Describe what "pressurization" achieves in a PWR.

In a Pressurized Water Reactor (PWR), pressurization is crucial as it serves to maintain the water in a liquid state, even when it is heated to temperatures above its normal boiling point. In the PWR system, the primary coolant is water that is kept under high pressure, typically around 2,200 psi. This high pressure raises the boiling point of the water, allowing the reactor to operate at temperatures around 300 degrees Celsius without the water turning into steam. Maintaining the coolant in a liquid state is vital for effective heat transfer from the reactor core to the steam generators, where steam is produced to drive the turbines.

By ensuring that the water remains liquid, pressurization also plays a significant role in the safety and efficiency of the reactor. If the coolant were to vaporize, it would hinder heat transfer and could lead to overheating of the reactor core, potentially causing fuel damage or a loss of system control. Thus, pressurization is a fundamental aspect of the mechanics of a PWR, ensuring that the reactor operates safely and efficiently at high temperatures.