Характеристики зварних з’єднань поглинаючих елементів зі сплаву 42ХНМ для стрижнів системи управління та захисту ВВЕР-1000

• Дата: 2023
• Автори: Kushtym, A., Zigunov, V., Grytsyna, V., Krasnorutskyy, V., Slabospytska, O., Mukhin, M., Bondarenko, S., Kovaliuk, O.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: State Scientific and Technical Center for Nuclear and Radiation Safety 2023
• Онлайн доступ: https://nuclear-journal.com/index.php/journal/article/view/1057
• Назва журналу: Nuclear and Radiation Safety

The article presents the results of studying weld joints in the absorbing rods of the rod cluster control assembly (RCCA) for VVER-1000 power reactors produced by electric arc welding in an argon and helium atmosphere. The design and welding modes of absorbing rod surveillance specimens, dummies and pilot samples, and prototype fuel rods ensuring their specified design characteristics are presented. The results of developments and studies with regard to the influence of the welding mode of claddings with end parts (cone and tip) made of 42CrNiMo alloy on the parameters of weld joints are presented. It is shown that the highest quality weld joints are obtained at a welding speed of 4.4 mm/s. At lower values, complete penetration of the cladding and filling of the entire joint bottom is not always ensured. The results of mechanical tests of the absorbing rod dummies by static tension on a tensile machine are presented. It is shown that the tensile strength of weld joints of end parts with the cladding is not less than the tensile strength of the absorbing rod cladding. The results of metallographic studies of weld joint materials performed on longitudinal and transverse polished sections cut from weld joints of the absorbing rod dummies and surveillance specimens are presented. The dependence of welded joint width and penetration depth on welding modes was studied, and the optimal modes were selected to ensure leak tightness and required strength of the absorbing rods. The material structure of the studied weld joints is fine-grained, and the grain size ranges from 3...4 μm (13 points) to 4...10 μm (10 points). The microhardness value of the weld material is 185...238 HV. A description of the methods used to control the absorbing rods is presented.