The cantilever truss, the second piece of the ‘melt trap’, with the weight of 145 tons and the diameter of over 9 meters, has been installed at its final position, under the reactor vault, at the Kursk NPP-2 second power block. That said, one of the governmental assignments for 2020 has been completed.
‘We continue working on the construction of the safety system for the 2nd power block replacing the existing power plant’, Viacheslav Fedyukin, the director of the Kursk NPP, said. ‘A melt trap is our national ‘know-how’ with regard to the off-design accident handling systems’.
It is important to note that a ‘melt trap’ consists of three pieces: a framework, a cantilever truss, and a slide plate.
The reactor building already houses the ‘melt trap’ framework filled with special material (primarily made of ferric and aluminium oxides, this filling material is solved in the molten core material to reduce its power density). The reactor vault has been circled at the height of 7 meters. This is where the cantilever truss was installed.
The main designation of a cantilever truss is to facilitate amenities – water supply, heat removal, ventilation, passages for measuring instruments and for melt trap device examinations. Another idea behind the cantilever truss is for it to serve as a basis for other installations, such as the slide plate and the dry reactor shielding.
Consolidation will be the next stage. Connecting legs serving as service corridors will be welded to the large part, with the total weight of the piece growing up to 200 tons. Following that, the construction team will install the slide plate, the third heavy-weight element of the melt trap. If necessary, this plate will protect the whole structure from the heat impact of the corium (the fuel-containing mass and the construction materials).