IAEA TECDOC Series No. – Serie

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.

This TECDOC offers practical guidance on implementing a graded approach to the Systematic Approach to Training (SAT) for personnel at nuclear facilities. A graded approach to SAT benefits nuclear facilities by raising the quality and effectiveness of training, which in turn makes a significant contribution to safety and performance. This TECDOC is intended for managers and specialists associated with training and personnel in nuclear facilities and regulatory organizations, as a supplement to IAEA Nuclear Energy Series No. NG-T-2.8, Systematic Approach to Training for Nuclear Facility Personnel: Processes, Methodology and Practices.

Between 1979 and 2011, three severe nuclear power plant (NPP) accidents occurred at Three Mile Island (TMI, USA), Chornobyl (ChNPP, Ukraine), and Fukushima Daiichi (IF, Japan), resulting in melted reactor cores. Additionally, PAKs NPP Unit 2 (Hungary) experienced a loss of cooling accident in 2003 during the cleaning of irradiated fuel. The accidents at TMI and PAKs have been remediated to the extent that the material is either in monitored safe storage or is packaged pending processing. ChNPP Unit 4, which was destroyed during the accident, was finally stabilized in 2016 with the installation of new safe containment. The decommissioning of IF NPP remains a major challenge as three of the first-generation reactor cores suffered meltdown. In 2015, the Coordinated Research Project on the management of severely damaged spent fuel and corium was established. This publication examines the efforts of participating Member States in the characterization, recovery, and management of fuel containing materials (fuel assemblies, fuel debris, corium and melted corium-concrete interaction products) to support future decommissioning and environmental remediation activities. It also provides an overview of the loss of cooling accidents and insights into the evolution of corium and fuel debris in storage conditions, which will support ongoing decision-making on the management of these materials.

This publication examines the benefits and challenges of recovering uranium from phosphate ores as an alternative to conventional uranium mining. It considers the low cost of uranium extraction from phosphate ores, its potential profitability and discusses the relative speed of equipping fertilizer plants with uranium recovery units (i.e. two to three years), compared with conventional uranium mines, which can take ten years or longer to develop. These issues are examined in detail, alongside supply security and environmental concerns. This TECDOC is intended for policy makers working on uranium supply security; mining and mineral processing experts working on unconventional uranium recovery and/or solvent extraction; and for researchers working on uranium concentrations in fertilizers and potential natural uranium accumulation in agricultural soils.

Regulatory enforcement is a core regulatory function and an important aspect of the regulatory oversight of nuclear facilities and activities. IAEA Safety Standards Series Nos. GSR Part I (Rev. 1) and GSG-13 provide requirements and recommendations for establishing and implementing enforcement policy. However, the lessons identified from various IAEA expert missions, peer reviews and regulatory conferences have revealed inconsistencies in the understanding, development and implementation of effective enforcement policies by regulatory bodies, highlighting the need for specific guidance on regulatory enforcement. The objective of this TECDOC is to assist regulatory bodies in developing and implementing an enforcement policy and process, in line with the IAEA safety standards. It includes practical guidance from regulatory bodies with relevant experience and provides recommendations for enhancing enforcement actions in line with effectiveness, efficiency, and consistency. Additionally, it provides methods for evaluating the significance of non-compliances using a graded approach and applying the appropriate enforcement actions. This publication is intended for regulatory bodies, technical support organizations and competent authorities responsible for the oversight of nuclear facilities and activities.

This publication highlights innovations, advances and developments in the specification and control of water chemistry for PWRs and WWERs that have led or are likely to lead to performance improvement in nuclear safety, as well as an increase in asset value. It also showcases technological transformations in areas such as simulation modelling, on-line monitoring, and the use of robotics. The publication is intended to support established operators striving for excellence or planning to extend the operational life of their plants beyond the original design period. It also serves as a valuable resource for operators with limited experience or access to the latest technology, as well as for newcomers and recently commissioned plants, enabling them to take informed steps at an early stage in the operation. The final section of this publication contains a concise summary of the most significant developments, and throughout this publication guidelines from international organizations are acknowledged and referenced to avoid unnecessary repetition.

