Water quality - Technetium-99 - Part 1: Test method using liquid scintillation counting (ISO 22125-1:2019)

This standard specifies a method for the measurement of 99Tc in all types of waters by liquid
scintillation counting (LSC).
The detection limit depends on the sample volume and the instrument used. The method described in
this standard, using currently available LSC counters, has a detection limit of approximately 5 to 20
Bq•kg-1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq•L-1).
These values can be achieved with a counting time of 30 minutes for a sample volume varying
between 14 to 40 mL. The methods presented in this standard are not intended for the determination of
ultra-trace amount of 99Tc.

Wasserbeschaffenheit - Technetium-99 - Teil 1: Verfahren mit dem Flüssigszintillationszähler (ISO 22125-1:2019)

Dieses Dokument legt ein Verfahren zur Messung von 99Tc in allen Wasserarten durch Flüssigszintillations-zählung (en: liquid scintillation counting, LSC) fest.
Das Verfahren ist auf Untersuchungsproben von Versorgungs-/Trinkwasser, Regenwasser, Oberflächen- und Grundwasser sowie Kühlwasser, Prozesswasser, häusliches und gewerbliches Abwasser nach geeigneter Probenahme, Probenbehandlung und Vorbereitung der Untersuchungsprobe anwendbar. Es ist eine Filtration der Untersuchungsprobe notwendig.
Die Nachweisgrenze hängt vom Probenvolumen und dem verwendeten Gerät ab. Das in diesem Dokument beschriebene Verfahren hat, bei Verwendung der derzeit verfügbaren Flüssigszintillationszähler, eine Nach¬weisgrenze von etwa 5 Bq·kg−1 bis 20 Bq·kg−1; dies liegt unter den WHO  Kriterien für den sicheren Ver¬zehr von Trinkwasser (100 Bq·l−1) [3]. Diese Werte lassen sich bei einer Messdauer von 30 min bei einem Probenvolumen von 14 ml bis 40 ml erreichen. Das in diesem Dokumente beschriebene Verfahren ist nicht für die Bestimmung von 99Tc im Ultraspurenbereich vorgesehen.
In diesem Dokument werden die Aktivitätskonzentrationswerte bezogen auf die Masseneinheit statt auf die Volumeneinheit der Probe ausgedrückt, wie dies üblicherweise in vergleichbaren Normen der Fall ist. Der Grund dafür ist, dass 99Tc in verschiedenen Matrixtypen wie Süßwasser oder Meerwasser gemessen wird, die sich hinsichtlich ihrer Dichte signifikant unterscheiden. Durch Messen des Probenvolumens können die Aktivitätskonzentrationswerte auf einfache Weise auf die Volumeneinheit der Probe bezogen umgerechnet werden. Dies führt allerdings zur Erhöhung der Messunsicherheit des Aktivitätskonzentrationsergebnisses.
Das in diesem Dokument beschriebene Verfahren ist bei Notfallsituationen anwendbar; dies gilt allerdings nicht, wenn 99mTc in Mengen vorhanden ist, die eine Interferenz verursachen könnte, und auch nicht, wenn 99mTc als Ausbeutetracer verwendet wird.
Die Analyse von Tc, das an Schwebstoffen adsorbiert ist, wird nicht durch dieses Verfahren abgedeckt.
Es liegt in der Verantwortung des Anwenders, die Validität dieses Prüfverfahrens für die zu prüfenden Wasserproben sicherzustellen.

Qualité de l'eau - Technétium-99 - Partie 1: Méthode d’essai par comptage des scintillations en milieu liquide (ISO 22125-1:2019)

Le présent document spécifie une méthode de mesure du 99TC dans tous les types d'eaux par comptage des scintillations en milieu liquide (CSL).
La méthode est applicable aux échantillons pour essai d'eau de distribution/potable, d'eau pluviale, d'eau de surface et souterraine, ainsi que d'eau de refroidissement, d'eau industrielle, d'eau usée domestique et industrielle après échantillonnage, manipulation de l'échantillon et préparation de l'échantillon pour essai. Il est nécessaire de filtrer l'échantillon pour essai.
La limite de détection dépend du volume d'échantillon et de l'instrument utilisé. La méthode décrite dans le présent document, qui a recours aux instruments CSL actuellement disponibles, a une limite de détection d'environ 5 Bq·kg−1 à 20 Bq·kg−1, ce qui est inférieur aux critères de potabilité de l'eau de l'OMS (100 Bq l−1).[3] Ces valeurs peuvent être obtenues avec une durée de comptage de 30 min pour un volume d'échantillon variant entre 14 ml et 40 ml. La méthode présentée dans le présent document n'est pas applicable à la détermination de la quantité de 99Tc à l'état d'ultra-traces.
Les valeurs d'activité volumique indiquées dans le présent document sont exprimées en masse d'échantillon et non en unité de volume d'échantillon comme c'est habituellement le cas dans des normes similaires. La raison est que 99Tc est mesuré dans différents types de matrices tels que l'eau douce ou l'eau de mer, qui présentent des masses volumiques très différentes. Les valeurs d'activité volumique peuvent être facilement converties en unité de volume d'échantillon en mesurant le volume d'échantillon. Cependant, cela accroît l'incertitude applicable au résultat de l'activité volumique.
La méthode décrite dans le présent document est applicable en cas d'urgence, mais pas si 99mTc est présent à des quantités susceptibles de provoquer des interférences et pas si 99mTc est utilisé comme traceur de rendement.
L'analyse du Tc adsorbé dans la matière en suspension n'est pas couverte par la présente méthode.
Il incombe à l'utilisateur de s'assurer que la méthode d'essai relative aux échantillons d'eau soumis à essai est valide.

