0verheating failure analysis of steatm generator tubes; Validation analysis of explosive torch overheating test

Hamada, Hirotsugu  

Neighboring tubes in an FBR Steam Generator (SG) would suffer from overheating if a sodium-water reaction jet were formed due to water leakage in the SG. On the safety aspect of the SGs, it is important to confirm that the neighboring tubes would not fail under such an overheating condition. An analytical model using the structural integrity analysis code, FINAS, has been prepared to evaluate the overheating failure and here an explosive torch overheating test was analyzed to validate the FINAS model. These experiments and analysis indicate that the overheating failure is closely associated with heat transfer coefficients (HTCs) of outer and inner tube wall and that the FINAS model conservatively predicts the overheating failure within acceptable accuracy. For making progress in further tests like an explosive torch test and its code validation, it would be required that sodium-water reaction experiments should be performed to provide the data on the HTCs, high pressurized and superheated steam should be supplied in the explosive torch test, and that a multidimensional analytical model should be developed to closely predict the temperature distribution in the axial(z-) and circumferential(-) directions on the tube wall.