SIST EN ISO 19361:2020

SLOVENSKI STANDARD
oSIST prEN ISO 19361:2019
01-december-2019
Merjenje radioaktivnosti - Ugotavljanje aktivnosti oddajnikov beta - Preskusna
metoda s tekočinskim scintilacijskim štetjem (ISO 19361:2017)
Measurement of radioactivity - Determination of beta emitters activities - Test method
using liquid scintillation counting (ISO 19361:2017)
Nachweis der Radioaktivität - Bestimmung der Aktivität von Betastrahlern - Verfahren mit
Flüssigszintillationszählung (ISO 19361:2017)
Mesurage de la radioactivité - Détermination de l'activité des radionucléides émetteurs
bêta - Méthode d'essai par comptage des scintillations en milieu liquide (ISO
19361:2017)
Ta slovenski standard je istoveten z: prEN ISO 19361
ICS:
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 19361:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 19361:2019
INTERNATIONAL ISO
STANDARD 19361
First edition
2017-08
Measurement of radioactivity —
Determination of beta emitters
activities — Test method using liquid
scintillation counting
Mesurage de la radioactivité — Détermination de l’activité des
radionucléides émetteurs bêta — Méthode d’essai par comptage des
scintillations en milieu liquide
Reference number
ISO 19361:2017(E)
©
ISO 2017

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oSIST prEN ISO 19361:2019
ISO 19361:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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the requester.
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Tel. +41 22 749 01 11
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copyright@iso.org
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normatives references . 1
3 Terms and definitions . 1
4 Symbols, abbreviations and units . 2
5 Principle . 2
6 Reagents and equipment . 3
6.1 Reagents. 3
6.1.1 Blank material . 3
6.1.2 Calibration source solutions . 3
6.1.3 Scintillation solution. 4
6.1.4 Quenching agent. 4
6.2 Equipment . 4
6.2.1 General. 4
6.2.2 Liquid scintillation counter . 4
6.2.3 Counting vials . 5
7 Sampling and samples . 5
7.1 Sampling . 5
7.2 Sample storage . 5
8 Procedure. 5
8.1 Determination of background . 5
8.2 Determination of detection efficiency . 6
8.3 Quench correction . 6
8.4 Sample preparation . 7
8.5 Preparation of the scintillation sources to be measured . 7
8.6 Counting procedure . 7
8.6.1 Control and calibration. 7
8.6.2 Measurement conditions . 7
8.6.3 Interference control . 8
9 Expression of results . 9
9.1 General . 9
9.2 Calculation of activity concentration, without preparation . 9
9.3 Decision threshold, without preparation .10
9.4 Detection limit, without preparation .10
9.5 Confidence interval limits, without preparation .10
9.6 Calculations using the activity per unit of mass, without preparation .11
10 Test report .11
Annex A (informative) Internal standard method .12
Annex B (informative) TDCR Liquid Scintillation Counting .14
Annex C (informative) Cerenkov measurement with LSC and TDCR counter .17
Bibliography .19
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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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection.
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Introduction
Everyone is exposed to natural radiation. The natural sources of radiation are cosmic rays and
naturally occurring radioactive substances which exist in the earth and within the human body. Human
activities involving the use of radiation and radioactive substances add to the radiation exposure
from this natural exposure. Some of those activities, such as the mining and use of ores containing
naturally-occurring radioactive materials (NORM) and the production of energy by burning coal that
contains such substances, simply enhance the exposure from natural radiation sources. Nuclear power
plants and other nuclear installations use radioactive materials and produce radioactive effluent and
waste during operation and on their decommissioning. The use of radioactive materials in industry,
agriculture and research is expanding around the globe.
All these human activities give rise to radiation exposures that are only a small fraction of the global
average level of natural exposure. The medical use of radiation is the largest and a growing man-made
source of radiation exposure in developed countries. It includes diagnostic radiology, radiotherapy,
nuclear medicine and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in
industry, medicine and research using radiation or radioactive substances, as well as by passengers
and crew during air travel and for astronauts. The average level of occupational exposures is generally
[13]
below the global average level of natural radiation exposure .
As uses of radiation increase, so do the potential health risk and the public’s concerns. Thus, all these
exposures are regularly assessed in order to: (1) improve the understanding of global levels and
temporal trends of public and worker exposure; (2) to evaluate the components of exposure so as to
provide a measure of their relative importance, and; (3) to identify emerging issues that may warrant
more attention and study. While doses to workers are mostly directly measured, doses to the public are
usually assessed by indirect methods using radioactivity measurements performed on various sources:
waste, effluent and/or environmental samples.
To ensure that the data obtained from radioactivity monitoring programs support their intended use, it
is essential that the stakeholders (for example, nuclear site operators, regulatory and local authorities)
agree on appropriate methods and procedures for obtaining representative samples and then handling,
storing, preparing and measuring the test samples. An assessment of the overall measurement
uncertainty need also to be carried out systematically. As reliable, comparable and ‘fit for purpose’
data are an essential requirement for any public health decision based on radioactivity measurements,
international standards of tested and validated radionuclide test methods are an important tool for
the production of such measurement results. The application of standards serves also to guarantee
comparability over time of the test results and between different testing laboratories. Laboratories
apply them to demonstrate their technical qualifications and to successfully complete proficiency
tests during interlaboratory comparison, two prerequisites for obtaining national accreditation.