Kakovost vode - Tehnecij Tc-99 - 1. del: Preskusna metoda s štetjem s tekočinskim scintilatorjem (ISO 22125-1:2019)

Ta standard določa metodo za merjenje tehnecija 99Tc v vseh vrstah vode s štetjem s tekočinskim scintilatorjem (LSC). Meja zaznavanja je odvisna od količine vzorca in uporabljenega instrumenta. Metoda, opisana v tem standardu, s trenutno razpoložljivimi tekočinskimi scintilatorji ima mejo zaznavnosti približno 5–20 Bq•kg-1, ki je nižja od meril Svetovne zdravstvene organizacije za varno porabo pitne vode (100 Bq•l-1). Te vrednosti je mogoče doseči v času štetja 30 min za količino vzorca od 14 do 40 ml. Metode, predstavljene v tem standardu, niso namenjene določanju količine ultra-sledov tehnecija 99Tc.

General Information

Status
Published
Public Enquiry End Date
19-Oct-2018
Publication Date
12-Jan-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Dec-2019
Due Date
16-Feb-2020
Completion Date
13-Jan-2020

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SLOVENSKI STANDARD
SIST EN ISO 22125-1:2020
01-februar-2020
Kakovost vode - Tehnecij Tc-99 - 1. del: Preskusna metoda s štetjem s
tekočinskim scintilatorjem (ISO 22125-1:2019)

Water quality - Technetium-99 - Part 1: Test method using liquid scintillation counting

(ISO 22125-1:2019)
Wasserbeschaffenheit - Technetium-99 - Teil 1: Verfahren mit dem
Flüssigszintillationszähler (ISO 22125-1:2019)
Qualité de l'eau - Technétium-99 - Partie 1: Méthode d’essai par comptage des
scintillations en milieu liquide (ISO 22125-1:2019)
Ta slovenski standard je istoveten z: EN ISO 22125-1:2019
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
SIST EN ISO 22125-1:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 22125-1:2020
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SIST EN ISO 22125-1:2020
EN ISO 22125-1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2019
EUROPÄISCHE NORM
ICS 13.060.60; 17.240
English Version
Water quality - Technetium-99 - Part 1: Test method using
liquid scintillation counting (ISO 22125-1:2019)

Qualité de l'eau - Technétium-99 - Partie 1: Méthode Wasserbeschaffenheit - Technetium-99 - Teil 1:

d'essai par comptage des scintillations en milieu Verfahren mit dem Flüssigszintillationszähler (ISO

liquide (ISO 22125-1:2019) 22125-1:2019)
This European Standard was approved by CEN on 8 September 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, 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 22125-1:2019 E

worldwide for CEN national Members.
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SIST EN ISO 22125-1:2020
EN ISO 22125-1:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 22125-1:2020
EN ISO 22125-1:2019 (E)
European foreword

This document (EN ISO 22125-1:2019) 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 May 2020, and conflicting national standards shall be

withdrawn at the latest by May 2020.

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.

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, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 22125-1:2019 has been approved by CEN as EN ISO 22125-1:2019 without any

modification.
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SIST EN ISO 22125-1:2020
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SIST EN ISO 22125-1:2020
INTERNATIONAL ISO
STANDARD 22125-1
First edition
2019-11
Water quality — Technetium-99 —
Part 1:
Test method using liquid scintillation
counting
Qualité de l'eau — Technétium-99 —
Partie 1: Méthode d’essai par comptage des scintillations en milieu
liquide
Reference number
ISO 22125-1:2019(E)
ISO 2019
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© 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.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
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
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and symbols ............................................................................................................................................................ 2

4 Principle ........................................................................................................................................................................................................................ 3

5 Sampling and storage ...................................................................................................................................................................................... 4

6 Procedure..................................................................................................................................................................................................................... 4

6.1 Sample preparation for measurement ............................................................................................................................... 4

