The Hydraulic Bursting of Teledial Fuel Element Pins from FE X155

This technical note forms the third part of DPTN/465, Part I being ''Post-Irradiation Measurements on the Dragon -Teledial 1.5(3) and Second Gadolinium Experiment with particular reference to Bowing''. The object of the FE X 155 teledial irradiation experiment was to produce deliberate failure of the graphite structure. While no failures actually occurred, an attempt was made to evaluate the locked-in stresses in the graphite by cutting axial strips and measuring and analysing the relaxation bowing of the strips, as reported in Part 2 of DPTN/465. The pins were also tested by hydraulically pressurising the teledial fuel cavities to give the actual bursting pressures and the sites of the fractures. This data was compared with the results of a finite element stress analysis by A.N. Kinkead, et al [1] postulating the bursting pressures and the location of the maximum tensile stresses (Fig.1).