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[en] A survey of risk assessment methodology which is being given a lot of attention in the scientific world is presented in this paper. The maximum credible accident approach used for reactor safety assessment in the past has proved inadequate and a probabilistic approach has now caught the fancy of the scientific world. This method took to evaluating single accidents and making them the basis for decisions. This non-probabilistic approach had obvious drawbacks. Most importantly, it undermined less severe accidents which might be more important due to a high frequency of occurrence. (J.A.)
[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] Highlights: • Nuclear accident consequence index can assess overall consequences of an accident. • Correlations between the index and release parameters are developed. • Relation between the index and release amount follows power function. • The exponent of the power function is the key to the relation. - Abstract: Nuclear accident consequence index (NACI) which can assess the overall consequences of a severe accident on people and the environment is developed based on findings from previous studies. It consists of three indices: radiation effect index, relocation index and decontamination index. Though the NACI can cover large range of consequences, its assessment requires extensive resources. The authors then attempt to simplify the assessment, by investigating the relations between the release parameters and the NACI, in order to use the release parameters for severe accident consequence assessment instead of the NACI. NACI and its components increase significantly when the release amount is increased, while the influences of the release period and the release starting time on the NACI are nearly negligible. Relations between the release amount and the NACI and its components follow simple power functions (y = ax"b). The exponent of the power functions seems to be the key to the relations. The exponent of the relation between the release amount and the NACI was around 0.8–1.0 when the release amount is smaller than 100 TBq, and it increased to around 1.3–1.4 when the release amount is equal to or larger than 100 TBq.
[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.