du radon .11
9.3 Perte du polonium .11
10 Rapport d'essai.11
Bibliographie.12
© ISO 2010 – Tous droits réservés iii
---------------------- Page: 3 ----------------------
ISO 11704:2010(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 11704 a été élaborée par le comité technique ISO/TC 147, Qualité de l'eau.
iv © ISO 2010 – Tous droits réservés
---------------------- Page: 4 ----------------------
NORME INTERNATIONALE ISO 11704:2010(F)
Qualité de l'eau — Mesurage des activités alpha globale et bêta
globale des eaux non salines — Méthode de comptage par
scintillation liquide
AVERTISSEMENT — Il convient que l'utilisateur de la présente Norme internationale connaisse bien
les pratiques courantes de laboratoire. La présente Norme internationale n'a pas pour but de traiter
tous les problèmes de sécurité qui sont, le cas échéant, liés à son utilisation. Il incombe à l'utilisateur
d'établir des pratiques appropriées en matière d'hygiène et de sécurité, et de s'assurer de la
conformité à la réglementation nationale en vigueur.
IMPORTANT — Il est absolument essentiel que les essais réalisés conformément à la présente Norme
internationale soient exécutés par un personnel ayant reçu une formation adéquate.
1 Domaine d'application
La présente Norme internationale spécifie une méthode de détermination des activités alpha globale et bêta
globale dans les eaux, pour les radionucléides qui ne sont pas volatils à 80 °C. Les isotopes du radon et leurs
produits de désintégration à période courte ne sont pas inclus dans la détermination.
La méthode est applicable aux eaux brutes et potables ayant un résidu sec inférieur à 5 g/l et lorsque aucune
correction n'est nécessaire pour l'affaiblissement lumineux de couleur.
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 5667-3, Qualité de l'eau — Échantillonnage — Partie 3: Lignes directrices pour la conservation et la
manipulation des échantillons d'eau
ISO/CEI 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais
ISO 80000-10, Grandeurs et unités — Partie 10: Physique atomique et nucléaire
© ISO 2010 – Tous droits réservés 1
---------------------- Page: 5 ----------------------
ISO 11704:2010(F)
3 Symboles, définitions et unités
Pour les besoins du présent document, les définitions, symboles et abréviations définis dans l'ISO 80000-10
ainsi que les symboles, définitions et unités suivants s'appliquent.
−1
a , a Activités alpha et bêta par unité de masse
Bq g
α β
−1
a* Seuil de décision
Bq g
#
−1
a Limite de détection
Bq g
−1
aa, Limites inférieure et supérieure de l'intervalle de confiance
Bq g
A , A Activité de la solution de référence certifiée d'émetteur alpha ou bêta utilisée pour
Bq
α β
les sources d'étalonnage α et β
m Masse de l'échantillon pour essai g
m Masse de l'échantillon initial soumis à la chaleur ou éventuellement à une g
1
concentration
m Masse de l'échantillon chauffé ou concentré g
2
Masse d'échantillon chauffé ou concentré transférée dans le flacon
m g
3
m , m Masse de solutions de référence certifiées d'émetteurs alpha et bêta, g
Sα Sβ
respectivement
−1
r , r Taux de comptage brut par seconde de l'échantillon, dans les fenêtres alpha et bêta s
gα gβ
respectivement
−1
r , r , r Taux de comptage du blanc par seconde, dans les fenêtres alpha, bêta et totale, s
0α 0β 0T
respectivement
−1
r , r , r Taux de comptage de la source d'étalonnage alpha dans la fenêtre alpha, bêta et s
Sα,α Sα,β Sα,T
totale
−1
r , r , r Taux de comptage de la source d'étalonnage bêta dans la fenêtre alpha, bêta et s
Sβ,α Sβ,β Sβ,T
totale
t Durée de comptage de l'échantillon s
g
t Durée de comptage du blanc s
0
t , t Durée de comptage des sources d'étalonnage α et β s
sα sβ
−1
u (a) Incertitude-type associée au résultat de mesure Bq g
−1
U Incertitude élargie, calculée par U = ku (a) où k = 1, 2. Bq g
−1
ua() Incertitude-type de a en fonction de sa valeur vraie Bq g
α
α
ε , ε Rendement de comptage pour alpha et bêta, respectivement —
α β
→
τχ() Interférence alpha — Fraction d'impulsions observées dans la fenêtre bêta par —
ααβ
rapport au nombre total d'impulsions mesuré par le compteur lorsqu'un émetteur
alpha est mesuré
→
Interférence bêta — Fraction d'impulsions observées dans la fenêtre alpha par
τχ()
—
ββα
rapport au nombre total d'impulsions mesuré par le compteur lorsqu'un émetteur
bêta est mesuré
4 Principe
Les activités alpha globale et bêta globale sont déterminées par comptage par scintillation liquide sur un
échantillon d'eau mélangé à un cocktail de scintillation.
