Distinguished Merit Award: Development and commissioning of an internal pressure fatigue test rig

The team displayed dedication, innovation and problem solving skills in a tight schedule with limited budget to develop a unique internal pressure fatigue test rig to assess the impact of a coating on the fatigue behaviour of fuel cladding. This unqiue apparatus used state-of-the-art technologies that when combined, enabled control of the test environment to measure strain in the specimen, cycles to fatigue failure and detection of fatigue failure. The test required heating specimens to high temperature (350°C), pressurizing internally with an oil to a maximum pressure of 50 MPa and cycling the internal pressure at a 1 Hz frequency. With the fatigue test rig built upon the biaxial burst apparatus (BBA), two key challenges needed to be overcome: the ability to cycle the pressure at a rapid rate (1 Hz) and acheiving a sufficiently uniform temperature on the test section. The high cycling rate of the pressure required significant design and testing activities to ensure that the cycling rate could be acheived, as well as ensuring that the cycling could be maintained reliably over the long duration of typical testing. Similarly, obtaining a sufficiently uniform temperature on the test section required novel design and testing efforts, especially ensuring uniformity at the high temperature of 350°C. In addition to the novel design challenges, the team had to ensure that testing could be performed safely and that the operator would be protected from the temperature and the sudden burst of the test specimens when fatigue failure occurred.