[en] After specifying the notions of 'safety' and 'quality', the terms and conditions governing the intervention of the public authorities in the matter of safety of nuclear plants are described: individual permits, the establishing and application of technical rules of a general character, surveillance of the plants. The criteria and regulations guiding the evaluation of safety and quality and, in conclusion, insisting on the necessity for permanent discussions among the various organizations concerned are presented

[en] For more than 40 years, IPSN then IRSN has conducted research and development on nuclear safety, specifically concerning pressurized water reactors, which are the reactor type used in France. This publication reports on the progress of this research and development in each area of study - loss-of-coolant accidents, core melt accidents, fires and external hazards, component aging, etc. -, the remaining uncertainties and, in some cases, new measures that should be developed to consolidate the safety of today's reactors and also those of tomorrow. A chapter of this report is also devoted to research into human and organizational factors, and the human and social sciences more generally. All of the work is reviewed in the light of the safety issues raised by feedback from major accidents such as Chernobyl and Fukushima Daiichi, as well as the issues raised by assessments conducted, for example, as part of the ten-year reviews of safety at French nuclear reactors. Finally, through the subjects it discusses, this report illustrates the many partnerships and exchanges forged by IRSN with public, industrial and academic bodies both within Europe and internationally

[en] For over thirty years, IPSN and subsequently IRSN has played a major international role in the field of nuclear power reactor core melt accidents through the undertaking of important experimental programmes (the most significant being the Phebus-FP programme), the development of validated simulation tools (the ASTEC code that is today the leading European tool for modelling severe accidents), and the coordination of the SARNET (Severe Accident Research Network) international network of excellence. These accidents are described as 'severe accidents' because they can lead to radioactive releases outside the plant concerned, with serious consequences for the general public and for the environment. This book compiles the sum of the knowledge acquired on this subject and summarises the lessons that have been learnt from severe accidents around the world for the prevention and reduction of the consequences of such accidents, without addressing those from the Fukushima accident, where knowledge of events is still evolving. The knowledge accumulated by the Institute on these subjects enabled it to play an active role in informing public authorities, the media and the public when this accident occurred, and continues to do so to this day. Following the introduction, which describes the structure of this book and highlights the objectives of R and D on core melt accidents, this book briefly presents the design and operating principles (Chapter 2) and safety principles (Chapter 3) of the reactors currently in operation in France, as well as the main accident scenarios envisaged and studied (Chapter 4). The objective of these chapters is not to provide exhaustive information on these subjects (the reader should refer to the general reference documents listed in the corresponding chapters), but instead to provide the information needed in order to understand, firstly, the general approach adopted in France for preventing and mitigating the consequences of core melt accidents and, secondly, the physical phenomena, studies and analyses described in Chapters 5 to 8. Chapter 5 is devoted to describing the physical phenomena liable to occur during a core melt accident, in the reactor vessel and the reactor containment. It also presents the sequence of events and the methods for mitigating their impact. For each of the subjects covered, a summary of the physical phenomena involved is followed by a description of the past, present and planned experiments designed to study these phenomena, along with their modelling, the validation of which is based on the test results. The chapter then describes the computer codes that couple all of the models and provide the best current state of knowledge of the phenomena. Lastly, this knowledge is reviewed while taking into account the gaps and uncertainties, and the outlook for the future is presented, notably regarding experimental programmes and the development of modelling and numerical simulation tools. Chapter 6 focuses on the behaviour of the containment enclosures during a core melt accident. After summarising the potential leakage paths of radioactive substances through the different containments in the case of the accidents chosen in the design phase, it presents the studies of the mechanical behaviour of the different containments under the loadings that can result from the hazards linked with the phenomena described in Chapter 5. Chapter 6 also discusses the risks of containment building bypass in a core melt accident situation. Chapter 7 presents the lessons learned regarding the phenomenology of core melt accidents and the improvement of nuclear reactor safety. Lastly, Chapter 8 presents a review of development and validation efforts regarding the main computer codes dealing with 'severe accidents', which draw on and build upon the knowledge mainly acquired through the research programmes: ASTEC (IRSN and GRS), MAAP-4 (FAI (US)) and used by EDF and by utilities in many other countries, and MELCOR (SNL (US)) for the US Nuclear Regulatory Commission (US NRC)

