Space systems — Probabilistic risk assessment (PRA)

This document supports and complements the implementation of the risk management process defined in ISO 17666 in situations when the application of a quantitative risk assessment is deemed necessary. This document defines the principles, process, implementation and requirements for conducting a quantitative risk assessment and explains the details of probabilistic risk assessment (PRA) as applied to safety. While PRA can be applied to project risk management involving cost and schedule, this application is outside the scope of this document. This document provides the basic requirements and procedures for the use of PRA techniques to assess safety or mission risk and success in space programmes and projects. This document is applicable to all international space projects involving: — the design of space vehicles for the transportation of personnel in space; — the design of space and non-terrestrial planetary stations inhabited by human beings; — the design of space and launch vehicles powered by, or carrying, nuclear materials; — other projects as directed by the authorities or clients. These types of projects generally involve scenarios, chains of events or activities that could result in the death of, or serious injury to, members of the public, astronauts or pilots, or the workforce, or the loss of critical or high-value equipment and property. For other types of projects, it is intended that PRA be performed at the discretion of the project management.

Systèmes spatiaux — Évaluation du risque probabiliste (PRA)

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9020 - International Standard under periodical review
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ISO 11231:2019 - Space systems -- Probabilistic risk assessment (PRA)
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Standards Content (Sample)

Second edition
Space systems — Probabilistic risk
assessment (PRA)
Systèmes spatiaux — Évaluation du risque probabiliste (PRA)
Reference number
ISO 11231:2019(E)
ISO 2019

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ISO 11231:2019(E)

© 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.
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Phone: +41 22 749 01 11
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ii © ISO 2019 – All rights reserved

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ISO 11231:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 4
4 Principles of probabilistic risk assessment . 4
4.1 General . 4
4.2 Mission success and system safety risk assessment concept . 4
4.3 PRA general process . 7
5 Objectives, uses and benefits of probabilistic risk assessment . 8
5.1 Objectives of a probabilistic risk assessment . 8
5.2 Probabilistic risk assessment results usage . 8
5.3 Benefits of a probabilistic risk assessment . 9
6 PRA requirements and detailed process . 9
6.1 Probabilistic risk assessment requirements . 9
6.2 Overview of the probabilistic risk assessment process . 9
6.3 Probabilistic risk assessment basic tasks .10
6.3.1 General.10
6.3.2 Task 1: Objectives and approach definition .10
6.3.3 Task 2: System familiarization .

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