6.2 Sample measurement ........................................................................................................................................................................ 5

7 Quality assurance and quality control program .................................................................................................................. 5

7.1 General ........................................................................................................................................................................................................... 5

7.2 Variables that could influence the measurement ......... ............................................................................................. 5

7.3 Instrument verification.................................................................................................................................................................... 5

7.4 Contamination ......................................................................................................................................................................................... 5

7.5 Interference control ............................................................................................................................................................................ 5

7.6 Method verification ............................................................................................................................................................................. 5

7.7 Demonstration of analyst capability .................................................................................................................................... 6

7.8 Sample measurement ........................................................................................................................................................................ 6

8 Expression of results ........................................................................................................................................................................................ 6

8.1 Sample activity, recovery and uncertainties .................................................................................................................. 6

8.2 Decision threshold ............................................................................................................................................................................... 8

8.3 Detection limit ......................................................................................................................................................................................... 9

8.4 Confidence interval limits.............................................................................................................................................................. 9

8.5 Calculation using the activity per unit of volume ..................................................................................................... 9

8.6 Conversion of activity concentration to mass concentration ......................................................................10

8.7 Conversion of mass concentration to volume unit ...............................................................................................10

9 Test report ................................................................................................................................................................................................................10

Annex A (informative) Method 1 — TEVA resin .....................................................................................................................................12

Annex B (informative) Method 2 — TRU resin ........................................................................................................................................15

Annex C (informative) Method 3 — Anion exchange resin .........................................................................................................18

Bibliography .............................................................................................................................................................................................................................20

© ISO 2019 – All rights reserved iii
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(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 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.
A list of all the parts in the ISO 22125 series can be found on the ISO website.

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 © ISO 2019 – All rights reserved
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)
Introduction

Radioactivity from several naturally-occurring and anthropogenic sources is present throughout the

environment. Thus, water bodies (such as 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

may 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 the

[2]

environment and water bodies. Drinking waters are monitored for their radioactivity content 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 planned or existing situation, the WHO guidelines

−1 99
for guidance level in drinking water is 100 Bq·l for Tc activity concentration.

NOTE 1 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 .

[5]

In the event of a nuclear emergency, the WHO Codex Guideline Levels mentioned that the activity

−1 99

concentration on contaminated food might not be greater than 10 000 Bq·kg for Tc.

NOTE 2 The Codex guidelines levels (GLs) apply to radionuclides contained in foods destined for human

consumption and traded internationally, which have been contaminated following a nuclear or radiological

emergency. These GLs apply to food after reconstitution or as prepared for consumption, i.e. not to dried or

concentrated foods, and are based on an intervention exemption level of 1 mSv in a year for members of the

[5]
public (infant and adult) .

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.

© ISO 2019 – All rights reserved v
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)

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 may be used during planned, existing and emergency

exposure situations as well as for wastewaters and liquid effluents with specific modifications that can

increase the overall uncertainty, detection limit, and threshold.

The test method(s) may be used for water samples after proper sampling, sample handling, and test

sample preparation (see the relevant part of the ISO 5667 series).

This document has been developed to answer the need of test laboratories carrying out these

measurements, that are sometimes required by national authorities, as they may 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.
vi © ISO 2019 – All rights reserved
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SIST EN ISO 22125-1:2020
INTERNATIONAL STANDARD ISO 22125-1:2019(E)
Water quality — Technetium-99 —
Part 1:
Test method using liquid scintillation counting

WARNING — Persons using this document should be familiar with normal laboratory practices.

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 and to

determine the applicability of any other restrictions.

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 measurement of Tc in all types of waters by liquid

scintillation counting (LSC).

The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water,

as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling

and handling, and test sample preparation. A filtration of the test sample is necessary.

The detection limit depends on the sample volume and the instrument used. The method described

in this document, using currently available LSC instruments, has a detection limit of approximately

−1 −1

5 Bq·kg to 20 Bq·kg , which is lower than the WHO criteria for safe consumption of drinking water

−1 [3]

(100 Bq l ) . These values can be achieved with a counting time of 30 min for a sample volume varying

between 14 ml to 40 ml. The method presented in this document is not intended for the determination

of ultra-trace amount of Tc.

The activity concentration values in this document are expressed by sample mass unit instead of

sample volume unit as it is usually the case in similar standards. The reason is that Tc is measured in

various matrix types such as fresh water or sea water, which have significant differences in density. The

activity concentration values can be easily converted to sample volume unit by measuring the sample

volume. However, it increases the uncertainty on the activity concentration result.

The method described in this document is applicable in the event of an emergency situation, but not

99m 99m

if Tc is present at quantities that could cause interference and not if Tc is used as a recovery tracer.

The analysis of Tc adsorbed to suspended matter is not covered by this method.

