Water quality -- Plutonium and neptunium -- Test method using ICP-MS

This document specifies methods used to determine the concentration of plutonium and neptunium isotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) (239Pu, 240Pu, 241Pu and 237Np). The concentrations obtained can be converted into activity concentrations of the different isotopes[9]. Due to its relatively short half-life and 238U isobaric interference, 238Pu can hardly be measured by this method. To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell, ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, as described in ISO 13167[10], is currently used[11]. This method is applicable to all types of water having a saline load less than 1 g·l−1. A dilution of the sample is possible to obtain a solution having a saline load and activity concentrations compatible with the preparation and the measurement assembly. A filtration at 0,45 μm is needed for determination of dissolved nuclides. Acidification and chemical separation of the sample are always needed. The limit of quantification depends on the chemical separation and the performance of the measurement device. This method covers the measurement of those isotopes in water in activity concentrations between around[12][13]: — 1 mBq·l−1 to 5 Bq·l−1 for 239Pu, 240Pu and 237Np; — 1 Bq·l−1 to 5 Bq·l−1 for 241Pu. In both cases, samples with higher activity concentrations than 5 Bq·l−1 can be measured if a dilution is performed before the chemical separation. It is possible to measure 241Pu following a pre-concentration step of at least 1 000.

Qualité de l'eau -- Plutonium et neptunium -- Méthode d'essai par ICP-MS

Le présent document décrit des méthodes permettant de déterminer la concentration des isotopes du plutonium et du neptunium dans l'eau, par spectrométrie de masse avec plasma ŕ couplage inductif (ICP-MS) (239Pu, 240Pu, 241Pu et 237Np). Les concentrations obtenues peuvent ętre converties en activités volumiques des différents isotopes[9]. En raison de sa période relativement courte et des interférences isobariques de 238U, 238Pu est difficilement mesurable par cette méthode. Pour quantifier cet isotope, il est possible d'utiliser d'autres techniques (ICP-MS avec cellule de collision-réaction, ICP-MS/MS avec cellule de collision-réaction ou séparation chimique). Un mesurage par spectrométrie alpha, comme décrit dans l'ISO 13167[10], est couramment réalisé[11]. La présente méthode est applicable ŕ tous types d'eau ayant une charge saline inférieure ŕ 1 g·l−1. Une dilution de l'échantillon est possible afin d'obtenir une solution ayant une charge saline et une activité volumique compatibles avec la préparation et l'appareillage de mesure. Une filtration ŕ 0,45 μm est nécessaire pour déterminer les nucléides dissous. Une acidification et une séparation chimique de l'échantillon sont toujours nécessaires. La limite de quantification est fonction de la séparation chimique et des performances du dispositif de mesure. Cette méthode couvre le mesurage des isotopes présents dans les eaux dont l'activité volumique est approximativement comprise[12][13]: — entre 1 mBq·l-1 et 5 Bq·l-1 pour 239Pu, 240Pu et 237Np; — entre 1 Bq·l-1 et 5 Bq·l-1 pour 241Pu. Dans les deux cas, des échantillons ayant une activité volumique supérieure ŕ 5 Bq·l-1 peuvent ętre soumis au mesurage s'ils sont dilués avant la séparation chimique. Il est possible de mesurer le 241Pu aprčs une étape de préconcentration d'au moins 1 000.

Kakovost vode - Plutonij in neptunij - Preskusna metoda masne spektrometrije z induktivno sklopljeno plazmo (ICP/MS)

Ta dokument določa metode za določanje koncentracije izotopov plutonija in neptunija v vodi prek masne spektrometrije z induktivno sklopljeno plazmo (ICP-MS) (239Pu, 240Pu, 241Pu in 237Np). Pridobljene koncentracije je mogoče pretvoriti v koncentracije aktivnosti različnih izotopov[9]. Zaradi relativno kratke razpolovne dobe in izobarnih motenj 238U je s to metodo težko izmeriti 238Pu. Za količinsko določitev tega izotopa je mogoče uporabiti druge tehnike (ICP-MS s kolizijsko/reakcijsko celico, ICP-MS/MS s kolizijsko/reakcijsko celico ali kemično separacijo). Trenutno se uporablja alfa spektrometrija, kot je opisano v standardu ISO 13167[10][11]. Ta metoda se uporablja za vse vrste vode z manj kot 1 g l−1 soli. Z redčenjem vzorca je mogoče pridobiti raztopino s koncentracijo fiziološke raztopine in koncentracijo aktivnosti, združljivo s pripravo in merilnim sklopom. Za določitev raztopljenih nuklidov je potrebna filtracija pri 0,45 µm. Vedno sta potrebna okisanje in kemična
separacija vzorca. Meja količinskega določanja je odvisna od kemične separacije in učinkovitosti
merilne naprave. Ta metoda zajema merjenje teh izotopov v vodi v koncentraciji aktivnosti med približno[12][13]:
– 1 mBq·l−1 do 5 Bq·l−1 za 239Pu, 240Pu in 237Np;
– 1 Bq·l−1 do 5 Bq·l−1 za 241Pu.
V obeh primerih je mogoče izmeriti vzorce z višjo koncentracijo aktivnosti kot 5 Bq l-1, če se pred kemično separacijo opravi redčenje.
Po koraku predkoncentracije vsaj 1000 je mogoče izmeriti 241Pu.

General Information

Status
Published
Publication Date
30-Aug-2018
Current Stage
6060 - International Standard published
Start Date
08-Aug-2018
Completion Date
31-Aug-2018

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INTERNATIONAL ISO
STANDARD 20899
First edition
2018-09
Water quality — Plutonium and
neptunium — Test method using ICP-
Qualité de l'eau — Plutonium et neptunium — Méthode d'essai par
ICP-MS
Reference number
ISO 20899:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 20899:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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 2018 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 20899:2018(E)
Contents Page

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

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

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

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

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

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

5 Reagents ........................................................................................................................................................................................................................ 4

6 Apparatus ..................................................................................................................................................................................................................... 5

7 Sampling ........................................................................................................................................................................................................................ 5

8 Sample preparation ........................................................................................................................................................................................... 5

8.1 General ........................................................................................................................................................................................................... 5

8.2 Storage ........................................................................................................................................................................................................... 5

8.3 Chemical separation ........................................................................................................................................................................... 5

9 Measurement procedure .............................................................................................................................................................................. 6

9.1 General ........................................................................................................................................................................................................... 6

9.2 Quantification with internal calibration and isotopic dilution ...................................................................... 6

10 Expression of results ........................................................................................................................................................................................ 6

10.1 General ........................................................................................................................................................................................................... 6

10.2 Mass bias evaluation .......................................................................................................................................................................... 7

10.3 Internal calibration and isotopic dilution ........................................................................................................................ 7

11 Uncertainties for isotopic dilution .................................................................................................................................................... 8

12 Instrumental detection limit ................................................................................................................................................................... 8

13 Limit of quantification .................................................................................................................................................................................... 8

14 Activity concentration determination ............................................................................................................................................ 9

15 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Chemical separation of plutonium and neptunium by specific resin ................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2018 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 20899:2018(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.

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 2018 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 20899:2018(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

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

[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

[4]

using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3

[5]
and 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

239 240 241

for guidance level in drinking water is 1 Bq/l activity concentration for Pu, Pu and Pu.

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 .

[7]

In the event of a nuclear emergency, the WHO Codex guideline levels (GLs) states that the activity

239 240 241

concentration might not be greater than 1 Bq/l and 10 Bq/l for Pu, Pu, Pu, respectively, for

infant and for others than infant.

NOTE 2 The Codex 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

[7]

on an intervention exemption level of 1 mSv in a year for members of the 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 test results of the radionuclide activity concentrations can be

verified to be below the guidance levels required by a national authority for either planned/existing

[6][7][8]
situations 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 2018 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 20899:2018(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

could 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).
239 240 241 237

An International Standard on a test method for Pu, Pu, Pu and Np concentration in water

samples is justified for test laboratories carrying out these measurements, required sometimes by

national authorities, as laboratories 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 2018 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 20899:2018(E)
Water quality — Plutonium and neptunium — Test method
using ICP-MS

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 in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies methods used to determine the concentration of plutonium and neptunium

239 240 241

isotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) ( Pu, Pu, Pu

237

and Np). The concentrations obtained can be converted into activity concentrations of the different

[9]
isotopes .
238 238

Due to its relatively short half-life and U isobaric interference, Pu can hardly be measured by

this method. To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell,

ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, as

[10] [11]
described in ISO 13167 , is currently used .

