Volgodonsk branch of Russia’s AEM-Technologies (part of Rosatom’s mechanical engineering division Atomenergomash) said on 16 April that it had completed the machining of two primary circuit collectors for the Akkuyu NPP under construction in Turkey.
Primary circuit collectors are large component parts of the steam generator. The height of each is 5 metres, the maximum diameter is more than 1 metre, and the weight is 16 tons. The key stage in the manufacture is the drilling of 10,978 holes.
Mechanical processing takes 35 days during which specialists drill holes, then perform a sweep to relieve metal stress. The collector then enters the finishing section for finishing including deburring the sharp edges of the holes along the outer and inner diameters of the collector. Manufacture is completed by cleaning, rinsing and drying all holes, as well as carrying out quality control measures.
Two collectors of the primary circuit are installed in the body of the steam generator and welded to the nozzles. Then specialists form a tube bundle of heat exchange tubes in the form of coils. Stainless tubes 9-17 metres long are fixed in the holes of the collectors. During operation at the NPP, heat exchange takes place in the collector between the coolants of the first and second circuits of the reactor plant.
The previous day, Izhorskiye Zavody (part of the OMZ Group) completed welding of the assembly seam of the reactor pressure vessel (RPV) for unit 2 of the Akkuyu NPP under a contract with AEM-Technologies. The annular seam connecting the two half-shells of the reactor was made by automatic welding under a layer of flux for 10 days. After welding, the body will undergo heat treatment, control and hydraulic tests, which will confirm the quality of welded joints and sealing surfaces. The final stage in the manufacture of the RPV before shipment to the customer will be control assembly of the internals (shaft, baffle, block of protective pipes) and a cover for the upper block. The RPV will be shipped in August 2021.
Izhorskiye Zavody has already produced and shipped hydraulic tanks for the emergency reactor core cooling system (ECCS) for Akkuyu 2. Currently, in addition to the RPV, it is producing an upper block, thrust and support rings, a shaft, a baffle and other equipment, as well as the main circulation pipeline.
The Akkuyu NPP construction project is being implemented by Akkuyu Nuclear following an intergovernmental agreement signed between Russian and Turkey in 2010. The Akkuyu NPP, with four VVER-1200 units, is being constructed on a build-own-operate basis by Rosatom, with commissioning of the first unit planned for 2023.