Today, over a hundred international standards, prepared by Technical Committees of the International
Standardization Organization, including those produced by ISO/TC 85, and the International
Electrotechnical Commission (IEC), are available for application by testing laboratories to measure the
main radionuclides.
Generic standards help testing laboratories to manage the measurement process by setting out the
general requirements and methods to calibrate and validate techniques. These standards underpin
specific standards which describe the test methods to be performed by staff, for example, for different
types of sample. The specific standards cover test methods for:
40 3 14
— Naturally-occurring radionuclides (including K, H, C and those originating from the thorium
226 228 234 238 210
and uranium decay series, in particular Ra, Ra, U, U, Pb) which can be found in
materials from natural sources or can be released from technological processes involving naturally
occurring radioactive materials (e.g. the mining and processing of mineral sands or phosphate
fertilizer production and use);
— Human-made radionuclides, such as transuranium elements (americium, plutonium, neptunium,
3 14 90
and curium), H, C, Sr and gamma emitting radionuclides found in waste, liquid and gaseous
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effluent, in environmental matrices (water, air, soil, biota) and food and feed as a result of authorized
releases into the environment and of fallout resulting from the explosion in the atmosphere of
nuclear devices and accidents, such as those that occurred in Chernobyl and Fukushima.
Many of these radionuclides are beta emitters that can be measured by liquid scintillation counting,
following appropriate sample preparation.
A generic international standard on liquid scintillation counting is justified for test laboratories carrying
out beta emitter measurements in fulfilment of national authority requirements. For example, testing
laboratories need to obtain a specific accreditation for radionuclide measurement for the monitoring of
drinking water, food, the environment or the discharges, as well as for biological samples for medical
purpose.
This document describes (after appropriate sampling, sample handling and test sample preparation)
the generic requirements to quantify the activity concentration of beta emitters using liquid
scintillation counting. In the absence of a specific pre-treatment of the test sample (such as distillation
3 14
for H measurement, or after benzene synthesis for C measurement), this document is to be used
as a screening method unless the interference of beta emitters, others than those to be quantified, is
considered negligible in the test portion.
This document is one of a set of generic International Standards on measurement of radioactivity.
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oSIST prEN ISO 19361:2019
INTERNATIONAL STANDARD ISO 19361:2017(E)
Measurement of radioactivity — Determination of beta
emitters activities — Test method using liquid scintillation
counting
1 Scope
This document applies to liquid scintillation counters and requires the preparation of a scintillation
source obtained by mixing the test sample and a scintillation cocktail. The test sample can be liquid
(aqueous or organic), or solid (particles or filter or planchet).
This document describes the conditions for measuring the activity of beta emitter radionuclides by
[14][15]
liquid scintillation counting .
The choice of the test method using liquid scintillation counting involves the consideration of the potential
presence of other beta emitter radionuclides in the test sample. In this case, a specific sample treatment
by separation or extraction is implemented to isolate the radionuclide of interest in order to avoid any
interference with other beta-, alpha- and gamma-emitting radionuclides during the counting phase.
This document is applicable to all types of liquid samples having an activity concentration ranging from
−1 6 −1
a few Bq·l to 10 Bq·l . For a liquid test sample, it is possible to dilute liquid test samples in order to
obtain a solution having an activity compatible with the measuring instrument. For solid samples, the
activity of the prepared scintillation source shall be compatible with the measuring instrument.
The measurement range is related to the test method used: nature of test portion, preparation of the
scintillator - test portion mixture, measuring assembly as well as to the presence of the co-existing
activities due to interfering radionuclides.
3 14
Test portion preparations (such as distillation for H measurement, or benzene synthesis for C
measurement, etc.) are outside the scope of this document and are described in specific test methods
[2][3][4][5][6][7][8][9]
using liquid scintillation .
2 Normatives 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 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/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 18589-2, Measurement of radioactivity in the environment — Soil — Part 2: Guidance for the selection
of the sampling strategy, sampling and pre-treatment of samples
3 Terms and definitions
No terms and definitions are listed in this document.
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ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
4 Symbols, abbreviations and units
[10]
For the purposes of this document, the symbols and abbreviations defined in ISO 80000-10 ,
[11] [12]
ISO/IEC Guide 98-3 , ISO/IEC Guide 99 and the following apply.