This method is applicable to all types of water having a saline load less than 1 g·l . A dilution of the

sample is possible to obtain a solution having a saline load and activity concentrations compatible with

the preparation and the measurement assembly.

A filtration at 0,45 μm is needed for determination of dissolved nuclides. Acidification and chemical

separation of the sample are always needed.

The limit of quantification depends on the chemical separation and the performance of the

measurement device.

This method covers the measurement of those isotopes in water in activity concentrations between

[12][13]
around :
−1 −1 239 240 237
— 1 mBq·l to 5 Bq·l for Pu, Pu and Np;
−1 −1 241
— 1 Bq·l to 5 Bq·l for Pu.

In both cases, samples with higher activity concentrations than 5 Bq·l can be measured if a dilution is

performed before the chemical separation.
241

It is possible to measure Pu following a pre-concentration step of at least 1 000.

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 2018 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 20899:2018(E)

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

ISO 17294-1:2004, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 1: General guidelines

ISO 17294-2:2016, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 2: Determination of selected elements including uranium isotopes
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

3 Terms, definitions, symbols and abbreviated terms

For the purposes of this document, the terms, definitions, symbols and abbreviated terms 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/
Symbol or
Term abbreviated Unit symbol Definition
term
Mass concentration ρ μg·l Analyte mass for a given radionuclide per
sample unit volume.
Mass concentration of the ρ μg·l Mass of internal standard radionuclide element
internal standard solution per unit volume of the internal standard
solution.
Internal standard mass m μg Mass of the isotope dilution tracer added
Standard uncertainty u(ρ) μg·l Standard uncertainty associated with the
measurement result
Expanded uncertainty U(x) Product of the standard uncertainty and the
coverage factor k with k = 1, 2,…, U = k · u
Standard uncertainty u(x) Standard uncertainty associated with the
measurement result of x
Detection limit DL μg·l DL is the lowest amount of an analyte that is
detectable using an instrument, as determined
by repeated measurement of a regent blank.
Limit of quantification LOQ μg·l LOQ is the smallest concentration of an analyte
in the test sample which can be determined with
mBq.l
a fixed precision.
Standard deviation of the s Standard deviation of replicates of the blank.
blank
Instrumental limit of LOQ Counts.s LOQ is the LOQ expressed in counts rate for
ins ins
quantification the chosen mass on charge ration (m/z), due to
the blank and the instrument.

Instrumental detection limit IDL Counts.s IDL is the DL expressed in counts rate for the

chosen mass on charge ration (m/z).
Volume of the sample V l
Background N Counts.s Counts rates for a given mass in the blank
solution.
Counts N Counts.s Gross counts rates: uncorrected counts rate of a
measurement.
Net counts N Counts.s N-N
net 0
2 © ISO 2018 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 20899:2018(E)
Symbol or
Term abbreviated Unit symbol Definition
term
Net counts of the internal N Counts.s At the internal standard mass.
netT
standard
Bias per unit mass α
Mass m Isotope mass number.
Mass difference Δm m -m
i j
Measured isotopic ratio r
True isotopic ratio R
Specific activity C Bq·g Activity corresponding to one gram of the
radionuclide.
Activity concentration C Bq·l Corresponding to the mass concentration ρ
measured for a given radionuclide.
4 Principle

The principle of measurement of analysis using ICP-MS is described in ISO 17294-1 and ISO 17294-2.

239 240 241

ICP-MS can be used to measure the mass concentrations of plutonium isotopes ( Pu, Pu, Pu)

237
and Np in water samples.

The results can be converted in activity concentrations using conversion factors given in Table 1.

[12][13]
Table 1 — Plutonium and neptunium isotopes half-lives and specific activities
Half-life Specific activity
Plutonium isotope
years Bq·g
239 9 6
Pu 24 100 (±11) 2,296·10 (±2,000·10 )
240 9 6
Pu 6 561 (±7) 8,396·10 (±9,000·10 )
241 12 10
Pu 14,33 (±0,04) 3,829·10 (±1,100·10 )
242 5 8 6
Pu 3,73 (±0,03)·10 1,465·10 (±1,180·10 )
244 6 5 3
Pu 81,1 (±0,6)·10 6,683·10 (±7,600·10 )
Half-life Specific activity
Neptunium
years Bq·g
237 6 7 4
Np 2,144 (±0,007)·10 2,603·10 (±9,000·10 )

The water sample has to be measured after filtration (at 0,45 μm porosity) for the determination of

dissolved radionuclides and a specific chemical separation shall be performed to limit potential

[14]

interferences due to uranium isotopes . An example of chemical separation is given in Annex A.

As described in the ISO 17294 series, a tracer is needed to evaluate the recovery in chemical separation

and to perform an isotopic dilutio
...

SLOVENSKI STANDARD
SIST ISO 20899:2019
01-december-2019
Kakovost vode - Plutonij in neptunij - Preskusna metoda masne spektrometrije z
induktivno sklopljeno plazmo (ICP/MS)
Water quality - Plutonium and neptunium - Test method using ICP-MS
Qualité de l'eau - Plutonium et neptunium - Méthode d'essai par ICP-MS
Ta slovenski standard je istoveten z: ISO 20899:2018
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
17.240 Merjenje sevanja Radiation measurements
SIST ISO 20899:2019 en

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

---------------------- Page: 1 ----------------------
SIST ISO 20899:2019
---------------------- Page: 2 ----------------------
SIST ISO 20899:2019
INTERNATIONAL ISO
STANDARD 20899
First edition
2018-09
Water quality — Plutonium and
neptunium — Test method using ICP-
Qualité de l'eau — Plutonium et neptunium — Méthode d'essai par
ICP-MS
Reference number
ISO 20899:2018(E)
ISO 2018
---------------------- Page: 3 ----------------------
SIST ISO 20899:2019
ISO 20899:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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 2018 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 20899:2019
ISO 20899:2018(E)
Contents Page

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

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

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

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

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

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

5 Reagents ........................................................................................................................................................................................................................ 4

6 Apparatus ..................................................................................................................................................................................................................... 5

7 Sampling ........................................................................................................................................................................................................................ 5

8 Sample preparation ........................................................................................................................................................................................... 5

8.1 General ........................................................................................................................................................................................................... 5

8.2 Storage ........................................................................................................................................................................................................... 5

8.3 Chemical separation ........................................................................................................................................................................... 5

9 Measurement procedure .............................................................................................................................................................................. 6

9.1 General ........................................................................................................................................................................................................... 6

9.2 Quantification with internal calibration and isotopic dilution ...................................................................... 6

10 Expression of results ........................................................................................................................................................................................ 6

10.1 General ........................................................................................................................................................................................................... 6

10.2 Mass bias evaluation .......................................................................................................................................................................... 7

10.3 Internal calibration and isotopic dilution ........................................................................................................................ 7

11 Uncertainties for isotopic dilution .................................................................................................................................................... 8

12 Instrumental detection limit ................................................................................................................................................................... 8

13 Limit of quantification .................................................................................................................................................................................... 8

14 Activity concentration determination ............................................................................................................................................ 9

15 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Chemical separation of plutonium and neptunium by specific resin ................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2018 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 20899:2019
ISO 20899:2018(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.

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 2018 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 20899:2019
ISO 20899:2018(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

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

[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

[4]

using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3

[5]
and 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

239 240 241

for guidance level in drinking water is 1 Bq/l activity concentration for Pu, Pu and Pu.

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 .

[7]

In the event of a nuclear emergency, the WHO Codex guideline levels (GLs) states that the activity

239 240 241

concentration might not be greater than 1 Bq/l and 10 Bq/l for Pu, Pu, Pu, respectively, for

infant and for others than infant.

