Abstract : During the construction of a nuclear power plant, a large number of documents of various types will be generated. In order to strengthen the management of document classification, archiving, identification, and retrieval in Jiangsu Tianwan Nuclear Power Station, the owner required all units involved in the project to use a document coding system. This paper mainly introduces the application of the document coding system in the design work. Keywords : document organizer; main activity; document type The construction cycle of a nuclear power plant is relatively long (5-8 years), involving numerous participating units (up to hundreds). During construction, various types of documents are generated, resulting in a massive quantity and complexity. From the initial construction phase, it is essential to anticipate a series of issues related to the classification, archiving, identification, and retrieval of these engineering documents. Based on its experience with document coding at the Daya Bay Nuclear Power Plant, the owner of the Jiangsu Tianwan Nuclear Power Plant (Jiangsu Nuclear Power Co., Ltd.) developed a document coding procedure (procedure number J-Eng.3.06) for the Jiangsu Tianwan Nuclear Power Plant. All units involved in the project's construction are required to implement the J-Eng.3.06 procedure, and all officially published documents must be coded. Documents that do not meet the coding requirements will be returned for revision. As is well known, the management of nuclear power plants is stricter than that of thermal power plants, due to their importance. This article will primarily introduce the application of the document coding system in the design of the Tianwan Nuclear Power Plant for reference by colleagues. 1. Document Coding Structure The Tianwan Nuclear Power Plant document coding system consists of eight squares. J-Eng. 3.06 Program Document Requirements: All officially published engineering documents must include the eight square markers shown above. For drawing documents: place the eight squares below the icon (the same length as the icon). For text documents (e.g., feasibility study and preliminary design specifications): place them at the bottom of each page. From these eight square markers, the following eight important pieces of information can be gleaned: project name, unit number, document preparation unit, main activities (e.g., preliminary design, construction drawings, as-built drawings), sub-activities, document type, document number, and document language. Knowing these eight pieces of information for a document greatly facilitates its classification, archiving, retrieval, and computer-generated sorting. Below, we will introduce the design-related content of these eight squares in sequence. 1.1 Project Code Usually uses the initials "IYG" of the Chinese pinyin for Lianyungang (the location of the Jiangsu Tianwan Nuclear Power Plant). 1.2 Generator Code Constitutes a single digit. 1 - Only for Unit 1; 2 - Only for Unit 2; 0 - On-site (outside the plant perimeter) and documents treating the nuclear power plant as a whole; 9 - Shared areas of the two units (inside the perimeter) and DI (Item Drawing) type documents; x - Identical documents for both units (not applicable to construction design); 3-8 - Reserved for expansion projects of this project; 1.3 Document Compiler Code Constitutes a four-digit code. The first two digits are letters, representing the document compiler's code (see Table 1). The 3rd and 4th digits are numbers, representing the document compiler's internal code, compiled by the document compiler and can represent the internal specialty or department. The internal code of the Northeast Electric Power Design Institute (used to represent specialties) is detailed in Table 2. 1.4 Major Activity Code Constitutes a two-digit code, covering all major activities (or phases) related to the construction of the nuclear power plant (see Table 3). Those marked with "*" are major activities related to design. 1.5 Sub-Activity Code In each major activity of the nuclear power plant construction. This may include sub-activities of different natures and specialties. To distinguish them, a special 5th square is used for labeling. Sub-activity codes consist of 5-8 characters. The labeling of sub-activities is relatively complex, involving many tables, and is omitted here. 1.6 Document Type Code Consisting of 2 letters, see Table 4 for details. Documents marked with * are related to the design work. 1.7 Document Sequence Number Consisting of 4 digits, an internal sequence number created by the document compiler. Numbering can be skipped but cannot be repeated. For ease of memorization and retrieval, it should generally be numbered sequentially by each specialty according to different main activities, starting from 0001. 1.8 Document Language Consisting of one Latin letter, indicating the language of the document. R – Russian; E – English; H – Chinese; S – Two or more languages. 2 Conclusion During the design process of the Tianwan Nuclear Power Plant project, our institute carefully implemented the document coding procedure and, according to J-Eng... 3.06 The program has formulated the "Detailed Rules for the Implementation of Document Coding". At present, the feasibility study, preliminary design, technical design, construction drawing design, equipment purchase technical specifications, installation and construction technical specifications and system design manual have been successfully completed. There have been no cases of rejection due to non-compliance of document coding requirements. Through the document coding work of Jiangsu Tianwan Nuclear Power Plant Project, the following experiences have been gained: (1) The document coding system is a kind of nuclear power plant management software technology. Through document coding, a lot of useful information can be obtained. It is very suitable for computer management, retrieval and listing. It is a management technology worth learning from by the archives department of thermal power system. (2) At present, most owners of thermal power projects have not put forward clear requirements for document coding work. However, with my country's accession to WTO and the increase in power design fees, project owners will tend to be stricter, more meticulous and standardized in project construction management. They will put forward newer and higher requirements for the computerized management of project documents. In this regard, my country's power design departments should take the initiative to adapt. (3) If it is desired to apply the document coding system in the thermal power system, it can be simplified based on the document coding system of Tianwan Nuclear Power Plant, and the "sub-item activity code", "document type code" and "document language code" can be cancelled.