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[en] A diagram presents the whole of the works that will be made on the French fleet of nuclear reactors. The diagram includes the works necessary for the decenal reviews, the lifetime extension projects, usual reactor maintenance and the post-Fukushima measures. (A.C.)
[en] The article describes the properties and (potential) benefits of small modular reactors (SMRs), current situation (SMRs in use, in construction, to be started up soon, under development, micro-SMRs), and examples (Akademik Lomonosov floating NPP, NuScale Power). (P.A.)
[en] Highlights: • Adopting thermal-hydraulic phenomena (list of 116 phenomena – published). • Exploiting capabilities of existing numerical tools & existing experimental database. • Procedure to plan new-prioritized research in nuclear thermal-hydraulics. - Abstract: The difficulty in predicting locally and globally the transient evolution of two-phase or multiphase flows in complex systems is well recognized in nuclear thermal-hydraulics. Large efforts involving the expenditure of huge resources during the last three decades in previous century brought to the creation of giant databases (e.g. including experimental data and results of computer code calculations) and to the perception that the safety of nuclear reactors is guaranteed notwithstanding residual areas of unawareness. Nowadays, thousands of scientists continued to generate progress in the area having available much lower resources: more and more dead-ends for established research outcomes are experienced; the progress in knowledge resembles the slow expansion of a swamp rather than the fast moving of a river. In this paper a procedure is proposed to identify directions for research in nuclear thermal-hydraulics which are consistent with the needs in nuclear reactor safety. Two pillars for the procedure are constituted by the characterization of phenomena and by the application of qualified computational tools. Decision makers and scientists may prioritize research in areas where large impacts upon design and safety issues are identified in advance.
[en] The work presents the determination of the thermodynamic potential of oxygen in sodium deoxidized by chromium by means of the EMF-method using a solid oxide electrolyte based on hafnium dioxide stabilized with gadolinium oxide in the temperature range from 300 to 500 ° C. The errors of a separate measurement of the EMF, the errors of the equation coefficients and the comparison of the obtained data with the references are given
[ru]В работе приведено определение термодинамического потенциала кислорода в натрии, раскисленного хромом, методом ЭДС с использованием твердого оксидного электролита на основе диоксида гафния, стабилизированного оксидом гадолиния в интервале температур от 300 до 500 ° C. Приведены погрешности отдельного измерения ЭДС, погрешности коэффициентов уравнения и сравнение полученных данных с литературными
[en] In this paper the methods for determining the characteristics of hot traps operating in the following modes are considered: for sodium purification at nominal parameters; for sodium purification in stop modes with sodium heating at the trap entrance; for sodium purification in modes of transition from stop mode to nominal parameters
[ru]В работе рассмотрены методики определения характеристик горячих ловушек, работающих в следующих режимах: для очистки натрия на номинальных параметрах, для очистки натрия в стояночных режимах с подогревом натрия на входе в ловушку, для очистки натрия в режимах выхода из стояночного режима на номинальные параметры
[en] Highlights: • A BBN model that estimates the number of software faults and reliability is proposed. • A model was established based on the SDLC and software-self characteristics. • Three rounds of expert elicitation were used to estimate the BBN model parameters. • A BBN model was applied to target digital protection software to assess its feasibility. - Abstract: As the instrumentation and control (I&C) systems in nuclear power plants (NPPs) have been replaced with digital-based systems, the need has emerged to not only establish a basis for incorporating software behavior into digital I&C system reliability models, but also to quantify the software reliability used in NPP digital protection systems. Therefore, a Bayesian belief network (BBN) model which estimates the number of faults in a software considering its software development life cycle (SDLC) is developed in this study. The model structure and parameters are established based on the information applicable to safety-related systems and expert elicitation. The evidence used in the model was collected from three stages of expert elicitation. To assess the feasibility of using BBN in NPP digital protection software reliability quantification, the BBN model was applied to the Integrated Digital Protection System–Reactor Protection System and estimated the number of defects at each SDLC phase and further assessed the software failure probability. The developed BBN model can be employed to estimate the reliability of deployed safety-related NPP software and such results can be used to evaluate the quality of the digital I&C systems in addition to estimating the potential reactor risk due to software failure.