It is the user’s responsibility to ensure the validity 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/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)

ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated

terms (VIM)
ISO 3696, Water for analytical laboratory use — Specification and test methods
© ISO 2019 – All rights reserved 1
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)

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 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste waters

ISO 10703, Water quality — Determination of the activity concentration of radionuclides — Method by

high resolution gamma-ray spectrometry

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 19361, Measurement of radioactivity — Determination of beta emitters activities — Test method using

liquid scintillation counting

ISO 20042, Measurement of radioactivity — Gamma emitting radionuclides — Generic test method using

gamma spectrometry
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms, definitions and symbols
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 80000-10, ISO 11929,

ISO/IEC Guide 98-3 and ISO/IEC Guide 99 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/
3.2 Symbols

For the purposes of this document, the symbols and designations given in ISO 80000-10, ISO 11929,

ISO/IEC Guide 98-3, ISO/IEC Guide 99 and the following apply.
Symbol Term Unit
* decision threshold Bq·kg
detection limit Bq·kg
 
lower and upper limits of the confidence interval Bq·kg
c , c
A A
detection limit in mass concentration g·kg
A activity of the calibration source Bq
A tracer activity Bq
A tracer activity measured Bq
c activity concentration Bq·kg
c mass concentration g·kg
C specific activity Bq∙g
2 © ISO 2019 – All rights reserved
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)
Symbol Term Unit
DPM disintegrations per minute
f quench factor
m test sample mass kg
m sub sample mass of the eluate for Tc measurement by LSC g
m sub sample mass of the eluate for recovery measurement g
m eluate mass g
tracer mass g
m mass of tracer added to the reagent blank for the calculation of r g
TB b
m empty container mass of the eluate g
m full container mass of the eluate g
m tracer mass measured g
m tracer solution mass g
r reagent blank count rate counts∙s
R chemical recovery
r sample count rate counts∙s
R mass ratio
r calibration count rate counts∙s
r spiked reagent blank count rate for r calculation counts∙s
sp o
99 −1
r Tc count rate from the tracer counts∙s
r unspiked reagent blank count rate for r calculation counts∙s
us o
SQPE spectral quench parameter of the external standard
t background counting time s
TDCR triple to double counts ratio
t sample counting time s
t calibration counting time s
tSIE transformed spectral index of the external standard
 characteristic limits Bq·kg
U expanded uncertainty, calculated by U = ku(c ) with k = 1, 2…, Bq·kg
u(c ) standard uncertainty associated with the measurement result Bq·kg
V test sample volume l
ε detection efficiency
ρ sample density kg∙l
4 Principle

Technetium is mainly an anthropogenic element, but trace amounts are found in uranium ores. It has

99 235 [8]

no stable isotope. Tc is a significant fission product of U (approximatively 6 % yield ) with a

5 [9]
maximum beta-energy of (294 ± 1) keV and a half-life of (2,1 ± 0,1) × 10 years .

To determine Tc in water, a water sample is collected, filtered, acidified, and oxidized (see Clause 5).

A tracer is added before the chemical separation to take into account the losses of recovery during

the purification step. Enough tracer is added to obtain a good statistical precision and be easily

95m 99m

distinguished from a blank sample. The tracers that can be used are stable Re, Tc and Tc. Stable

[8]

Re is often used as a recovery tracer for Tc measurement due to its similar reactivity . It has the

advantages of being easily available and stable. Tc and Re do not behave similarly when heated in an

© ISO 2019 – All rights reserved 3
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SIST EN ISO 22125-1:2020
ISO 22125-1:2019(E)
[10][11]

acidic solution. Tc is more volatile ; thus Re cannot be used as a recovery tracer when the method

includes a vaporization step.

— When Re is used as a chemical recovery tracer, a sub-sample (m ) of known mass is taken before

the LSC measurement for the recovery determination. It is recommended to complete the recovery

determination before counting the sample.
Rhenium can be measured for example by:
[12]
— ICP-OES according to ISO 11885
[13]
— AAS according to ISO 15586
[14][15]
— UV-visible spectroscopy
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— When Tc or Tc is used as a chemical recovery tracer, the chemical recovery is determined

[8] 99m 95m

by gamma spectrometry . Enough activity of Tc or Tc is added to obtain 10 000 counts

when counting the sample. The sample is directly placed in the gamma counter, without any sample

pre-treatment. It is measured according to the instrument specifications and in accordance with

ISO 10703 and ISO 20042.
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Tc or Tc should completely decay before measuring the sample by LSC. It can take several days for

99m 95m 99m

Tc and several months for Tc depending of the initial quantity added. The tracer Tc is usually

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preferred to Tc due to a faster decay and also because commercial Tc standard solutions may

99 [8]
contain a significant amount of Tc .
Tc is chemically purified f
...

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