E6 Core Cooling

Topic

A coolant circulates continuously around the core to absorb the heat generated by the three mechanisms described in the previous model and transport it away from the core to where it can be utilized. Ordinary water is the most common coolant; it is chosen for its excellent heat absorption and transport capabilities and—in many designs—for its ability to simultaneously serve as the moderator described in another model in this catalog.

However, it is not the only option: gases offer chemical stability at high temperatures; liquid metals—such as sodium or molten lead—can operate at higher temperatures without requiring extreme pressurization and transport heat very efficiently; and molten salts combine high thermal capacity with chemical stability at elevated temperatures. These options are not interchangeable without consequences: the choice of coolant dictates the operating temperature and pressure, the efficiency with which the heat can subsequently be converted into electricity, the structural materials that can be used in contact with it, and the safety strategies available in the event of a loss of cooling capacity—a scenario explored in greater detail in the section on anomalies in this catalog.

Thus, this module—which begins with a coolant absorbing heat from three established mechanisms—concludes by demonstrating that selecting a coolant involves more than just deciding how heat is removed from the core; it means determining, from the outset, almost every other aspect of the reactor's design: its temperature, its efficiency, and its safety strategies.

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