Transient performance of air-cooled condensing heat exchanger in long-term passive cooling system under decay heat load

The transient performance of an air-cooled condensing heat exchanger in a long-term passive cooling system was evaluated under a decay heat load modeled by the ANS-73 curve. An experiment was conducted in a 1/2500-volume scaled-down model of the emergency cooldown tank (ECT) of the system-integrated modular advanced reactor (SMART). It was confirmed that the scaled design requirement of cooling capacity of the air-cooled condensing heat exchanger was well satisfied under the decay heat load. It was also confirmed that the water level in the emergency cooldown tank was maintained continuously for longer than 72 h by the collection of steam in the air-cooled condensing heat exchanger under the decay heat load.