On October 25, one of the most important construction milestones was completed at Kursk NPP-2 - welding of the pearlitic part of the reactor coolant pipeline. The welding and thermal treatment of all the welding joints was completed in 55 days instead of 88 envisaged by the schedule, which is an absolute record for this operation.
“Very stringent requirements are imposed on the reactor coolant pipeline welded joints. During the welding works, specialists of the general contractor and the customer performed a step-by-step inspection of all the operations: visual, measurement, radiographic, penetrant and ultrasonic tests”, said Andrey Osharin, Acting Director of Kursk NPP. “In spite of a high rate of the works, the quality of the joints comply with all the requirements”.
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Specialists of Energospetsmontazh JSC were involved in the works. The works were carried out 24 hours per day by 24 welders and 24 installation specialists who replaced each other performing welding and trimming of welding joints.
“In accordance with the master schedule, the works for the reactor coolant pipeline welding were to be completed in 80 days”, said Mikhail Pinchuk, general director of Energospetsmontazh JSC. “However, thanks to the introduction into the work execution plans of the most effective proposals for improvement that have been earlier implemented at Novovoronezh NPP-2, Belarus NPP and Rooppur NPP units, we managed to significantly reduce the duration of the works. Besides, highly qualified specialists of grades 5-6 were involved. These specialists have vast experience of such works at other NPPs”.
“The reactor coolant pipeline is the main artery that unites the equipment of the nuclear steam supply system of the NPP power unit. From the point of view of technology of civil and construction works, the completion of the reactor coolant pipeline makes it possible to commence the installation of safety systems and other adjacent process systems. Actually, the preparation for the next milestone begins, which is the commencement of safety systems flushing with the open reactor”, said Oleg Shperle, Vice President of ASE JSC - Director of Kursk NPP construction project.
Currently, coating with austenitic stainless steel is being performed which will protect the pipeline from the aggressive medium. These works will be completed before the end of October.
For reference:
The reactor coolant pipeline has the diameter of 850 mm, the wall thickness is 70 mm and its length is over 140 meters. The reactor coolant pipeline connects the main equipment of the primary circuit - the reactor, the steam generators and the reactor coolant pumps. Considering high requirements for quality and operational conditions, the reactor coolant pipeline welding is one of the most complicated and important stages of civil and construction works at the power unit. The reactor coolant pipeline carries the water heated in the reactor into the steam generators from which the steam goes to the turbine and generates electricity.
The construction of Power Units 1 and 2 of Kursk NPP-2 is performed within the framework of federal project “Designing and construction of reference power units of nuclear power plants” of comprehensive program “Development of research and technology in the field of use of atomic energy in the Russian Federation up to 2024”.