This article is about: How does Nuclear Power Plant work?
In a nuclear power plant, the nuclear reactor generates heat. This heat is used to generate steam (directly or via a steam generator) which drives a steam turbine.
- Nuclear reactors in these power plants are “only” used to generate heat. This heat is used to generate steam which drives a steam turbine connected to a generator that produces electricity.
- Typical reactor nominal thermal power is about 3400MW. The heat is produced by fission in a nuclear reactor and passes into the primary cooling water.
- For PWRs, the coolant (water) is heated in the reactor core from about 290°C (554°F) to approximately 325°C (617°F) as the water flows through the core.
- The hot coolant is then pumped via main coolant pumps into steam generators.
- In steam generators, this heat is transferred through the walls of these tubes to the lower pressure secondary coolant located on the secondary side of the exchanger, where the coolant evaporates to pressurized steam (saturated steam 280°C; 536°F; 6,5 MPa).
- This pressurized steam is then routed into the steam turbine, in which steam expands from pressures of about 6 MPa to pressures of about 0.008 MPa. Steam turbines in western nuclear power plants are among the largest steam turbines ever.
- A steam turbine is connected to the main generator, which generates electricity.
Most nuclear power plants operate a single-shaft turbine-generator consisting of one multi-stage HP turbine and three parallel multi-stage LP turbines, the main generator, and an exciter. HP Turbine is usually a double-flow impulse turbine (or reaction type) with about 10 stages with shrouded blades and produces about 30-40% of the gross power output of the power plant unit. LP turbines are usually double-flow reaction turbines with about 5-8 stages (with shrouded blades and free-standing blades of the last 3 stages). LP turbines produce approximately 60-70% of the gross power output of the power plant unit. Each turbine rotor is mounted on two bearings, i.e., double bearings between each turbine module.