Work has begun at unit 2 of the Kursk-II NPP site to construct another of the tallest cooling towers in Russia, with a height of 179 metres, the plant said on 17 June. The first such cooling tower was erected at Kursk-II unit 1. Installation of the columns for the base of the evaporative cooling tower for Kursk-II unit 2 is underway. Specialists from Titan-2 have installed eight of the hundred reinforced concrete columns of the inclined colonnade. “Using the experience of assembling an inclined column of the cooling tower at the first power unit, we are optimising the process and timing of similar work at the cooling tower for unit 2,” said Aleksey Buldygin, head of construction at Kursk-II. “The installation time for one column has been reduced by almost half: on average, specialists assemble two columns each 11-hour shift. We plan to assemble all 100 columns along the circumference of the ring foundation by the end of August.”
Due to the complexity of the work, installation is carried out only during the day shift. The installation of each column, 13.6 metres high and weighing 20 tons, is accompanied by a geodetic survey, during which the height and the angle of inclination of the column are checked. The inclined colonnade of the cooling tower has two main functions: it absorbs the load from the shell of the exhaust tower and transfers it to the foundation, and also provides unhindered air access to effectively cool the circulating water. Simultaneously with the installation of the columns, the foundation slab of the catchment basin is being concreted.
Earlier in June, Atomenergomash (the mechanical engineering division of Rosatom) reported that Petrozavodskmash (part of AEM-Technologies) had started assembling hydraulic tanks for the passive core bay system (SPZAZ) with internal devices for unit 1 of Kursk-II. One power unit is equipped with eight SPZAZ tanks, each with a volume of 120 cubic metres and made of stainless steel. The product consists of three shells and two bottoms; ladders and service platforms, as well as other internals, which are installed inside the body. Petrozavodskmash has assembled and welded all eight SPZAZ half-shells: three shells each with a lower bottom. In one of the hulls, the first deck was installed, which is a prefabricated welded structure from a round bar. The diameter of the flooring is about 4 metres, the weight is 546 kilograms. Three such structures are installed in each container.
SPZAZ is part of the second stage of the passive NPP safety system designed to remove residual heat release from the primary coolant of the reactor. During operation at the station, an aqueous solution of boric acid is stored in tanks, heated to a temperature of about 60 degrees. When the pressure in the primary circuit drops below a certain level, the liquid is automatically supplied to the reactor and the core is cooled.
Kursk-II is a replacement station for the current Kursk nuclear plant. Commissioning of the first two units with the new design VVER-TOI reactors will be synchronised with the decommissioning of the RBMK reactors at Kursk 1&2 of the operating plant.
Meanwhile a lengthy repair outage of 138 days has begun at unit 4 of the original Kursk NPP. “The duration of the repair is due to the large amount of work to be done,” said Vyacheslav Fedyukin, director of the Kursk NPP. “Repair of the power unit involved more than 1000 different pieces of equipment.” The repair program for power unit 4 includes expanded in-core control of 240 process channels and 10 control channels of the control and protection system, control and measurement of various parameters of equipment, overhaul of two block turbine generators, repairs of pipeline valves, main circulation pumps, other systems and devices. Currently, units 1 and 3 are in operation at the Kursk NPP with unit 2 also closed for scheduled repair.