CSA N290.19:18

Risk-informed decision making for nuclear power plants

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  Standards Update Service

  CSA N290.19:18

  December 2018

  
  

  Title: Risk-informed decision making for nuclear power plants

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CSA N290.19:18

Risk-informed decision making for nuclear power plants

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Contents

Technical Committee on Reactor Safety and Risk Management 3 Subcommittee on Risk-Informed Decision Making for Nuclear Power Plants 5 Preface 7

0 Introduction 8

1. General 8

2. Overview 8

3. Users 8

4. Benefits of using RIDM 8

1. Scope 9

   
   

2. Reference publications 9

   
   

3. Definitions and abbreviations 12

   1. Definitions 12

   2. Abbreviations 14

      
      

4. RIDM principles and considerations 15

   1. Management principles 15

      1. Management system 15

      2. RIDM process management 15

   2. RIDM process outcome 15

   3. RIDM process application 16

   4. Communication and stakeholder engagement 16

      1. Areas of RIDM Communication 16

      2. Communication plan 16

      3. Risk terminology 16

      4. Stakeholder engagement 16

      5. Opposition to decision 17

   5. Expectations for conduct of assessment 17

      1. General 17

      2. Objectives of assessment 17

      3. Items to consider during the assessment 17

      4. Tools 18

      5. Input data 18

      6. Risk categories 18

      7. Screening out risk contributors 19

      8. Dealing with uncertainties 20

   6. Risk tolerability and accepted limits 20

      1. Tolerability regions 20

      2. Identification of risks for activities 20

      3. Assessing incremental risk 21

      4. Accepted limits 21

      5. Intolerable region 21

5. RIDM process 22

   1. General 22

   2. RIDM communication 22

   3. Initiation 23

   4. Preliminary assessment 23

   5. Detailed assessment 24

   6. Risk integration 26

   7. Recommended RCMs 27

   8. Making decisions 28

   9. Implementation of risk control 28

   10. Evaluation of effectiveness of risk control 28

   11. Document the process 28

Annex A (informative) — RIDM process considerations 29

Annex B (informative) — Cost-benefit analysis 35

Annex C (informative) — RIDM tools examples 38

Annex D (informative) — Example of risk evaluation methodology 40

Technical Committee on Reactor Safety and Risk Management

Subcommittee on Risk-Informed Decision Making for Nuclear Power Plants

The Subcommittee would like to acknowledge the following individuals for their contributions to the development of this Standard:

Vinod Chugh (Power Generation Integrated Consulting Inc.) Roger Humphries (Amec Foster Wheeler)

Greg Paoli (Risk Sciences International)

Preface

This is the first edition of CSA N290.19, Risk-informed decision making for nuclear power plants.

This Standard provides requirements and guidance regarding the risk-informed decision making (RIDM) process employed for nuclear power plants (NPPs). It reflects Canadian regulatory requirements, operating experience of the Canadian nuclear industry, and international good practices, including those of the International Atomic Energy Agency.

Users of this Standard are reminded that the site selection, design, manufacture, construction, installation, commissioning, operation, and decommissioning of nuclear facilities in Canada are subject to the Nuclear Safety and Control Act and its Regulations. The Canadian Nuclear Safety Commission might impose additional requirements to those specified in this Standard.

The CSA “N” Standards provide an interlinked set of requirements for the management of nuclear facilities and activities. CSA N286 Standard provides overall direction to management to develop and implement sound management practices and controls, while the other CSA Group nuclear Standards provide technical requirements and guidance that support the management system. This Standard works in harmony with CSA N286 and does not duplicate the generic requirements of CSA N286; however, it might provide more specific direction for those requirements.

This Standard was prepared by the Subcommittee on Risk-Informed Decision Making for Nuclear Power Plants, under the jurisdiction of the Technical Committee on Reactor Safety and Risk Management and the Strategic Steering Committee on Nuclear Standards, and has been formally approved by the Technical Committee.

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CSA N290.19:18

Risk-informed decision making for nuclear power plants

0 Introduction

1. General

   Risk-informed decision making (RIDM) is a process that provides a formalized, rational, and systematic methodology for identifying, assessing, and communicating the various factors that support making a risk-informed decision. It helps ensure consistency from one decision to the next, helps ensure that important considerations are not overlooked, and provides a framework for the comprehensive documentation of the basis on which decisions are made.

   
   

2. Overview

   The objective of this Standard is to provide a systematic approach to assist in decision making at nuclear power plants (NPPs) using a RIDM process.

   
   

   This Standard describes the application of RIDM, the bases for risk-informed decisions, the key steps in the RIDM process, and management of the RIDM process.

   
   

   This Standard is intended specifically to address matters of concern that have potential safety implications as well as those that have an adverse impact on operations of NPPs.

   
   

3. Users

   This Standard is primarily intended for use by designers, operators, regulators, and individuals or organizations providing support to regulators and utilities.

4. Benefits of using RIDM 0.4.1

An RIDM process supports a consistent, transparent, and balanced approach to safety. Its benefits include

1. improved safety by providing enhanced awareness of factors influencing safety and taking each of these factors into account in a decision and in implementation;

2. optimized maintenance activities by evaluating risk, including reducing radiological exposure;

3. improved efficiency through increased installation performance, operational flexibility, and cost effectiveness of operations; and

4. support for the development and improvement of accident management measures and procedures aimed at ensuring that the risk of accidents with undesirable consequences is extremely low.

0.4.2

The RIDM approach is particularly valuable where

1. the decision has the potential to involve significant costs or adverse safety impacts;

2. the ramifications of alternatives are complex or difficult to understand;