NOTE 2 The Codex 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

[7]

on an intervention exemption level of 1 mSv in a year for members of the 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 test results of the radionuclide activity concentrations can be

verified to be below the guidance levels required by a national authority for either planned/existing

[6][7][8]
situations 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 2018 – All rights reserved v
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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

could 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).
239 240 241 237

An International Standard on a test method for Pu, Pu, Pu and Np concentration in water

samples is justified for test laboratories carrying out these measurements, required sometimes by

national authorities, as laboratories 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 2018 – All rights reserved
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SIST ISO 20899:2019
INTERNATIONAL STANDARD ISO 20899:2018(E)
Water quality — Plutonium and neptunium — Test method
using ICP-MS

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 in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies methods used to determine the concentration of plutonium and neptunium

239 240 241

isotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) ( Pu, Pu, Pu

237

and Np). The concentrations obtained can be converted into activity concentrations of the different

[9]
isotopes .
238 238

Due to its relatively short half-life and U isobaric interference, Pu can hardly be measured by

this method. To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell,

ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, as

[10] [11]
described in ISO 13167 , is currently used .

This method is applicable to all types of water having a saline load less than 1 g·l . A dilution of the

sample is possible to obtain a solution having a saline load and activity concentrations compatible with

the preparation and the measurement assembly.

A filtration at 0,45 μm is needed for determination of dissolved nuclides. Acidification and chemical

separation of the sample are always needed.

The limit of quantification depends on the chemical separation and the performance of the

measurement device.

This method covers the measurement of those isotopes in water in activity concentrations between

[12][13]
around :
−1 −1 239 240 237
— 1 mBq·l to 5 Bq·l for Pu, Pu and Np;
−1 −1 241
— 1 Bq·l to 5 Bq·l for Pu.

In both cases, samples with higher activity concentrations than 5 Bq·l can be measured if a dilution is

performed before the chemical separation.
241

It is possible to measure Pu following a pre-concentration step of at least 1 000.

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 2018 – All rights reserved 1
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ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste waters

ISO 17294-1:2004, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 1: General guidelines

ISO 17294-2:2016, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 2: Determination of selected elements including uranium isotopes
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

3 Terms, definitions, symbols and abbreviated terms

For the purposes of this document, the terms, definitions, symbols and abbreviated terms 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/
Symbol or
Term abbreviated Unit symbol Definition
term
Mass concentration ρ μg·l Analyte mass for a given radionuclide per
sample unit volume.
Mass concentration of the ρ μg·l Mass of internal standard radionuclide element
internal standard solution per unit volume of the internal standard
solution.
Internal standard mass m μg Mass of the isotope dilution tracer added
Standard uncertainty u(ρ) μg·l Standard uncertainty associated with the
measurement result
Expanded uncertainty U(x) Product of the standard uncertainty and the
coverage factor k with k = 1, 2,…, U = k · u
Standard uncertainty u(x) Standard uncertainty associated with the
measurement result of x
Detection limit DL μg·l DL is the lowest amount of an analyte that is
detectable using an instrument, as determined
by repeated measurement of a regent blank.
Limit of quantification LOQ μg·l LOQ is the smallest concentration of an analyte
in the test sample which can be determined with
mBq.l
a fixed precision.
Standard deviation of the s Standard deviation of replicates of the blank.
blank
Instrumental limit of LOQ Counts.s LOQ is the LOQ expressed in counts rate for
ins ins
quantification the chosen mass on charge ration (m/z), due to
the blank and the instrument.

Instrumental detection limit IDL Counts.s IDL is the DL expressed in counts rate for the

chosen mass on charge ration (m/z).
Volume of the sample V l
Background N Counts.s Counts rates for a given mass in the blank
solution.
Counts N Counts.s Gross counts rates: uncorrected counts rate of a
measurement.
Net counts N Counts.s N-N
net 0
2 © ISO 2018 – All rights reserved
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SIST ISO 20899:2019
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Symbol or
Term abbreviated Unit symbol Definition
term
Net counts of the internal N Counts.s At the internal standard mass.
netT
standard
Bias per unit mass α
Mass m Isotope mass number.
Mass difference Δm m -m
i j
Measured isotopic ratio r
True isotopic ratio R
Specific activity C Bq·g Activity corresponding to one gram of the
radionuclide.
Activity concentration C Bq·l Corresponding to the mass concentration ρ
measured for a given radionuclide.
4 Principle

The principle of measurement of analysis using ICP-MS is described in ISO 17294-1 and ISO 17294-2.

239 240 241

ICP-MS can be used to measure the mass concentrations of plutonium isotopes ( Pu, Pu, Pu)

237
and Np in water samples.

The results can be converted in activity concentrations using conversion factors given in Table 1.

[12][13]
Table 1 — Plutonium and neptunium isotopes half-lives and specific activities
Half-life Specific activity
Plutonium isotope
years Bq·g
239 9 6
Pu 24 100 (±11) 2,296·10 (±2,000·10 )
240 9 6
Pu 6 561 (±7) 8,396·10 (±9,000·10 )
241 12 10
Pu 14,33 (±0,04) 3,829·10 (±1,100·10 )
242 5 8 6
Pu 3,73 (±0,03)·10 1,465·10 (±1,180·10 )
244 6 5 3
Pu 81,1 (±0,6)·10 6,683·10 (±7,600·10 )
Half-life Specific activity
Neptunium
years Bq·g
237 6 7 4
Np 2,144 (±0,007)·10 2,603·10 (±9,000·10 )

The water sample has to be measured after filtration (at 0,45 μm porosity) for the determination of

dissolved radionuclides and a specific chemical separation shall be performed to limit potential

[14]

interferences due to uranium isotopes . An example of chemical separation is given in Annex A.

As described in the ISO 17294 series, a tracer is needed to evaluate the recovery in chemical separation

and to perform an isotopic dilution. A known amount of pure certified tracer standard solution is added

to the sample test portion and the calculation of isotope concentration is based on the isotopic ratios.

Even if activity certified standard solutions are available, external calibration is not used as it is quite

239 240 241 237

difficult to find mass certified standard solutions of plutonium isotopes ( Pu, Pu, Pu) and Np.

242 244

For the determination of plutonium isotopes in water, Pu is commonly used but Pu can also

be chosen.

The chemical yield obtained for plutonium may be applied to neptunium. This may lead to a potential

bias that shall be quantified. Other methods should be used such as external calibration, addition of the

239 237

short lived Np as tracer, standard additions of Np in several tests portions of the sample, etc.

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ISO 20899:2018(E)
It is also important to evaluate the mass bias and to correct it (see 10.2).

Examples of limits of quantification that can be obtained with a quadrupole ICP-MS are given in Table 2.

[15][16]
Table 2 — Examples of limits of quantification
LOQ LOQ
Isotope
−1 −1
μg·l mBq·l
237
Np 3,85E-07 0,01
239
Pu 8,70E-07 2
240
Pu 4,76E-07 4
241
Pu 3,93E-07 1 500

Through chemical separation, high uranium decontamination factor can be achieved but remaining

238

uranium concentration is likely to be still above the typical Pu concentration expected in water.

238

In addition, this Pu concentration is expected to be lower than the LOQ reported. For this reason,

238

current instrumentation is not suited for Pu measurements, in normal conditions. However,

assuming that a collision-reaction cell could be installed onto a more sensitive instrument, such a newer

instrument could be more suited for the separation of isobaric interferences.
5 Reagents
Use only reagents of recognized analytical grade.
5.1 Laboratory water, grade 3 quality as specified in ISO 3696.
5.2 Blank.

A blank sample is taken through the entire procedure, including chemical separation.

Diluted acid solution is used to determine the background spectra for the various masses.

5.3 Certified standard solutions of isotopes.

Use of a certified standard solution with known isotopic composition is recommended to evaluate the

mass bias.

Use of a reference solution with known actinide isotopic composition is recommended for standard

bracketing (measured at least twice, before and after the sample, in several repetitions).

242
5.4 Tracer solution (for example Pu).

Prepare this solution by successive dilutions of the certified standard solution, the last dilution being in

1 % to 2 % nitric acid (volume). Concentration is adjusted in link with the method validation. The water

samples are spiked with a known amount of this solution at the beginning of the procedure.

