scholarly journals Regulatory analysis for the resolution of Generic Issue 153: Loss of essential service water in LWRs

1993 ◽  
Author(s):  
T.M. Su
Keyword(s):  
Service Water ◽  
Regulatory Analysis ◽  
Essential Service

Research on Operating Strategy of Total Loss of Essential Service Water System With RHR Not Connected in PWR Unit

2020 ◽  
Author(s):  
Shengtao Zhang ◽  
Ke Yi
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Heat Sink ◽  
Nuclear Power ◽  
Cooling System ◽  
Water System ◽  
Total Loss ◽  
Operating Strategy ◽  
Service Water ◽  
Essential Service

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.

Data Analysis for RPV Life Management Studies of Temperature Measurements From Monitoring of Safety Injection Fluid in Spent Fuel Pit Cooling and Treatment System Storage Tank

2003 ◽  
Author(s):  
Dominique Lagrange ◽  
Vincent Venturini ◽  
Georges Bezdikian ◽  
Jacques Salaun
Keyword(s):  
Storage Tank ◽  
Treatment System ◽  
Spent Fuel ◽  
Temperature Dependent ◽  
External Temperature ◽  
Life Management ◽  
Service Water ◽  
The Stability ◽  
Essential Service ◽  
Reactor Pressure

In Electricite´ de France (EDF) probabilistic analyses for Reactor Pressure Vessel (RPV) life management, it’s used to take the temperature of the Reactor Spent fuel Pit cooling and treatment System storage tank as a constant. The aim of our study is to evaluate the stability of this temperature. Since 1999, we collected for several sites, and several nuclear plant units, the temperature of the Reactor Spent fuel Pit cooling and treatment System storage tank. Our results illustrate that this temperature depends on the season and the site. We first proposed to give a modelisation of this temperature dependent of the external temperature; even if this modelisation leads to a good R2, it’s not optimum. We also proposed to explain the temperature using the temperature of the essential service water or for lack the temperature of the river. In the case of extreme quantile study (meaning low temperature), we proposed to use the normal approximation, which seems to be conservative.

Study on Effects of Environment Conditions on Essential Service Water System of Nuclear Power Station

2017 ◽  
Author(s):  
Yang Ting ◽  
Li Guang Sheng ◽  
Li Zeng Fen ◽  
Peng Yue ◽  
Hu Jian
Keyword(s):  
Environmental Conditions ◽  
Nuclear Power ◽  
Water System ◽  
Open Water ◽  
Water Levels ◽  
Negative Effects ◽  
Power Stations ◽  
Service Water ◽  
Physical And Chemical ◽  
Essential Service

For nuclear power stations, the main function of Essential Service Water System (ESWS) is to discharge the waste heat from reactor core and spent fuel pool to the environment controllably, which is directly related to the safety and economy of nuclear power stations. Usually ESWS use open water from sea, rivers, lakes, reservoirs, as heat transfer medium. Extremely harsh environmental conditions may disable system functions and even lead to ESWS failure, directly reduce the safety and economy of nuclear power stations, and cause serious nuclear accidents. Failure of ESWS is one of the main reasons that lead to the Fukushima nuclear accident because of the loss of electricity after the earthquake and tsunami. Based on the typical ESWS configuration and conditions of serving nuclear power stations in China, the influence of environmental conditions on the function of water system is studied, and the corresponding measures are analyzed. These conditions can be divided into three categories: temperatures, water levels, and physical and chemical characteristics. Temperatures affect cooling characteristic of ESWS mainly. Nuclear power stations in tropical areas need to focus on cooling capacity might be reduced by high temperature. Those in cold region need attention to excessive cooling and freezing problems caused by low temperature. The influence of water levels is mainly fluid transport capacity and selection of equipment to ESWS. When the range of natural water level is too wide, designers shall consider measures to narrow it, such as the construction of highly reliable reservoir. Inland nuclear power stations shall try to ensure the reliability of ESWS; prevent water level changes beyond the scope of design caused by drought and flood disasters. The effects of physical and chemical properties are derived from the open water characteristics, including high salinity, high chloride ion concentration, carrying solid particles, suspended solids, and aquatics, and so on. These characteristics will cause the equipment and pipeline eroded or even damaged, aqueducts of intake and output jammed, heat exchangers of the final heat sink weakened and other negative effects, resulting in ESWS performance decline. Some of these factors are the characteristics of station site natural environment, some others are changes caused by human activities. Some factors are sustained, long-term; some others may be sudden, temporary. Influence on these factors need to be taken measures from many aspects, including structure, biological disinfection, special materials and equipment, environmental protection measures around the nuclear power station, and so on. On the whole, the environmental factors that affect ESWS in the nuclear power stations are wide, and the influence mechanism is more complex. These factors ultimately act on ESWS, but most of them cannot be banished inside of ESWS or the final heat sink system. Against the negative effects from environmental conditions, it has to be considered from all steps in the engineering of nuclear power stations, including design, construction and operation. All the measures shall be suitable to local conditions, in order to ensure the safety and economy of nuclear power stations.

