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[en] This paper presents a conceptual design for a plant-wide autonomous operation system that uses artificial intelligence techniques. The autonomous operation system has the power and ability to perform the control functions needed for the emergency operation of a nuclear power plant (NPP) with reduced operator intervention. This paper discusses the emergency operation and level of automation in an NPP and presents the design requirements for an autonomous emergency operation system (A-EOS). Then, an architecture that consists of several modules is proposed, with descriptions of the functions. Finally, this paper introduces a prototype of the suggested autonomous system that integrates the authors’ previous works
[en] Super fine-grained graphite is a type of advanced nuclear graphite which was developed for Molten Salt Reactor (MSR). It is necessary to establish a failure assessment method used for nuclear graphite components in MSR. A modified assessment approach based on ASME BPVC-III-52017 is presented. The new approach takes a new parameter, KIC, into account and abandons the parameter, grain size, which is unrealistic for super fine-grained graphite as the computation is enormous if we use conventional methods. Three methodologies (KTA 3232, ASME, New approach) were also evaluated by theoretical prediction and experimental verification. The results indicated the new developed code can be used for design and failure assessment of super fine-graphite components and has more extensive applicability.
[en] Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation Ⅲ nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part I, finite element (FE) models establishment and validations for both the aircrafts and NPP buildings are performed. (i) Airbus A320 and A380 aircrafts are selected as the representative medium and large commercial aircrafts, and the corresponding fine FE models including the skin, beam, fuel and etc. are established. By comparing the numerically derived impact force time-histories with the existing published literatures, the rationality of aircrafts models is verified. (ii) Fine FE model of the Chinese Zhejiang Sanao NPP buildings is established, including the detailed structures and reinforcing arrangement of both the containment and auxiliary buildings. (iii) By numerically reproducing the existing 1/7.5 scaled aircraft model impact tests on steel plate reinforced concrete (SC) panels and assessing the impact process and velocity time-history of aircraft model, as well as the damage and the maximum deflection of SC panels, the applicability of the existing three concrete constitutive models (i.e., K&C, Winfrith and CSC) are evaluated and the superiority of Winfrith model for SC panels under deformable missile impact is verified. The present work can provide beneficial reference for the integral aircraft crash analyses and structural damage assessment in the following two parts of this paper.
[en] During transients or accidents, the reactor core is uncovered, and droplets entrained above the quench front collides with the uncovered fuel rod surface. Droplet impact cooling can reduce the peak cladding temperature. Besides zirconium-based cladding, versatile accidental tolerant fuel (ATF) claddings, including FeCrAl, have been proposed to increase the accident coping time. In order to investigate the effect of surface properties on droplet impact cooling of cladding surfaces, the droplet impact phenomena are photographed on the FeCrAl and zircaloy-4 (Zr-4) surfaces under different conditions. On the oxidized FeCrAl surface, the Leidenfrost phenomenon is not observed even when the surface temperature is as high as 550 °C with We > 30. Comparison of the impact behaviors observed on different materials shows that nucleate and transition boiling is more intensive on surfaces with larger thermal conductivity. The Leidenfrost point temperature (LPT) decreases with the solid thermal effusivity (kρCp). However, the CHF temperature is relatively insensitive to the surface oxidation and Weber number. Droplet spreading diameter is analyzed quantitatively in the film boiling stage. Based on the energy balance a correlation is proposed for droplet maximum spreading factor. A mechanistic model is also developed for the LPT based on homogeneous nucleation theory.
[en] This comprehensive document issued by the Swiss Nuclear Safety Inspectorate ENSI in October 2020 reports on its activities in accordance with Article 32 of the Joint Convention on the Safety of Spent Fuel and Radioactive Waste Management. The report is composed of ten Sections. An introduction presents basic information and an overview. Further sections cover aspects such as polices and practices, scope of application, inventories and lists, legislative and regulatory system, general safety provisions, safety of spent fuel management, safety of radioactive waste management, transboundary movement and disused sealed sources. Finally, general efforts to improve safety are discussed. Two Annexes complete the report.
[en] This new edition of the Nuclear Law Bulletin Index covers the first 103 issues of the Nuclear Law Bulletin (NLB). By established practice, the plan of the Index is not a replica of the Bulletin, as it was considered more useful for research purposes to group together all the information concerning legislative and regulatory activities, case law and bilateral agreements and to classify this information by country. Following classification by country, references to the work of international organisations, multilateral agreements, studies and articles are set out in separate sections. The 'Bibliography and News Briefs' section is omitted from the Index. A separate chapter of the Index has been devoted to the listing of the instruments published in the Supplements to the Bulletin, or in the Chapter 'Texts' from past Bulletins, up until the present date. Each item in the Index is followed by a reference to the relevant Bulletin. Legislative and regulatory texts, as well as agreements reproduced in the Bulletins or their Supplements, are also referenced