• ageing management
• long term operation
• research reactor
• riam
• risk-informed ageing management

The long-term operation (LTO) of research reactors is being pursued by many utilities worldwide, with several having received operating licenses for beyond 60 years of operation. Therefore, implementing an effective Ageing Management Programme (AMP), is essential to ensure the safe continued operation of these facilities. The effectiveness of the AMP can be enhanced by adopting a framework that optimizes inspection, testing, repair, and mitigation activities recommended to manage the potential effects of ageing [1].
This thesis presents the development and application of a risk-informed strategy for a research reactor AMP. This strategy intends to optimize the already existing programmes and to increase their effectiveness.
The objective of the thesis is to Risk Inform the Ageing Management Programs, following the approach defined by EPRI Technical Report ‘Leveraging Risk Insights for Ageing Management Program Implementation’ [1]. The goal is to work towards a more effective resources allocation, optimizing the use of limited available resources by setting a strategy to prioritize actions based on risk signicance.
The benefits of applying this approach would be both in terms of safety, as the use of risk-informed techniques would emphasize the SSCs to prioritize in the framework of the actions performed for management of ageing reactor’s systems, and of reliability and production, as the economic resources would be allocated more efficiently.
The methodology involves collecting information from literature, plant data, regulatory information, and previous risk-informed applications for the selected AMP(s). This data is used to develop risk matrices for each ageing mechanism affecting the SSCs. The matrices provide justification for possible revision of the ageing management strategies, either reducing effort where it is excessive or increasing it where necessary.
The risk-informed strategy is applied to a case study: the High Flux Research Reactor (HFR) in Petten. To assess the applicability of risk-informed techniques, two pilot studies were conducted: one focusing on the valves of the primary cooling system, and the second on the civil structures and components of the reactor.
This work led to the achievement of a risk-informed approach for the management of the components part of the pilot studies. It includes assessments of risk contribution levels and proposes revision strategies that could serve as basis for future cost-benefit evaluations.

The thesis aims to study the application of a risk informed approach to the already developed ageing management programme of a research reactor, investigating whether the available information are sufficient for the objective.
The work focuses on:
- The study of the existing ageing management programmes present at the HFR to risk inform;
- The gathering of data necessary to the implementation of the EPRI strategy, from literature study of physical ageing mechanisms, components structures and materials, and insights from operational experience present in site;
- The proposal of revision strategies specific for the AMPs under review.
The structure of this document is as follows:
- Summary provides a concise overview of the objectives, methodology, and main findings;
- Chapter 1 introduces the motivation for the work, defines its objectives and scope, and provides an overview of the thesis structure;
- Chapter 2 describes the State of Art and comprehends review of the regulatory framework for research reactors, the current ageing management, and the relevant literature on ageing mechanisms;
- Chapter 3 describes the background of the RIAM strategy developed by EPRI, and introduces the thesis proposal;
- Chapters 4 and 5 describe Pilot A and B, the practical applications of the RIAM programme to selected ageing management programmes of a selected research reactor, including methodology, data sources and results;
- Chapter 6 presents the conclusions and final considerations, including summary of the main outcomes, discussion of limitations and possible future developments of the work;
- Chapter 7 lists the references of all cited literature and sources used for the work.