Update on Code Case N-755 Revision Class 3 Polyethylene Piping

2009 ◽  
Author(s):  
Matthew G. Golliet
Keyword(s):  
United States ◽  
Nuclear Regulatory Commission ◽  
Water Systems ◽  
Polyethylene Pipe ◽  
Nuclear Plants ◽  
Service Water ◽  
Asme Code ◽  
Pipe Replacement ◽  
Regulatory Commission ◽  
Essential Service

Nuclear plants have received United States Nuclear Regulatory Commission (NRC) approval to use polyethylene pipe in safety related systems such as essential service water systems. ASME Code Case N-755 is the basis for the utility requests. ASME Nuclear Code committees are developing a revision to provide clarification to the code case requirements and address NRC concerns. Polyethylene pipe replacement projects provide a solution to the age degradation issues such as corrosion and fouling of buried carbon steel pipe.

The Root Cause Analysis of the Bolt Fracture in the Nuclear Power Plant Essential Service Water System

2017 ◽  
Author(s):  
Li Nan ◽  
Lao Yi ◽  
Che Yinhui
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Water System ◽  
Element Distribution ◽  
Material Microstructure ◽  
Root Cause ◽  
Check Calculation ◽  
Service Water ◽  
Essential Service

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.

Analysis of ASME Class 3 Buried HDPE Piping Systems Related to Code Case N-755-1

2013 ◽  
Author(s):  
Young Seok Kim ◽  
Jung Kwang Yoon ◽  
Young Ho Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Design Procedure ◽  
Piping System ◽  
Service Water ◽  
Hdpe Pipe ◽  
Division 1 ◽  
Piping Systems ◽  
Asme Code ◽  
Essential Service

This paper proposes an analysis method for Section III, Division 1, Class 3 buried High Density polyethylene (HDPE) piping system in the nuclear power plants (NPP). Although HDPE pipe would yield at high temperature (limited to 140°F), it may be suitable for the areas prone to earthquakes; owing to its comparable ductility and flexibility. Thus, the buried HDPE piping may be applicable for the safety related Essential Service Water (ESW) system in the NPPs. Despite some limitations to buried HDPE piping, the piping could be designed based on ASME Code Case [1]. Generally, codes and standards including ASME Code Case [1] do not provide load combinations for the design of both buried steel piping and HDPE piping. Meanwhile, EPRI Report [4] provides load combinations including thermal expansion effects and seismic loads with detailed seismic criteria for polyethylene pipe. In this paper, load cases and load combinations for buried HDPE piping are suggested for implementation of reference documents and a buried HDPE piping system is analyzed referring to EPRI Report [4] to evaluate stress, force, and moment using a piping stress analysis program. Additionally, this paper will recommend the design procedure in accordance with ASME Code Case [1] using an example of buried HDPE piping analysis. An investigation of soil spring coefficients and the design considerations for hydrostatic tests are suggested for the enhanced analysis of buried HDPE piping.

Investigation of Effects of Piping Configuration and Water Supply Pressure on Air Intrusion

2012 ◽  
Author(s):  
Jaehyok Lim ◽  
Basar Ozar ◽  
Christopher E. Henry ◽  
Kevin B. Ramsden
Keyword(s):  
Power Plant ◽  
Water Supply ◽  
Storage Tank ◽  
Nuclear Power ◽  
Water Pressure ◽  
Water System ◽  
Supply Pressure ◽  
Service Water ◽  
Essential Service ◽  
Supply Water

An evaluation of the effects of geometry and water supply pressure on the void transport has been performed using RELAP5/MOD3.3 (patch03). Two different piping configurations were considered for a hypothetical nuclear power plant. The cases that were analyzed considered switchover between two different water supplies, i.e. condensate storage tank (CST) and essential service water system (SX) for a safety system that acted as the ultimate heat sink. In addition, two different pressures were considered for the pressure of SX to investigate the effect of supply water pressure on void transport. Results were interpreted based on the differences in the geometries of the piping configurations and supply water pressures.

Use of HDPE Piping in the Callaway Nuclear Plant Essential Service Water System

2009 ◽  
Author(s):  
Shannon L. Abel ◽  
Matthew D. Brandes ◽  
Lonnie J. Corley ◽  
Joseph L. Fortman ◽  
Thomas M. Musto ◽  
...  
Keyword(s):  
Water System ◽  
The United States ◽  
Nuclear Plant ◽  
Lessons Learned ◽  
Metallic Materials ◽  
Service Water ◽  
Design Qualification ◽  
Qualification Testing ◽  
Microbiologically Induced Corrosion ◽  
Essential Service

Callaway Nuclear Plant is the first nuclear plant in the United States to utilize high density polyethylene (HDPE) piping in a nuclear safety-related application. HDPE is being installed in buried sections of the plant’s ASME Section III, Class 3 Essential Service Water (ESW) system. Due to its resistance to erosion, corrosion and microbiologically induced corrosion (MIC), HDPE is well suited to raw water system applications. As with any other first of a kind project, the use of HDPE piping in the Callaway ESW system has presented challenges in all phases of the project. Design, qualification and installation considerations for thermally-fused HDPE in an ASME Class 3 system differ significantly from those for traditional metallic materials. This paper will examine the challenges and lessons learned in the design, qualification testing, installation, examination and pressure testing of the HDPE piping at Callaway Nuclear Plant.

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