ISO INTERNATIONAL STANDARD 11231 Second edition 2019-05 Space systems Probabilistic risk assessment (PRA) Systemes spatiaux - Evaluation du risque probabiliste (PRA) Reference number IS0 11231:2019(E) so @ IS0 2019 IS0 11231:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ 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: +4122 749 0111 Fax: +41 22 749 09 47 Email: copyright@iso.org Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 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 successand system safety riskassessment concept ..4 4.3 PRA general process. .7 Objectives, uses and benefits of probabilistic risk assessment. .8 5 5.1 Objectivesofaprobabilisticriskassessment ..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 Probabilisticriskassessmentreguirements .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. .11 6.3.4 Task 3: Initiating event identification .11 6.3.5 Task 4: Scenario modelling .12 6.3.6 Task 5: Failure modelling 12 6.3.7 Task 6: Quantification. .13 6.3.8 Task 7: Uncertainty analysis .13 6.3.9 Task 8: Sensitivity analysis. .14 6.3.10 Task 9: Ranking. ..14 6.3.11 Data analysis. ..15 7 Peer review .15 7.1 General .15 7.2 Internal peer reviews .15 7.3 External peer reviews .15 8 Probabilistic risk assessment report Data content requirements .16 Annex A (informative) Example of space systems unit-value/mission-criticality category definitions ..17 Annex B (informative) Capability-based PRA process tailoring guidance ..18 Bibliography .22 @ IS0 2019 - All rights reserved iii