EN ISO 10704:2019

SLOVENSKI STANDARD
01-maj-2019
1DGRPHãþD
SIST EN ISO 10704:2015
SIST ISO 10704:2013
Kakovost vode - Skupna alfa in skupna beta aktivnost - Preskusna metoda z
odlaganjem v tankem sloju (ISO 10704:2019)
Water quality - Gross alpha and gross beta activity - Test method using thin source
deposit (ISO 10704:2019)
Wasserbeschaffenheit - Bestimmung der Gesamt-Alpha- und der Gesamt-Beta-Aktivität
in nicht-salzhaltigem Wasser - Dünnschichtverfahren (ISO 10704:2019)
Qualité de l'eau - Activités alpha globale et bêta globale - Méthode d'essai par dépôt
d'une source fine (ISO 10704:2019)
Ta slovenski standard je istoveten z: EN ISO 10704:2019
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10704
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2019
EUROPÄISCHE NORM
ICS 13.060.60; 13.280 Supersedes EN ISO 10704:2015
English Version
Water quality - Gross alpha and gross beta activity - Test
method using thin source deposit (ISO 10704:2019)
Qualité de l'eau - Activités alpha globale et bêta globale Wasserbeschaffenheit - Bestimmung der Gesamt-
- Méthode d'essai par dépôt d'une source fine (ISO Alpha- und der Gesamt-Beta-Aktivität in nicht-
10704:2019) salzhaltigem Wasser - Dünnschichtverfahren (ISO
10704:2019)
This European Standard was approved by CEN on 16 February 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10704:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10704:2019) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2019, and conflicting national standards
shall be withdrawn at the latest by September 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 10704:2015.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 10704:2019 has been approved by CEN as EN ISO 10704:2019 without any modification.

INTERNATIONAL ISO
STANDARD 10704
Second edition
2019-02
Water quality — Gross alpha and gross
beta activity — Test method using thin
source deposit
Qualité de l'eau — Activités alpha globale et bêta globale — Méthode
d'essai par dépôt d'une source fine
Reference number
ISO 10704:2019(E)
©
ISO 2019
ISO 10704:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
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Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 10704:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
4 Principle . 3
5 Chemical reagents and equipment . 3
5.1 Reagents. 3
5.1.1 General. 3
5.1.2 Standard solutions . 3
5.1.3 Wetting or surfactant agents . 4
5.1.4 Volatile organic solvents . . 4
5.1.5 Water . 4
5.1.6 Specific reagents for alpha-emitting radionuclides co-precipitation . 4
5.2 Equipment . 4
5.2.1 Laboratory equipment for direct evaporation . 4
5.2.2 General equipment . . 4
5.2.3 Special equipment for alpha-emitting radionuclide co-precipitation . 5
5.2.4 Measurement equipment . 5
6 Sampling . 5
7 Procedure. 5
7.1 Preliminary . 5
7.2 Source preparation . 5
7.2.1 Preparation of planchet . 5
7.2.2 Evaporation . 6
7.2.3 Co-precipitation . 6
7.3 Counting stage . 7
7.4 Background and blank determination . 7
7.5 Preparation of counting standard for calibration . 7
7.6 Preparation of calibration source for self-absorption determination . 8
7.6.1 General. 8
7.6.2 Spiking one of two test portions . 8
7.6.3 Self-absorption curve . . 8
8 Expression of results . 9
8.1 General . 9
8.2 Alpha activity concentration . 9
8.3 Beta activity concentration . 9
8.4 Standard uncertainty of the alpha activity concentration .10
8.5 Standard uncertainty of the beta activity concentration .10
8.6 Decision threshold .12
8.6.1 Decision threshold of the alpha activity concentration.12
8.6.2 Decision threshold of the beta activity concentration .12
8.7 Detection limit .12
8.7.1 Detection limit of the alpha activity concentration .12
8.7.2 Detection limit of the beta activity concentration .13
8.8 Confidence limits.13
9 Control of interferences .13
9.1 General .13
9.2 Relative humidity .14
9.3 Geometry of the deposit .14
9.4 Crosstalk .14
ISO 10704:2019(E)
9.5 Gamma emitters .15
9.6 Low beta energy.15
9.7 Chlorides .15
9.8 Organic matter .15
9.9 Contamination .15
9.10 Losses of activity .15
9.11 Contribution of the natural radionuclides .15
9.12 Losses of activity .16
10 Test report .16
Annex A (informative) Numerical applications .18
Bibliography .19
iv © ISO 2019 – All rights reserved

ISO 10704:2019(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.
