Abstract: SiC/SiC composites represent one of the primary long-term objectives for accident-tolerant fuel cladding in pressurized water reactor (PWR) nuclear power plants. To establish relevant testing capabilities and acquire phased mechanical property data, shortened specimens extracted from meter-length tubular materials were employed to conduct axial tensile and internal pressure burst tests on SiC/SiC composite cladding tubes at ambient temperature. Experimental results demonstrate that the SiC/SiC composite cladding tubes exhibit similar “quasi-plastic” stress-strain behavior under both stress states, characterized by progressive failure mechanisms. The tubes fabricated with 45° fiber orientation relative to the tube axis demonstrate comparable axial and hoop strengths, achieving the objective of balanced mechanical properties in both directions. Mechanical property testing of parallel samples from different production batches shows acceptably small variations, indicating that the current manufacturing process can reliably produce meter-length tubes with satisfactory uniformity in axial mechanical properties.

Key words: SiC/SiC composites, cladding, mechanical property evaluation, axial tensile test, internal pressure burst test