prEN ISO 7753
(Main)Nuclear criticality safety - Use of criticality accident alarm systems for operations (ISO 7753:2023)
Nuclear criticality safety - Use of criticality accident alarm systems for operations (ISO 7753:2023)
This document provides requirements and guidance regarding the use of CAAS for operations of a nuclear facility. Requirements and guidance on CAAS design are provided in the IEC 60860.
This document is applicable to operations with fissile materials outside nuclear reactors but within the boundaries of nuclear establishments.
This document applies when a need for CAAS has been established. Information about the need for CAAS is given in Annex C.
This document does not include details of administrative steps, which are considered to be activities of a robust management system (ISO 14943 provides details of administrative steps).
Details of nuclear accident dosimetry and personnel exposure evaluations are not within the scope of this document.
This document is concerned with gamma and neutron radiation rate-sensing systems. Specific detection criteria can also be met with integrating systems; systems detecting either neutron or gamma radiation can also be used. Equivalent considerations then apply.
Kritikalitätssicherheit - Einsatz von Kritikalitätsdetektions- und Alarmsystemen im Betrieb (ISO 7753:2023)
Sûreté-criticité - Systèmes de détection et d’alarme de criticité dans le cadre de l’exploitation (ISO 7753:2023)
Varnost jedrske kritičnosti - Uporaba alarmnih sistemov za obvladovanje kritičnih nesreče pri obratovanju (ISO 7753:2023)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2025
Varnost jedrske kritičnosti - Uporaba alarmnih sistemov za obvladovanje kritičnih
nesreče pri obratovanju (ISO 7753:2023)
Nuclear criticality safety - Use of criticality accident alarm systems for operations (ISO
7753:2023)
Kritikalitätssicherheit - Einsatz von Kritikalitätsdetektions- und Alarmsystemen im Betrieb
(ISO 7753:2023)
Sûreté-criticité - Systèmes de détection et d’alarme de criticité dans le cadre de
l’exploitation (ISO 7753:2023)
Ta slovenski standard je istoveten z: prEN ISO 7753
ICS:
13.280 Varstvo pred sevanjem Radiation protection
13.320 Alarmni in opozorilni sistemi Alarm and warning systems
27.120.20 Jedrske elektrarne. Varnost Nuclear power plants. Safety
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 7753
Second edition
2023-09
Nuclear criticality safety — Use of
criticality accident alarm systems for
operations
Sûreté-criticité — Systèmes de détection et d’alarme de criticité dans
le cadre de l’exploitation
Reference number
ISO 7753:2023(E)
ISO 7753:2023(E)
© ISO 2023
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
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 7753:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General design, detection principle . 2
4.1 CAAS functions. 2
4.1.1 Main function . 2
4.1.2 Additional functions (optional) . 3
4.2 Resilience . 3
4.3 Detection criterion . 3
5 Management of unavailability .4
6 System design . 4
6.1 General . 4
6.2 Alarm. 4
6.3 Connections . 5
6.4 Failure of detectors, false alarms, detection logic . 5
6.5 Obsolescence, replacement parts . 5
6.6 Supervising . 5
7 Criteria for positioning .6
7.1 General . 6
7.2 Positioning of detectors and detection zone . 6
7.3 Alarm signal . 6
7.4 Positioning of other CAAS components . 6
8 Testing. 6
9 Personnel familiarization . 7
Annex A (informative) Elements for the definition of the minimum accident of concern .8
Annex B (informative) Principles for CAAS detectors positioning .16
Annex C (informative) Examples of CAAS need considerations .24
Bibliography .28
iii
ISO 7753:2023(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.
This second edition cancels and replaces the first edition (ISO 7753:1987), which has been technically
revised.
The main changes are as follows:
— clarification of the scope and title: this standard is intended for CAAS users;
— improved differentiation with IEC 60860, intended for CAAS designers, manufacturers, providers…;
— removal of CAAS need considerations from the normative part;
— more open definition of the MAC to reflect the variety of practices and possibilities;
— more developed clauses regarding management of unavailability, reliability, positioning of CAAS
components;
— addition of a “continuum of detection” concept;
— better integration with other existing ISO standards related to criticality-safety (ISO 1709,
ISO 11320, ISO 27467, ISO 14943, ISO 16117 and ISO 21391);
— rewriting and expansion of informative Annexes A and B:
— Elements for the definition of the minimum accident of concern;
— Principles for CAAS detectors positioning;
— creation of an informative Annex C: Examples of CAAS need considerations.
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 7753:2023(E)
Introduction
Nuclear criticality safety programs at facilities that might use or store significant quantities and
concentrations of fissile material are primarily directed at avoiding nuclear criticality accidents.
However, the possibility of such accidents exists and the consequences can be life-threatening. Nuclear
criticality accidents are complex events that can take various forms and without warning signs. For
facilities that are judged to have potential for a nuclear criticality accident, the defense-in-depth
principle requires limiting their radiological consequences.
Criticality accident alarm systems (CAAS) provide a means to detect nuclear criticality accidents and to
trigger an alarm to prompt the evacuation to a radiologically safe location.
This detection is very specific because of the various possible neutron kinetics and radiation fields
produced by a nuclear criticality accident comprising neutrons and photons (i.e. gamma radiation) with
a broad spectrum of energies. The primary purpose of CAAS is to prompt personnel to evacuate as
soon as possible during a nuclear criticality accident, thus limiting individual and collective radiological
doses. A CAAS cannot, and is not intended to, protect personnel from radiation from a nuclear criticality
accident prior to prompt evacuation or other protective actions.
Considerations about emergency preparedness and response, including the evacuation procedure
related to nuclear criticality accidents, are addressed in ISO 11320.
This document is supplemented by three informative annexes:
— Annex A outlines elements for the definition of the minimum accident of concern (MAC);
— Annex B provides examples of application of this document for the positioning of CAAS detectors;
— Annex C looks at the factors which are considered when assessing whether a CAAS is needed or not,
through examples.
v
INTERNATIONAL STANDARD ISO 7753:2023(E)
Nuclear criticality safety — Use of criticality accident
alarm systems for operations
1 Scope
This document provides requirements and guidance regarding the use of CAAS for operations of a
nuclear facility. Requirements and guidance on CAAS design are provided in the IEC 60860.
This document is applicable to operations with fissile materials outside nuclear reactors but within the
boundaries of nuclear establishments.
This document applies when a need for CAAS has been established. Information about the need for
CAAS is given in Annex C.
This document does not include details of administrative steps, which are considered to be activities of
a robust management system (ISO 14943 provides details of administrative steps).
Details of nuclear accident dosimetry and personnel exposure evaluations are not within the scope of
this document.
This document is concerned with gamma and neutron radiation rate-sensing systems. Specific detection
criteria can also be met with integrating systems; systems detecting either neutron or gamma radiation
can also be used. Equivalent considerations then appl
...
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