FprEN ISO 9697

• Abstract:

  This document specifies a test method for the determination of gross beta activity concentration in non-saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or higher. Measurement of low energy beta emitters (e.g. 3H, 228Ra, 210Pb, 14C, 35S and 241Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine) might not be included in the gross beta quantification using the test method described in this document.; This test method is applicable to the analysis of raw and drinking waters. The range of application depends on the amount of total soluble salts in the water and on the performance characteristics (background count rate and counting efficiency) of the counter used.; It is the laboratory's responsibility to ensure the suitability of this method for the water samples tested.

• Status: Not Published
• Publication Date: 31-Jan-2027
• ICS: 13.060.60 - Examination of physical properties of water
• ICS: 13.280 - Radiation protection
• Technical Committee: CEN/TC 230 - Water analysis
• Current Stage: 5020 - Submission to Vote - Formal Approval
• Start Date: 03-Sep-2026
• Completion Date: 03-Sep-2026
• Ref Project: kSIST FprEN ISO 9697:2026 - Water quality - Gross beta activity - Test method using thick source (ISO/FDIS 9697:2026)

• Consolidated By: ISO/FDIS 9697 - Water quality — Gross beta activity — Test method using thick source
• Effective Date: 12-Feb-2026
• Revises: EN ISO 9697:2019 - Water quality - Gross beta activity - Test method using thick source (ISO 9697:2018)
• Effective Date: 19-Jun-2024

FprEN ISO 9697 is a CEN draft standard for measuring gross beta activity in water by the thick source method. It specifies a laboratory test method for non-saline waters, mainly raw and drinking water, and covers sample preparation, beta counting, calculation of results, and quality control for laboratories that monitor radioactivity in water.

What does FprEN ISO 9697 specify?

FprEN ISO 9697 specifies a test method for determining gross beta activity concentration in non-saline waters. The document is organized into Clauses 1 to 10, which cover scope, references, terms and symbols, principle, reagents and equipment, procedure, quality assurance, expression of results, and test reporting, plus informative Annex A.

Annex	What it covers
A	Example performance criteria from validation work

FprEN ISO 9697 applies to raw water and drinking water, with practical performance influenced by the total soluble salts in the water and the counter used. The method is intended for non-volatile radionuclides with beta energies of about 0.3 MeV or higher. It is not aimed at low-energy beta emitters such as tritium or lead-210, or at some gaseous or volatile radionuclides such as radon and radioiodine. The laboratory is responsible for checking whether the method is suitable for the samples it receives, and the method is not designed for rapid field analysis.

What are the key requirements of FprEN ISO 9697?

FprEN ISO 9697 is a laboratory screening method, not a radionuclide-specific assay. In practice, that means the result represents gross beta activity relative to a chosen calibration source, so the choice of standard, source thickness, and counting setup affects the reported value.

Sampling and sample preparation

Clause 7.1 requires sampling, preservation, and handling to follow the ISO 5667 series named in the document. Filtration is carried out immediately after collection and before acidification. That order matters because acidification can move radionuclides off suspended particles and change the measured result.

Clauses 7.2 to 7.5 then guide the preparation of a thick source. The sample is concentrated, converted to the sulfate form, baked, and weighed so the residue loading on the planchet is controlled. In practice, this is what makes the method a thick source method and helps keep the sample and calibration geometry comparable.

Counting, calibration, and source geometry

Clause 5 states that the residue is measured with a beta counter, preferably a gas-flow proportional counter, after calibration against a suitable beta standard such as potassium-40 or strontium-90/yttrium-90 in equilibrium. If gross alpha and gross beta are measured on the same water sample, the document notes that the procedure is similar to ISO 9696, but the source thickness must stay below the stated limit for that combined use.

Clause 6 sets the main laboratory materials and equipment. Reagents must be analytical grade and free of detectable beta activity, the counter must suit the method, the planchet must have sufficient surface density, and the furnace must hold the required baking temperature. These details matter because contamination, geometry, and drying conditions can shift the count rate and the calculated concentration.

Clause 7.6 requires the source to be spread evenly on the planchet and dry to constant mass before counting. Clause 7.7 says counting should begin promptly after drying to reduce the effect of ingrowth from natural radionuclides. In practice, laboratories need to control timing, source appearance, and sample history, not just the detector setting.