2 © ISO 2010 – Tous droits réservés
---------------------- Page: 6 ----------------------
ISO 11704:2010(F)
Les déterminations alpha globale et bêta globale ne sont pas des déterminations absolues de la teneur
radioactive de l'échantillon, mais des déterminations relatives en référence à un émetteur alpha ou bêta
spécifique qui constitue les sources d'étalonnage de référence. Ces types de déterminations sont également
connus en tant qu'indices alpha et bêta.
L'échantillon aqueux est acidifié à l'aide d'acide nitrique et chauffé. L'eau à faible teneur en sels peut ensuite
être concentrée thermiquement par évaporation lente afin d'améliorer la sensibilité de la méthode. Une
aliquote de l'échantillon est transférée dans un flacon de scintillation liquide avec un cocktail de scintillation;
les scintillations provenant du flacon sont alors mesurées au moyen d'un appareillage équipé d'un dispositif
de discrimination alpha et bêta.
Le compteur est préalablement optimisé en ce qui concerne le réglage du discriminateur alpha et bêta, puis
étalonné par rapport aux solutions de référence certifiées d'émetteurs alpha et bêta. Lors de l'évaluation des
résultats, aucune correction n'est appliquée pour l'affaiblissement lumineux chimique, car le mode opératoire
est conçu pour fournir des échantillons ayant un niveau d'affaiblissement lumineux constant.
222
La méthode ne tient pas compte du Rn et de ses descendants à période courte et n'est pas appropriée
3 14
pour le mesurage de H et C.
Quand des matériaux en suspension sont présents en quantité significative, une étape de filtration est requise
avant l'acidification.
5 Réactifs et matériel
Tous les réactifs doivent être de qualité analytique reconnue, à l'exception du cocktail de scintillation, et ne
doivent pas présenter d'activités alpha et bêta détectables, à l'exception des solutions de référence
radioactives certifiées.
5.1 Acide nitrique, c(HNO ) = 15,8 mol/l, ρ = 1,42 g/ml, fraction massique w(HNO ) = 70 %.
3 3
[1]
5.2 Eau, ISO 3696 , qualité 3.
222
L'eau déionisée peut contenir des quantités détectables de Rn et de produits de désintégration à période
courte. Il est donc fortement recommandé de faire bouillir l'eau en l'agitant vigoureusement, puis de la laisser
reposer pendant une journée avant de l'utiliser. Il est également possible d'utiliser un barbotage d'azote
d'environ 1 h pour un échantillon de 2 l.
5.3 Cocktail de scintillation. Cocktails de scintillation disponibles dans le commerce pour discrimination
alpha et bêta (par exemple cocktails à base de diisopropylnaphtalène).
