Operating Principles of Nuclear Power Plants

A nuclear power plant is a facility at which energy released by the fissioning of atoms is converted to electrical energy under strictly regulated operating conditions.

The major processes are the same as those in nonnuclear (conventional) power plants except that the coal or oil fired boiler is replaced by a nuclear reactor.

In each plant, whether nuclear or fossil-fueled, the following basic components are present:

• Heat source: Provides heat to generate steam. In a nuclear power plant, the heat source is the nuclear reactor, often referred to as the reactor core.
• Turbine/generator: Uses the energy of the steam to turn a turbine/generator that produces electricity.
• Condenser: Condenses the steam back to water so that it can be returned to the heat source to be heated again.
• Pump: Provides the force to circulate the water through the system.

Just as water vapor condenses on a cool drinking glass on a warm day, a power plant's condenser uses a cool surface to condense the steam from the turbine.

This cool surface is provided by cooling water pumped from a nearby water supply such as a river, lake or ocean.

The water used to cool the condenser is slightly warmer after use. Because this water is released back into the environment, a cooling tower is sometimes used to prevent a harmful temperature rise in the water supply.

A cooling tower is a large heat exchanger. This heat is carried up the stack and is visible as water vapor.

Cooling towers are used at many large nuclear as well as non-nuclear power plants. Because cooling towers are part of a nonradioactive system, no radioactive material is released from them.