Research Paper / Mechaical Behavior : Hydride Formation and Failure Characteristics of Nuclear Fuel Cladding Tubes
김순길Soon Kil Kim,이강욱Kang Wook Lee,홍순익Sun Ig Hong,김규택Kyu Tae Kim
Abstract
The hydride formation characteristics and its effect on the failure mechanism of nuclear fuel claddings were investigated. The effect of cooling rate on the size, morphology and distribution of hydrides was also examined. Hydrides were more homogeneously distributed with high cooling rate (i.e, air-cooled) and clustered with low cooling rate (i.e, furnace-cooled). The room temperature strength increased slightly and the ductility decreased with hydrides formation. The size and distribution of hydrides were found to have insignificant effect on the mechanical properties. Secondary cracks along the platelets of hydrides were observed on the fracture surfaces of claddings fractured at low temperature. The loss of ductility at low temperature is thought to be associated with the cracking along the hydride platelets. Above 200℃, hydrides were dissolved during deformation and no secondary cracks were observed, suggesting that hydrides may not be detrimental to the high temperature ductility.