Abstract: This paper introduces the design of an invalid reporting system for nuclear power plant equipment based on .NET. Due to the use of a component-based development approach, the system is easily expandable and has low maintenance costs. Using this system can further improve the efficiency of data collection and statistical analysis of nuclear power plant equipment operation and enhance nuclear safety management. Keywords: nuclear power plant; N-layer architecture; probabilistic safety analysis; reliability data Application of .NET technique in the invalid reporting system of nuclear power plant equipment XU Li, ZHENG Wei, LI He, HAo Bao-shui, WANG Qi (1. Beijing Information Technology Institute, Beijing 100085, China; 2. Guangdong Dayabay Nuclear Power Station, Shenzhen of Guangdong Prov . 518124, China; 3. China Institute of Atomic Energy, Beijing 102413, China) This system possesses the characteristics of easy expansion and lower cost of maintenance due to the application developed from module, and further improves the efficiency for the collection of the running data of nuclear power plant devices and the statistic analysis, as well as the administrative level of nuclear safety. Keywords : nuclear power plant; N-level system structure; probability safety assessment; reliable data Due to the severity of the consequences of nuclear accidents, nuclear safety is the top priority in the development of nuclear energy in all countries. According to China's nuclear safety regulations, a strict licensing system is implemented for the construction and operation of different nuclear facilities. The site selection, design, construction, operation and decommissioning of nuclear power plants are all under the strict supervision and management of the national nuclear safety authorities [1]. After the Three Mile Island nuclear power plant accident in the United States, the probability safety assessment (PSA) method was widely used. With the in-depth application of PSA technology in nuclear power plants, PSA application research results such as Living PSA, Risk Monitor, and RCM (Reliability Centred Maintenance) have emerged. Living PSA is a PSA study that reflects the current design and operation characteristics and parameters of nuclear power plants in a timely manner based on PSA [2]. After a nuclear power plant has been in operation for a period of time, the reliability data used in the original PSA model needs to be updated accordingly based on the accumulated equipment failure records. In order to ensure the integrity and traceability of various information during the operation of the nuclear power plant, avoid duplication of work, save human resources, improve work efficiency and nuclear safety management level, based on our previous experience in making reliability data collection reports for PSA research, we use modern computer technology, database technology and network communication technology to study and develop the equipment failure reporting system, thereby improving the previous equipment operation reliability data collection, storage, analysis and transmission methods. At present, due to the limitations of software technology at that time, the enterprise information network of nuclear power plants in my country is difficult to solve the communication problem between heterogeneous systems and achieve true network information sharing, forming several data silos. .NET is a design architecture launched by Microsoft for the future Internet. This technology enables the development of applications for different environments and devices, overcoming one of the biggest problems in the software industry [3]: seamless data exchange between applications and devices written in different languages ​​and for different environments. Therefore, using .NET technology to develop the "equipment failure reporting system" can make more effective use of network resources, avoid data silos, and achieve high-level sharing of network information. 1. System Design Objectives The Equipment Failure Reporting System is a distributed database application system based on the internal network of a nuclear power plant. Its main purpose is to quickly and accurately provide PSA (Power Supply Authority) with equipment reliability parameters and generate the reports required for reliability data collection. Simultaneously, it provides data for activities such as safety assessment, preventative maintenance, accident prediction, and spare parts optimization management in the nuclear power plant. The system consists of four main functional modules: Equipment Management, Operation Management, Reliability Data Statistics, and Reliability Parameter Calculation. Specifically: The Equipment Management module primarily handles the maintenance and querying of equipment information, equipment failure modes, periodic testing (PT) procedures, equipment maintenance, and power plant system information. Since the reliability parameters of power plant equipment are calculated by equipment category, equipment information is the most fundamental data in the system. The Operation Management module primarily handles the daily maintenance and querying of operator log data, periodic test data, and 24-hour event descriptions. It also downloads operator log reports, periodic test reports, and 24-hour event reports as required for inclusion in the reliability report. The data managed by this module is the raw data used for reliability data statistics. Reliability Data Statistics