Which statement best describes the role of steam in driving the turbine in a nuclear plant?

• A. Steam expands through turbine blades to do work on the shaft
• B. Steam simply cools the reactor core
• C. Steam directly generates electricity without moving parts
• D. Steam reduces neutron population in the core

Answer: (A)

Steam transfers the reactor’s heat into mechanical energy by expanding through the turbine blades, which applies torque to the turbine shaft. That rotation drives the generator, turning mechanical energy into electrical energy for the grid. After doing work, the steam is condensed and recycled, continuing the cycle.

The other statements miss the actual role: steam in the secondary loop is not used to cool the reactor core, it’s there to transfer heat to the turbine; electricity is produced by the generator, not by steam alone; and steam does not alter neutron population in the core—that control comes from reactor design and control mechanisms, not the turbine steam.