At the Volgodonsk branch of JSC “AEM-technology” “Atommash” (part of the Rosatom machine-building division - Atomenergomash), specialists have started the welding of circumferential welds on upper semi-vessel of the reactor for Unit No. 7 Tianwan NPP (China).


This is considered to be the key milestone in manufacturing of the nuclear reactor. The upper semi-vessel has been put together from two shells and a flange, total mass of the construction is 180 tons. At welding stand professionals have begun the automatic welding of two circumferential welds. The operation is going on within 25 days upon continuous heating of weld zone with total consumption of 5000 kg of flux and 3500 kg of welding wire.


After welding operation, the product is heated up to 300 degrees and moved to furnace for heat treatment, which will go on for three days. Heating and holding process in furnace carries at the maximum temperature of 620 degrees.


After heat treatment professionals will perform a set of required inspections on the semi-vessel, carry out internal anti-corrosion overlaying at weld zones.


The reactor represents a vertical cylindrical body with an elliptical head, inside of which there are the Core and the Internals. On top, it is sealed with a Cover with drives mechanisms and regulating bodies installed on top for the protection of the reactors and nozzles, intended for the sensor cables output for in-core monitoring. In the upper part of the vessel, there are nozzles for the coolant input and output, as well as nozzles for emergency supply of the coolant if the circuit is depressurized.


Tianwan NPS is located in Jiangsu Province, People’s Republic of China. The first power units No.1 and No.2 with VVER-1000 reactors were handed over to the customer and put into warranty operation in 2007. Units No.3 and No.4 were introduced into warranty operation in 2018. On June 8, 2018, an intergovernmental protocol and a framework contract for construction of power units No.7 and No.8 of Tianwan NPS with VVER-1200 reactors, which belong to the newest generation "3+", were signed in Beijing. The design and construction of the object are carried out by the Engineering Division of the State Corporation “Rosatom”.




Joint-Stock Company "AEM-technology", founded in 2007 in the structure of JSC "Atomenergomash", an engineering division of the state corporation Rosatom, is currently one of the leading Russian companies in the field of power engineering. The structure of the company includes an engineering department, staffed by experienced designers and process-engineers, as well as two production sites: the Branch of JSC "AEM-technology" "Petrozavodskmash" in Petrozavodsk and the Branch of JSC "AEM-technology" "Atommash" in Volgodonsk.


Welding of the upper semi-vessel of the reactor for Tianwan NPP has been started at Atommash
Welding of the upper semi-vessel of the reactor for Tianwan NPP has been started at Atommash