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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radioactivity measurements.
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.
This second edition cancels and replaces the first edition (ISO 10704:2009), which has been technically
revised. The main changes compared to the previous edition are as follows:
— Introduction: an introduction has been added;
— Clause 1: the scope has been modified to specify applicability to emergency situations and
applicability of waste water as a test sample; information about the exclusion of low energy beta
emitters has also been added;
— Clause 4: the filtration has been specified to be carried out at 0,45 µ;
— 5.1.2.2: Cs has been introduced as a standard that can be used;
— 5.2.4: the recommended thickness has been increased to up to 400 µg/cm ;
— 7.6.3.1: in order to evaluate self-absorption phenomena, spiking method has been recommended to
mimic the nature of the salt;
— Clause 8:
— a new Formula (9) has been introduced to obtain the beta activity concentration when systematic
correction is not required;
— the subsequent Formulae have been renumbered;
— Clause 9: several limitations and interferences have been given;
— 9.1: the natural radionuclides contributions have been given.
ISO 10704:2019(E)
Introduction
Radioactivity from several naturally-occurring and anthropogenic sources is present throughout
the environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain
radionuclides of natural, human-made, or both origins:
40 3 14
— natural radionuclides, including K, H, C, and those originating from the thorium and uranium
226 228 234 238 210 210
decay series, in particular Ra, Ra, U, U, Po and Pb can be found in water for
natural reasons (e.g. desorption from the soil and washoff by rain water) or can be released from
technological processes involving naturally occurring radioactive materials (e.g. the mining and
processing of mineral sands or phosphate fertilizers production and use);
— human-made radionuclides such as transuranium elements (americium, plutonium, neptunium,
3 14 90
curium), H, C, Sr, and gamma emitting radionuclides can also be found in natural waters.
Small quantities of these radionuclides are discharged from nuclear fuel cycle facilities into the
environment as a result of authorized routine releases. Some of these radionuclides used for
medical and industrial applications are also released into the environment after use. Anthropogenic
radionuclides are also found in waters as a result of past fallout contaminations resulting from
the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in
Chernobyl and Fukushima.
Radionuclide activity concentration in water bodies can vary according to local geological
characteristics and climatic conditions and can be locally and temporally enhanced by releases from
[1]
nuclear installation during planned, existing, and emergency exposure situations . Drinking-water
can thus contain radionuclides at activity concentrations which could present a risk to human health.
The radionuclides present in liquid effluents are usually controlled before being discharged into
[2]
the environment and water bodies. Drinking waters are monitored for their radioactivity as
[3]
recommended by the World Health Organization (WHO) so that proper actions can be taken to ensure
that there is no adverse health effect to the public. Following these international recommendations,
national regulations usually specify radionuclide authorized concentration limits for liquid effluent
discharged to the environment and radionuclide guidance levels for waterbodies and drinking waters
for planned, existing, and emergency exposure situations. Compliance with these limits can be assessed
using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3 and
[4]
ISO 5667-20 .
Depending on the exposure situation, there are different limits and guidance levels that would result
in an action to reduce health risk. As an example, during a planned or existing situation, the WHO
guidelines for guidance level in drinking water is 0,5 Bq/l for gross alpha activity and 1 Bq/l for gross
beta activity.
NOTE The guidance level is the activity concentration with an intake of 2 l/d of drinking water for one year
that results in an effective dose of 0,1 mSv/a for members of the public. This is an effective dose that represents a
[3]
very low level of risk and which is not expected to give rise to any detectable adverse health effects .
