As part of the work to install a unified drainage system at the construction site of unit 1 at the Akkuyu NPP in Turkey, builders have connected the discharge channel and the siphon well – facilities that will ensure the removal of sea and desalinated water after cooling of the plant equipment, project company Akkuyu Nuklear said on 27 April. The construction of discharge channels and siphon wells was carried out in parallel for Akkuyu units 1 and 2. The construction involved 700 workers and specialists who work in continuous shifts.

In the siphon well, the flows are mixed and the temperature of the water coming from the condenser and other NPP cooling systems is equalised before being discharged into the outlet channel. Builders will pour 17,600 cubic metres of concrete to form the reinforced concrete structures of the siphon well. During the construction of the drainage channel, more than 40,000 cubic metres of concrete will be used.

A channel about 950 metres long is being constructed along the coastline of the site. It consists of 34 separate sections, connected by special seams, which ensure that the channel can withstand external influences, such as air temperature fluctuations, seismic phenomena, soil settlement.

Akkuyu Nuklear General Director Anastasia Zoteeva noted: “The complex of high-tech onshore facilities at the Akkuyu NPP area a unique engineering design by Russian and Turkish specialists.”

Before construction of coastal facilities began, a large amount of engineering preparation took place, including strengthening the soils, the construction of siphon wells and outlet channels. The next stage, will see the installation of tunnels and pipelines.

The complex of marine hydraulic structures was designed to cool the main equipment of the Akkuyu NPP with sea water. A water intake facility with a total capacity of 334 cubic metres is being built consisting of nine concrete supply channels and a water intake basin. After passing through the cooling system, the water will be returned to the sea through 10 lines of prefabricated fiberglass pipes with a diameter of 2-4 metres and a total length of 10 km.

The VVER-1200 reactors being built at Akkuyu are two-loop systems: the first loop is closed and water circulates from the reactor, with the help of pumps. The heat from the first circuit is transferred to the water of the second circuit, which boils, turns into steam and rotates the turbine. The steam leaving the turbine enters the condenser, where it is again converted to a liquid state. The water from the primary circuit does not come into contact with the water of the secondary circuit ensuring there is no radioactive contamination of the water discharged into the sea.

Rosatom is building four VVER-1200 reactors at the site, under a build-own-operate model. Construction of the first unit began in 2018, with start-up planned for 2023. The 4800MWe plant when completed is expected to meet about 10% of Turkey's electricity needs.