The Chornobyl NPP site consists of two main functional complexes: an industrial site of NPP with outdoor switchgear, cooling pond and construction base. The industrial site of NPP and a construction base are situated in the limits of control area within a radius of 3 km, circumscribed around of axis of ventilation stack. The general plant layout provides the rational location of all buildings and installations taking into account the organization of technological transport inside the site: automobile, railway and also surface and underground service.
The plant layout of industrial buildings and installations meet the main hygiene and sanitary principle of NPP designing – an allocation of all territory, buildings and premises into the zones: the security (controlled) and free procedures.
The protected area includes a territory, buildings and premises of the plant, where there is a possibility of radiation factors influence on personnel. The personnel is allowed to the protected area only through the change facility. In the protected area all the premises are allocated into serviced, half-serviced and out service. In the serviced premises the influence of radiation factors on the personnel during six hours working day doesn’t exceed the permissible norms. The personnel is allowed to the half-serviced premises periodically for the time excluding the personnel exposure over the reference levels. The personnel is allowed to the out service premises during the operation of equipment by special programs. In the free area during the normal operation of equipment the radiation factors influence is completely excluded.
The left plant layout from intake channel was designed. The constant butt is directed to the cooling pond. The outdoor switchgear of 110, 330 and 750 KV is situated behind the intake channel from the outside of turbine hall. The main building of the plant is partitioned into five blocks:
- blocks A and Б,- the reactors №№ 1, 2, 3, 4 with technological equipment are located;
- block B,- the equipment of special water purification, gas circuit and others of stages 1 and 2 is located;
- block Г, - a turbine hall where turbines №№ 1-8 with auxiliary equipment are located;
- block Е, - a maintenance facility of “dirty” equipment is located (main circulation pumps, special pumps, heat exchangers, maintenance tool sets, etc.).
The link of the main building with administrative and service buildings is carried out by pedestrian gallery. In the united auxiliary building the chemical water purification, a mechanical workshop, warehouses, etc. are located. The liquid and solid waste storages are linked with the main building by transport-technological surface gallery, joint with box of special ventilation, which is attached to the ventilation stack by 150m in length. In the ventilation stack basis the gas-holder of endurance is installed.
The fresh fuel storage and spent fuel storage are located in the separate buildings and have the railways. In the diesel power plant of NPP stage 1 (is designed for the power supply of special responsible consumers), 8 diesel engines are installed of 3500 kilowatt of power each and at the NPP stage 2 – 6 diesel engines of 5500 kilowatt of power each.
Service water-supply
For the Chernobyl NPP the reverse scheme of service water-supply with off-river cooling pond by 98 million m³ is designed, water-surface area is about 22.9 km². The cooling pond water infill and makeup is carried out from Pripyat’ River by pumping facility. The periodical let-down of cooling pond is carried out through water outlet by maximum full-capacity discharge of 20 m³.
Circulation scheme
From cooling pond the water is supplied by the opened channel to two pumping facilities of service water-supply of NPP stages 1 and 2, located in front of the main building from the outside of turbine hall. Each pumping facility consists of two blocks: first - circulating, assures the water supply to the turbines condensers and second – force-pump for water supply of heat-exchangers of technological equipment of Unit. In the circulating block there are 12 vertical pumps of NPP stage 1 and 9 vertical pumps of NPP stage 2, assuring the maximum supply of water flow – 105m³/sec. with pressure of 7.1m of water column. In the force-pump block there are 4 pumps of NPP stage 1 and 6 pumps of NPP stage 2, assuring the maximum supply of water flow – 9.7m³/sec. with pressure of 28m of water column. The circulating pumps supply water to the pressure basin by 40000 m³ water-surface area of 30000 m², and then water flows by gravity through water intake facility supplies to the turbine condensers. Such scheme is substantially increase the reliability of NPP operation.
Basic heat diagram
The Unit heat diagram is a direct cycle and includes a reactor and two turbo-generators that mean the direct steam arrival to the turbines generated inside the reactor. The heat rejection is carried out by coolant (water) from fuel assemblies and graphite column of reactor. The water is circulating forcedly through the technological channels of reactor and is heating up from 265°С to the temperature saturation at pressure 70 kgf/sm² and partially evaporating. The steam-water mixture arrives to the drum-separator where there is a process of its separation into two phases: steam and water. The steam is arriving in the main steam pipes to the turbines and the separated water in the sinking pipes returns to the intake headers of the circulating pumps which carrying out its multiple forced circulation through the reactor. The input to the turbines steam with a pressure 69.5 kgf/sm², and a temperature of 280.4°С, at the dryness fraction of 0.995, is arriving through the blocks of steam valves and high-pressure cylinder (HPC). After HPC the steam with a pressure 3.53 kgf/sm² and a temperature 141.1°С , at the dryness fraction of 0.846, is arriving by receivers to the separators-re-heaters, where the moisture is removed from it and the two-stage live-steam overheating up to the temperature of 263°С is carried out.
At pressure of 3.0 kgf/sm² and a temperature of 263°С the steam arrives to the low-pressure cylinders, where the expansion of steam occurs up to end pressure of 0.04 kgf/sm². From the condensers by the condensate pumps of stage 1, the condensate through the coolers of the main ejectors, the ejectors of compacting and condenser purification the steam arrives to the condensate pumps of stage 2. The condensate pumps pump the steam through five surface heaters of low pressure (HLP) to the deaerators. The condensate discharge of heating steam of HLP is carried out by the cascade system into the turbine condensers. By heat scheme the two-stage deaeration of the main condensate is stipulated.
For assuring radiation safety during the plant equipment operation there are the separate systems for collection of radioactive water with its subsequent purification and reversion.