What is the main purpose of coolant in a nuclear reactor?

The primary purpose of coolant in a nuclear reactor is to transfer heat generated in the reactor core and convert it into steam, which is then used to drive turbines for electricity generation. As nuclear fission reactions occur in the reactor core, they produce a significant amount of thermal energy. The coolant absorbs this heat and usually circulates through a heat exchanger where it either directly or indirectly converts water into steam. This steam is vital for driving turbines in power plants, making the conversion of thermal energy into mechanical and then electrical energy possible.

While the other functions mentioned in the answer choices are important in the context of a nuclear reactor, they are not the primary role of the coolant. The coolant indeed contributes to maintaining safe operational temperatures within the reactor core and managing heat effectively. However, its essential role culminates in generating steam, which is critical for the overall process of electricity production in a nuclear power plant.