Nuclear Safety Training on Plant Renewals, Modifications, and Upgrades in Ghana

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority 18 - 22 June 2018 Accra, Ghana Module XII Plant renewals, modifications and upgrades, ageing Franck Lignini Framatome franck.lignini@framatome.com

Learning objectives 1) To understand international requirements and guidance on this matter 2) To understand what are plant renewals, modifications and upgrades 3) To understand what is ageing management 4) To understand what is long term operation (LTO) 5) To understand periodic safety review (PSR) 6) To understand how all of the topics above relate Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 2

Contents Use of terms International requirements and guidance Ageing management Long term operation Modifications and upgrades Periodic safety review Summary key points Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 3

Introduction During the whole lifetime of a nuclear installation Prime responsibility for safety rests with the licensee. This implies inter alia : Ensuring that required safety functions of systems, structures and components are fulfilled over the entire operating lifetime Performing systematic safety assessments Actively evaluating progress in science and technology as well as relevant information from the feedback of experience, in order to identify and to make those safety improvements that are considered practicable applying to the regulatory body (RB) for permission to begin or continue carrying out certain activities, as specified by the regulatory body Managing modifications The RB is responsible for ensuring that appropriate regulatory control is exercised Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 4

Major stages of life cycle and typical licensing steps for nuclear installations Site Licence Construction Licence Siting and site evaluation PSAR Design (*) Periodic Safety Reviews (e.g. every 10 years) Construction Commissioning ISAR Operation Decommissioning Authorization for fuel loading Release from regulatory control Operation Licence FSAR (*) SSG-12 will be superseded by DS473 Functions and processes of the regulatory body for safety Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 5

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority Accra, Ghana 18-22 Juin 2018 Use of Terms Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018

Modifications Reasons for modifications: Economic reasons Increased power Use of mixed oxide fuel Recovery from an identified fault condition or a plant failure Forms of modifications: Modifications to the physical configuration of the plant The management and organization of the plant The operating limits and conditions (OLCs) and operating procedures The utilization of the facility Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 7

Renewals - Upgrades Renewals Replacement or refurbishment of equipment items that have reached their end of life Replacement or refurbishment of equipment items that no longer meet reliability standards Upgrades Changes in structures, systems and components (SSCs) needed to mitigate ageing and other degradation mechanisms Changes in SSCs to take advantage of advances in technology and operating experience Changes in SSCs to upgrade the performance and safety of the installation Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 8

Power uprates Power uprates: A range from small uprates of a few % to major uprates of 20 % or more. Small uprates: Without changes to the plant Better analytical techniques Larger uprates: Changes to instrumentation set points Major plant modifications usually concern: Improvements or replacement of the main turbine Changes in fuel enrichment and fuel loading pattern Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 9

Periodic safety review (PSR) An effective way to obtain an overall view of actual plant safety and the quality of the safety documentation. To determine reasonable and practical modifications: To ensure safety of the plant To improve safety to an appropriate high level Time scale: The first PSR about ten years after the start of operation Subsequent PSRs every ten years until the end of operation The duration should not exceed three years A part of the regulatory system in many states Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 10

The objective of a PSR To determine by means of a comprehensive assessment of an operational nuclear power plant: The extent to which the plant conforms to current national and international safety standards and practices The extent to which the licensing basis remains valid The adequacy of the arrangements that are in place to maintain plant safety The safety improvements to be implemented to resolve identified safety issues Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 11

Ageing Ageingdegradation is defined as ageing effects that could impair the ability of a structure, system or component to function within its acceptance criteria Ageing effects results from a variety of degradation mechanisms, physical or chemical: Irradiation Fatigue Creep Cracking Embrittlement Wear Erosion Corrosion Oxidation Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 12

Long term operation (LTO) Definition: Operation beyond an established time frame set forth by, for example, the licence term, design, standards, licence and/or regulations, which has been justified by safety assessment, with consideration given to life limiting processes and features of systems, structures and components (SSCs). Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 13

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority Accra, Ghana 18-22 Juin 2018 International Requirements and Guidance Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018

IAEA Safety Standards (*) (*) => DS473 ( ) => DS485 (#) => DS497 ( ) (#) Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 15

SSR-2/2 (rev 1) Provides requirements for commissioning and operation related to the topic of this module such as: Requirement 10: Control of plant configuration Requirement 11: Management of modifications Requirement 12: Periodic safety review Requirement 13: Equipment qualification Requirement 14: Ageing management Requirement 15: Records and reports Requirement 16: Programme for long term operation Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 16