Uranium hexafluoride plays a crucial role in the nuclear fuel cycle, particularly due to its use in the most widely adopted enrichment methods. This publication provides a comprehensive overview of the properties of uranium hexafluoride and the potential challenges associated with its production, transport, handling and storage. It is designed to support professionals involved in any stage of the uranium hexafluoride lifecycle by offering detailed, practical information. It is especially useful for those seeking to enhance aspects of their existing programmes, including management systems, safety protocols, emergency preparedness and response.

With a focus on facilities designed to handle small and medium volumes of NORM waste, this TECDOC provides guidance on cost estimation for its disposal. It establishes a clear definition of NORM waste, explores the typical sources of small to medium quantities and outlines the range of disposal options according to the associated waste hazards. The report introduces a lifecycle-based cost estimation model, which serves as a foundational framework for developing cost estimates. It also identifies key components and variables within disposal plans that may influence cost variability. In addition, this publication presents high-level insights into various cost-estimation methodologies. Rather than offering a catalogue of specific costs, this TECDOC aims to equip Member States with a structured approach for collecting and applying their own cost data in the planning and development of NORM waste disposal facilities, acknowledging that cost elements are highly context-dependent and may vary across Member States.

This publication is a revision of IAEA TECDOC No. 1263 and offers practical guidance for establishing, implementing and improving in-service inspection programmes based on non-destructive testing methods for research reactors. The publication addresses all aspects of programme development and execution, including its review and continuous improvement. It adopts a methodological approach and incorporates practical examples from operating research reactors to support programme implementation. This guidance is intended for research reactor operating organizations, designers, and support organizations.

Fusion neutron sources have many important practical uses, such as irradiation testing of materials and components, facilitating the production of various isotopes such as tritium, driving subcritical cores, characterizing spent nuclear fuel, and manufacturing medical isotopes. All these applications can be potentially improved by achieving higher neutron yields and fluxes in compact fusion neutron sources (CFNSs). This publication is a compilation arising from an IAEA coordinated research project on this topic and presents the project's main results and findings with the aim of supporting stakeholders in the development of CFNSs in the transition from conceptual to engineering design.

This publication highlights the importance of mentoring and coaching for knowledge transfer across the generations of the workforce. It captures successful mentoring and coaching practices and approaches being followed by different types of nuclear organizations including at nuclear power plants, technical support organizations, national nuclear organizations and regulatory bodies. The publication also includes case studies from Member State organizations that have used mentoring and coaching as an effective tool for knowledge transfer, skill building and performance improvement.

Radiological environmental impact assessment models are important tools for public and environmental protection, for example, in planning measures to be taken in the event of accidental releases. This publication was developed to report on results from international model validation exercises conducted within the IAEA's MODARIA I programme to test and improve the modelling for predictions used for environmental transfer and dose assessment in urban areas. Model exercises were focused on: contamination densities and activity concentrations in air following short range atmospheric dispersion and deposition events; prediction of atmospheric dispersion and application of decision support systems under complex meteorological and topographic conditions; and expected reductions in ambient dose rates and activity concentrations due to protective actions following a nuclear accident. The report builds on past IAEA publications and provides relevant examples for use in strengthening the global nuclear safety framework as part of emergency preparedness and response planning following a nuclear or radiological emergency.

As well as the application to food irradiation, nuclear techniques can be used in the detection of contaminants and the verification of the origins and authenticity of food. This publication presents the findings of a joint FAO/IAEA coordinated research project (CRP) on utilizing isotope and trace element analysis, and other complementary analytical techniques, to characterize the origin of authentic milk and dairy products sampled by the participating institutes. The purpose of the CRP was to develop a methodology to implement a sustainable system for the independent verification of the claimed origin of food. Questions concerning origin are among the first to be asked when a food safety incident arises. The results of the project described in this publication will assist Member States to better communicate the qualities and origin related attributes, or terroir, of different food commodities. In addition, verifying the origin of food can help to prevent fraud and thereby reduce barriers to trade and protect and promote added-value products with a strong regional or national identity.

