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[en] This paper presents an overview of modelling features of the first revision of the V2.1 major version of the European severe accident integral code ASTEC which has been set-up by IRSN and delivered to the ASTEC worldwide community end of 2016. After some generalities concerning the software structure and the packaging of ASTEC V2.1 revision 1, the phenomena addressed by the different modules constitutive of ASTEC are detailed. Finally, perspectives as concerns the development of future versions of ASTEC V2.1 at IRSN are outlined. (author)
[en] • Rationale: – INPRO methodology (safety area) requires that “a major release of radioactivity should be prevented for all practical purposes. – Innovative nuclear energy system would not need relocation or evacuation measures outside the plant site. – Satisfying this requirement is crucial for public acceptance and for the sustainability of nuclear energy. • Objective: – Demonstrate that the evolution of safety requirements and related technical and institutional innovations in nuclear technologies provide continued progress to meet the INPRO requirement.
[en] Conclusion: IVR is one of important severe accident management strategies of CAP1400. The purpose of IVR-ERVC experiments is to obtain CHF at RPV lower head and research its relevant mechanism. IVR-ERVC experiment facility was designed and built with a series of improvements. Insights achieved in IVR-ERVC experiments contribute to IVR evaluation, design improvement and safety review of CAP1400.
[en] The experience from the last 40 years has shown that severe accidents can subject electrical and instrumentation and control (I&C) equipment to environmental conditions exceeding the equipment’s original design basis assumptions. Severe accident conditions can then cause rapid degradation or damage to various degrees up to complete failure of such equipment. This publication provides the technical basis to consider when assessing the capability of electrical and I&C equipment to perform reliably during a severe accident. It provides examples of calculation tools to determine the environmental parameters as well as examples and methods that Member States can apply to assess equipment reliability.
[en] Recent literature has included many papers on the costs of nuclear accidents. The French Nuclear Energy Society (SFEN) considered that it had become relevant to help establish a structured analysis, so that studies can be compared and some meaning given to results which appear often very different. In this document, we address the economic consequences of a severe nuclear accident occurring within a nuclear power plant, i.e. an accident classified as level 6 or 7 on the International Nuclear Event Scale (INES). This paper explains the main factors used to calculate the costs of accidents. It reviews the notion of overall cost, which is generally established in a not fully consistent way. It also suggests organizing the results of studies according to their characteristics and the questions they set out to answer. It shows current limitations of studies in which the probability of occurrence of the accidents whose consequences are being studied is not calculated or even addressed in a qualitative way. (author)
[en] • Good response to the meeting invitation - Continued interest = importance of subject; • ST means different things to different people and organizations: - Diverse uses of the ST: - Risk and EI assessment; - Validation of AM; - Emergency planning; - Appropriate response to challenges through design or procedure optimization.
[en] Experimental study on the thermal fragmentation of melt, including Sn, Pb and Sn-Pb alloy, has been carried out based on the SSFT (Small-Scale Fragmentation Tests) facility. The effects of the melt properties, release distance, initial melt temperature, and coolant temperature on the thermal fragmentation have been studied. By analyzing the debris characteristics and the distribution, several specific thermal fragmentation mechanisms have been given, corresponding to different parameters. Finally, a partition map of thermal fragmentation mechanisms has been drawn based on the previous work. (authors)
[en] Response activities are important parts of both safety and security activities as a layer of defence, if prevention activities fail and deviation from compliance has been detected. Three levels of response can be differentiated based on the expected occurrence frequency of the event, its actual or potential consequences, and the scope of the involvement of various organizations. The operative level response to most frequently occurring, the least serious events requires efforts mainly from the operator by strictly following the routine procedures developed in advance; however, their repetition may attract the attention of the regulator and initiate enforcement actions. Examples for such events are the anticipated operational occurrences, expected failures of equipment, false and nuisance alarms, certain less serious unintentional or intentional human errors. Joint response with the involvement of more internal organizational units and competent authorities is needed to manage more serious events, which still have no unacceptable radiological consequences. Such events are accidents within and beyond the design basis, security events within the design basis threat. The response actions to those events are developed in advance and described in detail in the emergency operating procedures, severe accident management guidelines and the security contingency plans. The third and most severe level of response is needed, if unacceptable radiological consequences may or do appear on-site and off-site the facility, when the emergency response plans and if appropriate the contingency plans shall be implemented. (author)
[en] Conclusions: • Development of SAMG is a structured process, once strategies are selected; • Use a logic diagram to execute the various SAMG in proper order; • Develop Computational Aids to support SAMG; • Develop guidance for the TSC how to handle the SAMG, often called TSGs (Tech. Support. Gls); • Develop guidance for the MCR if the TSC is not readily available - e.g., for fast developing accidents.
