IMPROVING THE THERMAL EFFICIENCY OF NUCLEAR REACTORS: AN ANALYSIS OF COOLING SYSTEMS AND HEAT EXCHANGE PROCESSES

About two-thirds of the heat generated in a nuclear reactor is rejected to the environment through the condenser, making the type of cooling system the second major factor determining the actual efficiency achieved by the plant. This paper quantitatively evaluates the impact of the dry cooling technology selected for the nuclear power plant in the Jizzakh region on thermal efficiency. The steam cycle of a VVER-1000 unit was modelled using IAPWS-IF97 properties and twelve-month climate normals for Jizzakh. The calculations show that, in July, condenser pressure increases from 7.03 kPa under an evaporative cooling tower to 14.65 kPa under an air-cooled condenser, while gross efficiency decreases from 32.90% to 31.01%, corresponding to a loss of 1.89 percentage points. On an annual average basis, the thermodynamic penalty is 0.91 percentage points, or 27.3 MW, while the additional fan power demand is 33.9 MW. Thus, the larger share of the annual loss is attributable to parasitic fan power rather than increased condenser back-pressure. Together, these two effects reduce unit output by 6.1%. In return, two units save 31.5–47.3 million m³ of water per year. The authors recommend a hybrid configuration with seasonal wet assistance, which can recover half of the thermodynamic penalty while using only one-quarter of the corresponding water requirement.

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