This publication aims to guide Member States in fulfilling the IAEA Safety Standards requirements for capacity building in nuclear safety. It emphasizes a comprehensive approach based on self-assessed needs analysis, covering education and training (E&T), human resource development (HRD), knowledge management (KM), and knowledge networks (KN). The document also clarifies the roles and responsibilities of key stakeholders, including government bodies, regulatory authorities, technical support organizations, operators and educational institutions, in developing, implementing and periodically assessing capacity building needs. It includes a comprehensive self-assessment questionnaire.

Gamma irradiation of food is a simple, reliable, and mature technology. However, more use of alternative irradiation technologies, based on electrically generated sources, would help complement the available capacity. Electron beams and X rays generated from electricity are technologies that avoid the procurement, transport, storage, disposal, and safeguarding issues associated with the use of radioisotopes. Arising from an IAEA coordinated research project, this publication reports on research to develop new tools in food irradiation and to rapidly ascertain treatment parameters before irradiation, including high energy (MeV) and low energy (keV) electron beam and X ray irradiation. Comparative studies of gamma, electron beam and X ray irradiation for food and phytosanitary uses are also presented.

Written for use by operating organizations of nuclear power plants and regulatory bodies, this Safety Guide provides specific recommendations on maintenance, testing, surveillance and inspection to ensure that the levels of reliability and availability of all structures, systems and components important to safety remain in accordance with the assumptions and intent of the design, and also that the safety of the plant is not adversely affected after the commencement of operation. The publication covers the establishment and implementation of preventive and corrective maintenance programmes; testing surveillance and inspection; the repair of defective plant equipment; the provision of related facilities and equipment; procurement; and generating and retaining records of maintenance activities

This publication is the result of a collaborative effort, between the IAEA, OECD Nuclear Energy Agency and European Commission, to develop a standard taxonomy for nuclear facility decommissioning and thereby facilitate the sharing of knowledge on this topic. Adoption of the taxonomy will support the capture of knowledge from the ongoing implementation of decommissioning activities involving nuclear power plants, research reactors, and fuel cycle facilities. This publication will benefit a wide range of professionals working on gathering and organizing knowledge to be shared in the field of decommissioning, including government officials, managers of nuclear facility operating organizations, regulators, and industrial organizations offering decommissioning and waste management services.

The suitable design and quality of systems, structures, and components important to safety is vital for the construction and operation of nuclear power plants. The IAEA has developed this publication to provide information on approaches to evaluating the suitability of commercial grade items for use in nuclear power plant safety systems. Nuclear power plants in long-term operation have greatly benefited from the use of commercial-grade products, while the near-term deployment of advanced reactor designs, including small modular reactors, is expected to leverage such products to a large extent. The intended audience ranges from nuclear power plant senior management to experts procuring and controlling products and services vital for safety.

With an increasing interest in Small Modular Reactors (SMRs) and their applications, a Technical Meeting on Considerations for the Back End of the Fuel Cycle of Small Modular Reactors was organized in September 2022 to facilitate the exchange of information and discussions to enable experts to collaboratively identify the opportunities and challenges faced at all stages needed for managing the spent fuels from different SMR technologies (e.g. storage, transportation, reprocessing and recycling, and disposal), the gaps in current infrastructure and the knowledge required to ensure an integrated approach to the overall spent fuel management strategy, as well as the potential ways to move forward in addressing them in the near, medium and long terms. This TECDOC presents the proceedings, session summaries and conclusions of the Technical Meeting, as well as the 27 extended abstract/full papers presented at the meeting.