ISO 1709:2018

INTERNATIONAL ISO
STANDARD 1709
Third edition
2018-02
Nuclear energy — Fissile materials
— Principles of criticality safety in
storing, handling and processing
Énergie nucléaire — Matières fissiles — Principes de sûreté-criticité
lors des opérations d'entreposage, de manutention et de mise en
oeuvre du procédé
Reference number
©
ISO 2018
© 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

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Procedures . 3
4.1 General . 3
4.2 Responsibility . 3
4.3 Equipment design. 3
4.4 Criticality assessment . 3
4.5 Written procedures . 3
4.6 Review of procedures . 4
4.7 Processing violations . 4
4.8 Training . 4
5 Technical criteria . 4
5.1 General . 4
5.2 Methods of control . 4
5.3 Achievement of control . 4
5.4 Factors affecting criticality . 5
5.4.1 General. 5
5.4.2 Mass . 5
5.4.3 Geometry . 5
5.4.4 Volume . 5
5.4.5 Concentration . 5
5.4.6 Moderation. 5
5.4.7 Neutron absorbers . 5
5.4.8 Physical and chemical form . 6
5.4.9 Density . 6
5.4.10 Enrichment . 6
5.4.11 Reflection . . 6
5.4.12 Interaction . 6
5.4.13 Temperature . 6
5.5 Possible abnormalities . 7
5.6 Bases of assessment . 7
5.7 Margin of criticality safety . 7
5.8 Demonstration of safety . 7
6 Equipment control . 8
7 Material control . 8
8 Dispatch and receipt of material . 8
9 Monitoring of procedures . 8
10 Need for an emergency plan and criticality alarm . 8
Bibliography . 9
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: 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.
This third edition cancels and replaces the second edition (ISO 1709:1995), which has been technically
revised.
A list of all parts in the ISO 1709 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 1709:2018(E)
Nuclear energy — Fissile materials — Principles of
criticality safety in storing, handling and processing
1 Scope
This document specifies the basic principles and limitations which govern operations with fissile
materials. It discusses general nuclear criticality safety criteria for equipment design and for the
development of operating controls, while providing guidance for the assessment of procedures,
equipment, and operations. It does not cover specific quality assurance requirements or details of
equipment or operational procedures.
This document does not deal with the issues associated with administrative criteria relating to nuclear
criticality safety. These issues are covered by ISO 14943. It does not cover the effects of radiation on
man or materials, unless the material properties affect nuclear criticality safety.
These criteria apply to operations with fissile materials outside nuclear reactors but within the
boundaries of nuclear establishments. They are concerned with the limitations which are imposed on
operations because of the properties of these materials which permit them to support nuclear chain
reactions. These principles apply to quantities of fissile nuclides in which nuclear criticality safety is
required to be established.
This document can also be applied to the transport of fissile materials outside the boundaries of nuclear
establishments.
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 7753, Nuclear energy — Performance and testing requirements for criticality detection and alarm systems
ISO 11320, Nuclear criticality safety — Emergency preparedness and response
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
critical
having an effective neutron multiplication factor equal to unity
3.2
double batching
unintended increase in the quantity of a material that is controlled for Nuclear Criticality Safety such
that twice the intended quantity is present
Note 1 to entry: This typically applies to processes involving discrete quantities of material.
3.3
fissile material
material, other than natural or depleted uranium, that is capable of sustaining a thermal neutron chain
reaction
3.4
fissile nuclide
nuclide capable of undergoing fission by interaction with neutrons of any energy
3.
...