Thus, the test method can be adapted so that the characteristic limits, decision threshold, detection
limit and uncertainties ensure that the radionuclide activity concentrations test results can be verified
to be below the guidance levels required by a national authority for either planned/existing situations
[5][6][7]
or for an emergency situation .
Usually, the test methods can be adjusted to measure the activity concentration of the radionuclide(s)
in either wastewaters before storage or in liquid effluents before being discharged to the environment.
The test results will enable the plant/installation operator to verify that, before their discharge,
wastewaters/liquid effluent radioactive activity concentrations do not exceed authorized limits.
The test method(s) described in this document can be used during planned, existing and emergency
exposure situations as well as for wastewaters and liquid effluents with specific modifications that
could increase the overall uncertainty, detection limit, and threshold.
vi © ISO 2019 – All rights reserved

ISO 10704:2019(E)
The test method(s) can be used for water samples after proper sampling, sample handling, and test
sample preparation (see the relevant part of the ISO 5667 series).
An International Standard on a test method of gross alpha and gross beta activity concentrations in
water samples is justified for test laboratories carrying out these measurements, required sometimes
by national authorities, as laboratories might have to obtain a specific accreditation for radionuclide
measurement in drinking water samples.
This document is one of a set of International Standards on test methods dealing with the measurement
of the activity concentration of radionuclides in water samples.
INTERNATIONAL STANDARD ISO 10704:2019(E)
Water quality — Gross alpha and gross beta activity — Test
method using thin source deposit
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document 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.
IMPORTANT — It is absolutely essential that tests conducted according to this document be
carried out by suitably trained staff.
1 Scope
This document specifies a method for the determination of gross alpha and gross beta activity
concentration for alpha- and beta-emitting radionuclides. Gross alpha and gross beta activity
measurement is not intended to give an absolute determination of the activity concentration of all
alpha and beta emitting radionuclides in a test sample, but is a screening analysis to ensure particular
reference levels of specific alpha and beta emitters have not been exceeded. This type of determination
is also known as gross alpha and gross beta index. Gross alpha and gross beta analysis is not expected
to be as accurate nor as precise as specific radionuclide analysis after radiochemical separations.
Maximum beta energies of approximately 0,1 MeV or higher are well measured. It is possible that low
3 55 241 14
energy beta emitters can not detected (e.g. H, Fe, Pu) or can only be partially detected (e.g. C,
35 63 210 228
S, Ni, Pb, Ra).
The method covers non-volatile radionuclides, since some gaseous or volatile radionuclides (e.g. radon
and radioiodine) can be lost during the source preparation.
The method is applicable to test samples of drinking water, rainwater, surface and ground water as well
as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample
handling, and test sample preparation (filtration when necessary and taking into account the amount of
dissolved material in the water).
The method described in this document is applicable in the event of an emergency situation, because
the results can be obtained in less than 1 h. Detection limits reached for gross alpha and gross beta are
less than 10 Bq/l and 20 Bq/l respectively. The evaporation of 10 ml sample is carried out in 20 min
followed by 10 min counting with window-proportional counters.
It is the laboratory’s responsibility to ensure the suitability of this test method for the water
samples tested.
