Nuclear power plants use ______ to turn the turbines that produce electricity.

• A. Steam
• B. Water
• C. Gas
• D. Oil

Answer: (A)

Steam is used to turn the turbines because it efficiently converts heat energy into mechanical work. In a nuclear plant, the reactor’s heat boils water to produce high-pressure steam. That steam expands as it flows through turbine blades, pushing them around to rotate the generator and produce electricity. The phase change from water to steam is key here: steam carries a lot of energy and can do work as it expands, making it ideal for driving large turbines. Liquid water wouldn’t push the blades effectively and would require prohibitively high pressures to deliver similar force. Gas could power a turbine in a different kind of plant, but conventional nuclear plants rely on steam turbines driven by steam generated from the reactor’s heat. Oil isn’t used as the working fluid to drive the turbine in power generation.