[en] In the context of CAREM-25 Project, with the aim of applying the general classification methodology safety functions to preventive monitoring and monitoring functions for event management and severe accidents it has been developed criteria to identify Lower Level Safety Functions (FSNB). These criteria will allow the classification of structures, systems and components (SSCs) that implement them. The FSNB Monitoring, both associated with preventive functions as well as monitoring functions for event management and severe accidents arising from Plant Level Safety Function (FSNP): S2- Preventive and control of EP and mitigation of ASP monitoring of important parameters for safety. In line with the internalization in the design of defense in depth principle in the CAREM-25 Project, the definition of monitoring FSNB has been framed taking into account the relationship between FSNB and levels of defense in depth. It is due to preventive monitoring FSNB are associated with Level 1 Defense in Depth. The FSNB monitoring required to control initiating event is defined according to the strategy event management (Levels 2 and 3) and mitigation of severe accidents (Levels 4 and 5) defined in CAREM-25 in accordance with the provisions of international references. On the other hand, in accordance with mentioned references are considered types of monitoring functions: for taking planned manual actions, monitoring of fundamental safety functions, for evaluating the condition of damage barriers radioactive material (Fuel Elements and Primary System, Containment, Irradiated Fuel Elements stored in pool), to evaluate the performance of systems, to determine the extent of any actual or potential release of radioactivity. Finally, Monitoring FSNB are obtained. These FSNB are categorized with the same criteria for categorizing other FSNB in the installation. Then, as part of this work, parameters to be monitored for each FSNB are been identified. In addition, these parameters have been classified according to the classification scheme in CAREM-25 Project. (author)
[es]En el marco del Proyecto CAREM-25, con el objetivo de aplicar la metodología general de clasificación de seguridad a funciones de monitoreo preventivo y funciones de monitoreo para gestión de eventos y accidentes severos y clasificación de las Estructuras, Sistemas y Componentes (ESC) que las implementan, se han desarrollado criterios para obtener las respectivas Funciones de Seguridad de Nivel Básico (FSNB). Las FSNB de Monitoreo, tanto asociadas a funciones preventivas como así también funciones de monitoreo para la gestión de eventos y accidentes severos, se desprenden de la Función de Seguridad a Nivel de Planta (FSNP): S2- Monitoreo preventivo y para gestión de EP y ASP de parámetros importantes para la seguridad. En consonancia con la internalización en el diseño del Principio de Defensa en Profundidad en el Proyecto CAREM-25, la definición de las FSNB de monitoreo ha sido encuadrada teniendo en cuenta la relación entre las FSNB y los Niveles de Defensa en Profundidad. Es por esto que se identifican FSNB de monitoreo preventivo, asociadas al Nivel 1 de Defensa en Profundidad (DenP). Las FSNB de monitoreo que tienen que ver con el control del evento iniciante se establecen de acuerdo a la estrategia de gestión de eventos (Niveles 2 y 3 de DenP) y mitigación de accidentes severos (Niveles 4 y 5 de DenP) definida en CAREM-25, de acuerdo con lo establecido en referencias internacionales. Por otro lado, en concordancia con dichas referencias, se consideran tipos de funciones de monitoreo: para tomar acciones manuales planificadas, de Funciones Fundamentales de Seguridad, para evaluación de la condición de daño de las barreras del material radiactivo (Elementos Combustibles y envuelta de presión del Sistema Primario, Envuelta de presión de la Contención, Elementos Combustibles Irradiados almacenados en Pileta), para evaluación de la actuación de sistemas, para determinar la magnitud de cualquier liberación potencial o real de radioactividad. Finalmente se obtienen las FSNB de Monitoreo. Estas FSNB son categorizadas con los mismos criterios establecidos para la categorización de FSNB de toda la instalación. Luego, como parte de este trabajo, se han identificado también los parámetros a monitorear correspondientes a cada FSNB. Además, estos parámetros han sido clasificados siguiendo el esquema de clasificación establecido en el Proyecto CAREM-25. (author)