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 3696, Water for analytical laboratory use — Specification and test methods
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 11929, Determination of the characteristic limits (decision threshold, detection limit and limits of the
confidence interval) for measurements of ionizing radiation — Fundamentals and application
ISO 10704:2019(E)
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, definitions and symbols given in ISO 80000-10 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
A activity of the calibration source Bq
A activity spiked in sample a, prepared for self-absorption estimation purposes Bq
a
−1
c activity concentration Bq l
A
*
−1
c decision threshold Bq l
A
#
−1
c
detection limit Bq l
A

−1
c,c lower and upper limits of the confidence interval Bq l
AA
f , f self-absorption factor of sample a for α and β, respectively —
aα aβ
m mass of the deposit mg
d
m mass of the planchet mg
p
m mass of the planchet and the deposit mg
pd
m mass of the planchet and the filter mg
pf
m mass of the planchet, the filter and the deposit mg
pfd
−1
r , r background count rate from the α and β windows, respectively s
0α 0β
−1
r , r self-absorption sample a count rate from the α and β windows, respectively s
aα aβ
−1
r , r sample gross count rate from the α and β windows, respectively s
gα gβ
−1
r , r calibration count rate from the α and β windows, respectively s
sα sβ
t background counting time s
t sample counting time s
g
t calibration counting time s
s
−1
U expanded uncertainty calculated by U = k ⋅ u(c ) with k = 1, 2,… Bq l
A
2 © ISO 2019 – All rights reserved

ISO 10704:2019(E)
−1
u(c ) standard uncertainty associated with the measurement result Bq l
A
V volume of test sample l
ε , ε counting efficiency for α and β, respectively —
α β
ε , ε counting efficiency of sample a for α and β, respectively —
aα aβ
χ alpha-beta crosstalk —
4 Principle
The gross alpha and gross beta activity of the deposit is measured by counting in an alpha- and
beta-particle detector or counting system previously calibrated against alpha- and beta-emitting
standards. In order to obtain a thin and homogeneous deposit directly on a planchet, the sample can
be progressively evaporated to dryness at a temperature below about 85 °C. Alternatively, for the
gross alpha determination, radionuclides can be concentrated via a co-precipitation, the filtered co-
[8]
precipitate deposited on the planchet being measured .
When suspended matter is present, filtration through 0,45 µm filter media is required and the gross
alpha and gross beta activity can also be determined for the material retained on the filter.
IMPORTANT — Gross alpha and gross beta determinations are not absolute determinations
of the sample alpha and beta radioactive contents, but relative determinations referenced to
specific alpha and beta emitters that constitute the standard calibration sources.
5 Chemical reagents and equipment
5.1 Reagents
5.1.1 General
All reagents shall be of recognized analytical grade and shall not contain any detectable alpha and beta
activity, except for radioactive standards solutions.
5.1.2 Standard solutions
5.1.2.1 Alpha standard.
The choice of alpha standard depends on the knowledge of the type of radioactive contaminant likely to
be present in the waters being tested. In general, this leads to a choice between naturally occurring and
man-made alpha emitters.
Commonly used standards of artificial alpha-emitting radionuclides employed for this purpose are
241 239 239 241
Am solutions and Pu solutions. When Pu is used, the presence of Pu as an impurity shall
be taken into account as it leads to growth of Am in prepared standard solutions of sources. When
Am is used, take into account the interferences of its x and γ emission.
NOTE A uranium compound of certified natural or known isotopic composition has one arguable advantage,
in that its specific activity can be calculated from established physical constants and isotopic abundance date
which are independent of the calibration procedures of a particular organization. However, a uranium compound
of known isotopic composition is difficult to obtain. Furthermore, since the energies of the alpha emissions from
uranium isotopes are less than those from the artificial transuranic nuclides, the use of a uranium standard
tends to give a high result for transuranic elements.
ISO 10704:2019(E)
5.1.2.2 Beta standard.
The choice of beta standard depends on knowledge of the type of radioactive contaminant likely to be
present in the waters being tested.
As a natural material, K as potassium chloride, dried to constant mass at 105 °C, can be used. Standard
90 137
solutions of artificial beta-emitting radionuclides Sr/Y in equilibrium or Cs are commonly used.
5.1.3 Wetting or surfactant agents
5.1.3.1 Vinyl acetate.
5.1.4 Volatile organic solvents
5.1.4.1 Ethyl alcohol.
5.1.5 Water
5.1.5.1 Water, complying with the requirements of ISO 3696, grade 3.
5.1.6 Specific reagents for alpha-emitting radionuclides co-precipitation
5.1.6.1 Ammonium hydroxide solution, c(NH OH) = 6 mol/l.
5.1.6.2 Nitric acid, concentrated, c(HNO ) = 15,8 mol/l.
5.1.6.3 Sulfuric acid solution, c(H SO ) = 1 mol/l.
2 4
5.1.6.4 Iron carrier, solution of 5 mg of iron per millilitre.
5.1.6.5 Barium carrier, solution of 5 mg of barium per millilitre.
5.2 Equipment
5.2.1 Laboratory equipment for direct evaporation
Usual laboratory apparatus to store and prepare the sample as specified in ISO 5667-3.
