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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] 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] • 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] 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] 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] Principles of Accident Management: Operating procedures exist for • Normal operation; • Anticipated occurrences; • Alarm Response procedures; • Accident conditions; • Emergency Operating Procedures (EOPs); • Design Basis Accident; • Limited or no fuel damage; • Severe Accident Management Guidelines (SAMGs); • Fuel damage.
[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)