5.5 Quality control solution.

Solution of certified plutonium concentration, different than the one used for isotopic dilution should

be used.
5.6 Argon gas, at least 99,995 % pure.
5.7 Diluted nitric acid, 2 % volume, for example.
4 © ISO 2018 – All rights reserved
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6 Apparatus
The usual laboratory apparatus and, in particular, the following.
6.1 Analytical balance, accurate to 1/10 mg.
6.2 Argon supply, equipped with low pressure control.

6.3 ICP-MS apparatus with associated software, installed in an air-conditioned room.

6.4 Auto-sampler device, if available.
6.5 Membrane filter, 0,45 μm.
7 Sampling

For the determination of trace amounts, the prevention of all contamination or losses shall be of primary

concern. Dust in the laboratory, impurities in the reagents and on the laboratory equipment which are

in contact with the samples could be potential sources of contamination. The sample containers can

lead to positive or negative bias in the determination of trace elements by superficial desorption or

adsorption.

Perform the storage and pre-treatment steps (filtration and acidification) described in Clause 8 when

sampling or immediately afterwards.

Sampling, handling and storage of the water shall be done as specified in ISO 5667-1, ISO 5667-3 and

[17] [21]

ISO 5667-10. Guidance for the different types of water is given in ISO 5667-4 to ISO 5667-8 .

It is important that the laboratory receives a sample that is truly representative and has not been

damaged or modified during transportation or storage.
8 Sample preparation
8.1 General

Filter the sample on a 0,45 μm membrane filter (6.5) as soon as possible, using a glass or single-use

filtration apparatus.

Acidify with nitric acid (5.7) to ensure that the pH of the sample is less than 2.

For a representative analysis of drinking water, filtration is not required.
8.2 Storage
Follow ISO 5667-3. Perform the analysis as soon as possible.
8.3 Chemical separation

A chemical separation from potential interferents is performed, for example, as explained in Annex A.

Other procedures for chemical separation can also be used (such as those described in References [11]

[14], [15], [16], [22], [23], [24] and [25]).
Measure the volume of the test portion V.

A pre-concentration step can be added (see Reference [10]), for example, using a co-precipitation method

with Fe solution. This precipitation consists of the addition of FeCl and the precipitation of iron with

© ISO 2018 – All rights reserved 5
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ISO 20899:2018(E)

the addition of ammonia to pH 10. The supernatant is discarded and the iron hydroxide precipitate,

which contains the plutonium and the other actinides, is dissolved with concentrated nitric acid.

9 Measurement procedure
9.1 General

Follow the instructions provided by the instrument manufacturer and the steps described in

ISO 17294-1:2004, Clauses 7 and 9 in particular and ISO 17294-2:2016, Clauses 8 to 11 in particular.

The sensitivity, the instrumental detection limit and the precision should be established for each

analysis performed in the instrument.
238 +

Although the chemical separation is done to avoid common interferences (mainly with U and UH

effect at 239 m/z area), the potential interferences for the masses of interest should be reported in a

separate table. It is recommended to measure the count rate corresponding to 238 m/z to assess if the

238
amount of remaining U is sufficiently low so as not to interfere.
Before any sample measurement, measure
...

SLOVENSKI STANDARD
oSIST ISO 20899:2019
01-september-2019
Kakovost vode - Plutonij in neptunij - Preskusna metoda masne spektrometrije z
induktivno sklopljeno plazmo (ICP/MS)
Water quality - Plutonium and neptunium - Test method using ICP-MS
Qualité de l'eau - Plutonium et neptunium - Méthode d'essai par ICP-MS
Ta slovenski standard je istoveten z: ISO 20899:2018
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
17.240 Merjenje sevanja Radiation measurements
oSIST ISO 20899:2019 en

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

---------------------- Page: 1 ----------------------
oSIST ISO 20899:2019
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oSIST ISO 20899:2019
INTERNATIONAL ISO
STANDARD 20899
First edition
2018-09
Water quality — Plutonium and
neptunium — Test method using ICP-
Qualité de l'eau — Plutonium et neptunium — Méthode d'essai par
ICP-MS
Reference number
ISO 20899:2018(E)
ISO 2018
---------------------- Page: 3 ----------------------
oSIST ISO 20899:2019
ISO 20899:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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 2018 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 20899:2019
ISO 20899:2018(E)
Contents Page

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

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

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

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

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

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

5 Reagents ........................................................................................................................................................................................................................ 4

6 Apparatus ..................................................................................................................................................................................................................... 5

7 Sampling ........................................................................................................................................................................................................................ 5

8 Sample preparation ........................................................................................................................................................................................... 5

8.1 General ........................................................................................................................................................................................................... 5

8.2 Storage ........................................................................................................................................................................................................... 5

8.3 Chemical separation ........................................................................................................................................................................... 5

9 Measurement procedure .............................................................................................................................................................................. 6

9.1 General ........................................................................................................................................................................................................... 6

9.2 Quantification with internal calibration and isotopic dilution ...................................................................... 6

10 Expression of results ........................................................................................................................................................................................ 6

10.1 General ........................................................................................................................................................................................................... 6

10.2 Mass bias evaluation .......................................................................................................................................................................... 7

10.3 Internal calibration and isotopic dilution ........................................................................................................................ 7

11 Uncertainties for isotopic dilution .................................................................................................................................................... 8

12 Instrumental detection limit ................................................................................................................................................................... 8

13 Limit of quantification .................................................................................................................................................................................... 8

14 Activity concentration determination ............................................................................................................................................ 9

15 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Chemical separation of plutonium and neptunium by specific resin ................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2018 – All rights reserved iii
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oSIST ISO 20899:2019
ISO 20899:2018(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.

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 2018 – All rights reserved
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oSIST ISO 20899:2019
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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

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

[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

[4]

using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3

[5]
and 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

239 240 241

for guidance level in drinking water is 1 Bq/l activity concentration for Pu, Pu and Pu.

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 .

[7]

In the event of a nuclear emergency, the WHO Codex guideline levels (GLs) states that the activity

239 240 241

concentration might not be greater than 1 Bq/l and 10 Bq/l for Pu, Pu, Pu, respectively, for

infant and for others than infant.

NOTE 2 The Codex 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

[7]

on an intervention exemption level of 1 mSv in a year for members of the 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 test results of the radionuclide activity concentrations can be

verified to be below the guidance levels required by a national authority for either planned/existing

[6][7][8]
situations 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 2018 – All rights reserved v
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oSIST ISO 20899:2019
ISO 20899:2018(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

could 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).
239 240 241 237

An International Standard on a test method for Pu, Pu, Pu and Np concentration in water

samples is justified for test laboratories carrying out these measurements, required sometimes by

national authorities, as laboratories 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 2018 – All rights reserved
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oSIST ISO 20899:2019
INTERNATIONAL STANDARD ISO 20899:2018(E)
Water quality — Plutonium and neptunium — Test method
using ICP-MS

WA R N I NG — Per s on s u s i n g t h i s do c u ment shou ld b e f a m i l i a r w it h nor m a l l ab or at or y pr ac t ic e .

T h i s do c u ment do e s not pu r p or t t o add r e s s a l l of t he s a f e t y pr oblem s , i f a ny, a s s o c i at e d w it h it s

u s e . It i s t he r e s p on s ibi l it y of t he u s er t o e s t abl i sh appr opr i at e s a f e t y a nd he a lt h pr ac t ic e s .

I M P ORTA N T — It i s ab s olut el y e s s ent i a l t h at t e s t s c onduc t e d i n ac c or d a nc e w it h t h i s do c u ment

b e c a r r ie d out by s u it abl y qu a l i f ie d s t a f f .
1 Scope

This document specifies methods used to determine the concentration of plutonium and neptunium

239 240 241

isotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) ( Pu, Pu, Pu

237

and Np). The concentrations obtained can be converted into activity concentrations of the different

[9]
isotopes .
238 238

Due to its relatively short half-life and U isobaric interference, Pu can hardly be measured by

this method. To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell,

ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, as

[10] [11]
described in ISO 13167 , is currently used .

This method is applicable to all types of water having a saline load less than 1 g·l . A dilution of the

sample is possible to obtain a solution having a saline load and activity concentrations compatible with

the preparation and the measurement assembly.

A filtration at 0,45 μm is needed for determination of dissolved nuclides. Acidification and chemical

separation of the sample are always needed.