A hot plate, an automatic evaporator or any other appropriate apparatus.
5.2.2 General equipment
5.2.2.1 Filters, of pore size 0,45 µm.
5.2.2.2 Planchet (counting trays).
The planchet shall be lipped and of stainless steel. The diameter of the planchet is determined taking
account of the detector diameter and source holder dimensions of the counter used. In the specific case
of co-precipitation, an annular support is used to fix the filter on to a filter holder or on to the planchet.
As the source, test portion and standard, is spread directly on to the planchet for evaporation, it is
easier to produce an even deposit on a roughened metal surface; sand blasting or chemical etching can
be applied for this purpose, alternatively, a rippled planchet can be used.
4 © ISO 2019 – All rights reserved

ISO 10704:2019(E)
5.2.3 Special equipment for alpha-emitting radionuclide co-precipitation
5.2.3.1 Hot plate with stirring equipment.
5.2.3.2 Infrared lamp.
5.2.3.3 Vacuum filtration system.
5.2.3.4 Filters, of pore size 0,45 µm.
5.2.4 Measurement equipment
5.2.4.1 Alpha-beta counter.
Gross alpha and gross beta activity can be measured using either a silicon surface barrier (SSB) detector
or a proportional counter (windowless). Ion-implanted Si detectors and window-proportional counters
−2 −2
(between 80 µg cm to 400 µg cm ) may also be used. Gross alpha and gross beta activity can also
be counted using a silver-activated zinc sulfide scintillation screen and plastic scintillation detector,
respectively.
6 Sampling
Sample, handle and store water samples in accordance with ISO 5667-1 and ISO 5667-3. Additional
information on sampling of different types of waters can be found in the relative parts of the
[9][10][11][12][13][14][15][16]
ISO 5667 series .
The laboratory sample is not usually acidified as the test portion is directly evaporated on the planchet.
Acidification minimizes the loss of radioactive material from solution by adsorption on the wall of the
vial, but is done after filtration, as otherwise it desorbs radioactive material already adsorbed on the
particulate material and, also, increases the salt content of the test sample, and thus the thickness of the
deposit. If necessary, concentrated nitric acid can be used (it is recommended to avoid hydrochloric acid).
7 Procedure
7.1 Preliminary
Calculate the volume of laboratory sample for gross alpha measurement, i.e. the volume of the test
−2
portion, in order to produce a deposit with a surface density lower than 5 mg cm on the planchet. For
−2
deposits of surface density below 5 mg cm , self-absorption phenomena can be neglected for gross
137 [17]
beta measurement except when using low energy beta emitter such as Cs for calibration .
When using the same deposit for the simultaneous gross alpha and gross beta measurement, the
planchet surface density limit for alpha activity determinations applies.
7.2 Source preparation
IMPORTANT — Due to the ingrowth of radon decay products over time, the results are dependent
on the time elapsed between sample preparation and measurement. For comparison purposes,
it is recommended that the measurement be performed at the same time after the preparation
of the sample.
7.2.1 Preparation of planchet
Degrease planchets (5.2.2.2) using a solvent or a surfactant to ensure that the test portion is well
distributed over the entire surface and consequently that there is a deposit of uniform surface density
ISO 10704:2019(E)
bonded to the planchets. Some suppliers degrease planchets at the end of a cycle of fabrication and
deliver, on demand, a certificate of attestation.
Keep planchets that are not to be used immediately in a dessicator to prevent any modification by
ambient atmosphere in the laboratory.