Module: This module primarily converts equipment operating data into annual cumulative reliability data for each equipment category based on operator logs, periodic tests, and 24-hour events. The statistically analyzed equipment reliability data includes: annual cumulative operating hours for each equipment category, annual cumulative demand count for each equipment category, annual cumulative operating failure count for each equipment category, and annual cumulative demand failure count for each equipment category. The statistical results are saved to a database for use in generating equipment category failure trend charts and calculating reliability parameters. Reliability Parameter Module: In reliability engineering, there are two types of statistical inference methods for reliability parameters: traditional statistical inference methods and Bayesian methods. This module provides methods for automatically or manually selecting appropriate methods to estimate the operating failure rate and demand failure probability under various failure modes for each equipment category, based on the characteristics of specific data and expert opinions. The calculation results are saved to a database for later querying and browsing. It also provides the function of generating statistical reports required for reliability reports by equipment category. The generated reports include: Failure Mode List, Reliability Data Statistics Results, Reliability Data Summary Table, Prior Data Table, Bayes Calculation Results, and Classical Calculation Results. 2 System Structure The system implementation adopts an N-layer architecture, as shown in Figure 1. The presentation layer, or application client layer, is responsible for interacting with the user. This layer includes the interfaces for the device management module, operation management module, reliability data statistics module, and reliability parameter module. The presentation layer only performs shallow processing of input, handling only validity rules and descriptions of input events. Specific operations such as insertion are handled by objects in the business logic layer. The business layer, also known as the middleware layer, breaks down complex business relationships into multiple single-function services, each capable of performing a specific task. These services can be implemented using relatively independent service components. By distributing these components, data processing load can be balanced, logical relationships coordinated, and business scale and rules adjusted. This layer can be deployed anywhere on the network. In this system, we further subdivide the business layer into a logic layer and a data access layer. The logic layer mainly includes the following components: 1) LOGICBASE: The base class for all objects in the business layer. This class provides a data access layer object, a connection string variable, and a DataSet object. This object serves as the intermediate layer data storage object. Before being committed to the database, all the results of data addition, deletion, and modification operations will be stored in this intermediate layer object. After the data update is committed, the connection to the database is established. This can greatly reduce the database server load and make better use of client computer resources. 2) EQUIPGROUP: Encapsulates all operations related to device classes. Almost all functional modules of the entire program use this class. 3) EQUIPMENTL: Encapsulates all operations related to device data. 4) EVENTLIST: Encapsulates all operations related to 24-hour event information. 5) EXPER: Encapsulates all operations related to periodic tests. 6) OPERATORLOG: Encapsulates all operations related to operator logs. 7) PTRULEL: Encapsulates all operations related to PT procedures. 8) Statistics: Encapsulates all code related to statistical operations. 9) ToExcel: Encapsulates all output operations for Excel files, providing support for outputting operator logs, 24-hour events, periodic test data, etc. The data access layer completes the interaction with the database. This layer contains only one component, SQLSERVER, which encapsulates all access to the SQL Server database, including populating DataSet, executing specific stored procedures, updating data modifications to the database, etc. The data layer is the backend database. The backend database of this system is the SQL Server database. Separating independent applications into different layers or parts can increase the scalability of the application and reduce the complexity of the entire application [4]. This makes the system easy to expand and has low maintenance costs. 3 Software Development The database application system uses Visual Studio.NET 2003 as the development tool and C# (read as C Sharp) as the programming language. Visual Studio.NET is an integrated development environment (IDE) designed for building .NET Framework applications. It contains many key technologies and simplifies the development, deployment and maintenance process for creating secure, scalable and highly available web applications and web services. C# evolved from C/C++ and is a new programming language characterized by simplicity, modernity, object-oriented features, and type safety. It combines the high efficiency of VB with the powerful functionality of C++, enabling developers to quickly and easily build solutions for the Microsoft .NET platform. 