Atommash, the Volgodonsk branch of JSC AEM-Technologies (part Rosatom’s mechanical engineering division Atomenergomash) has begun welding the closing seam connecting two half-shells of the VVER-1200 reactor pressure vessel (RPV) for unit 3 of the Xudabao NPP under construction in China’s Liaoning province. Previously, specialists with the help of a crane moved the lower half-hull weighing 160 tons to the welding machine and connected it to the upper half-hull with an accuracy of 1 mm. The total weight of the product is 333 tons.

Welding lasts about 10 days with continuous heating in the weld zone – from 150 to 300 degrees. During this time, 1.5 tons of flux and more than a ton of wire with a diameter of 4 millimeters will be consumed. After welding, the product will be heated to 300 degrees and with the help of a crane it will be transferred to the furnace, where the heat treatment of the product will take place for two days. Next, the specialists will carry out the entire range of control measures in the areas of the weld: x-ray flaw detection, ultrasonic and capillary controls.

The product is a vertical cylindrical body with an elliptical bottom, inside which the active zone and internal devices are located. From above, the equipment is hermetically sealed with a lid with drives of mechanisms and control and protection organs installed on it, branch pipes for the output of cables of in-reactor control sensors.

For Xudabao 3&4, Atommash will manufacture two RPVs with internals, a cover and an upper unit, and two sets of steam generators.

In 2018, Russia and China signed agreements for the construction of two VVER-1200 as units 3&4 at the Xudabao NPP site. Further agreements signed in June 2019 included a general contract for the construction Xudabao 3&4, as well as a contract for the supply of nuclear fuel. Rosatom will design the nuclear island and supply key equipment, as well as provide installation supervision and commissioning services for the equipment. Turbine generators for the plants will be supplied by China. The power units are expected to be commissioned in 2027-2028.

Image: Welding the closing seam of the VVER-1200 reactor pressure vessel for unit 3 of the Xudabao NPP (courtesy of Atomenergomash)