New state-of-the-art regulatory document has been developed and implemented in Ukraine to present requirements for seismic hazard assessment of nuclear power plant (NPP) sites and seismic resistance of nuclear power units taking into account lessons learnt from the accident at Fukushima-1 NPP. One of the new important regulatory requirements in this document is the extension of the list of mandatory load combinations, which should be considered in assessing seismic resistance of unit components. Advantages and disadvantages of the algorithm proposed by the operating organization to determine the necessity to consider some load combinations in assessing the seismic resistance of pipelines and thermomechanical equipment based on previously performed seismic strength calculations have been analyzed in the paper. The pipelines as well as the thermomechanical equipment of Zaporizhzhya NPP Unit 3, for which seismic strength evaluation was calculated, have been considered. The results of expert seismic calculations of YP13S02 valve of ZNPP-1 and ZNPP-3 have been provided. The paper presents the comparative analysis of the floor response spectra for the lower, middle and high elevations of ZNPP-3 containment with the corresponding floor response spectra of other Ukrainian NPPs and conclusions. The possibility for disseminating results obtained by the operating organization for ZNPP-3 to other units of the Ukrainian NPPs has been analyzed.
According to Articles 22 and 24 of the Law of Ukraine “On Nuclear Energy Use and Radiation Safety” and with the aim of improving the regulatory and legal documents regulating nuclear and radiation safety of nuclear installations, the regulation “Requirements for Seismic Resistance Design and Evaluation of Seismic Safety of Ukrainian NPPs: NP 306.2.208-2016” was developed. The paper presents modern requirements included into NP 306.2.208-2016. The emphasis was done on new requirements that were not previously available in PNAE G-006-87, but should be taken into account both in the design of new NPP units and in the assessment/reassessment of seismic resistance of operating units.
Nuclear energy is a strategic Ukrainian industry that produces more than 50% of electricity at present. Over the last decade during the operation of Ukrainian NPPs, the set of technical matters have been found and corresponding tasks shall be decided with engaging of scientific potential of the country. One of such matter is a safety justification of NPP components and structures for the period that is bigger than an initial design one and that is defined as transition from design operation to the long-term operation (LTO). From the end of 2010 to the beginning of 2020, the State Nuclear Regulatory Inspectorate of Ukraine granted 11 licenses for 11 power units based on positive results of the state assessment and review of Periodic Safety Review Reports considering mandatory safety review each ten years. These results became possible due to the coordinated, conscientious and longstanding work of thousands of highly qualified nuclear experts, which led to the fact that Ukraine now has a unique experience in preparation for a transition of various types of WWER-1000 and WWER-440 reactors to LTO. The summarized results and lessons learnt from the practice of transition to LTO are presented in this paper.
Seismic resistance of equipment and piping of nuclear power plant units is determined, particularly, by seismic resistance of their steel support structures. A significant number of these structures are located in the reactor building of nuclear power plants and belong to seismic resistance categories I and II. Therefore, such support structures of nuclear power plant equipment and piping, in general, shall perform their functions under seismic hazards that correspond to the safe shutdown earthquake and design-basis earthquakes, respectively. Steel support structures of serial equipment (piping valves, electric and pneumatic drives of piping and pump valves, expansion tanks, etc.) are often designed “on site” in the limited conditions of their actual location. Therefore, it is necessary to design steel support structures of a number of equipment taking into account the fact that it can be connected, in particular, to existing piping with their actual routing. In connection with the above, the research of operation for such support structures under seismic loads is relevant. The article presents the research results for the spectrum of natural oscillation frequencies of the equipment support structure, and the stress-strain state of the considered structure under seismic loads is determined. At the same time, the parameters during normal operation and maximum design basis accident at the nuclear power plant power unit are considered. The calculated combination of loads, which simultaneously includes two episodic impacts (maximum design basis accident and an earthquake) is considered.
Регламентована нормативними вимогами номенклатура сполучень технологічних умов експлуатації сталевих опорних конструкцій обладнання, трубопроводів атомних станцій та сейсмічних впливів є досить широкою і містить всі можливі випадки технологічних умов їх експлуатації. Під час виконання оцінки сейсмостійкості опорних конструкцій постає питання щодо можливості обґрунтованої оптимізації встановленої нормативними вимогами номенклатури сполучень навантажень. Така оптимізація може бути виконана на підставі дослідження впливу зміни технологічних умов експлуатації сталевих опорних конструкцій обладнання та трубопроводів енергоблоків атомних станцій на їх сейсмічну міцність. У статті визначено номенклатуру параметрів технологічних умов експлуатації опорних конструкцій обладнання та трубопроводів енергоблоків атомних станцій, що впливають на їх сейсмічну міцність. Досліджено вплив зміни цих параметрів на сейсмічну міцність опорних конструкцій. Стаття входить до циклу публікацій в журналі «Ядерна та радіаційна безпека», присвячених розгляду різних аспектів практичного використання нормативних вимог до оцінки сейсмостійкості елементів енергоблоків атомних станцій.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.