5.4 Solvants organiques volatils. Méthanol ou éthanol.
5.5 Solutions de référence certifiées. Un laboratoire d'étalonnage établit la traçabilité de ses propres
sources d'étalonnage et instruments de mesure au Système international d'unités (SI) au moyen d'une chaîne
ininterrompue d'étalonnages ou de comparaisons les reliant à des solutions de référence certifiées
appropriées des unités SI de mesure. Le lien avec les unités SI peut être réalisé par référence à des
matériaux de référence nationaux certifiés. Ceux-ci peuvent être des réalisations primaires des unités SI, ou
des représentations agréées des unités SI fondées sur des constantes physiques fondamentales, ou peuvent
être des matériaux secondaires qui sont des matériaux certifiés par un autre institut national de métrologie.
Lorsque l'on fait appel à des services d'étalonnage externe, la traçabilité des mesurages doit être assurée en
ayant recours à des services d'étalonnage de laboratoires capables de démontrer leur compétence et leur
aptitude en matière de mesure et de traçabilité. Les certificats d'étalonnage émis par ces laboratoires doivent
contenir les résultats de mesure, y compris l'incertitude de mesure et/ou une déclaration de conformité à une
spécification métrologique identifiée.
NOTE Les laboratoires d'étalonnage satisfaisant aux exigences de la présente Norme internationale sont considérés
comme compétents. Un certificat d'étalonnage portant le logo d'un organisme d'accréditation, émis par un laboratoire
© ISO 2010 – Tous droits réservés 3
---------------------- Page: 7 ----------------------
ISO 11704:2010(F)
d'étalonnage accrédité conformément à la présente Norme internationale pour l'étalonnage concerné, est une preuve
suffisante de la traçabilité des données d'étalonnage consignées.
En général, les paramètres expérimentaux (rendement, discrimination optimale alpha et bêta) dépendent des
énergies alpha et bêta; en conséquence, le choix des solutions de référence certifiées d'émetteurs alpha et
bêta dépend de la connaissance du type de contaminant radioactif susceptible d'être présent dans les eaux
[4]
soumises à essai (voir l'ISO 9696 et la Référence [11]).
5.5.1 Solution de référence certifiée d'émetteur alpha. La solution de référence certifiée d'émetteur
alpha ne doit contenir aucune activité alpha et bêta détectable inattendue.
236
NOTE U est un choix convenable lorsque les eaux sont contrôlées pour leur teneur en radioactivité naturelle car
son énergie est proche de celle de la plupart des radionucléides naturels les plus répandus (isotopes de l'uranium et du
226
thorium, Ra, par exemple) et il est disponible dans le commerce sans produits de désintégration à période courte. Le
fournisseur peut fournir des informations relatives à l'absence de produits de désintégration.
241 239
Am est couramment utilisé lorsqu'une contamination par des radionucléides artificiels est suspectée. Pu peut
également être utilisé dans de telles circonstances.
5.5.2 Solution de référence certifiée d'émetteur bêta. La solution de référence certifiée d'émetteur bêta
ne doit pas contenir de radio-isotopes émetteurs alpha.
90 90 40
NOTE Un mélange Sr et Y ou K sont couramment utilisés. Une solution de potassium pour spectrométrie
d'absorption atomique offre un avantage défendable en ce que son activité massique peut être calculée à partir de
constantes physiques établies et de données de teneur isotopique qui sont indépendantes des procédures d'étalonnage
d'un organisme particulier.
5.6 Matériel.
5.6.1 Balance analytique.
5.6.2 Plaque chauffante avec agitateur magnétique et barreau agitateur.
5.6.3 pH-mètre.
5.6.4 Flacons à échantillons en polyéthylène haute densité à large ouverture, d'une capacité de
100 ml à 500 ml.
5.6.5 Compteur à scintillation liquide, avec option de discrimination alpha et bêta, de préférence un
compteur à niveau de bruit de fond ultra-bas pour obtenir de meilleures limites de détection.
5.6.6 Flacons de scintillation en polyéthylène, d'une capacité de 20 ml, flacons en poly(téréphtalate
d'éthylène) (PET), flacons en PET à faible diffusion ou flacons en polyéthylène revêtu de
polytétrafluoroéthylène (PTFE).