The limit of quantification depends on the chemical separation and the performance of the

measurement device.

This method covers the measurement of those isotopes in water in activity concentrations between

[12][13]
around :
−1 −1 239 240 237
— 1 mBq·l to 5 Bq·l for Pu, Pu and Np;
−1 −1 241
— 1 Bq·l to 5 Bq·l for Pu.

In both cases, samples with higher activity concentrations than 5 Bq·l can be measured if a dilution is

performed before the chemical separation.
241

It is possible to measure Pu following a pre-concentration step of at least 1 000.

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

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oSIST ISO 20899:2019
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ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste waters

ISO 17294-1:2004, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 1: General guidelines

ISO 17294-2:2016, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-

MS) — Part 2: Determination of selected elements including uranium isotopes
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

3 Terms, d efinitions , symbols and abbreviated terms

For the purposes of this document, the terms, definitions, symbols and abbreviated terms 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/
S y mb ol or
Term a bbr e v i at e d Un i t s y mb ol D e f i n i t ion
term
Mass concentration ρ μg·l Analyte mass for a given radionuclide per
sample unit volume.
Mass concentration of the ρ μg·l Mass of internal standard radionuclide element
internal standard solution per unit volume of the internal standard
solution.
Internal standard mass m μg Mass of the isotope dilution tracer added
Standard uncertainty u(ρ) μg·l Standard uncertainty associated with the
measurement result
Expanded uncertainty U(x) Product of the standard uncertainty and the
coverage factor k with k = 1, 2,…, U = k · u
Standard uncertainty u(x) Standard uncertainty associated with the
measurement result of x
Detection limit DL μg·l DL is the lowest amount of an analyte that is
detectable using an instrument, as determined
by repeated measurement of a regent blank.
Limit of quantification LOQ μg·l LOQ is the smallest concentration of an analyte
in the test sample which can be determined with
mBq.l
a fixed precision.
Standard deviation of the s Standard deviation of replicates of the blank.
blank
Instrumental limit of LOQ Counts.s LOQ is the LOQ expressed in counts rate for
ins ins
quantification the chosen mass on charge ration (m/z), due to
the blank and the instrument.

Instrumental detection limit IDL Counts.s IDL is the DL expressed in counts rate for the

chosen mass on charge ration (m/z).
Volume of the sample V l
Background N Counts.s Counts rates for a given mass in the blank
solution.
Counts N Counts.s Gross counts rates: uncorrected counts rate of a
measurement.
Net counts N Counts.s N-N
net 0
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oSIST ISO 20899:2019
ISO 20899:2018(E)
S y mb ol or
Term a bbr e v i at e d Un i t s y mb ol D e f i n i t ion
term
Net counts of the internal N Counts.s At the internal standard mass.
netT
standard
Bias per unit mass α
Mass m Isotope mass number.
Mass difference Δm m -m
i j
Measured isotopic ratio r
True isotopic ratio R
Specific activity C Bq·g Activity corresponding to one gram of the
radionuclide.
Activity concentration C Bq·l Corresponding to the mass concentration ρ
measured for a given radionuclide.
4 Principle

The principle of measurement of analysis using ICP-MS is described in ISO 17294-1 and ISO 17294-2.

239 240 241

ICP-MS can be used to measure the mass concentrations of plutonium isotopes ( Pu, Pu, Pu)

237
and Np in water samples.

The results can be converted in activity concentrations using conversion factors given in Table 1.

[12][13]

Table 1 — Plut on iu m a nd nep t u n iu m i s ot op e s h a l f-l i ve s a nd s p e c i f ic ac t i v it ie s

Half-life S p e c i f ic ac t i v i t y
Plutonium isotope
years Bq·g
239 9 6
Pu 24 100 (±11) 2,296·10 (±2,000·10 )
240 9 6
Pu 6 561 (±7) 8,396·10 (±9,000·10 )
241 12 10
Pu 14,33 (±0,04) 3,829·10 (±1,100·10 )
242 5 8 6
Pu 3,73 (±0,03)·10 1,465·10 (±1,180·10 )
244 6 5 3
Pu 81,1 (±0,6)·10 6,683·10 (±7,600·10 )
Half-life S p e c i f ic ac t i v i t y
Neptunium
years Bq·g
237 6 7 4
Np 2,144 (±0,007)·10 2,603·10 (±9,000·10 )

The water sample has to be measured after filtration (at 0,45 μm porosity) for the determination of

dissolved radionuclides and a specific chemical separation shall be performed to limit potential

[14]

interferences due to uranium isotopes . An example of chemical separation is given in Annex A.

As described in the ISO 17294 series, a tracer is needed to evaluate the recovery in chemical separation

and to perform an isotopic dilution. A known amount of pure certified tracer standard solution is added

to the sample test portion and the calculation of isotope concentration is based on the isotopic ratios.

Even if activity certified standard solutions are available, external calibration is not used as it is quite

239 240 241 237

difficult to find mass certified standard solutions of plutonium isotopes ( Pu, Pu, Pu) and Np.

242 244

For the determination of plutonium isotopes in water, Pu is commonly used but Pu can also

be chosen.

The chemical yield obtained for plutonium may be applied to neptunium. This may lead to a potential

bias that shall be quantified. Other methods should be used such as external calibration, addition of the

239 237

short lived Np as tracer, standard additions of Np in several tests portions of the sample, etc.

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oSIST ISO 20899:2019
ISO 20899:2018(E)
It is also important to evaluate the mass bias and to correct it (see 10.2).

Examples of limits of quantification that can be obtained with a quadrupole ICP-MS are given in Table 2.

[15][16]
Table 2 — E x a mple s of l i m it s of qu a nt i f ic at ion
LOQ LOQ
Isotope
−1 −1
μg·l mBq·l
237
Np 3,85E-07 0,01
239
Pu 8,70E-07 2
240
Pu 4,76E-07 4
241
Pu 3,93E-07 1 500

Through chemical separation, high uranium decontamination factor can be achieved but remaining

238

uranium concentration is likely to be still above the typical Pu concentration expected in water.

238

In addition, this Pu concentration is expected to be lower than the LOQ reported. For this reason,

238

current instrumentation is not suited for Pu measurements, in normal conditions. However,

assuming that a collision-reaction cell could be installed onto a more sensitive instrument, such a newer

instrument could be more suited for the separation of isobaric interferences.
5 Reagents
Use only reagents of recognized analytical grade.
5.1 Laboratory water, grade 3 quality as specified in ISO 3696.
5.2 Blank.

A blank sample is taken through the entire procedure, including chemical separation.

Diluted acid solution is used to determine the background spectra for the various masses.

5.3 Certified standard so lutions of isotopes.

Use of a certified standard solution with known isotopic composition is recommended to evaluate the

mass bias.

Use of a reference solution with known actinide isotopic composition is recommended for standard

bracketing (measured at least twice, before and after the sample, in several repetitions).

242
5.4 Tracer solution (for example Pu).

Prepare this solution by successive dilutions of the certified standard solution, the last dilution being in

1 % to 2 % nitric acid (volume). Concentration is adjusted in link with the method validation. The water

samples are spiked with a known amount of this solution at the beginning of the procedure.

5.5 Quality control solut ion.

Solution of certified plutonium concentration, different than the one used for isotopic dilution should

be used.
5.6 Argon gas, at least 99,995 % pure.
5.7 Diluted nitric acid, 2 % volume, for example.
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oSIST ISO 20899:2019
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6 Apparatus
The usual laboratory apparatus and, in particular, the following.
6.1 Analytical balance, accurate to 1/10 mg.
6.2 Argon supply, equipped with low pressure control.

6.3 ICP-MS apparatus w ith associated software, installed in an air-conditioned room.

6.4 Auto-sampler device, if available.
6.5 Membrane filter, 0,45 μm.
7 Sampling

For the determination of trace amounts, the prevention of all contamination or losses shall be of primary

concern. Dust in the laboratory, impurities in the reagents and on the laboratory equipment which are

in contact with the samples could be potential sources of contamination. The sample containers can

lead to positive or negative bias in the determination of trace elements by superficial desorption or

adsorption.

