Qualification of Ultrasonic Examination for RPV Nozzle to Shell Welds of EPR Nuclear Power Plant

Author(s):  
WeiQiang Wang ◽  
Zhe Yu ◽  
Xin Ye ◽  
HuaiDong Chen ◽  
GuanBing Ma

European Pressurized Reactor (EPR) nuclear power plant is now under construction in China. One of the biggest changes in the EPR reactor pressure vessel (RPV) is the nozzle to shell welds are designed as “set-on” principle instead of “set-in” principle in the CPR1000 units. The nozzle to shell welds of the EPR pressure vessel must be inspected according to the RSE-M code. This is necessary in order to guarantee the integrity of the primary circuit. The In-Service Inspection (ISI) program of EPR nuclear power plant demands the automatic ultrasonic inspection of the nozzle to shell welds from nozzle inner surface. This paper presents the technical characteristics of the EPR reactor vessel, and analyzes the in-service examination requirements of nozzle to shell welds. Technical solutions have been designed to perform the examination of the component. The qualification process of the ultrasonic examination of the nozzle to shell welds is also presented.

Author(s):  
J. C. Kim ◽  
J. B. Choi ◽  
Y. H. Choi

Since early 1950’s fracture mechanics has brought significant impact on structural integrity assessment in a wide range of industries such as power, transportation, civil and petrochemical industries, especially in nuclear power plant industries. For the last two decades, significant efforts have been devoted in developing defect assessment procedures, from which various fitness-for-purpose or fitness-for-service codes have been developed. From another aspect, recent advances in IT (Information Technologies) bring rapid changes in various engineering fields. IT enables people to share information through network and thus provides concurrent working environment without limitations of working places. For this reason, a network system based on internet or intranet has been appeared in various fields of business. Evaluating the integrity of structures is one of the most critical issues in nuclear industry. In order to evaluate the integrity of structures, a complicated and collaborative procedure is required including regular in-service inspection, fracture mechanics analysis, etc. And thus, experts in different fields have to cooperate to resolve the integrity problem. In this paper, an integrity evaluation system on the basis of cooperative virtual reality environment for reactor pressure vessel which adapts IT into a structural integrity evaluation procedure for reactor pressure vessel is introduced. The proposed system uses Virtual Reality (VR) technique, Virtual Network Computing (VNC) and knowledge based programs. This system is able to support 3-dimensional virtual reality environment and to provide experts to cooperate by accessing related data through internet. The proposed system is expected to provide a more efficient integrity evaluation for reactor pressure vessel.


Author(s):  
Xueliang Zhang ◽  
Chunbing Shao ◽  
Ximing Tang ◽  
Cheng Yang ◽  
Huixing Feng

The latest edition of French In-service Inspection Rules RSE-M2010, incorporating the up-to-date upstream French regulations, orders and requirements for pressure equipments, and taking into account both of the radioactive risk and industrial risk in nuclear power plant (NPP), has been adopted as the applicable rule for in-service inspection (ISI) of EPR units. In RSE-M2010, the previously used benchmark for classification Safety Class has been replaced by the Nuclear Pressure Equipments Class (ESPN Class), and the category of pressure equipments has been introduced to monitor the industry risks of NPP pressure equipments, making it much more precise and convenient to define the scope of equipments which subjected to ISI and corresponding ISI requirements on frequency and methods. This paper described the main differences of the ISI requirements in RSE-M2010 and previous edition of RSE-M, also introduced practices of applying RSE-M2010 when preparing the ISI program of Taishan EPR units. Based on the application practice of RSE-M2010 on Taishan EPR project, some proposals for future improvement of this code are presented. Preliminary thinking for future implementation of EPR ISI activities has also been described.


Author(s):  
Kenji Akagi ◽  
Masayuki Ishiwata ◽  
Kenji Araki ◽  
Jun-Ichi Kawahata

In nuclear power plant construction, countless variety of parts, products, and jigs more than one million are treated under construction. Furthermore, strict traceability to the history of material, manufacturing, and installation is required for all products from the start to finish of the construction, which enforce much workforce and many costs at every project. In an addition, the operational efficiency improvement is absolutely essential for the effective construction to reduce the initial investment for construction. As one solution, RFID (Radio Frequent Identification) application technology, one of the fundamental technologies to realize a ubiquitous society, currently expands its functionality and general versatility at an accelerating pace in mass-production industry. Hitachi believes RFID technology can be useful of one of the key solutions for the issues in non-mass production industry as well. Under this situation, Hitachi initiated the development of next generation plant concept (ubiquitous plant construction technology) which utilizes information and RFID technologies. In this paper, our application plans of RFID technology to nuclear power is described.


Author(s):  
Richard A. Hill

After several years of intense labor by many industry people, ASME is about to issue its newly approved PRA standard. This standard is for probabilistic risk assessment (PRA) for nuclear power plant applications. It is not a standard on how to build a PRA model; although, that could be inferred from the standard’s technical requirements. This Standard sets forth requirements for PRAs used to support risk-informed decisions related to design, licensing, procurement, construction, operation, and maintenance. It also prescribes a method for applying these requirements depending the degree to which risk information is needed and credited.


Author(s):  
Thomas Wermelinger ◽  
Florian Bruckmüller ◽  
Benedikt Heinz

In the context of long-term operation or lifetime extension most regulatory bodies demand from utilities and operators of nuclear power plants to monitor and evaluate the fatigue of system, structures and components systematically. As does the Swiss Federal Nuclear Safety Inspectorate ENSI. The nuclear power plant Goesgen started its commercial operation in 1979 and will go into long-term operation in 2019. The increased demand for monitoring and evaluating fatigue due to the pending long-term operation led the Goesgen nuclear power plant to expand the scope of their surveillance and therefore to install AREVA’s fatigue monitoring system FAMOSi in the 2014 outage. The system consists of 39 measurement sections positioned at the primary circuit and the feed-water nozzles of the steam generators. The locations were chosen due to their sensitivity for fatigue. The installed FAMOSi system consists of a total of 173 thermocouples which were mounted in order to get the necessary input data for load evaluation. The advantage of FAMOSi is the possibility to obtain real data of transients near places with highest fatigue usage factors. Examples of steam generator feed-in during heating-up and cooling-down will be given. In addition, spray events before and after the installation of closed loop controlled spray valves will be compared. The measurements and the results of the load evaluation are not only of interest for internal use e.g. in regard to optimization of operation modes (e.g. load-following), but must also be reported to ENSI annually. In addition, by evaluation of stresses and determination of usage factors combined with an optimization of operation modes an early exchange of components can be avoided.


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