oSIST prEN ISO 18256-2:2020

Nuclear fuel technology - Dissolution of plutonium dioxide-containing materials - Part 2: Dissolution of MOX pellets and powders (ISO 18256-2:2019)

This document specifies the dissolution of samples consisting of MOX pellets or powders to provide suitable aliquots for subsequent analysis of elemental concentration and isotopic composition.

Technologie du combustible nucléaire - Dissolution des matériaux contenant du dioxyde de plutonium - Partie 2: Dissolution de pastilles et poudres de MOX (ou mélanges d'oxydes) (ISO 18256-2:2019)

Le présent document spécifie un mode opératoire pour la dissolution d'échantillons composés de pastilles ou poudres de MOX (mélange d'oxydes) pour fournir des solutions appropriées afin de permettre l'analyse ultérieure de la concentration des éléments et de la composition isotopique.

Tehnologija jedrskih goriv - Raztapljanje materialov, ki vsebujejo plutonijev dioksid - 2. del: Raztapljanje peletov in praškov MOX (ISO 18256-2:2019)

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 18256-2:2020
01-november-2020

Tehnologija jedrskih goriv - Raztapljanje materialov, ki vsebujejo plutonijev dioksid

- 2. del: Raztapljanje peletov in praškov MOX (ISO 18256-2:2019)

Nuclear fuel technology - Dissolution of plutonium dioxide-containing materials - Part 2:

Dissolution of MOX pellets and powders (ISO 18256-2:2019)

Technologie du combustible nucléaire - Dissolution des matériaux contenant du dioxyde

de plutonium - Partie 2: Dissolution de pastilles et poudres de MOX (ou mélanges
d'oxydes) (ISO 18256-2:2019)
Ta slovenski standard je istoveten z: prEN ISO 18256-2
ICS:
27.120.30 Cepljivi materiali in jedrska Fissile materials and nuclear
gorivna tehnologija fuel technology
oSIST prEN ISO 18256-2:2020 en,fr,de

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

---------------------- Page: 1 ----------------------
oSIST prEN ISO 18256-2:2020
---------------------- Page: 2 ----------------------
oSIST prEN ISO 18256-2:2020
INTERNATIONAL ISO
STANDARD 18256-2
First edition
2019-01
Nuclear fuel technology — Dissolution
of plutonium dioxide-containing
materials —
Part 2:
Dissolution of MOX pellets and
powders
Technologie du combustible nucléaire — Dissolution des matériaux
contenant du dioxyde de plutonium —
Partie 2: Dissolution de pastilles et poudres de MOX (ou mélanges
d'oxydes)
Reference number
ISO 18256-2:2019(E)
ISO 2019
---------------------- Page: 3 ----------------------
oSIST prEN ISO 18256-2:2020
ISO 18256-2:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 18256-2:2020
ISO 18256-2:2019(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Summary of the method ............................................................................................................................................................................... 1

5 Apparatus and reagents ................................................................................................................................................................................ 2

5.1 Apparatus .................................................................................................................................................................................................... 2

5.2 Reagents........................................................................................................................................................................................................ 2

6 Sample dissolution ............................................................................................................................................................................................. 3

6.1 Procedure for common plutonium containing materials ................................................................................... 3

6.2 Solution adjustment (optional) ................................................................................................................................................ 5

7 Quality control ........................................................................................................................................................................................................ 6

Bibliography ................................................................................................................................................................................................................................ 7

© ISO 2019 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 18256-2:2020
ISO 18256-2:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,

and radiological protection, Subcommittee SC 5, Nuclear installations, processes and technologies.

A list of all the parts in the ISO 18256 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 18256-2:2020
ISO 18256-2:2019(E)
Introduction

This document describes a method to dissolve samples consisting of MOX pellets or powders to provide

suitable aliquots for subsequent analysis of elemental concentration and isotopic composition.

© ISO 2019 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST prEN ISO 18256-2:2020
---------------------- Page: 8 ----------------------
oSIST prEN ISO 18256-2:2020
INTERNATIONAL STANDARD ISO 18256-2:2019(E)
Nuclear fuel technology — Dissolution of plutonium
dioxide-containing materials —
Part 2:
Dissolution of MOX pellets and powders
1 Scope

This document specifies the dissolution of samples consisting of MOX pellets or powders to provide

suitable aliquots for subsequent analysis of elemental concentration and isotopic composition.

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 http: //www .electropedia .org/
4 Summary of the method

Among the factors affecting the formation of solid solution and hence, the ease of dissolution are:

— the method of fuel fabrication (i.e. mechanically blended oxides, co-precipitated oxides, microwave

denitrated oxides or sol-gel oxides);
— the degree of sintering.

Therefore, different dissolution methods are applied depending on the type of MOX sample to be

dissolved.

The radiological hazard of plutonium and the need to minimize the waste shall be taken into account

when choosing the mass of the sample to be dissolved. A MOX mass of 0,1 g to 10 g should be sufficient

for most of the analyses. Some analysis may however require more material.

For the highest possible assay accuracy only gravimetric dissolution methods are recommended.

However for a less critical assay, volumetric dissolution may be appropriate.
© ISO 2019 – All rights reserved 1
---------------------- Page: 9 ----------------------
oSIST prEN ISO 18256-2:2020
ISO 18256-2:2019(E)

For grain-size powders, the sample is transferred in a pre-weighed flask or vial made of glass, high-

density polyethylene (HDPE), polytetrafluoroethylene (PTFE), Nalgene or other container types,

but the choice of the container has consequences.

— When using a glass dissolution vessel, the added fluoride will attack the glass (resulting in a

falsification of the pre-weighed tare) but with the benefit that the fluoride is ultimately removed

from the solution via release of volatile SiF . The resulting reduction in fluoride content of the final

solution guards against the formation of insoluble plutonium fluoride (especially below 8 M), which

would negatively bias the plutonium element content up to 0,1 % [or more when large quantities of

hydrofluoric acid (HF) are used). The tare mass of the etched glass vessel may be re-established by

careful cleaning, drying and re-weighing of the vessel.
TM1)

— HDPE, PTFE or Nalgene dissolution vessels are not reactive to HF, therefore tare mass remains

unaffected. However, these materials have the disadvantage that fluoride ions in the dissolution

liquor promote the precipitation of insoluble plutonium fluoride when the oxidation state of

plutonium is reduced from IV to III (e.g. by later volume adjustments using a low molarity acid).

An aqueous dissolving mixture comprising nitric acid (about 8 mol/l to 14 mol/l) and an effective

catalytic amount of fluoride ions from either hydrofluoric acid (abou
...