I. Overview
The key welding materials currently used in the manufacturing and installation of nuclear power equipment are lagging behind developed countries such as nuclear power for welding R&D and technical reserves. The technical level and quality stability of nuclear welding materials and localization of nuclear power. There is still a certain gap in construction needs. Due to the shortcomings of imported welding consumables, difficulties in communication and supervision during production, and high prices, it has become one of the bottlenecks affecting the development speed of nuclear power in China. To a certain extent, it has affected China's development of nuclear power and comprehensive nuclear power. The goal of localization. Therefore, in recent years, the National Energy Administration, the Ministry of Science and Technology and other units initiated by the nuclear power units such as China Guangdong Nuclear Power and National Nuclear Technology Co., Ltd., and the related industries of production, education and research in the welding consumables industry, focusing on the supply, research and development, production of raw materials for domestic welding materials. Professional teams in the fields of application and evaluation have carried out a series of technical research on the localization of welding consumables for nuclear power and achieved good results.
2. Research and application status of localization of welding consumables for nuclear power
1. Progress in localization of welding consumables for nuclear power
(1) Welding materials used in nuclear grade welding consumables are classified into nuclear grade welding consumables and non-nuclear grade welding consumables due to different quality assurance grades and performance indexes. Nuclear grade welding consumables are mainly used in the manufacture and installation of nuclear grade equipment. in. Due to the late start of domestic nuclear grade welding consumables, it is currently mainly supplied by foreign manufacturers. However, in recent years, with the vigorous promotion of the state and the increased investment in research and development of related enterprises, the research and development and production of nuclear grade welding consumables have made great breakthroughs.
In July 2009, the nuclear grade welding consumables produced by Atlantic Welding Materials successfully passed the ASME warranty review and were approved by Westinghouse. In September of the same year, the first batch of E9018 welding rods for the welding of AP 1000 steel containment shells arrived at the construction site of the Sanmen Nuclear Power Plant project (the first AP 100 project in China), marking the localization of nuclear grade welding consumables. breakthrough.
In August 2013, Shanghai Electric Power Repairing Co., Ltd. passed the acceptance test for the “National R&D and Experimental Platform for Nuclear Grade Nickel-Based Welding Materials”. The platform aims to continuously improve the nuclear safety and quality assurance system and continue to deepen the development of serialized products for nuclear grade welding consumables. Actively explore innovative business models.
After more than two years of technical research, the National Energy Application Technology Research and Engineering Demonstration Project “National Development and Application Research of Nuclear Grade Welding Materials” successfully developed the welding rod and solid wire for the carbon steel series of ACP R1000 units. Flux cored wire, submerged arc welding wire flux, stainless steel series welding rod, welding strip flux, low alloy steel series electrode, metal powder type flux cored wire, nickel base alloy series electrode and welding wire, etc., 9 varieties In March and July 2014, the two batches passed the scientific and technological achievements appraisal organized by China Nuclear Energy Industry Association and China Welding Association, and the remaining varieties were undergoing third-party test verification.
CAP1400 unit national nuclear power major project "Development of welding materials for nuclear power equipment" has made positive progress, involving austenitic stainless steel surfacing welding materials, stainless steel welding materials for the inner basket of the inner basket of the reactor, 690 nickel-base alloy welding materials, low Five sub-projects, such as alloy steel welding materials, have passed the stage review and completed the milestone node, and have the conditions for conducting follow-up third-party evaluation and test research.
(2) Conventional island welding materials Conventional island welding materials have been basically localized, but some special varieties of welding consumables still rely on imports. In recent years, the domestic joint research and development of special-purpose welding consumables has been carried out in the form of project research. For example, the project “Development of welding materials for nuclear power conventional island anti-fluid erosion corrosion” has successfully developed WB36CN1 steel which is completely matched with steel. 20-controlled chrome steel special welding consumables, the composition of the welding consumables, mechanical properties, process performance and other indicators are well matched with the parent metal. In addition, the project participants have developed a localized anti-fluid erosion corrosion welding material manufacturing process specification and The quality control technology requirements form the enterprise technical standards.