Background, cross-talk, and calibration sources

Clause 7.8 requires background measurement with a clean planchet. Clause 7.9 covers preparation of calibration sources, including a beta calibration source and, when a gas-flow proportional counter is used, an alpha calibration source for alpha-to-beta cross-talk correction. This matters because the method can be sensitive to alpha events entering the beta window, especially in gas-flow proportional systems.

Clause 7.10 explains that the method is a gross measurement, so a specific radionuclide bias cannot be stated in the same way as for a separated analysis. Clause 7.11 stresses that the sample source and standard source should be as similar as possible in mass loading and distribution. That is the practical control that keeps the comparison between sample and calibration source meaningful.

Quality assurance and interference control

Clause 8 requires the work to be done under a quality assurance programme such as ISO/IEC 17025. It also requires contamination checks on reagents and on the full measurement system. This is important because a small background contribution or contaminated reagent can be enough to affect low-activity samples.

Clause 8.3 addresses natural radionuclide interference, including uranium, radium, lead, and polonium decay products. The document points out that the contribution of these radionuclides can change with time between collection, preparation, and analysis. In practice, the laboratory needs to fix and document the counting strategy, because timing can change the apparent gross beta result.

Clause 8.4 and 8.5 call for periodic method verification and demonstration of analyst capability. That means intercomparisons, reference materials, spiked samples, and replicate checks are part of routine control, not optional extras.

Result calculation and reporting

Clause 9 gives the calculation route for activity concentration from gross count rate, background, counting efficiency, and alpha-beta cross-talk. It also provides the approach for standard uncertainty, decision threshold, detection limit, and coverage intervals, using ISO 11929 concepts. If cross-talk is negligible with other detector types, the correction factor can be taken as zero.

Clause 10 defines what the test report needs to contain under ISO/IEC 17025. The report must identify the sample, state the units, give the result in the correct form relative to the decision threshold or detection limit, and record the relevant dates. If the detection limit is higher than the applicable guidance value, that should be documented in the report.

What terms does FprEN ISO 9697 define?

• Gross beta activity concentration - The activity concentration measured by the thick source beta method, expressed as a screening result for beta-emitting radionuclides in the water sample.
• Decision threshold - The result level above which the measured activity is treated as detected according to the ISO 11929 approach.
• Detection limit - The lowest activity concentration that the method is expected to detect with the stated decision and confidence settings.
• Counting efficiency - The fraction that links the known activity of the calibration source to the measured count rate for the chosen source geometry.
• Alpha-beta cross-talk - The portion of alpha counts that appears in the beta window of a gas-flow proportional counter.
• Coverage interval - The uncertainty interval reported around the result, either as a probabilistically symmetric interval or as the shortest interval.
• Planchet - The prepared counting support on which the dried residue is spread before beta measurement.

Who uses FprEN ISO 9697?

FprEN ISO 9697 is used by water testing laboratories, radioactivity measurement laboratories, and public health or environmental monitoring teams that need a gross beta screening result for water. It is also used by quality managers and technical buyers who need to specify a laboratory method for raw water or drinking water monitoring.

In practice, the document supports:

• routine monitoring of drinking water and other non-saline waters
• compliance checking against national or guidance levels
• laboratory validation, calibration, and uncertainty work
• reporting of gross beta screening results in a form that regulators can use

What changed in FprEN ISO 9697 from the previous edition?

FprEN ISO 9697 replaces the fourth edition, ISO 9697:2018, and the foreword says this fifth edition is technically revised. The stated changes are:

• an updated introduction to match the current template
• updated normative references
• an updated symbols table, including additional symbols for coverage interval and uncertainty calculations
• an updated test report to align with current ISO standards

Which standards are used with FprEN ISO 9697?

Standard	What it contributes
ISO 5667-1	Guidance on water sampling programme design and sampling techniques
ISO 5667-3	Preservation and handling of water samples
ISO 5667-14	Quality assurance and quality control for environmental water sampling and handling
ISO 11929 (all parts)	Decision threshold, detection limit, and coverage interval calculations for ionizing radiation measurements
ISO 80000-10	Quantities and units for atomic and nuclear physics
ISO/IEC 17025	Laboratory competence and test report requirements
ISO/IEC Guide 98-3	Expression of measurement uncertainty

The document also names related methods and companions. ISO 11704 is suggested as a better fit when low-energy beta emitters need to be included, and ISO 9698, ISO 13162, and ISO 22908 are named for separate analysis of tritium, carbon 14, and radium 226/radium 228. ISO 9696 is cited for the similar thick source approach used when gross alpha and gross beta are measured together.

What does the FprEN ISO 9697 document contain?