[en] In a collection which aims at providing those who are performing activities in relationship with ionizing radiations, notably in the nuclear industry, with elements of cultural technique related to the prevention and to the management of associated risks, this volume addresses pressurised water reactors (PWRs) and more particularly those which build up the French nuclear fleet. A first part presents general contextual elements: health and biological effects of ionizing radiations and the system of radiation protection, organization of the control and regulation of nuclear installations and activities in France, the international and societal dimensions, nuclear reactors as complex social-technical systems and the importance of organizational and human factors. The second part addresses safety at the design level: development of nuclear energy based on the use of uranium-235 and some notions of PWR physics, general objectives, principles and fundamental concepts of the safety approach, safety options and considerations at the design level, study of operating conditions in the safety deterministic analysis, the accident with loss of primary cooling, the particular case of steam generator tubes, the taking of aggressions of internal or external origin into account, complementary event domain, development and use of safety probabilistic studies, specific aspects related to fuel warehousing pools, integration of organizational and human factors during the design of installations, study and taking into account of core fusion accidents, new generation reactors. The third part addresses safety during exploitation: start tests of PWRs, general rules of exploitation, rules and practices with the return on experience of events, return on experience due to a weakness of the initial design of reactors or to the maintenance quality, return on experience related to interventions, to electricity sources and distributions, or to internal or external aggressions, strengthening of the protection of sites along an estuary or river (examples in Le Blayais and Cruas-Meysse), the taking of organisational and human factors for the exploitation of installations, the maintenance of installations, in-service monitoring and control of equipment, managements, control and evolutions of the nuclear fuel, the compliance of installations, periodic re-examinations, optimization of radiation protection and limitation of doses received by workers. The fourth part addresses the accidents of Three Mile Island, Chernobyl and Fukushima, lessons learned, and the management of emergency situations. The fifth part is dedicated to studies, researches and developments in the safety of PWRs, and to simulation software

[en] Everything that is important to know about pressurized water reactor safety in nuclear power plants is compiled in this work of reference, from safety fundamentals and reactor design to provisions for managing a radiological or nuclear emergency. The book narrates the determined and continuous quest to enhance nuclear safety. Jean Couturier, coordinator and senior editor, covers the forty-year history of evolution in the safety objectives, approaches, analysis methods and assessment criteria that have defined pressurized water reactor safety, mainly within the French nuclear power plant fleet, from the 1970's up to today's Flamanville 3 EPR. Everyone, including current and future generations of engineers, researchers and, more broadly, any citizen interested in nuclear safety issues will find that the book reinforces their knowledge on this important subject, providing an understanding of the fundamentals, to the benefit of nuclear and radiological risk control. The first part of the book presents relatively general fundamental information and concepts that are not specific to pressurized water reactors: the effects of ionizing radiation and the radiological protection system, the organizations involved in nuclear safety in France and their roles, the evolution of regulations, the increasing role of civil society and the international context - two areas that have undergone particularly significant development since the 1990's - and the importance of human and organizational factors for achieving a high level of reliability in nuclear facilities and their operations, which represent complex sociotechnical systems, especially with regard to nuclear power reactors. Subsequent sections, covering design, operation, lessons learned from the three major accidents mentioned above, and emergency preparedness and response, are much more focused on pressurized water reactors, primarily those in the French nuclear power plant fleet, as well as the same type of reactors operated in other countries which have experienced anomalies or events that have provided beneficial operating feedback for the French nuclear power plant fleet. Finally, information concerning the contributions of research and development in nuclear safety, as well as simulation software, are included in the last part of the book