Construction  sites. Rosatom began welding the closing seam on the reactor pressure  vessel for the Kudankulam NPP Unit 5 in India. This is a key stage in  the manufacture of equipment.  Previously, the lower half-hull weighing  150 tons was moved to the welding machine and connected to the upper  half-hull with an accuracy of 1 mm.  According to the procedure, welding  is carried out for 10 days with continuous heating in the zone of the  weld.  Then, the reactor pressure vessel will undergo heat treatment in a  furnace.  Rosatom is building six power units with VVER-1000 reactors  in India at the Kudankulam site.  The first two units are already in  operation.