A Pressurizer is a component of a pressurized water reactor. The basic design of the pressurized water reactor includes a requirement that the coolant (water) in the reactor coolant system must not boil. Put another way, the coolant must remain in the liquid state at all times, especially in the reactor vessel. To achieve this, the coolant in the reactor coolant system is maintained at a pressure sufficiently high that boiling does not occur at the coolant temperatures experienced while the plant is operating or in an analyzed transient. To pressurize the coolant system to a higher pressure than the boiling point of the coolant at operating temperatures, a separate pressurizing system is required. That is the function of the pressurizer.

Read more about Pressurizer:  Design, Pressure Control

Other articles related to "pressurizer":

Pressurized Water Reactors - PWR Reactor Design - Pressurizer
... the primary circuit is maintained by a pressurizer, a separate vessel that is connected to the primary circuit and partially filled with water which is heated to the saturation ... To achieve a pressure of 155 bar, the pressurizer temperature is maintained at 345 °C (653 °F), which gives a subcooling margin (the difference between the pressurizer temperature ... transients in the reactor coolant system result in large swings in pressurizer liquid volume, total pressurizer volume is designed around absorbing these transients without uncovering the ...
Loss-of-pressure-control Accident - Causes of A Loss of Pressure Control
... A rupture in the pressurizer vessel, which would also be a loss-of-coolant accident ... as the relatively cool spray collapses the pressurizer vessel bubble) or the heaters of the pressurizing system ... Thermal Stratification of the liquid portion of the pressurizer ...
Pressurizer - Secondary Functions - Over-pressure Relief System
... Part of the pressurizer system is an over-pressure relief system ... In the event that pressurizer pressure exceeds a certain maximum, there is a relief valve called the pilot-operated relief valve (PORV) on top of the pressurizer which opens to allow steam from ...