3.1 Development Methodology Software development adopts a component-based development method, which involves creating applications based on one or more sets of components. This elevates traditional object-oriented programming to a new level, implementing a service within a component, improving component reusability and maintainability. The Visual Studio .NET integrated development environment provides rich tools to support the development of .NET Framework components, making component development very easy. 3.2 Key Technologies in Software Design 1) Base Class for Logic Layer Objects. Since all logic layer objects in the system use data access layer objects and DataSet objects, if the definition of data access layer objects and the passing of connection strings are unified in a base class, the scalability of the entire system's logical structure will be greatly enhanced. Therefore, when designing the logic layer, a common base class object was written. The main program is as follows: public abstract class LogicBase: System.ComponentModel1. Component { // Defines the base class as an abstract class, which cannot be directly instantiated. protected SQLSERVER dataSource; // Protected data access layer object, so that subclasses inheriting from this class can also access this protected member. private static string strConn; // Private static member, used to store the connection string. protected DataSet mData // Protected member, this member is the dataset object used in the logic to store intermediate layer data. public DataSet LDATASET // Public method, this method returns a reference to the dataset { ... } public static string ConnectionString // Public static property, through which the private variable strCon used to store the connection string can be accessed { ... } public LogicBase() { // Constructor of the base class, creates the database connection object and instantiates the dataset object dataSource— new SQLSERVER (str—Conn); this. `mData = new DataSet();` The variable storing the data connection string is defined as static because regardless of how many subclasses inheriting from the base class are created, the same connection string will be used. This also facilitates setting the database connection string at program startup and during database configuration. 2) Design of an annual trend chart for device failures. A third-party component called Infragistics NetAdvanced is used here. It provides a WinChart component that can perfectly display charts and supports data binding in .NET. The control's setup is basically wizard-driven and very simple to use. 3) Using data validation during data entry and before data statistical calculations ensures the accuracy of data storage and statistics. For example, when adding operator logs and calculating reliability data from them, check for possible errors in the logs. If the same device appears twice consecutively as either started or stopped, it indicates an error in the record, and the system will automatically remind the user. 4) Database existence check. If the server is not started or its location has changed, the user should be prompted when the program starts. The database startup check code is placed in the main form's load event. Since a 10-second timeout check is required during the check, and the program cannot be in an unresponsive state during this period, a new thread is created here to perform the database connection check. 3.3 Development Environment 1) Hardware Requirements. Several computers connected to the Internet. Minimum configuration for each computer: Pentium II processor, 450 MHz; 256 MB physical memory; at least 3.5 GB of free space on the installation drive. 2) Software Requirements. Windows 2000 or Windows XP; Visual Studio .NET Professional Edition; SQL Server 2000. 4 Application and Conclusion The Reliability Equipment Failure Reporting System is built on information technology and uses a systematic management approach to provide nuclear power plant managers with a platform for managing equipment reliability data during plant operation. This system can provide not only historical operating records and original characteristic parameters of equipment, but also equipment reliability parameters for PSA analysis in nuclear power plants; it can quickly and accurately generate data reports for nuclear power plant equipment reliability data collection and reporting, and can also guide nuclear safety management of nuclear power plants based on equipment failure trend analysis results. The system was used to perform statistical calculations on the historical operating data of pumps in the circulating water system (CRF) of a nuclear power plant from 19970101 to 20011231. Some calculation results are shown in Figures 2 and 3. References: [1] Sun Zaozhan, Yu Zusheng. Application prospects of database system in nuclear safety [J]. Nuclear Science and Engineering, 1998 (3). [2] Development of Methods for Optimization of Surveillance Testing and Maintenance of Safety Related Equipment at NPPs [-z]. IAEA Working Material, Vienna, Australia, 1997. [3] Microsoft Corporation, author. Translated by Yang Zhijuan, Li Pengpeng, et al. Developing XML Web services and server components with Visual Basic .NET and Visual C# .NET [M]. Beijing: Tsinghua University Press, 2003: 2-10. [4] Cheng Xiaolin, Song Miaoyun, et al. Visual Basic. Advanced .NET Database Tutorial [M]. Beijing: Tsinghua University Press, 2004: 296-325. [5] Archer, T. Translated by Ma Zhaohui. C# Technology Unveiled (Second Edition) [M]. Beijing: Machinery Industry Press, 2004.