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority Accra, Ghana 18-22 Juin 2018 Ageing Management Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018

Ageing Definition: a general process in which the characteristics of a structure, system or component gradually change with time or use. The main degradation mechanisms and ageing effects of concern: Changes in physical properties Irradiation embrittlement Thermal embrittlement Creep Fatigue Corrosion Wear Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 18

Ageing (cont.) The cumulative changes over time that may occur within a component or structure because of one or more of factors A complex process A significant factor in determining the limits of nuclear plant lifetime or life extensions No nuclear plant should be considered immune from its effects Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 19

Ageing management basic concepts Very important activities in maintaining plant safety: Detecting ageing effects on SSCs; Addressing the associated reductions in safety margins; Corrective actions before loss of integrity or functional capability occurs. Physical ageing of SSCs may increase the probability of common cause failures, i.e. the simultaneous degradation of physical barriers and redundant components, which could result in the impairment of one or more levels of protection provided by the defence in depth concept. Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 20

Systematic approach to ageing management Plan Preparing and coordinating and improving activities necessary for ageing management Act Do Preparing and coordinating and improving activities necessary for ageing management Correction and elimination of ageing effects UnderstandingAgeing Check Detection or monitoring and assessment of ageing effects Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 21

Effective ageing management programmes Maintenance In-service inspection and surveillance Operations Technical support programmes External programmes Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 22

Proactive ageing management Importance of Proactive Ageing management of SSCs and responsibilities of the operating organization throughout the plant s lifetime in: Design Fabrication and construction Commissioning Operation Decommissioning Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 23

Ageing management in operation Important tasks: Organizational arrangements Data collection and record keeping Scoping and screening of SSCs for the purposes of ageing management Ageing management review Condition assessment Development of ageing management programmes Implementation of ageing management programmes Improvement of ageing management programmes Identification of effective and appropriate actions and practices for managing ageing Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 24

Management of obsolescence of SSCs Should be managed proactively throughout their service life. A programme for the management of obsolescence: The policy, objectives and organizational arrangements; Appropriate resources: Human; Financial. Monitoring of the programme. Focus on the management of technological obsolescence. Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 25

Ageing management programmes (AMPs) IAEA Technical Meeting in 2009: An international platform for discussion between regulators and utilities regarding implementation of acceptable ageing management programmes (AMPs) The recommendations: Develop and maintain a document which can serve as a practical guide for implementing, maintaining and improving AMPs, made up of best practices and universal knowledge on proven AMPs for safety related SSCs A common basis for discussion between regulators and utilities. The IAEA initiated the International General Ageing Lessons Learned Programme (IGALL) Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 26

International ageing lessons learned (IGALL) The aim of the IGALL Programme: to develop and maintain documents and a database to provide a technical basis for and practical guidance on managing ageing of mechanical, electrical and instrumentation and control components and civil structures of nuclear power plants important to safety. Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 27

Ageing Ageing Physical (degradation mechanisms) + Obsolescence Non-Physical Evaluation of the consequences of their cumulative effects should be a continuous process initiated during the Design stage Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 28

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority Accra, Ghana 18-22 Juin 2018 Long Term Operation Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018

Long term operation LTO Conservative standards for NPPs Engineering technology for LTO Basis for continuing operation beyond the initially established time frame: conservative design conservative operation Operating experience and research Essential role in ensuring the safe operation of NPPs in the initially established time frame as well as in LTO Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 30

LTO approach principles Current operational practices The existing regulatory process The current licensing basis Existing nuclear power plant programmes Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 31

The decision to pursue LTO Basis - an evaluation of the following elements: Strategic elements Applicable regulatory requirements A technical assessment of the physical condition of the nuclear power plant A technical assessment of the environmental impact of LTO An economic assessment Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 32

Preconditions for LTO Plant programmes and documentation A management system: Quality assurance Configuration management Original time limited ageing analyses Current safety analysis report or other licensing basis documents Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 33

Plant programmes for LTO Maintenance Equipment qualification In-service inspection (ISI) Surveillance and monitoring Monitoring of chemical regimes Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 34

Ageing management review for LTO Main steps: Scoping and screening method Demonstration of the effects of ageing for each structure or component Revalidation of time-limited ageing analyses Identification of the requirements for modifications: Existing plant programmes Development of new programmes Documentation of the review Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 35

