The 340-tonne reactor vessel could now be installed before the end of the year at the new unit being built by Rosatom at the Kursk nuclear power plant.
The flushing of the active and passive safety systems with the open reactor are described as a key moment in the pre-start-up checks for the first reactor at Kursk II nuclear power plant.
The dome of the outer containment shell has been hoisted into place at the first reactor under construction at the Kursk II nuclear power plant, Russian state nuclear corporation Rosatom announced.
The structure weighing 256 tonnes has a diameter of 36 metres and has been installed in the design position on the reactor building of Kursk II's second unit.