Perform the storage and pre-treatment steps (filtration and acidification) described in Clause 8 when

sampling or immediately afterwards.

Sampling, handling and storage of the water shall be done as specified in ISO 5667-1, ISO 5667-3 and

[17] [21]

ISO 5667-10. Guidance for the different types of water is given in ISO 5667-4 to ISO 5667-8 .

It is important that the laboratory receives a sample that is truly representative and has not been

damaged or modified during transportation or storage.
8 Sample preparation
8.1 General

Filter the sample on a 0,45 μm membrane filter (6.5) as soon as possible, using a glass or single-use

filtration apparatus.

Acidify with nitric acid (5.7) to ensure that the pH of the sample is less than 2.

For a representative analysis of drinking water, filtration is not required.
8.2 Storage
Follow ISO 5667-3. Perform the analysis as soon as possible.
8.3 Chemical separatio n

A chemical separation from potential interferents is performed, for example, as explained in Annex A.

Other procedures for chemical separation can also be used (such as those described in References [11]

[14], [15], [16], [22], [23], [24] and [25]).
Measure the volume of the test portion V.

A pre-concentration step can be added (see Reference [10]), for example, using a co-precipitation method

with Fe solution. This precipitation consists of the addition of FeCl and the precipitation of iron with

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oSIST ISO 20899:2019
ISO 20899:2018(E)

the addition of ammonia to pH 10. The supernatant is discarded and the iron hydroxide precipitate,

which contains the plutonium and the other actinides, is dissolved with concentrated nitric acid.

9 Measurement procedure
9.1 General

Follow the instructions provided by the instrument manufacturer and the steps described in

ISO 17294-1:2004, Clauses 7 and 9 in particular and ISO 17294-2:2016, Clauses 8 to 11 in particular.

The sensitivity, the instrumental detection limit and the precision should be established for each

analysis performed in the instrument.
238 +
Although the chemic
...

NORME ISO
INTERNATIONALE 20899
Première édition
2018-09
Qualité de l'eau — Plutonium et
neptunium — Méthode d'essai par
ICP-MS
Water quality — Plutonium and neptunium — Test method using
ICP-MS
Numéro de référence
ISO 20899:2018(F)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 20899:2018(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2018

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Publié en Suisse
ii © ISO 2018 – Tous droits réservés
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ISO 20899:2018(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

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

1 Domaine d'application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes, définitions, symboles et abréviations ..................................................................................................................... 2

4 Principe .......................................................................................................................................................................................................................... 3

5 Réactifs ........................................................................................................................................................................................................................... 4

6 Appareillage .............................................................................................................................................................................................................. 5

7 Échantillonnage ..................................................................................................................................................................................................... 5

8 Préparation des échantillons .................................................................................................................................................................. 5

8.1 Généralités .................................................................................................................................................................................................. 5

8.2 Conservation ............................................................................................................................................................................................. 6

8.3 Séparation chimique .......................................................................................................................................................................... 6

9 Mode opératoire de mesure ...................................................................................................................................................................... 6

9.1 Généralités .................................................................................................................................................................................................. 6

9.2 Quantification avec étalonnage interne et dilution isotopique ..................................................................... 7

10 Expression des résultats............................................................................................................................................................................... 7

10.1 Généralités .................................................................................................................................................................................................. 7

10.2 Evaluation du biais en masse ...................................................................................................................................................... 7

10.3 Etalonnage interne et dilution isotopique ...................................................................................................................... 8

11 Incertitudes pour dilution isotopique ........................................................................................................................................... 8

12 Limite de détection instrumentale .................................................................................................................................................... 8

13 Limite de quantification ............................................................................................................................................................................... 9

14 Détermination de l'activité volumique ......................................................................................................................................... 9

15 Rapport d'essai ...................................................................................................................................................................................................... 9

Annexe A (informative) Séparation chimique du plutonium et du neptunium avec une

résine spécifique ...............................................................................................................................................................................................11

Bibliographie ...........................................................................................................................................................................................................................13

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ISO 20899:2018(F)
Avant-propos

L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes

nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est

en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.

L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents

critères d'approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/directives).

L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de

droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de

brevets reçues par l'ISO (voir www .iso .org/brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion

de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir www .iso .org/avant -propos.

Le présent document a été élaboré par le Comité technique ISO/TC 147, Qualité de l'eau, Sous-comité

SC 3, Mesurages de la radioactivité.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www .iso .org/fr/members .html.
iv © ISO 2018 – Tous droits réservés
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ISO 20899:2018(F)
Introduction

La radioactivité provenant de sources d'origine naturelle et anthropique est présente partout dans

l'environnement. Par conséquent, les masses d'eau (par exemple eaux de surface, eaux souterraines,

eaux de mer) peuvent contenir des radionucléides d'origine naturelle, d'origine anthropique ou les deux:

40 3 14

— les radionucléides naturels, y compris K, H, C, et ceux provenant des chaînes de désintégration

226 228 234 238 210 210

du thorium et de l'uranium, en particulier Ra, Ra, U, U, Po et Pb, peuvent se trouver

dans l'eau pour des raisons naturelles (par exemple, désorption par le sol et lessivage par les eaux

pluviales) ou ils peuvent être libérés par des processus technologiques impliquant des matériaux

radioactifs existant à l'état naturel (par exemple, extraction et traitement de sables minéraux ou

production et utilisation d'engrais phosphatés).

— Les radionucléides artificiels, tels que les éléments transuranium (américium, plutonium, neptunium,

3 14 90

curium), H, C, Sr et les radionucléides émetteurs gamma peuvent aussi se trouver dans les eaux

naturelles. De petites quantités de ces radionucléides sont déversées dans l'environnement par les

installations à cycle de combustible nucléaire en conséquence de leur rejet périodique autorisé.

Certains de ces radionucléides utilisés dans le cadre d'applications médicales et industrielles sont

également rejetés dans l'environnement suite à leur utilisation. Les radionucléides anthropiques

peuvent également se trouver dans les eaux du fait de contaminations par retombées d'éléments

radioactifs rejetés dans l'atmosphère lors de l'explosion de dispositifs nucléaires ou lors d'accidents

nucléaires, tels que ceux de Tchernobyl et de Fukushima.

L'activité volumique des radionucléides dans les masses d'eau est variable en fonction des

caractéristiques géologiques et des conditions climatiques locales, et peut être renforcée localement

et dans le temps par les rejets d'installations nucléaires dans des situations d'exposition planifiée,

[1]

d'exposition d'urgence et d'exposition existante . L'eau potable peut alors contenir des radionucléides

à des valeurs d'activité volumique représentant potentiellement un risque sanitaire pour l'Homme.

Les radionucléides présents dans les effluents liquides sont habituellement contrôlés avant d'être

[2]

déversés dans l'environnement et les masses d'eau. La radioactivité des eaux potables est surveillée

)[3]

conformément aux recommandations de l'Organisation mondiale de la santé (OMS de manière à ce

que les actions appropriées puissent être conduites pour garantir l'absence d'effets indésirables sur

la santé du public. Conformément à ces recommandations internationales, les législations nationales

spécifient généralement des limites de concentration en radionucléides autorisées pour les effluents

liquides déversés dans l'environnement ainsi que des limites indicatives concernant les teneurs en

radionucléides dans les masses d'eau et les eaux potables dans les situations d'exposition planifiées,

existantes et d'urgence. La conformité à ces limites peut être évaluée à partir des résultats de mesure et

[4] [5]

des incertitudes qui y sont associées, comme spécifié par le Guide 98-3 de l'ISO/IEC et l'ISO 5667-20 .

Selon la situation d'exposition, différentes limites et différents niveaux indicatifs entraîneront une

action pour réduire le risque sanitaire. A titre d'exemple, durant une situation planifiée ou existante,

les lignes directrices de l'OMS concernant la limite indicative dans l'eau potable sont de 1 Bq/l pour

239 240 241
l'activité volumique de Pu, Pu et Pu.

