The Regional Cooperative Agreement for Research, Development, and Training Related to Nuclear Science and Technology for Asia and the Pacific (RCA) was established in 1972 and has since benefited from the IAEA Technical Cooperation (TC) programme. Highlighting the socio-economic impact of the RCA in the region is crucial. Therefore, National RCA Representatives have endorsed an initiative to conduct a social and economic impact assessment of the RCA programme supported under the IAEA TC programme from 2000 to 2023. The results of these assessments will be published and disseminated to RCA State Parties, relevant stakeholders, and the public. This report is one of the planned four reports in the areas of air quality monitoring, food safety, groundwater and nuclear medicine.

In March 2023, the IAEA organized a Technical Meeting on the Safety Approach for Liquid Metal Cooled Fast Reactors [LMFRs] and the Analysis and Modelling of Severe Accidents. This publication summarizes the material that was presented during this meeting, related to the analysis and modelling of severe LMFR accidents. It covers knowledge on the physical phenomena and the development of models and numerical tools, and their validation through experimental data related to the progression of severe accidents. This publication is intended for public and private sector organizations developing LMFRs, research facilities, organizations responsible for designing LMFRs, operators and contractors, including prospective operators, and regulatory bodies.

The objective of this TECDOC is to support the guidance given in SSG-9 (Rev. 1), by providing the state-of-the-practice and detailed technical elements related to the evaluation of probabilistic seismic hazard assessment (PSHA) on the basis of observational data. This publication defines the methodology and provides practical guidance for evaluating the elementary and integral steps of PSHA, with the help of examples from case studies and describes the type of observational data that may be used in the evaluation. This publication also discusses the ways of using the evaluation results to check the center, body and range of the epistemic uncertainties to encourage PSHA developers to update or reconsider unrealistic assumptions or combination of unrealistic branches in the logic tree. The technical information and practical guidance provided here will be valuable to nuclear power plant operators, regulatory bodies, vendors, technical support organizations and researchers working in the field of seismic hazard assessment for nuclear installations.

This publication covers two main aspects of safety against external events including the site hazard assessment and the robustness of the installation against external hazards. This publication provides practical guidance and information for the development of the technology-neutral safety framework for assessing the applicability of site evaluation requirements considering site-installation interactions and taking into account the innovative safety features of the advanced reactors. A methodology is provided for an overall optimization of safety measures against external hazards, including the use of a risk-informed approach, supporting the effective and balanced implementation of the defence in depth concept. This methodology covers the application of grading that considers the safety features of the nuclear installation, allowing for a reduced implementation time/cost while ensuring robustness of the installation for applicable hazards. This publication is useful for both new and existing nuclear installations and is intended to be used by regulatory bodies, designers, operating organizations, vendors, research institutes, and technical support organizations working in the area of nuclear safety.

This publication complements existing IAEA publications and provides a methodology for evaluating the adequacy of design safety margins against external events based on the performance goals applicable to a nuclear installation. The aim is to provide procedures which can be used to assess if protection against external hazards achieved by the design corresponds to the design safety requirements established after the Fukushima Daiichi accident. It is intended for use by regulatory bodies, designers, operating organizations, vendors, research institutes, and technical support organizations working in the area of nuclear safety.

The Coordinated Research Project on Probabilistic Safety Assessment Benchmarks for Multiunit Multi Reactor Sites (2018-2022) brought together the experts from the IAEA Member States with mainly water-cooled reactor technologies to utilize, test and further develop their current or planned probabilistic safety assessments methods and assumptions by conducting and comparing results of meaningful multiunit multi reactor type probabilistic safety assessment (MUPSA) benchmark exercises. The objective was to share national expertise and participate in shared benchmark calculations. These calculations involved the development of MUPSA, based on single unit probabilistic safety assessments available in Member States. This publication is intended for nuclear engineers, researchers, code developers, experimentalists in nuclear energy fields, reactor vendors and developers, university professors and students, regulatory experts, and nuclear power plant planners.

This publication describes the practices and challenges related to risk aggregation for various hazards, various operational states, and considering all sources of potential radioactive releases at a nuclear installation site. It provides a methodology and technical basis for risk aggregation and describes the good practices and practical examples of risk aggregation developed by IAEA Member States. The description of practices is supplemented by the detailed discussion on risk communication and use of aggregated risk results to support decision making processes.

This publication addresses the basics of the application of a graded approach in the regulatory oversight of nuclear installations, describes the approaches currently implemented by several regulatory bodies around the world and, based on these examples, proposes a generic methodology for application of a graded approach to regulation of nuclear installations. The publication provides practical examples and information on developing and implementing strategies and processes for all regulatory functions.

The effectiveness of nuclear regulatory systems is enhanced by portraying transparency and openness in communicating all matters relating to safety to the public and stakeholders. This plays an important role in maintaining and enhancing public confidence on the safe use of nuclear energy for socioeconomic development. The regulatory body, in presenting the comprehensive safety status of nuclear installations, can use the outcome of integrated safety assessment mechanism which considers all important aspects of safety, with openness and transparency. This data driven process provides the public, relevant organizations and decision makers with comprehensive information on safety and regulatory decisions related to nuclear installations and is intended to provide a strong basis for, confidence in the regulatory decisions and information system. This publication provides practical information on the development of an integrated safety assessment mechanism by the regulatory bodies for nuclear installations. The integrated safety assessment model proposed in the publication comprises three steps: organizing input data for integrated safety assessment, trending and analysis, and development of overall results and conclusions.

Probabilistic safety assessment (PSA) is considered to be an important tool for assessing the safety of nuclear installations (typically used for safety assessment of nuclear power plants) in relation to potential initiating events that can be caused by random component failure and human error, as well as internal and external hazards. The purpose of seismic PSAs performed on nuclear installations is to provide risk insights related to their seismic robustness. The methodology for seismic safety evaluations includes a combination of deterministic and probabilistic approaches. Their applications typically address the impact of beyond design basis seismic events. This publication provides a detailed methodology for seismic PSA in line with the current international practices for seismic safety assessment of nuclear installations. Taking into account recommendations provided in IAEA safety standards and information reflected in internationally recognized technical standards, it reflects the current state of practice in the area of seismic PSA.

This publication discusses the development and application of a hierarchical structure of safety goals encompassing high level goals and detailed technical requirements that may assist in forming a coherent and consistent approach to nuclear safety. The suggested hierarchy of safety goals provides a practical approach to consistently embracing the set of safety related requirements, both qualitative and quantitative, and developing the interconnections between them. Specifically, the structure supports adding country specific safety goals (e.g. risk metrics) to the overall safety considerations in a consistent manner. This process can be aided by reference to the IAEA safety standards.

These proceedings present the outcomes of a workshop convened by the IAEA in 2015. The workshop brought experts together in seismology and earthquake engineering to discuss the applicability of so-called physics based fault rupture models to generate synthetic earthquake ground motion data for meaningful extrapolation of ground motion prediction in areas where there is a lack of sufficient observations. Fault rupture modelling is recommended for estimating strong motion in cases where nearby faults contribute significantly to the seismic hazard for nuclear installations. The overall aspects and process of the modelling and ground motion simulation are described in IAEA Safety Standards Series No. SSG-9, Seismic Hazards in Site Evaluation for Nuclear Installations, published in 2010. However, after the massive earthquake in Japan in 2011, there has been further progress in physics based fault rupture modelling. Therefore, the IAEA arranged this workshop and the publication arising from it. The intention is to provide practical, up-to-date information contributing to effective seismic hazard analysis.