β Maximum energy for the beta emission, in keV
max
V Volume of test portion, in litre
m Mass of test portion, in kilogram
ρ Density of the sample, in kilogram per litre
ε Preparation efficiency
p
a Activity per unit of mass, in becquerel per kilogram
c Activity concentration, in becquerel per litre
A
A Activity of the calibration source, in becquerel
t Background counting time, in second
0
t Portion counting time, in second
g
t Calibration counting time, in second
s
r Background count rate, per second
0
r Portion count rate, per second
g
r Calibration count rate, per second
s
ε Detection efficiency
ε Quenched efficiency
q
f Quench factor
q
uc Standard uncertainty associated with the measurement result; in becquerel per litre
()
A
U
Expanded uncertainty, calculated by U = k ⋅ uc with k = 1, 2,…, in becquerel per litre
()
A
*
Decision threshold, in becquerel per litre
c
A
#
Detection limit, in becquerel per litre
c
A
< >
Lower and upper limits of the confidence interval, in becquerel per litre
c , c
A A
5 Principle
The aqueous, organic or particles portion is mixed with the scintillation cocktail in a counting vial
to obtain a homogeneous medium (scintillation source). Electrons emitted from beta disintegration
transfer their energy to the scintillation cocktail molecules that are excited by this process before
returning to their ground state by emitting photons that are detected by photoelectron multiplier tubes
(phototubes).
The electronic pulses emitted by the phototubes are amplified. The peak pulse amplitude is
converted to a digital value by an analogue-to-digital convertor (ADC) and the pulse height stored
using a multichannel analyser (MCA). The pulses are analysed (in order to remove random events)
by the electronic systems and the data analysis software. The count rate of these photons allows the
determination of the activity in the test portion, after correcting for the background count rate and
detection efficiency, taking account of the quench correction. The requirements of the specific test
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method for specific beta emitting radionuclides, including test portion preparation and scintillation
source preparation, shall be determined according to the intended use of the measurement results and
the associated data quality objectives.
In order to determine the background count rate, a blank portion shall be prepared in the same way as
the test portion.
The conditions to be met for the blank sample, the test portion and the calibration source are:
— same scintillation cocktail;
— same type of counting vial;
— same filling geometry;
— same ratio between test portion and scintillation cocktail;
— same preparation conditions, minimizing photoluminescence and static electricity effects;
In addition, the quench indicating parameter should be within the range of the quench calibration
[16][17]
curve. An alternative method using the Cerenkov effect is treated in Annex C.
6 Reagents and equipment
Use only reagents of recognized analytical grade.
6.1 Reagents
6.1.1 Blank material
Blank material is used to prepare the blank portion. For direct counting of test portion, it shall be as
free as possible of chemical impurities to avoid quenching, and with radioactive impurities negligible in
comparison with the test portion activities to be measured.
If some preparation is required for the test portion, the blank portion shall be prepared with a reference
material of the lowest activity available.
This blank sample shall be kept physically remote from any radioactive material to avoid cross-
contamination.
For example, a water sample with a low tritium and carbon 14 activity concentration can be obtained
from (deep) subterranean water kept in a well-sealed borosilicate glass bottle in the dark at a controlled
temperature (see ISO 5667-3). When the volume of blank water is sufficiently large (e.g. 10 l to 20 l)
and well-sealed, tritium and carbon 14 activity concentrations remain stable for years, although it is
advisable to determine these activity concentrations at predetermined intervals (e.g. every year).
6.1.2 Calibration source solutions
To avoid cross-contamination, preparation of samples and calibration source solution shall be
segregated.
The standardized solution used to prepare the calibration source solution shall be provided with a
calibration certificate confirming traceability to a national or international standard of radioactivity.
Weigh and pour into a weighed volumetric flask (for example 100 ml) the required quantity of a
standardized solution of the radionuclide to be measured, so that the activity concentration generates
sufficient counts to reach the required measurement uncertainty after dilution with the blank
solution and thorough mixing. Calculate the activity concentrations of the resulting calibration source
solution (A). Note the date at which the standard solution was made up (t = 0).
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The radionuclide activity concentration of the calibration source solution at time t at which the samples
are measured shall be corrected for radioactive decay.
6.1.3 Scintillation solution
The scintillation cocktail is chosen according to the characteristics of the sample to be analysed and
[18][19]
according to the properties of the detection equipment .
For the measurement of usual environmental and drinking water sample or for test sample prepared as
an aqueous solution, it is recommended to use a hydrophilic scintillation cocktail.
For the direct measurement of particles in suspension, it is recommended to use a scintillation cocktail
that leads to a gel type mixture.
In all cases, the characteristics of the scintillation cocktail when mixed with the sample shall result in a
scintillation source with the form of a homogeneous and stable medium.
It is recommended to:
— store all samples in the dark and, particularly just before use, avoiding exposure to direct sunlight
or fluorescent light in order to prevent interfering luminescence;
— comply with storage conditions specified by the scintillation cocktail supplier.
The mixtures (scintillation cocktail and test sample) should be disposed of as chemical waste, and,
depending on the radioactivity, may require disposal as radioactive waste.
6.1.4 Quenching agent
Water, as well as dissolved oxygen, is a quenching agent for the scintillation cocktail.
Examples of chemical quenching agents include acetone, organochloride compounds, nitromethane, etc.
Some quenching agents are dangerous or toxic and shall be handled and disposed properly.
6.2 Equipment
6.2.1 General
Laboratory equipment, such as pipettes and balances, shall be employed that enables the
expected/agreed data quality objectives to be achieved, including the uncertainty attached to the
measurement.
Control of the quantity of liquid scintillation cocktail used in source preparation is essential to achieve
consistent
...