Les flacons en polyéthylène revêtu de PTFE sont le meilleur choix car ils empêchent à la fois la diffusion du
cocktail dans la paroi du flacon et l'absorption du radon provenant de l'environnement extérieur. Les flacons
en verre altèrent généralement la discrimination alpha et bêta.
6 Prélèvement
Prélever 0,1 l à 1 l d'eau dans un flacon en plastique (5.6.4) conformément à l'ISO 5667-3. Si nécessaire,
filtrer immédiatement après le prélèvement et avant l'acidification. Si possible, procéder immédiatement à
l'acidification avec de l'acide nitrique (5.1) de manière à atteindre un pH qui ne soit pas inférieur à 1,7 ± 0,2
(7.1) ou à 2,7 ± 0,2 si une préconcentration est souhaitée (7.2). Vérifier à l'aide d'un pH-mètre.
NOTE L'acidification de l'échantillon d'eau réduit au minimum la perte de matière radioactive de la solution par
adsorption. Si elle est effectuée avant la filtration, elle désorbe la matière radioactive déjà adsorbée sur la matière
particulaire.
4 © ISO 2010 – Tous droits réservés
---------------------- Page: 8 ----------------------
ISO 11704:2010(F)
L'acidification relativement faible de l'échantillon ne permet pas une conservation à long terme. Préparer
l'échantillon dans les 48 h qui suivent le prélèvement. Le
...
SLOVENSKI STANDARD
oSIST ISO 11704:2012
01-junij-2012
.DNRYRVWYRGH0HUMHQMHVNXSQHDOIDLQVNXSQHEHWDNRQFHQWUDFLMHDNWLYQRVWLY
QHVODQLKYRGDK0HWRGDãWHWMDVWHNRþLQVNLPVFLQWLODWRUMHP
Water quality - Measurement of gross alpha and beta activity concentration in non-saline
water - Liquid scintillation counting method
Qualité de l'eau - Mesurage des activités alpha globale et bêta globale des eaux non
salines - Méthode de comptage par scintillation liquide
Ta slovenski standard je istoveten z: ISO 11704:2010
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
oSIST ISO 11704:2012 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST ISO 11704:2012
---------------------- Page: 2 ----------------------
oSIST ISO 11704:2012
INTERNATIONAL ISO
STANDARD 11704
First edition
2010-07-01
Water quality — Measurement of gross
alpha and beta activity concentration in
non-saline water — Liquid scintillation
counting method
Qualité de l'eau — Mesurage des activités alpha globale et bêta globale
des eaux non salines — Méthode de comptage par scintillation liquide
Reference number
ISO 11704:2010(E)
©
ISO 2010
---------------------- Page: 3 ----------------------
oSIST ISO 11704:2012
ISO 11704:2010(E)
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Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 11704:2012
ISO 11704:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Symbols, definitions and units .2
4 Principle.2
5 Reagents and equipment.3
6 Sampling.4
7 Procedure.4
7.1 Direct counting .4
7.2 Thermal preconcentration.5
7.3 Sample preparation.5
7.4 Liquid scintillation measurement .5
8 Expression of results.7
8.1 Calculation of activity per unit of mass .7
8.2 Standard uncertainty.8
8.3 Decision threshold .8
8.4 Detection limit.9
8.5 Confidence limits.9
8.6 Quality control.10
9 Interference control.10
9.1 Contamination .10
9.2 Ingrowth of radon.10
9.3 Loss of polonium.10
10 Test report.10
Bibliography.12
© ISO 2010 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST ISO 11704:2012
ISO 11704:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11704 was prepared by Technical Committee ISO/TC 147, Water quality.
iv © ISO 2010 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 11704:2012
INTERNATIONAL STANDARD ISO 11704:2010(E)
Water quality — Measurement of gross alpha and beta activity
concentration in non-saline water — Liquid scintillation
counting method
WARNING — Persons using this International Standard should be familiar with normal laboratory
practice. This standard does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this International Standard
be carried out by suitably trained staff.