Time limited ageing analysis (TLAA) Identification of SSCs that are subject to time-limited analysis The calculations and analysis that: Involve SSCs within the scope of licence renewal; Consider the effects of ageing; Involve time-limited assumptions defined by the current operating term (for example 40 years); Were determined to be relevant by the licensee in making a safety determination; Involve conclusions or provide the basis for conclusions related to the capability of an SSC to perform its intended functions; Are contained or incorporated by reference in the licensing basis. Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 36

Examples of TLAA Fatigue analysis Environmental qualification of electrical equipment Embrittlement of reactor vessel Pressurized thermal shock Relaxation of pre-stressed tendons Settlement of the foundations Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 37

Major steps of a programme for LTO Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 38

IAEA Safety Aspects of Long Term Operation (SALTO) peer review service A newcomprehensive operational safety review service directly addressing strategy and the key elements for safe LTO of NPPs. Designed to: Assist NPP operators in adopting a proper approach to the LTO of their plants; Implementation of complete and appropriate activities to ensure that plant safety will be maintained during the LTO period. Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 39

Bases for the SALTO peer review of the LTO Specific Safety Requirements on NPP operation SSR-2/2 The IAEA Safety Report on Safe Long Term Operation of Nuclear Power Plants that addresses the following areas: LTO feasibility Scoping and screening of systems, structures, and components (SSCs) Assessment and management of SSCs for ageing degradation for LTO Time-limited ageing analyses (TLAAs) Documentation Conducted by a team of international experts Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 40

Basic Professional Training Course on Nuclear Safety Week 3 Ghana Nuclear Regulatory Authority Accra, Ghana 18-22 Juin 2018 Modifications and Upgrades Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018

Reasons for carrying out modifications Maintaining or strengthening existing safety provisions Recovering from plant faults Improving the thermal performance or increasing the power rating of the plant Increasing the maintainability of the plant, reducing the radiation exposure of personnel, or reducing the costs of plant maintenance Extending the design life of the plant (LTO) (#) (#) => DS497 Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 42

Modifications to reactors Roles and responsibilities of the operating organization Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 43

Regulatory body (RB) Agreement and approval of: Proposals for modification to SSCs and software important to safety Proposals for modification to OLCs that affect the basis for the operating licence Proposals for modification of procedures and other documents originally approved by the RB Other proposals as deemed appropriate Changes in the operating organization s structure Processes and management programmes that may have safety consequences Safety-related modifications Issuing a new or modified licence Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 44

Initial safety assessment Should be carried out before starting a modification Safety significance Application of a graded approach The regulatory constraints for plant design and operation The comprehensive safety assessment: Use of deterministic and probabilistic safety analysis Use of a plant-specific probabilistic model Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 45

Requirements for modifications An independent assessment of: The scope Safety implications Consequences of proposed modifications Minimizing deviations from the characteristics and intent of the original design Safety requirements for design: The capability of performing all safety functions shall not be degraded Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 46

Requirements for modifications (cont.) Verification and validation of modified operating procedures: Before use Operators should be trained in the revised procedures Strict configuration control throughout the modification process for software Installation of only those items that have been through the entire change process Use of comprehensive validation and verification process to establish suitability of the changes Consideration of the possible common mode failure of redundant computer-based safety systems Attention to interrelationships between modifications Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 47

Modifications to management systems Documented operations management programmes Improvements in the tools and data used in safety assessment of the plant: Probabilistic safety assessment Risk-informed decision making Advanced maintenance and inspection techniques Review of the modifications to the existing tools and processes: For their safety implications Should be submitted the regulatory body if required Modifications to neutronic or thermal-hydraulic computer codes or methods for core calculations and accident analysis: Should be submitted to the regulatory body as appropriate Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 48

Temporary modifications Minimum number A time limit for removal or conversion into permanent modifications The procedure for obtaining approval for a temporary modification The principles for managing modifications Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 49

The power uprate project Systematic review: The safety analysis Nuclear fuel Plant, structures, systems and components Feasibility study An opportunity to address equipment ageing and obsolescence issues Improved understanding of plant margins Incorporated plant efficiency improvements Better interaction with licence renewal Improved knowledge levelling of design and operations Engineering effort Module XII Plant renewals, modifications and upgrades, ageing June 18-22, 2018 50