FprEN ISO 9697 contains a worked laboratory method rather than just a definition of the measurand. Clause 7 gives the step-by-step procedure for sampling, pre-treatment, concentration, sulfation, baking, source preparation, measurement, background counting, and calibration source preparation.

Clause 9 contains the calculation route for activity concentration, standard uncertainty, decision threshold, detection limit, and coverage intervals. Annex A provides example performance criteria from validation work, which helps laboratories compare their own repeatability and reproducibility performance with a published example.

SLOVENSKI STANDARD
oSIST prEN ISO 9697:2026
01-januar-2026
Kakovost vode - Skupna beta aktivnost - Preskusna metoda robustnega vira
(ISO/DIS 9697:2025)
Water quality - Gross beta activity - Test method using thick source (ISO/DIS 9697:2025)
Wasserbeschaffenheit - Gesamt-Beta-Aktivität - Dickschichtverfahren (ISO/DIS
9697:2025)
Qualité de l'eau - Activité bêta globale - Méthode d'essai par source épaisse e (ISO/DIS
9697:2025)
Ta slovenski standard je istoveten z: prEN ISO 9697
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 9697:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 9697:2026
oSIST prEN ISO 9697:2026
DRAFT
International
Standard
ISO/DIS 9697
ISO/TC 147/SC 3
Water quality — Gross beta activity
Secretariat: AFNOR
— Test method using thick source
Voting begins on:
Qualité de l'eau — Activité bêta globale — Méthode d'essai par
2025-11-28
source épaisse
Voting terminates on:
ICS: 13.060.60; 13.280 2026-02-20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
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Reference number
ISO/DIS 9697:2025(en)
oSIST prEN ISO 9697:2026
DRAFT
ISO/DIS 9697:2025(en)
International
Standard
ISO/DIS 9697
ISO/TC 147/SC 3
Water quality — Gross beta activity
Secretariat: AFNOR
— Test method using thick source
Voting begins on:
Qualité de l'eau — Activité bêta globale — Méthode d'essai par
source épaisse
Voting terminates on:
ICS: 13.060.60; 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
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Published in Switzerland Reference number
ISO/DIS 9697:2025(en)
ii
oSIST prEN ISO 9697:2026
ISO/DIS 9697:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Symbols . 2
5 Principle . 3
6 Chemical reagents and equipment . 3
6.1 Chemical reagents .3
6.2 Equipment .4
7 Procedure . 4
7.1 Sampling .4
7.2 Pre-treatment .5
7.3 Concentration stage .5
7.4 Sulfation stage.5
7.5 Baking stage . .5
7.6 Source preparation .5
7.7 Measurement .6
7.8 Determination of counting background .6
7.9 Preparation of calibration sources .6
7.10 Sensitivity and bias .7
7.11 Optimization of the determination .7
8 Quality assurance and quality control . 7
8.1 General .7
8.2 Contamination check .7
8.3 Interference control of the contribution of the natural radionuclides .7
8.4 Method verification .8
8.5 Demonstration of analyst capability . .8
9 Expression of results . 8
9.1 Calculation of activity concentration .8
9.2 Standard uncertainty .9
9.3 Decision threshold .10
9.4 Limit of detection .10
9.5 Limits of the coverage intervals .10
9.5.1 Limits of the probabilistically symmetric coverage interval .10
9.5.2 The shortest coverage interval .11
10 Test report .11
Annex A (informative) Example of performance criteria .13
Bibliography . 14