1 Scope
This International Standard specifies a method for the determination of gross alpha and gross beta activity in
waters for radionuclides which are not volatile at 80 °C. Radon isotopes and their decay products of short half
life are not included in the determination.
The method is applicable to raw and potable waters with a dry residue less than 5 g/l and when no correction
for colour quenching is necessary.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5667-3, Water quality — Sampling — Part 3: Guidance on the preservation and handling of water
samples
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
© ISO 2010 – All rights reserved 1
---------------------- Page: 7 ----------------------
oSIST ISO 11704:2012
ISO 11704:2010(E)
3 Symbols, definitions and units
For the purposes of this document, the definitions, symbols and abbreviations defined in ISO 80000-10, as
well as the following symbols, definitions and units, apply.
−1
a , a Alpha and beta activity per mass Bq g
α β
−1
a* Decision threshold Bq g
#
−1
a Detection limit Bq g
−1
aa, Lower and upper limits of the confidence interval Bq g
A , A Activity of the alpha and beta emitter certified reference solution used for the Bq
α β
α and β calibration sources
m Mass of the test sample g
m Mass of initial sample subject to heating or possibly concentration g
1
m Mass of heated or concentrated sample g
2
m Mass of heated or concentrated sample transferred in the vial g
3
m , m Mass of alpha and beta emitters certified reference solutions, respectively g
Sα Sβ
−1
r , r Sample gross count rate, from the alpha and beta windows, respectively s
gα gβ
−1
r , r , r Blank count rate, from the alpha, beta and total windows, respectively s
0α 0β 0T
−1
r , r , r Count rate of the alpha calibration source in the alpha, beta and total window s
Sα,α Sα,β Sα,T
−1
r , r , r Count rate of the beta calibration source in the alpha, beta and total window s
Sβ,α Sβ,β Sβ,T
t Sample counting time s
g
t Blank counting time s
0
t , t Counting time of α and β calibration sources s
sα sβ
−1
u (a) Standard uncertainty associated with the measurement result Bq g
−1
U Expanded uncertainty, calculated from U = ku (a), where k = 1, 2 … Bq g
−1
ua() Standard uncertainty of a as a function of its true value Bq g
α α
ε , ε Counting efficiency for alpha and beta, respectively —
α β
α→β
τχ() Alpha interference — Fraction of counts observed in the beta window with —
α
respect to the total number of counts measured by the counter when an
alpha emitter is measured
β→α
τχ() Beta interference — Fraction of counts observed in the alpha window with —
β
respect to the total number of counts measured by the counter when a beta
emitter is measured
4 Principle
Gross alpha and beta activity concentrations are determined by using liquid scintillation counting of a water
sample mixed with a scintillation cocktail.
Gross alpha and beta determinations are not absolute determinations of the sample radioactive contents, but
relative determinations referred to a specific alpha or beta emitter which constitutes the standard calibration
sources. These types of determinations are also known as the alpha and beta index.
2 © ISO 2010 – All rights reserved
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oSIST ISO 11704:2012
ISO 11704:2010(E)
The aqueous sample is acidified using nitric acid and heated. Subsequently, water with low salt content can
be thermally concentrated by slow evaporation to improve the method sensitivity. An aliquot of sample is
transferred into a liquid scintillation vial with scintillation cocktail; scintillations from the vial are then counted by
equipment with an alpha and beta discrimination device.
The counter is previously optimized with respect to an alpha and beta discriminator setting and then calibrated
against alpha and beta emitter certified reference solutions. In data evaluation, no correction for chemical
quenching is applied, since the procedure is designed to provide samples with a constant quenching level.
222 3 14
The method does not account for Rn and its daughters of short half life and it is not suitable for H and C
measurement.
When suspended matter is present in significant quantities, a filtration step is required before acidification.
5 Reagents and equipment
All reagents shall be of recognized analytical grade, except for the scintillation cocktail, and shall not contain
any detectable alpha and beta activity, except for the radioactive certified reference solutions.
