BWR Reactor Recirculation Systems
The Recirculation System is used in the Boiling Water Reactor design. This system provides the following functions:
The Recirculation System consists of two (2) recirculation loops. Each loop consists of piping from the reactor to a recirculation pump, then piping to return the fluid back to the reactor. The recirculation pumps are driven by variable speed motors. As the speed increases, more voids are swept from the core, resulting in more thermal neutrons being produced. This, in turn, results in increasing power.
Jet pumps are considered as part of the reactor cooling system. The pumps are installed in the annular region between the core barrel and the outside reactor vessel. The driving head for these jet pumps is provided by the pressure head provided by the discharge of the recirculation pumps.
Several penetrations come off the recirculation loop, including:
Penetrations providing water to the recirculation system include:
Motor operated valves are typically provided for isolating the recirculation pumps for maintenance.
The key instrument typically provided for this system is the flow rate.
The NRC provides a very informative manual showing the various BWR systems, including the recirc system.
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