Construction workers have started concreting the third tier of the inner containment (ICE) at unit 2 of Russia’s Kursk-II NPP-2.

“The inner containment consists of a cylindrical part and a dome. Now the final stage of concreting the cylindrical part has begun – the total height of the structure at the moment is 36 metres,” explained Andrey Osharin, First Deputy Director for construction of the new units on 13 August. “After all the layings are concreted and the mixture gains strength, we will proceed with the installation of reinforced concrete blocks that make up the domed part of the inner shell.”

Concreting work is carried out by specialists of TrestRosSEM. Initially they laid 1,470 cubic metres of concrete mix. Concreting was carried out continuously for almost 32 hours. Quality control of the concrete mixture takes place throughout the process. Sampling is carried out from each mixer truck, and only when the required technological characteristics are confirmed, the concrete mixture is allowed for laying in the structure. In total, the concreting of the third tier will require about 3,000 cubic metres of mixture.

The inner containment is the main element of the hermetic enclosure of the reactor facility; its height will be 61.7 metres, and the wall thickness will be 1.2 metres. Compared with the serial Russian power units of earlier projects, the containment in the VVER-TOI project can withstand greater pressure. Kursk-II 1&2 are being built according to the VVER-TOI project (standard optimised informatised pressurised water power reactor), which is a development of the VVER-1200 reactor design with increased capacity and improved technical and economic indicators. Kursk II is being built near the village of Makarovka in the Kurchatov district of the Kursk region as a replacement station for the currently operating Kursk NPP, which comprises four RBMK reactors. The commissioning of unit 1 is scheduled for the end of 2025.

Meanwhile, Atommash (part of the mechanical engineering division of Rosatom – Atomenergomash) has begun welding circumferential seams on the upper semi-vessel of the reactor for Kursk-II unit 2. This is one of the key stages in the manufacture of the reactor pressure vessel. The upper semi-body was assembled from two shells and a flange. The total weight of the structure is 180 tons. Automatic welding of two circumferential seams will continue for 25 days with continuous heating of the weld zone.

Next, the upper semi-hull will be heated to 300 degrees and sent to the oven for heat treatment, which will last three days. The process of heating and holding in the furnace takes place at a maximum temperature of 620 degrees. After heat treatment, a number of necessary checks of welded joints will be carried out on the semi-hull. The product will be prepared for the application of an internal corrosion-resistant surfacing in the areas of welds.

Image: Concreting of the third tier of the inner containment at unit 2 of Russia’s Kursk-II NPP-2 has begun (photo courtesy of Rosatom)