CNNC fully grasps the in-service inspection technology of key equipment of VVER unit

Recently, the VVER-1000 unit horizontal steam generator heat transfer tube eddy current inspection equipment and technology independently developed by China National Nuclear Corporation has been successfully applied in Tianwan Nuclear Power Unit 3. This move broke China's dependence on foreign imported equipment in this field, marking that China National Nuclear Corporation fully grasped the in-service inspection technology of key equipment of VVER units. The equipment can achieve precise and fast positioning, high stability, greatly improve the inspection efficiency, and lay the foundation for the subsequent unit overhaul and commissioning optimization, in-service inspection capability and nuclear power operation and maintenance technology "going out".

The steam generator heat transfer tube is the weakest link in the primary circuit pressure boundary of the nuclear power plant, and is also the focus of in-service supervision during the operation of the nuclear power unit. At present, advanced eddy current inspection equipment and technology for horizontal steam generator heat transfer tubes are only available in a few countries. Before and during the pre-service and overhaul period of Units 1 and 2, the eddy current inspection of the steam generator heat transfer tube was carried out using imported equipment. Since the core design parameters cannot be mastered, the reliability of the inspection equipment has always been the focus and difficulty in the eddy current inspection process, and also limits the inspection technology and the optimization of the overhaul period.

Since 2012, Jiangsu Nuclear Power and China Nuclear Wuhan Nuclear Power Operation Technology Co., Ltd. have initiated the independent research on horizontal steam generator eddy current inspection equipment, and formed a research plan in 2013. Through nearly 4 years of research and development, it has overcome the key technical processes such as eddy current probe development, equipment prototype manufacturing and testing, and formal equipment finalization, and finally successfully applied in the pre-service inspection of Unit 3.

DOD Printer

There are three kinds of inkjet printers, piezoelectric inkjet technology, pressure valve inkjet technology and thermal foam inkjet technology, each of which has different working principles.

1) Piezoelectric inkjet technology: Piezoelectric Inkjet Printer is also called high resolution printer or high resolution image printer. On the integrated nozzle, 128 or more piezoelectric crystals are used to control multiple nozzle holes on the nozzle plate respectively. After processing by CPU, a series of electrical signals are output to each piezoelectric crystal through the driving plate. The volume is deformed so that the ink is ejected from the nozzle and falls on the surface of the moving object to form a dot matrix, thus forming text, figures or graphics. Then, the piezoelectric crystal is restored to its original state. Because of the surface tension of the ink, the new ink enters the nozzle. Because the ink dot density per square centimeter is very high, the application of piezoelectric technology can print high-quality text, complex logo and bar code information.

2) Solenoid Valve Type Printer (Large Character Printer): The nozzle is composed of 7 or 16 groups of high precision intelligent micro-valves. When printing, the characters or graphics to be printed are processed by the computer motherboard, and a series of electrical signals are output to the intelligent micro-solenoid valve through the output board. The valve opens and closes quickly, and the ink depends on the internal constant. Pressure dots are ejected, and the dots form characters or graphics on the moving surface of the printed matter.

DOD;Dod Printer,Dod Inkjet Printer,Handheld Dod Inkjet Printer,Handheld Dod Printer