Weigh the planchets before use, and record the mass, m . If a co-precipitation method is used, weigh the
p
filter (5.2.2.1) with the planchet before use, and record the mass, m .
pf
Avoid reuse of planchets to minimize cross-contamination. If the planchets are reused, their freedom
from contamination shall be demonstrated.
7.2.2 Evaporation
Transfer the test portion on to the planchet using automatic or non-automatic equipment with a known
uncertainty (pipette, water distribution system) and carefully evaporate to dryness.
The residue deposited should form a thin layer of uniform surface density to limit self-absorption
phenomena and to ensure similarity with the calibration source geometry.
After cooling the planchets to ambient temperature, weigh them and record the mass, m . The mass
pd
deposited, m , is given by Formula (1):
d
mm=− m (1)
dpdp
If hygroscopic salt deposit is expected the planchet can also be weight at the end of the measurement.
To minimize any loss by spitting, maintain the temperature below about 85 °C over the entire planchet
surface to avoid any overheated areas.
Before evaporating the test portion to dryness on the planchet, pre-evaporation can be performed with
appropriate equipment (5.2.1).
A homogeneous deposit is best achieved on etched or sandblasted planchets. If the deposit is not
homogeneously spread, add a wetting agent or surfactant (5.1.3).
7.2.3 Co-precipitation
The recommended working volume is 500 ml.
If a test portion of lower volume is to be analysed, make up to 500 ml with water.
If a test portion of higher volume is to be analysed, concentrate it by evaporation (5.2.1) to 500 ml.
Adjust the pH of the working volume to 7,0 ± 0,5.
Add 20 ml of sulfuric acid (5.1.6.3) and boil for 5 min on a hot plate while stirring.
At a temperature of approximately 50 °C, add 1 ml of the barium carrier solution (5.1.6.5) and stir
for 30 min.
The barium sulfate precipitates.
Then add 1 ml of the iron carrier solution (5.1.6.4).
Adjust the pH with ammonium hydroxide, (5.1.6.1) drop by drop until iron(III) hydroxide precipitates.
Continue stirring for 30 min.
Filter (5.2.3.4) the co-precipitates.
6 © ISO 2019 – All rights reserved

ISO 10704:2019(E)
Place the filter on to the identified planchet and fix it by an annular support to avoid deformation
while drying.
Dry at moderate temperature.
After cooling the planchet and the filter to ambient temperature, weigh them and record their mass,
m . Determine the mass deposited, m , using Formula (2):
pfd d
mm=− m (2)
dpfd pf
NOTE Radium, polonium and actinides co-precipitate quantitatively with barium sulfate or iron(III)
[7]
hydroxide .
7.3 Counting stage
Following evaporation (7.2.2) or co-precipitation (7.2.3), if the counting is not performed immediately
the planchet with the deposit can be stored in a desiccator.
The measurement of the residue activity on the planchet is performed by counting for an appropriate
duration to reach the required characteristic limits and depending on the test portion and background
count rates.
The counting strategy depends on the objectives of the measurements and the regulator requirements.
To monitor natural radionuclides ingrowth or decay (see 9.11), counting procedures should be repeated
periodically over a period of one month. If specific counting condition is applied, it is recommended to
mention it in the report.
When the counting strategy is defined, the laboratory shall apply it systematically for comparison
purposes.
7.4 Background and blank determination
Measure the background activity using a clean planchet (5.2.2.2) under conditions representative of
the measurement method. Repeated counts confirm the stability of the background level.
If reagents are used, measure the blank activity using a clean planchet and reagents under conditions
representative of the measurement method. Repeated counts confirm the stability of the blank level.
7.5 Preparation of counting standard for calibration
Prepare a geometry- and matrix-matched calibration source [planchet (5.2.2.2) or filter (5.2.3.4) with
precipitates and annular attachment to the planchet] to closely mimic the procedure applied to test
portions in order to obtain the same retro-diffusion effect.
Add an accurately known amount (about 5 Bq to 10 Bq) of a standard solution (5.1.2.1) to the starting
volume of water and use
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