2. The basis and deficiency of localization of welding consumables for nuclear power
China has a certain foundation in the localization of welding consumables for nuclear power, mainly reflected in the high enthusiasm of welding consumables enterprises, the complete supporting industrial systems, the continuous improvement of R&D and testing capabilities of enterprises, the scale effect of welding consumables enterprises and the long-term Experience feedback on the application of imported nuclear grade welding consumables.
However, compared with foreign advanced technology, China's nuclear power welding materials still have a large gap with foreign welding materials in terms of quality stability, product performance and performance, mainly due to insufficient product quality stability and the appearance of some products. , physical properties, welding processability, performance and so on, and the first-class products in foreign countries, the lack of accumulation of product performance data.
Third, the development trend of nuclear power welding materials localization
1. Key difficulties in the localization of nuclear welding consumables
Since 2011, domestic design institutes, research institutes, and consumables manufacturers have set up R&D teams through different R&D platforms to actively overcome the technical difficulties in the development of nuclear grade welding materials. The development of welding consumables has reached the corresponding design specifications and welding technology. The technical requirements of the material standard, but to achieve a true sense of full localization, there are still the following problems.
First, the performance design indicators of some welding materials (such as the content control of some trace elements) are very strict, and there are difficulties in the procurement of wire rods in the small batch development stage. It is still necessary to further verify the design indicators through test verification, so that the design requirements and The quality stability of batch production requires a better combination point. The welding materials in the strong irradiation area are verified by the irradiation test, and the irradiation test is subject to huge expenditure costs and uncertain test cycles. Therefore, many teams are not involved in the development of such welding materials, or The developed welding consumables lacked sufficient data for the support of the radiation test.
Second, the quality assurance system audit of welding materials enterprises is carried out by the user. Only a few companies in the country have compiled quality manuals or quality for nuclear welding materials based on relevant ASME standards, RCC-M standards, and HA F003 documents. Guaranteed outline. However, many enterprises involved in the production of nuclear grade welding consumables have not established a production quality assurance system document for nuclear grade welding materials. It is difficult to pass quality assurance audits, which makes users lack sufficient confidence in the quality stability of multiple batches of welding consumables.
Thirdly, the developed welding consumables have reached the technical requirements for the design of welding consumables for different nuclear power types of pressurized water reactors. Some of the consumables are gradually evaluated by the application unit, and carbon steel welding consumables and low alloy steel consumables have been supplied. However, there are still great difficulties in the promotion and application of welding materials for nuclear primary equipment. On the one hand, in recent years, there have been fewer nuclear power units in China, and the tight supply of imported welding consumables has been somewhat relieved. Second, the application units are cautious and conservative about nuclear primary welding materials that do not have nuclear power engineering application performance.
2. The development trend of localization
The localization of nuclear power welding materials has attracted the attention of the national ministries and commissions. In November 2014, the National Energy Administration agreed in the reply to the technical plan of Fujian Fuqing Units 5 and 6 to be upgraded to the "Hualong No. 1" technical plan, to make full use of China's current The nuclear power equipment manufacturing system supports the localization of key equipment, components and materials, and emphasizes that the localization ratio of key materials such as nuclear grade cables and welding consumables cannot be lower than 85%. Hualong Unit 1 has not completed all relevant design work for welding consumables. It can be expected that the nuclear grade welding materials used in Hualong No. 1 model will be different from those of A P1000 and CP R1000 units, so the nuclear level of R&D has been completed. Whether the welding consumables can meet the requirements of Hualong No.1, further testing and verification is required. If necessary, it is necessary to continue to optimize the design of the welding consumable alloy system and formula to realize the localization of the welding consumables of Hualong No.1 unit and support its “going”. The strategy of going out should be of concern to all welding consumables.
Each welding material research and development platform still needs to master the alloy system and formula design principle of nuclear grade welding consumables and the fundamental mechanism of impact on performance, and improve the technical service capability required for the subsequent promotion and application of nuclear grade welding consumables. Accelerate the establishment and improvement of the production quality assurance system for high-end welding materials, and ensure that the system operates effectively and improve its welding material quality management capabilities. All parties should create favorable conditions for the welding material application unit to be more deeply involved in the entire R&D and performance evaluation of the welding consumables, which will make the R&D and production process more transparent and will enhance the confidence of the end users in practical application.
About the author: Wang Haogang, etc., Suzhou Thermal Engineering Research Institute Co., Ltd.
