A cyclic integrated reversible-bending fatigue tester (CIRFT) was developed to support U.S. NRC and DOE Used Fuel Disposition Campaign studies on high burn-up (HBU) spent nuclear fuel (SNF) transportation during normal conditions of transport (NCT). Several HBU SNF samples from both Zr-4 and M5 clad were investigated. During CIRFT program development, finite element analysis (FEA) was used to translate CIRFT global measurement data to the localized stress-strain profiles. The stress concentration effect at pellet-pellet interface region was also observed from FEA and such phenomenon was also revealed by CIRFT testing where the majority SNF rod failures are located at pellet-pellet interface. The information resulting from these studies will be presented, as outlined below:
• Fuel support to the clad stiffness during random vibration
• Stress concentration effects on the clad at pellet-pellet interfaces
• The translation of CIRFT global measurements to local stress-strain levels
• Potential hydrogen effects on SNF vibration integrity
• Pellet-clad bonding efficiency on SNF mechanical properties
• Failure mechanisms of HBU SNF rods under reverse bending forces, and
• The potential impact of combined loading modes and loading rates on SNF vibration integrity.
Dr. John Jy-An Wang is a Distinguished Research Staff Member at Oak Ridge National Laboratory (ORNL). He received a Ph.D. from University of California, Berkeley, in 1988, in the field of mechanics of material and structural dynamics from Civil Engineering Department. Since 1989 he has been working at ORNL as a research scientist. During his residence at ORNL he has published over 170 technical reports and journal articles on subjects related to fatigue and fracture toughness evaluation of structural materials, the neutron radiation embrittlement predictions for pressure vessel steels, the development of power reactor and test reactor databases for reactor material aging research, spent nuclear fuel vibration reliability investigation, pipeline hydrogen embrittlement study, interfacial fracture toughness research for polymeric composites as well as for weld HAZ materials, cavitation damage simulation research, and high temperature power transmission conductor-connector system reliability investigation.
