Item Classification of Important Service Water System in Nuclear Power Plant and Its Impact Analysis

2021 ◽  
Author(s):  
Shengtao Zhang ◽  
Ke Yi

Abstract Essential Service Water System (WES) is part of the nuclear power plant cooling system which provides the final heat sink for nuclear power plants. Therefore, WES must operate stably, safely and reliably for a long time. The total loss of WES accident is a design extended condition and will result in the loss of the final heat sink of the unit. The consequences of the accident are severe. In order to deal with the accident quickly and effectively and ensure the safety and economics of the power plant in accident condition, it’s necessary to formulate corresponding treatment strategy to deal with the transient. This paper developed a strategy for dealing with the total loss of WES with Residual Heat Removal System (RHR) not connected condition in Generation III nuclear power plant. The structure of the WES system and the types of failures that may occur are analyzed, and thus the symptoms of the faults are obtained and the entry conditions for the operating strategy are determined. The effect of faults on unit equipment and safety functions and the impact on nuclear steam supply system (NSSS) control are analyzed in this paper. Combined with the unit design, the system and equipment for controlling and mitigating related safety functions are analyzed, and the mitigation method and the fallback strategy of the fault are determined. Thereby a complete operating strategy of total loss of WES with RHR not connected is obtained. In addition, this paper analyzes and evaluates the operating strategy by simulating thermal hydraulic calculation for the first time. The results show that without staff intervention Component Cooling System (WCC) temperature reached 55°C limits after running a few minutes. Based on the intervention of the operating strategy proposed in this paper, WCC temperature reached the 55°C limits when the unit was operated at about 4 hours and 55 minutes. The result shows that and the strategy can effectively alleviate the failure and provide sufficient intervention time for the operator to bring the unit to a safe state.


Author(s):  
Li Nan ◽  
Lao Yi ◽  
Che Yinhui

When inspecting in the nuclear power plant, the bolt of the 001/004 pump in Essential Service Water system was found fracture. The bolt in 001 pump had ever fractured before, and it had been replaced. In this paper, the material, microstructure, energy dispersive spectrometry and mechanical check calculation of the bolt are analyzed. The result shows, the bolt breakage is for stress corrosion cracking, the corrosion element is Cl−. When the martensitic stainless steel is in the heat treatment, the temperature is improper control, which causing the Cr element distribution changed. So the ability of material to resist corrosion becomes poor which is the root cause of the bolt fracture.


2021 ◽  
Author(s):  
Wang Yuqi ◽  
Sun Qian

Abstract Classification of System, Component and Structure (SSC) is the base as well as high level demand of nuclear power plant. Equipment classification including electric and Instrument and Control (I&C) equipment is the precondition of correct design regulation and standard. Safety function classification is key pass of electric and I&C equipment classification. This paper researches the method of nuclear power plant electric and I&C equipment safety function classification. Firstly from view of function, it explains the importance of function classification. Then function analysis and classification of equipment is implemented by design order. Lastly from view of accident analysis, function classification is validated, and a complete approach of function classification is formed. The purpose of this paper is the NPP electric and I&C equipment safety function classification as an example, to study and summarize the method of the electric and I&C equipment safety function classification, and to provide the basis for specific items design work according to design requirements. At the same time, a practical method is provided for other similar NPP electric and I&C equipment classification work. The electric and I&C equipment function classification of nuclear power plant satisfy the basic principles requirement of relative nuclear power rules and codes. It provides an important basis of equipment classification for next nuclear power plants.


2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Zhigang Lan

Focused on the utilization of nuclear energy in offshore oil fields, the correspondence between various hazards caused by blowout accidents (including associated, secondary, and derivative hazards) and the initiating events that may lead to accidents of offshore floating nuclear power plant (OFNPP) is established. The risk source, risk characteristics, risk evolution, and risk action mode of blowout accidents in offshore oil fields are summarized and analyzed. The impacts of blowout accident in offshore oil field on OFNPP are comprehensively analyzed, including injection combustion and spilled oil combustion induced by well blowout, drifting and explosion of deflagration vapor clouds formed by well blowouts, seawater pollution caused by blowout oil spills, the toxic gas cloud caused by well blowout, and the impact of mobile fire source formed by a burning oil spill on OFNPP at sea. The preliminary analysis methods and corresponding procedures are established for the impact of blowout accidents on offshore floating nuclear power plants in offshore oil fields, and a calculation example is given in order to further illustrate the methods.


2001 ◽  
Vol 136 (1) ◽  
pp. 76-88 ◽  
Author(s):  
Boris K. Bylkin ◽  
Galina B. Davydova ◽  
Yuri A. Zverkov ◽  
Alexander V. Krayushkin ◽  
Yuri A. Neretin ◽  
...  

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