NOTE 1 La limite indicative correspond à l'activité volumique pour une consommation de 2 l/j d'eau

potable pendant un an, aboutissant à une dose effective de 0,1 mSv/a pour les personnes du public. Cette dose

effective présente un niveau de risque très faible qui ne devrait pas entraîner d'effets indésirables pour la santé

[3]
détectables .
[7]

En situation d'urgence nucléaire, les limites directives du Codex de l'OMSl indiquent que

l'activité volumique ne pourrait pas être supérieure à 1 Bq/l et 10 Bq/l pour 239Pu, 240Pu, 241Pu,

respectivement, pour les nourrissons et autres personnes que les nourrissons.

NOTE 2 Les limites indicatives du Codex s'appliquent aux radionucléides contenus dans les aliments destinés

à la consommation humaine et commercialisés internationalement, qui ont été contaminés suite à une urgence

radiologique ou nucléaire. Ces limites indicatives s'appliquent aux aliments après reconstitution ou tels que

préparés pour la consommation, c'est-à-dire des aliments non séchés ou concentrés, et sont fondées sur un niveau

[7]

d'exemption d’intervention de 1 mSv en un an pour le public (nourrissons et adultes) .

© ISO 2018 – Tous droits réservés v
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ISO 20899:2018(F)

Ainsi il est possible d'adapter la méthode d'essai de façon à ce que les limites caractéristiques, le

seuil de décision, la limite de détection et les incertitudes garantissent qu'il soit possible de vérifier

que les résultats d'essai relatifs à l'activité volumique des radionucléides sont inférieurs aux limites

indicatives requises par une autorité nationale soit pour des situations existantes/planifiées, soit pour

[6][7][8]
une situation d'urgence .

En général, il est possible d'ajuster les méthodes d'essai pour mesurer l'activité volumique du ou des

radionucléides, soit dans les eaux usées avant stockage, soit dans les effluents liquides avant qu'ils

ne soient déversés dans l'environnement. Les résultats d'essai permettront à l'opérateur de l'usine/

de l'installation de vérifier que les concentrations d'activité radioactive des eaux usées/des effluents

liquides ne dépassent pas les limites autorisées, avant que ceux-ci ne soient rejetés.

La ou les méthodes d'essai décrites dans le présent document peuvent être utilisées dans des situations

d'exposition planifiées, existantes et d'urgence ainsi que pour les eaux usées et les effluents liquides,

avec des modifications spécifiques qui pourraient augmenter l'incertitude globale, la limite et le seuil

de détection.

La ou les méthodes d'essai peuvent être utilisées pour des échantillons d'eau après un échantillonnage,

une manipulation et une préparation de l'échantillon pour essai adaptés (voir la partie pertinente de la

série ISO 5667).

L'existence d'une Norme internationale décrivant une méthode de détermination pour la concentration

239 240 241 237

en Pu, Pu, Pu et Np dans les échantillons d'eau est justifiée pour les laboratoires d'essai

réalisant ces mesurages, parfois requis par les autorités nationales, car les laboratoires peuvent être

dans l'obligation d'obtenir une accréditation spécifique pour la réalisation de mesures de radionucléides

dans des échantillons d'eau potable.

Le présent document fait partie d'un ensemble de Normes internationales relatives aux méthodes

d'essai qui traitent du mesurage de l'activité volumique des radionucléides dans des échantillons d'eau.

vi © ISO 2018 – Tous droits réservés
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NORME INTERNATIONALE ISO 20899:2018(F)
Qualité de l'eau — Plutonium et neptunium — Méthode
d'essai par ICP-MS

AVERTISSEMENT — Il convient que l’utilisateur du présent document connaisse bien les

pratiques courantes de laboratoire. Le présent document n’a pas pour but de traiter tous les

problèmes de sécurité qui sont, le cas échéant, liés à son utilisation. Il incombe à l’utilisateur de

ce document d’établir des pratiques appropriées en matière d’hygiène et de sécurité.

IMPORTANT — Il est absolument essentiel que les essais conduits conformément au présent

document soient exécutés par du personnel titulaire d'une qualification appropriée.

1 Domaine d'application

Le présent document décrit des méthodes permettant de déterminer la concentration des isotopes du

plutonium et du neptunium dans l'eau, par spectrométrie de masse avec plasma à couplage inductif

239 240 241 237

(ICP-MS) ( Pu, Pu, Pu et Np). Les concentrations obtenues peuvent être converties en

[9]
activités volumiques des différents isotopes .
238 238

En raison de sa période relativement courte et des interférences isobariques de U, Pu est

difficilement mesurable par cette méthode. Pour quantifier cet isotope, il est possible d’utiliser d’autres

techniques (ICP-MS avec cellule de collision-réaction, ICP-MS/MS avec cellule de collision-réaction ou

[10]

séparation chimique). Un mesurage par spectrométrie alpha, comme décrit dans l'ISO 13167 , est

[11]
couramment réalisé .

La présente méthode est applicable à tous types d'eau ayant une charge saline inférieure à 1 g·l . Une

dilution de l'échantillon est possible afin d'obtenir une solution ayant une charge saline et une activité

volumique compatibles avec la préparation et l'appareillage de mesure.

Une filtration à 0,45 μm est nécessaire pour déterminer les nucléides dissous. Une acidification et une

séparation chimique de l'échantillon sont toujours nécessaires.

La limite de quantification est fonction de la séparation chimique et des performances du dispositif

de mesure.

Cette méthode couvre le mesurage des isotopes présents dans les eaux dont l'activité volumique est

[12][13]
approximativement comprise :
-1 -1 239 240 237
— entre 1 mBq·l et 5 Bq·l pour Pu, Pu et Np;
-1 -1 241
— entre 1 Bq·l et 5 Bq·l pour Pu.

Dans les deux cas, des échantillons ayant une activité volumique supérieure à 5 Bq·l peuvent être

soumis au mesurage s'ils sont dilués avant la séparation chimique.
241

Il est possible de mesurer le Pu après une étape de préconcentration d'au moins 1 000.

2 Références normatives

Les documents suivants cités dans le texte constituent, pour tout ou partie de leur contenu, des

exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les

références non datées, la dernière édition du document de référence s'applique (y compris les éventuels

amendements).

ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d’essai

© ISO 2018 – Tous droits réservés 1
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ISO 20899:2018(F)

ISO 5667-1, Qualité de l’eau —- Échantillonnage — Partie 1: Guide général pour l’établissement des

programmes d’échantillonnage

ISO 5667-3, Qualité de l’eau — Échantillonnage — Partie 3: conservation et manipulation des

échantillons d’eau

ISO 5667-10, Qualité de l’eau —- Échantillonnage —- Partie 10: Guide pour l’échantillonnage des eaux

résiduaires

ISO 17294-1:2004, Qualité de l’eau — Application de la spectrométrie de masse avec plasma à couplage

inductif (ICP-MS) — Partie 1: Lignes directrices générales.

ISO 17294-2:2016, Qualité de l’eau — Application de la spectrométrie de masse avec plasma à couplage

inductif (ICP-MS) —Partie 2: Dosage des éléments sélectionnés y compris les isotopes d’uranium

ISO 80000-10, Grandeurs et unités — Partie 10: Physique atomique et nucléaire.

ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d’étalonnages et d’essais.

3 Termes, définitions, symboles et abréviations

Pour les besoins du présent document, les termes, définitions, symboles et abréviations de

l'ISO 80000-10, ainsi que les suivants s'appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l’adresse https: //www .iso .org/obp

— IEC Electropedia: disponible à l’adresse http: //www .electropedia .org/
Symbole ou
Terme Unité Définition
abbréviation
Concentration en masse ρ μg·l Masse d'analyte pour un radionucléide donné
par unité de volume d'échantillon.

Concentration en masse de la ρ μg·l Masse de radionucléide étalon interne par unité

solution d'étalon interne de volume de solution d'étalon interne.
Masse de l’étalon interne m μg Masse du traceur de dilution isotopique ajouté
Incertitude type u(ρ) μg·l Incertitude-type associée au résultat de mesure
Incertitude élargie U(x) Produit de l'incertitude-type par le facteur
d'élargissement k, avec k = 1, 2,…, U = k · u
Incertitude type u(x) Incertitude-type associée au résultat de
mesure de x
Limite de détection DL μg·l La limite de détection est la plus petite quantité
d’analyte pouvant être détectée à l’aide d’un
instrument, comme déterminé par le mesurage
répété d’un blanc de réactif.
Limite de quantification LOQ μg·l La limite de quantification est la plus faible
concentration d’analyte dans l’échantillon pour
mBq.l
essai pouvant être déterminée avec une exacti-
tude définie.
Écart type du blanc s Ecart-type obtenu avec des réplicats du blanc.

