Residual Heat Removal Systeml

This system has been designed to reduce the pressure on the primary system and to remove the decay heat in case of loss of heat sink. It is a simple and reliable system that operates condensing steam from the primary system in emergency condensers.

The emergency condensers are heat exchangers consisting of an arrangement of parallel horizontal U tubes between two headers. The top header is connected via piping to the reactor vessel steam dome, while the lower header is connected to the reactor vessel below the reactor water level. The condensers are located in a pool inside of the containment building.

When the system is triggered, the outlet valves open automatically. The water drains from the tubes, steam from the primary system enters the tube bundles and is condensed on the cold surface of the tubes. The condensate is returned to the reactor vessel forming a natural circulation circuit, that removes heat from the reactor coolant and transfers it to the water of the pool by a boiling process. This evaporated water is then condensed in the suppression pool of the containment.

During the condensation process, heat is transferred to the pool water through boiling. The water thus evaporated is condensed in the containment depressurization pool.

The pool water inventory is sufficient to remove residual heat for a minimum period of 48 hours after reactor shutdown.