EN ISO 24459:2023

SLOVENSKI STANDARD
01-september-2023
Ugotavljanje vsebnosti urana v vzorcih iz jedrskega gorivnega cikla z L-
absorpcijsko robno spektrometrijo (ISO 24459:2021)
Determination of uranium content in samples coming from the nuclear fuel cycle by L-
absorption edge spectrometry (ISO 24459:2021)
Bestimmung von Uran in Lösungen des Kernbrennstoffkreislaufs - L-
Absorptionskantenspektrometrie (ISO 24459:2021)
Détermination de la quantité d'uranium dans des échantillons du cycle du combustible
nucléaire par spectrométrie de discontinuité d'absorption L (ISO 24459:2021)
Ta slovenski standard je istoveten z: EN ISO 24459:2023
ICS:
27.120.30 Cepljivi materiali in jedrska Fissile materials and nuclear
gorivna tehnologija fuel technology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 24459
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2023
EUROPÄISCHE NORM
ICS 27.120.30
English Version
Determination of uranium content in samples coming from
the nuclear fuel cycle by L-absorption edge spectrometry
(ISO 24459:2021)
Détermination de la quantité d'uranium dans des Bestimmung von Uran in Lösungen des
échantillons du cycle du combustible nucléaire par Kernbrennstoffkreislaufs - L-
spectrométrie de discontinuité d'absorption L (ISO Absorptionskantenspektrometrie (ISO 24459:2021)
24459:2021)
This European Standard was approved by CEN on 16 July 2023.

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

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

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 24459:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 24459:2021 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 24459:2023 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2024, and conflicting national standards shall
be withdrawn at the latest by January 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 24459:2021 has been approved by CEN as EN ISO 24459:2023 without any modification.

INTERNATIONAL ISO
STANDARD 24459
First edition
2021-10
Determination of uranium content
in samples coming from the nuclear
fuel cycle by L-absorption edge
spectrometry
Détermination de l'uranium dans les solutions du cycle du
combustible nucléaire par absorption de rayons X à la discontinuité L
Reference number
ISO 24459:2021(E)
ISO 24459:2021(E)
© ISO 2021
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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 24459:2021(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
6 Apparatus . 2
7 Method . 4
7.1 Pre-checks . 4
7.2 Reference spectrum . 4
7.3 Calibration . 4
7.4 Sample measurement . 5
7.5 Spectrum evaluation . 5
7.5.1 Region of interest . 5
7.5.2 Smoothing (optional) . 5
7.5.3 Background subtraction . 6
7.5.4 Calculation of the X-ray transmission . 6
7.6 Calculation of the concentration of uranium . 7
7.7 Quality control . 8
7.8 Uncertainty evaluation . 8
7.8.1 Standard uncertainty of the calibration factor . 8
7.8.2 Standard uncertainty of the uranium concentration . 9
Annex A (informative) Calculation method for correction factors of atomic mass and
temperature .10
Annex B (informative) Preparation of a solid quality control sample .11
Bibliography .13
iii
ISO 24459:2021(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 85, Nuclear energy, nuclear technologies,
and radio protection, Subcommittee SC 5, Analytical methodology in the nuclear fuel cycle.
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
INTERNATIONAL STANDARD ISO 24459:2021(E)
Determination of uranium content in samples coming from
the nuclear fuel cycle by L-absorption edge spectrometry
1 Scope
This document specifies a method for the determination of uranium concentrations in nitric acid or
TBP-DILUANT (for example TBP-kerosene) solutions coming from the nuclear fuel cycle.
The method is applicable
— for process control of solutions, free of suspension, which contain between 10 g/l to 300 g/l uranium,
and
— for high accuracy purposes (Safeguards) to nitric acid solutions, free of suspension, which contain
between 100 g/l and 220 g/l uranium.
Having
— the content of neptunium and plutonium impurities in the solution less than 1 % of the uranium
content.
— the content of neutron poisons (gadolinium, erbium) less than 1 % of the uranium content to ensure
the absence of significant interferences at the level of required precision, for high accuracy purposes.
The method is applicable to solid samples as well, provided that they can be fully dissolved in nitric acid.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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 https:// www .electropedia .org/
4 Principle
A highly collimated X-ray beam passes through a uranium solution with well-defined path length.
The transmission spectrum is recorded with a solid-state detector. A sharp jump of the photon
transmission, which is related to the concentration of uranium, occurs at the L-edge energy of uranium
(E = 17,17 keV). Uranium concentration is determined from the size of the jump using calibration and
LIII
spectrum processing algorithms.
The proposed spectrum processing algorithms require the acquisition of reference spectrum to cancel
out the influence of the matrix.
For high accuracy measurement, the isotopic composition of uranium and the temperature shall be
known and corrections may apply.
ISO 24459:2021(E)
The uncertainty of the number of counts in the channels before and after the L-edge is one of the main
contributors to the measurement uncertainty.
The acquisition time needed to reach the necessary number of counts depends of the total count
rate. The total count rate is a function of the intensity of the X-ray generator, of the characteristic of
instrument, and of the concentration of uranium.
It is therefore specific to the laboratory, which shall evaluate beforehand the fit-for-purpose accuracy
that will decide the target total count in the spectrum, the count rate and the acquisition time.
For high accuracy measurements, a minimum total number of counts of 2 000 000 in the fitting window
is required to ensure satisfactory statistics around the L-edge. The count rates and measurement times
given as indication in the document reflect this requirement. The reference, calibration and sample
spectra shall be recorded with the same count rate and the same high voltage (HV) cut-off.
For process control purposes, the necessary total number of counts will depend of the needed accuracy.
The measurement should be performed at the same HV cut-off and current.
5 Reagents and materials
Only analytical grade reagents shall be used.
All aqueous solutions shall be
...