Limite de quantification LOQ Coups.s La LOQ est la limite de quantification expri-

ins ins
instrumentale mée sous forme de taux de comptage pour le
rapport masse/charge (m/z) choisi, due au blanc
et à l'instrument.
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ISO 20899:2018(F)
Symbole ou
Terme Unité Définition
abbréviation
Limite de détection IDL Coups.s L’IDL est la limite de détection exprimée sous
instrumentale forme de taux de comptage pour le rapport
masse/charge (m/z) choisi.
Volume de l’échantillon V l
Bruit de fonds N Coups.s Taux de comptage pour une masse donnée dans
la solution à blanc.
Nombre de coups N Coups.s Taux de comptage brut: taux de comptage non
corrigé d’un mesurage
Net counts N Coups.s N-N
net 0
Nombre de coups net N Coups.s Pour la masse de l’étalon interne
netT
Biais par unité de masse α
Masse m Nombre de masse de l’isotope.
Différence de masse Δm m -m
i j
Rapport isotopique mesuré r
Rapport isotopique réel R
Activité spécifique C Bq·g Activité correspondant à un gramme de radio-
nucléide.
Activité volumique C Bq·l Correspondant à la concentration en masse ρ
mesurée pour un radionucléide donné.
4 Principe

Le principe de mesure de l'analyse par ICP- MS est décrit dans l'ISO 17294-1 et l'ISO 17294-2.

L'ICP-MS peut être utilisée pour déterminer les concentrations en masse des isotopes du plutonium

239 240 241 237
( Pu, Pu, Pu) et du Np dans des échantillons d'eau.

Les résultats peuvent être convertis en activité volumique en utilisant les facteurs de conversion du

Tableau 1.
[12][13]

Tableau 1 — Période et activité spécifique des isotopes du plutonium et du neptunium

Période Activité spécifique
Isotope du
plutonium
années Bq·g−1
239 9 6
Pu 24 100 (±11) 2,296·10 (±2,000·10 )
240 9 6
Pu 6 561 (±7) 8,396·10 (±9,000·10 )
241 12 10
Pu 14,33 (±0,04) 3,829·10 (±1,100·10 )
242 5 8 6
Pu 3,73 (±0,03)·10 1,465·10 (±1,180·10 )
244 6 5 3
Pu 81,1 (±0,6)·10 6,683·10 (±7,600·10 )
Période Activité spécifique
Neptunium
années Bq·g
237 6 7 4
Np 2,144 (±0,007)·10 2,603·10 (±9,000·10 )

L'échantillon d'eau doit être mesuré après filtration (à une porosité de 0,45 μm) pour la détermination

des radionucléides dissous et une séparation chimique spécifique doit être réalisée pour limiter les

[14]

interférences potentielles dues aux isotopes de l'uranium . Un exemple de séparation chimique est

donné en Annexe A.

Comme décrit dans la série ISO 17294, un traceur est nécessaire pour évaluer le rendement de

séparation chimique et effectuer une dilution isotopique. Une quantité connue de solution étalon de

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ISO 20899:2018(F)

traceur pure et certifiée est ajoutée à la prise d'essai et le calcul de la concentration des isotopes est

basé sur les rapports isotopiques.

Même si des solutions étalons dont l’activité est certifiée existent, l'étalonnage externe n'est pas utilisé

239 240 241

car il est difficile de trouver des solutions étalons d'isotopes du plutonium ( Pu, Pu, Pu) et du

237
Np, dont la masse est certifiée.
242 244

Pour déterminer les isotopes du plutonium dans l'eau, on utilise couramment le Pu mais le Pu

peut également convenir.

Le rendement chimique obtenu pour le plutonium peut être appliqué au neptunium. Cela peut

entraîner un biais potentiel qui doit être quantifié. Il est préférable d'utiliser d'autres méthodes comme

239 237

l'étalonnage externe, l'ajout du Np à courte période comme traceur, les ajouts dosés de Np dans

plusieurs prises d'essai de l'échantillon, etc.

Il est également important d'évaluer le biais en masse et de le corriger (voir 10.2).

Le Tableau 2 donne des exemples de limites de quantification qui peuvent être obtenues avec un ICP-MS

quadripolaire.
[15][16]
Tableau 2 — Exemples de limites de quantification
LOQ LOQ
Isotope
−1 −1
μg·l mBq·l
237
Np 3,85E-07 0,01
239
Pu 8,70E-07 2
240
Pu 4,76E-07 4
241
Pu 3,93E-07 1 500

Par la séparation chimique, il est possible d'obtenir un facteur élevé de décontamination de l'uranium

mais il est probable que la concentration en uranium restante sera encore supérieure à la concentration

238 238

type de Pu attendue dans l'eau. En outre, cette concentration du Pu est présumée inférieure

à la limite de quantification rapportée. Pour ces raisons, l'appareillage courant n'est pas adapté aux

238

mesurages du Pu, dans les conditions normales. Cependant, en supposant que l'on puisse monter une

cellule de collision-réaction sous pression sur un instrument plus sensible, ce nouvel appareil pourrait

être plus adapté à la séparation des interférences isobariques.
5 Réactifs
Utiliser uniquement des réactifs de qualité analytique reconnue.
5.1 Eau pour laboratoire, de qualité 3 telle que spécifiée dans l’ISO 3696.
5.2 Blanc

Un essai à blanc est réalisé durant tout le mode opératoire, y compris la séparation chimique.

Une solution d'acide dilué est utilisée pour déterminer les spectres de bruit de fond pour les

différentes masses.
5.3 Solutions étalons des isotopes certifiées

Il est recommandé d'utiliser une solution étalon certifiée de composition isotopique connue pour

évaluer le biais en masse.

De même l'emploi d'une solution de référence de composition isotopique d’actinide connue convient

pour le dosage par encadrement par l'étalon (au moins deux mesurages avant et après l'échantillonnage,

avec plusieurs répétitions).
4 © ISO 2018 – Tous droits réservés
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ISO 20899:2018(F)
242
5.4 Solution du traceur (par exemple Pu)

Préparer cette solution par dilutions successives de la solution étalon certifiée, le dernière dilution

dans de l'acide nitrique à 1 % à 2 % (en volume). Ajuster la concentration en fonction de la validation

de la méthode. Doper les échantillons d'eau avec une quantité connue de cette solution au début de la

procédure.
5.5 Solution de contrôle qualité

Il est recommandé d'utiliser une solution à concentration de plutonium certifiée différente de celle

utilisée pour la dilution isotopique.
5.6 Argon, de pureté au moins égale à 99,995 %.
5.7 Acide nitrique dilué, à 2 % en volume, par exemple.
6 Appareillage
Le matériel courant de laboratoire et, en particulier, ce qui suit.
6.1 Balance analytique, précise à 1/10 mg près.
6.2 Alimentation en argon, équipée d'un pressostat basse pression.
6.3 Spectromètre ICP‑MS avec logiciel, installé dans une salle climatisée.
6.4 Échantillonneur automatique, si disponible.
6.5 Membrane filtrante, 0,45 µm.
7 Échantillonnage

Pour le dosage des quantités à l'état de trace, la première préoccupation doit être la prévention de

toutes les contaminations ou pertes. La poussière présente dans le laboratoire, les impuretés dans les

réactifs et sur le matériel de laboratoire qui est en contact avec l'échantillon sont toutes des sources

potentielles de contamination. La désorption ou l'adsorption superficielle des récipients d'échantillons

peuvent conduire à un biais positif ou négatif, lors du dosage des éléments traces.

Réaliser les étapes de stockage et de prétraitement (filtration et acidification) décrites dans l’Article 8

pendant ou juste après l'échantillonnage.

L’échantillonnage, la manipulation et le stockage de l’eau doivent être réalisés comme spécifié dans

les ISO 5667-1, ISO 5667-3 et ISO 5667-10. Des recommandations sur les différents types d’eaux sont

[17] [21]
données da
...

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