[en] On March 11, 2011, the second ''major accident'' in a civilian nuclear power plant after Chernobyl took place in Fukushima Dai-ichi. A major earthquake and resulting tsunami lead to a core melt in three reactors and the following relocation of more than 100.000 residents. But still, worldwide there are 450 nuclear reactors operational today. Safety checks like the EU-Stresstest took place after Fukushima and possibilities for optimization have been identified basically everywhere. Fukushima emphasized the importance of taking natural events more thoroughly into account and led to the implementation of additional safety equipment. But still, events from internal and external causes continue to happen frequently. In addition to these ''conventional'' safety problems, also other threats gain in importance. Besides the danger of terrorist attacks on nuclear facilities, also the deterioration of the institutional environment due to a military or economic crisis has to be taken into account. Thus, nuclear power remains to be a technology with the inherent potential for catastrophic accidents.
[en] Highlights: • This paper provides a comprehensive overview of dependability analysis. • Dependability evaluation taxonomy includes metrics, threats, means, and techniques. • The limitations of the dependability analysis process are analyzed. • Highlights: various gaps, challenges and needs in the context of such systems. • Direction for future research is suggested to extend the furthest scope of research. - Abstract: Safety critical systems progressively used in domains such as nuclear power, transport, medical and information systems are often concerned with a formal process of dependability certification. The intent of dependability process is to ensure that these systems will deliver the expected services to its users. In order to ensure the dependability of large safety-critical systems, the software engineer or security professional needs a thorough knowledge of the process of dependability analysis. In the past several decades, a significant amount of attention has been devoted to the dependability assessment of safety-critical control systems from some perspectives such as reliability, availability, safety, and security. However, for analysis of the critical systems, there is no any universal accepted rigorous dependability analysis process, which helps to choose the metrics, techniques and methodologies for the dependability evaluation of such critical systems. This paper provides a comprehensive detailed literature survey in order to investigate different metrics, threats, means, techniques and methodologies to ensure the dependability of computer-based critical systems. The limitations of these elements are also analyzed with respect to their applicability in SC systems. In addition to this, highlighted various issues (gap), challenges and needs in the context of such systems. The direction for future research is suggested to extend the future scope of research. The purpose of this paper is to interpret a rigorous review concept, of relevance across a wide range of affairs. Therefore, this work helps to the academicians, researchers, and practitioners to put this into practice, analyze the shortcomings of existing research and identifying the open areas that are important for the related community.
[en] Highlights: • Transient scaling distortion of a single phase natural circulation is analyzed. • A Dynamical System Scaling (DSS) method is applied to assess the dynamic process. • The transient mass flow rate and temperature difference are compared and evaluated. - Abstract: Scaling analysis is widely used in the design of nuclear reactor passive safety systems to ensure those scaled-down test facilities can accurately capture important phenomena in a full-scale prototype. In this study, the transient scaling distortion of a single-phase natural circulation system was evaluated using the new Dynamical System Scaling (DSS) method. For convenience of comparison, the conventional Hierarchical Two-Tiered Scaling (H2TS) method, based on the initial static characteristic values, was applied first to determine the system scaling ratios. The different scaled-down cases based on the two methods were calculated with the Relap5 computational code. The results show that two different scaling number groups can be obtained based on the traditional H2TS method and the new DSS identity method, and both of the methods can effectively model the single phase natural circulation in a simple loop. The relative scaling distortion of the transient mass flow rate fluctuated sharply at the initial stage, when the power input increased step-wise, but gradually grew afterwards. In addition, with a smaller power ratio, the DSS identity method was more helpful for the scaled-down facility design.