iii
oSIST prEN ISO 9697:2026
ISO/DIS 9697:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radioactivity measurements.
This fifth edition cancels and replaces the fourth edition (ISO 9697:2018), which has been technically
revised.
The main changes are as follows:
— updates to the introduction to match the most recent template
— update of the normative references
— update of the update of the Symbols table for current formatting and additional symbols for the coverage
interval and uncertainty calculations
— update of the test report to conform to the current ISO standards
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
oSIST prEN ISO 9697:2026
ISO/DIS 9697:2025(en)
Introduction
Radionuclides are present throughout the environment; thus, water bodies (e.g. surface waters, ground
waters, sea waters) contain radionuclides, which can be of either natural or anthropogenic origin:
3 14 40
— Naturally-occurring radionuclides, including H, C, K and those originating from the thorium and
210 210 222 226 228 227 232 231 234 238
uranium decay series, in particular Pb, Po, Rn, Ra, Ra, Ac, Th, Pa, U, and U,
can be found in water bodies due to either natural processes (e.g., desorption from the soil and runoff by
rainwater) or released from technological processes involving naturally occurring radioactive materials
(e.g. mining, mineral processing, oil, gas, and coal production, water treatment and the production and
use of phosphate fertilisers);
55 59 63 90 99
— Anthropogenic radionuclides such as Fe, Ni, Ni, Sr, Tc, transuranic elements (e.g., Np, Pu, Am,
60 137
and Cm), and some gamma emitting radionuclides such as Co and Cs can also be found in natural
waters. Small quantities of anthropogenic radionuclides can be discharged from nuclear facilities to the
environment as a result of authorized routine releases. The radionuclides present in liquid effluents
[1]
are usually controlled before being discharged to the environment and water bodies. Anthropogenic
radionuclides used for medical and industrial applications can be released to the environment after use.
Anthropogenic radionuclides are also found in waters due to contamination from fallout resulting from
above-ground nuclear detonations and accidents such as those that have occurred at the Chernobyl and
Fukushima nuclear facilities.
Radionuclide activity concentrations in water bodies can vary according to local geological characteristics
and climatic conditions and can be locally and temporally enhanced by releases from nuclear facilities
[2][3]
during planned, existing, and emergency exposure situations. Some drinking water sources can thus
contain radionuclides at activity concentrations that can present a human health risk. The World Health
[4]
Organization (WHO) recommends to routinely monitor radioactivity in drinking waters and to take
proper actions when needed to minimize the health risk.
National regulations usually specify the activity concentration limits that are authorized in drinking waters,
water bodies, and liquid effluents to be discharged to the environment. These limits can vary for planned,
existing, and emergency exposure situations. As an example, during either a planned or existing situation,
−1[ ]
the WHO guidance level for gross beta activity in drinking water is 1,0 Bq·l 4 , see NOTES 1, 2 and 3.
Compliance with these limits is assessed by measuring radioactivity in water samples and by comparing the
[5]
results obtained, with their associated uncertainties, as specified by ISO/IEC Guide 98-3 and ISO 5667-20 .
NOTE 1 If the value is not specified in Annex 6 of Reference, [4] the value has been calculated using the formula
provided in Reference [4] and the dose coefficient data from References [6] and [7].
NOTE 2 Gross alpha and gross beta activity are often measured together: the WHO guidance level for gross alpha
−1[ ]
activity in drinking water is 0,5 Bq l 4 .
NOTE 3 The guidance level calculated in Reference [4] is the activity concentration that results in an effective dose
-1 −1
of 0,1 mSv·a to members of the public for an intake of 2 l·d of drinking water for one year. This is an effective
dose that represents a very low level of risk to human health and which is not expected to give rise to any detectable
[4]
adverse health effects .
This document contains method(s) to support laboratories, which need to determine the gross beta activity
concentration in water samples. The method(s) described in this document can be used for various types of
waters (see Clause 1). Minor modifications such as sample volume and counting time can be made if needed
to ensure that the decision threshold, detection limit, and uncertainties are below the required limits.
This can be done for several reasons such as emergency situations, lower national guidance limits, and
operational requirements.
[8]
NOTE To include low-energy beta emitters in the gross beta analysis, ISO 11704 may be better suited. For
3 14 228 [9] [10] [11]
separate analysis of H, C and Ra, standards such as ISO 9698, ISO 13162 and ISO 22908, respectively, may
be better suited.
v
oSIST prEN ISO 9697:2026
oSIST prEN ISO 9697:2026
DRAFT International Standard ISO/DIS 9697:2025(en)
Water quality — Gross beta activity — Test method using
thick source
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety issues, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document be
carried out by suitably trained staff.
1 Scope
This document specifies a test method for the determination of gross beta activity concentration in non-
saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately
3 228 210 14 35 241
0,3 MeV or higher. Measurement of low-energy beta emitters (e.g. H, Ra, Pb, C, S and Pu) and
some gaseous or volatile radionuclides (e.g. radon and radioiodine) are not be included in the gross beta
quantification using the test method described in this document.
This test method is applicable to the analysis of raw and drinking waters with low amounts of total soluble
salts in the water. Limit of detection depends on the performance characteristics (background count rate
and counting efficiency) of the counter used.
It is the laboratory’s responsibility to ensure the suitability of this method for the water samples tested.
As this method requires sample preparation in laboratory facilities, it is not suited for rapid, in-the-field
analysis.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and sampling
techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of
environmental water sampling and handling
ISO 11929 (all parts), Determination of the characteristic limits (decision threshold, detection limit and limits of
the confidence interval) for measurements of ionizing radiation — Fundamentals and application
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 80000-10 and ISO 11929 series apply.

