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Development and Performance Test of Thermal Fatigue Testing System for Simulated Specimens

This study develops a thermal fatigue test system to simulate the fatigue damage in the pipes and nozzles of nuclear power plants with the pre-test to confirm its performance. The test system was designed to apply cyclic thermal loads by periodically injecting coolant into the interior of the cylindrical specimen with the outer surface continuously heated. The confirmation test shows that it can be applied not only to pure thermal loads but also to combined thermal and mechanical loads to the specimen. The system also has the heating and cooling capacity to control performance to cool and reheat to a specific temperature within a limited time. It is also confirmed that the system can successfully generate a large temperature gradient in the wall of the specimen, resulting in fatigue damage.