Component and Closed Cooling Water Systems

Component and Closed Cooling Water Systems

Overview

In nuclear power plants, component or closed, cooling water systems are typically used for removing heat (cooling) systems containing potentially radioactive fluids. These systems are, in turn, then cooled by the ultimate cooling system - river, lake, sea, or ocean water. In some plant designs, as the Boiling Water Reactor, the system may be divided into subsystems for each building - Turbine Building Component Cooling Water, Reactor Building Component Cooling Water. In other plant designs, as the Westinghouse Pressurized Water Reactor, the system may be considered as one regardless of where cooling occurs.

Component Cooling and Reactor Building Closed Cooling Water Systems

PWR Component Cooling (CC) Water Systems and the BWR Reactor Building Closed Cooling Water (RBCCW) Systems cool heat exchangers for:

High Pressure Emergency Makeup Pump Seal Water
Low Pressure Emergency Makeup Pump Seal Water
Residual Heat Removal System
Containment Spray Pump Seal Water
Letdown or Reactor Water Cleanup
Reactor Coolant Pump or Recirculation Pump Seal Water
Spent Fuel Pool

These systems have separate subsystems, each with:

one or more pumps for circulating fluid through the systems
one heat exchanger to transfer heat to the Ultimate Cooling System
an automatic valve to regulate the heat removed from the Component Cooling or RBCCW system to the Ultimate cooling system.

There is usually a shared tank, called a surge tank, for the redundant sub-systems is used as a makeup supply if there is not enough water in the system, or to handle the surge (increase in level) if there is too much water in the system.

Turbine Building Closed Cooling Water Systems

The BWR Turbine Building Closed Cooling Water (TBCCW) Systems cool heat exchangers for:

Feedwater Pump Seal Water
Condensate Pump Seal Water
Heater Drain Pump Seal Water

Sample System Diagram

A typical system is illustrated by the 2 diagrams below.