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[en] Defense in Depth is the most important and basic concept of nuclear safety. The most important aspect of Defense in Depth concept is to provide independent effects based on different ideas from layer to layer (Independent Effectiveness). In the concept of Defense in Depth, provisions play an important role. This commentary describes the process of securing safety in the nuclear reactor facilities, control of risks, Defense in Depth and safeguarding measures, and points out many problems in the five layers of Defense in Depth of IAEA in the case of the Fukushima Daiichi accident. In addition, the authors describe the provisions for an event that deviates from within the design criteria, deepening of the concept of Defense in Depth, and three layers (levels) that realize Defense in Depth. The authors discuss the concept of new Defense in Depth, risk assessment to assess the response to situations exceeding standards, and the development of Defense in Depth via risk assessment. The authors rethink the meaning of exceeding design criteria. There are serious limitations in conventional designs, and the authors will touch on new safety design efforts in accordance with the Defense in Depth concept. (A.O.)
[en] This handbook was prepared primarily with the aim to provide information to experts of authorities or research facilities engaged in criticality-safety-related problems that will allow an adequate and rapid assessment of criticality safety issues already in the planning and preparation of nuclear facilities. However, it is not the intention of the authors of the handbook to offer ready solutions to complex problems of nuclear safety. Such questions have to remain subject to an in-depth analysis and assessment to be carried out by dedicated criticality safety experts. Compared to the previous edition dated December 1998, this handbook has been further revised and supplemented. The proven basic structure of the handbook remains unchanged. The handbook follows in some ways similar criticality handbooks or instructions published in the USA, UK, France, Japan and the former Soviet Union. The expedient use of the information given in this handbook requires a fundamental understanding of criticality and the terminology of nuclear safety. Therefore, in Vol. 1, "Criticality and Nuclear Safety", first the most important terms and fundamentals are introduced and explained. Subsequently, experimental techniques and calculation methods for evaluating criticality problems are presented. The following chapters of Vol. 1 deal i. a. with the effect of neutron reflectors and absorbers, neutron interaction, measuring methods for criticality, and organisational safety measures and provide an overview of criticality-relevant operational experience and of criticality accidents and their potential hazardous impact. Vol. 2 (part 1 and 2) finally compile criticality parameters in graphical and tabular form. The individual graph sheets are provided with an initially explained set of identifiers, to allow the quick finding of the information of current interest. Vol. 2, part 1 (former Vol. II) includes criticality parameters for systems with U as fissile material, while Vol. 2, part 2 (former Vol. III) deals with systems comprising U, plutonium and higher actinides.
[en] RITAC (Reactivity Initiated Transient Analysis Code), a coupled code of point reactor kinetics and thermal hydraulics, was developed in order to early out reactivity initiated transient (RIT) analysis of research reactor with plate type fuel. Now, the code has been modified for pin type fuel also. The code solves the coupled system of equations of neutron kinetics based on point reactor model and equations of thermal hydraulics for pin type fuel to carry out safety analysis of fuel assembly. Point kinetics equations are solved numerically by piecewise constant approximation (PCA) method while thermal hydraulics equations, including energy conservation equations for fuel and clad regions and mass, momentum and energy conservation equations for coolant region in pin type geometry, are solved by finite difference method along with Crank-Nicolson technique. For the calculation of heat transfer coefficient from clad to coolant in different boiling regimes, a number of correlations are used in RITACF. Finally, result of the code are validated against the known results of a pin type fuel based research reactor. (author)
[en] As the French fleet of 900 MWe nuclear power plants is about to be submitted to its fourth decennial inspection and to its fourth periodic safety review, this note highlights the context and stakes associated with this inspection and review context. After a presentation of the situation of the different reactors with respect to these inspections and reviews, the note proposes a discussed overview of stakes related to the operation extension beyond the 40 year threshold: a change of strategy, pressure of time, safety stakes, implementation of various measures. As this life extension is an important issue with which the public should be associated, the next part discusses the implementation of dialogue arrangements and outlines that they are far from facing the challenge or achieving an actual dialogue. Objectives of the fourth periodic safety review are then addressed through a comparison of associated safety requirements and objectives defined for new generation reactors (such as the EPR). The evolution of margins with respect to higher safety requirements is discussed, and this aspect is outlined as very important due to the unavoidable loss of some margins with respect to reactor initial condition. The importance of compliance of reactor condition is then discussed. The issue of delays is finally addressed
[en] Summary: • Evolution of robust safety design criteria coupled with guidelines – fundamental to assure safety; • Safety Design Criteria (SDC) document under preparation by AERB in discussion with IGCAR; • SDC is largely in line with the international approach. Discussions are under way w.r.t few demanding considerations; • Systematic studies and large R&D are essential to freeze the design concepts meeting the SDC; • Sustained efforts and collaboration is required among SFR countries.
[en] PRPP Working Group Objectives: • Facilitate introduction of PRPP features into the design process at the earliest possible stage of concept development. → PRPP by design: • Assure that PRPP results are an aid to informing decisions by policy makers in areas involving safety, economics, sustainability, and related institutional and legal issues. “Generation IV nuclear energy systems will increase the assurance that they are a very unattractive and the least desirable route for diversion or theft of weapons-usable materials, and provide increased physical protection against acts of terrorism.”
[en] This press kit presents the Saint-Laurent des Eaux NPP, its position in the French nuclear park, the nuclear safety priority (regulation, control, transparency, EdF's commitments after the Fukushima accident, risks management with public authorities), the protection of intervenors (radiation protection, safety culture), the environmental monitoring, the management of the future of the site (reactors safety re-evaluation, radioactive waste management, spent fuel recycling, Mox, decommissioning activities), the local economic impact of the NPP (local development, employment, partnerships), the public information, the 2018 key figures and important dates.
[en] This brochure presents the Saint-Alban Saint-Maurice NPP (Isere, France) and stresses on the nuclear safety aspects of the NPP, on the personnel skills and training, on the safety warranty and the radiation protection monitoring of intervenors, on the environment monitoring and the environmental impacts of the NPP, on the actions of information to the public, on the socio-economic impact and the involvement of the NPP in the local economy, and on the investment made for the lifetime extension of the NPP.