5.1 Nitric acid, c(HNO ) = 15,8 mol/l, ρ = 1,42 g/ml, mass fraction w(HNO ) = 70 %.
3 3
[1]
5.2 Water, ISO 3696 , grade 3.
222
Deionized water can contain detectable amounts of Rn and short half-life decay products. It is therefore
strongly recommended to boil water under vigorous stirring and let it stand for one day before use.
Alternatively, use nitrogen flushing for about 1 h for a 2 l sample.
5.3 Scintillation cocktail. Commercially available scintillation cocktails suitable for alpha and beta
discrimination (e.g. diisopropylnaphthalene-based cocktails).
5.4 Volatile organic solvents. Methanol or ethanol.
5.5 Certified reference solutions. A calibration laboratory establishes traceability of its own calibration
sources and measuring instruments to the International System of Units (SI) by means of an unbroken chain
of calibrations or comparisons linking them to relevant certified reference solutions of the SI units of
measurement. The link to the SI units may be achieved with respect to national certified reference materials.
These may be primary realizations of the SI units, or agreed representations of SI units based on fundamental
physical constants, or they may be secondary materials which are materials certified by another national
metrology institute. When using external calibration services, traceability of measurement shall be assured by
the use of calibration services from laboratories that can demonstrate competence, measurement capability,
and traceability. The calibration certificates issued by these laboratories shall contain the measurement results,
including the measurement uncertainty and/or statement of compliance with an identified metrological
specification.
NOTE Calibration laboratories fulfilling the requirements of this International Standard are considered to be
competent. A calibration certificate bearing an accreditation body logo from a calibration laboratory accredited to this
International Standard, for the calibration concerned, is sufficient evidence of traceability of the calibration data reported.
In general, the experimental parameters (efficiency, alpha and beta optimum discrimination) depend on alpha
and beta energies, thus the choice of alpha and beta emitter certified reference solutions will depend on
knowledge of the type of radioactive contaminant likely to be present in the waters being tested (see
[4]
ISO 9696 and Reference [11]).
5.5.1 Alpha emitter certified reference solution. The alpha emitter certified reference solution shall not
contain any unexpected detectable alpha and beta activity.
© ISO 2010 – All rights reserved 3
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oSIST ISO 11704:2012
ISO 11704:2010(E)
236
NOTE U is a convenient choice when waters are checked for their natural radioactivity content, as its energy is
226
close to the most widespread natural radionuclides (e.g. uranium and thorium isotopes, Ra) and it is commercially
available without decay products of short half life. The supplier can supply details of the absence of any decay product.
241 239
Am is commonly used when artificial radionuclide contamination is suspected. Pu can be used as well in such
circumstances.
5.5.2 Beta emitter certified reference solution. The beta emitter certified reference solution shall not
contain alpha-emitting radioisotopes.
90 90 40
NOTE A Sr and Y mixture or K are commonly used. A potassium solution for atomic absorption spectrometry
has one arguable advantage, in that its specific activity can be calculated from established physical constants and isotopic
abundance data which are independent of the calibration procedures of a particular organization.
5.6 Equipment.
5.6.1 Analytical balance.
5.6.2 Hot plate with magnetic stirrer and stirring bar.
5.6.3 pH meter.
5.6.4 Wide-mouth HDPE sample bottles, capacities between 100 ml and 500 ml.
5.6.5 Liquid scintillation counter, with α and β discrimination option, preferably an ultra low level counter
to achieve better detection limits.
5.6.6 Polyethylene scintillation vials, capacity 20 ml, such as PET vials, low diffusion PET vials or PTFE-
coated polyethylene vials.
PTFE-coated polyethylene vials are the best choice since they prevent both the diffusion of the cocktail into
the wall of the vial and the absorption of radon from the outer environment. Glass vials generally worsen α
and β discrimination.
6 Sampling
Collect 0,1 l to 1 l of water in a plastic bottle (5.6.4) in accordance with ISO 5667-3. If necessary, filter
immediately on collection and before acidification. If possible, acidify immediately with nitric acid
...
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