oSIST prEN ISO 9697:2026
ISO/DIS 9697:2025(en)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols
A beta activity in calibration source, at the time of calibration Bq
c beta activity concentration, without and with corrections Bq·l−1
A
*
Bq·l−1
decision threshold, without and with corrections
c
A
#
Bq·l−1
detection limit, without and with corrections
c
A

c possible or assumed true quantity values of the measurand Bq·l−1
A

Bq·l−1
lower limit of the probabilistically symmetric coverage interval
c
A

Bq·l−1
upper limit of the probabilistically symmetric coverage interval
c
A
<
Bq·l−1
lower limit of the shortest coverage interval
c
A
>
Bq·l−1
upper limit of the shortest coverage interval
c
A
Quantiles of the standardised normal distribution for the probabilities p (for instance p =
k
1−α , 1 - β or 1- γ /2)
p
Quantiles of the standardised normal distribution for the probabilities q (for instance q =
k
q
1−α , 1 - β or 1- γ /2)
m mass of baked residue from volume, V mg
m mass of the sample residue deposited on the planchet mg
r
r background count rate, from the alpha window s-1
0α
r background count rate, from the beta window s-1
0β
r sample gross count rate from the alpha window s-1
gα
r sample gross count rate from the beta window s-1
gβ
r calibration count rate of the alpha source from the alpha window s-1
sα
r calibration count rate of the beta source from the beta window s-1
sβ
r calibration count rate in the beta window when the alpha calibration source is measured s-1
sα→β
S surface area of the planchet mm2
t background counting time s
t sample counting time s
g
t calibration count time of the alpha and beta sources s
s
u(c ) standard uncertainty associated with the measurement result Bq·l−1
A
oSIST prEN ISO 9697:2026
ISO/DIS 9697:2025(en)

standard uncertainty of the estimator c as a function of an assumed true value c of the
A A
 
uc
()
A
measurand
urel (y) relative uncertainty of y
U expanded uncertainty calculated from U = ku(c ), with k = 1, 2 … Bq·l−1
A
V volume of test sample equivalent to the mass of solid on the planchet l
Vt volume of the water sample l
ε counting efficiency for the specified radioactive standard
ρ source thickness, of the sample residue deposited on the planchet mg·mm-2
s
alpha-beta cross-talk, percentage of alpha count going into the beta window from the
χ
alpha calibration source
5 Principle
Gross beta analysis is a screening method intended to ensure that the activity concentration of some beta
emitters does not exceed specified reference levels. This type of determination is also known as gross beta
index. Gross beta analysis is not expected to be as accurate nor as precise as specific radionuclide analysis
after radiochemical separations. Also, it is not an absolute determination of the activity concentration of all
beta-emitting radionuclides in a test sample.
The sample, taken, handled and preserved as specified in ISO 5667-1, ISO 5667-3 and ISO 5667-14, is evaporated
to almost dryness, converted to the sulfate form, and baked at 350 °C. A portion of the residue is transferred
onto a planchet and the beta activity is measured using a beta counter (e.g. a gas flow proportional counter),
which is calibrated against a suitable beta calibration source, such as potassium-40 ( K) or strontium-90/
90 90
yttrium-90 ( Sr + Y) in equilibrium.
If simultaneous gross alpha and beta measurements are required on the same water sample, the procedure
[12]
specified in this document is very similar to that of ISO 9696. However, the counting source thickness
2[13][14]
shall be less than 0,1 mg·mm- .
A performance criteria example is given in Annex A.
6 Chemical reagents and equipment
6.1 Chemical reagents
All reagents shall be of recognised analytical grade and shall not contain any detectable beta activity.
NOTE A method for preparing reagent blanks to check for the absence of any inherent beta radioactivity or
contamination is given in Clause 7.
6.1.1 Ultrapure water, with a resistivity of more than 18,2 MΩ cm at 25 °C and total organic carbon less
−1
than 1 μg∙l .
Unless otherwise stated, water refers to ultrapure water.
6.1.2 Calibration source, the choice of the beta calibration source depends on the knowledge of the type
90 40
of radioactive contaminant likely to be present in the waters being tested; Sr and K are commonly used.
40 −1 −1 [4]
NOTE The beta activit
...