ACOUSTIC-EMISSION FROM THERMAL-GRADIENT CRACKS IN UO2

A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO//2 pellets. In the apparatus used for these tests, two acoustic-emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic emission data. The accumulation of events displayed on a cathode ray tube screen indicates the total number of acoustic emission events at a particular location within the pellet stack. The tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO//2 pellets subjected to direct electrical heating. Acoustic emission monitoring could prove valuable in other experiments involving direct electrical heating techniques in which the results may be expected to be influenced by pellet cracking.