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Information × Registration Number 0216U002338, 0113U005930 , R & D reports Title "Increase of the resource of welded joints of the reducer welding together collector of steam generator PGV-1000M of reactorsVVER-1000 by defining of reasons and mechanisms of production and growth of operational defects" popup.stage_title Head Ozhigov Leonid Semenovich, Registration Date 18-02-2016 Organization National Science Center "Kharkiv Institute of Physics and Technology popup.description2 Report on SRW: pages - 47, figures - 45, references - 39 Results of damage of the unit of welding of branch pipe DU-1200 to the collector of steam generator PGV-1000M are analyzed according to the literature sources and our preliminary results. Welded joints of collector welding to the body of steam generator are one of the more weak places in power units of reactors WWER-1000. Beginning from 1998 year more than 30 repairs of such joints were performed. For determination of reasons and mechanisms of formation of "internal" discontinuities the complex of investigation of steel-ingot section cut out during repair on power unit #3 of SUNPS was realized. Analysis of structure components of the method was carried out. The presence of micro cracks, of voids and non-metallic inclusions was detected, the composition of such inclusions was determined. It was shown that nucleation and propagation of defects starts from embedment of silicon carbide, introduced into the metal during welding; cracks develop from these particles on cooling of power unit with high rate. The variation of microhardness of the metal is studied from joint base to its exterior surface. It is shown that in the area of joint base the accumulation of hydrogen is three times higher than in other sections of the metal of welded joint. The control of stressed-deformed state of the steel-ingot section metal of welded joint #111 of welding of branch pipe DU-1200 to the hot collector of steam generator PGV-1000M of power unit #3 of SUNPS is performed by magnetic methods. The results of measurements by magnetic methods correlate with the data of ultrasonic control and are confirmed by metallographic examination. By computer simulation and use of mathematical modeling the finite elements models of stresses and deformation distribution for each form of defected structure and discontinuities of the area of welded joint #111 of the unit of collector welding to branch pipe DU-1200 of steam generator PGV-1000M in conditions of operational loads were developed. The variations of stressed-deformed state near the welded joint and discontinuities at nominal, transient and critical modes of steam generator operation are studied. Calculation of stresses and deformation fields for elastic-ductile model of material behavior in conditions of steam generator accelerated cooling have shows the difference in the level of residual deformation for simulated defect nucleation. Key words: steam generator, welded joint #111, operational defects, microstructure of metal, thermal desorption, hydrogen, stressed-deformed state, magnetic methods, method o finite elements, stress fields Product Description popup.authors Бенедикт Людмила Олександрівна Василенко Руслан Леонідович Воєводін Вііктор Миколайович Гоженко Сергій Васильович Крайнюк Євген Олександрович Лісна Валентина Георгіївна Міщенко Павло Олександрович Митрофанов Анатолій Сергійович Неклюдов Іван Матвійович Ожигов Леонід Семенович Петухов Валентин Вікторович Руденко Олексій Геннадійович Ружицький Валерій Володимирович Савченко Володимир Іванович Толстолуцька Галина Дмитрівна Удалова Наталія Анатоліївна Шаповал Іван Миколайович Шрамченко Сергій Васильович popup.nrat_date 2020-04-02 Close