The Volgodonsk branch of Atommash AEM-Technologies (part of Rosatom’s mechanical engineering division Atomenergomash) has assembled the lower half-shell of the reactor for unit 7 of China’s Tianwan NPP, Atomenergomash said on 25 May. The specialists first assembled the bottom, the shell of the core, and the flange in a vertical position. The elements with a diameter of 4.5 metres had to be assembled with maximum precision with a tolerance of no more than 2mm. The 160-ton structure was then turned to a horizontal position by means of a rotator and installed on a welding machine for welding girth seams. Welding is carried automatically over 17 days with constant heating in the welded seam zones from 150 to 300 ?. A total of two circular seams will be welded. After that, heat treatment of the seams will take place to give the metal the necessary properties and to remove the residual welded stresses.
The reactor is a vertical cylindrical body with an elliptical bottom, inside which the core and internals are located. From above, it is hermetically sealed with a lid with installed drives of mechanisms and controls and protection of reactors and nozzles for outputting cables of sensors for in-reactor control. In the upper part of the body there are nozzles for supplying and removing the coolant, as well as nozzles for emergency supply of the coolant when the circuit is depressurised.
For Tianwan 7&8, Atommash will manufacture two reactor vessels with internals, a cover and an upper block, and two sets of steam generators. An intergovernmental protocol and a framework contract for the construction of VVER-1200 reactor sat the two units was signed in 2018 and first concrete was poured earlier in May. The of the facility is carried out by the Rosatom’s Engineering Division, ASE EC, is responsible for design and construction.