Ultrasonic Measurement Technology and Application on 14-Foot Fuel Assembly Deformation

In order to understand the deformation of the fuel assembly after irradiation and provide an auxiliary means for optimizing the refueling design and adjusting the loading sequence, this measurement technology can quickly measure the deformation of the fuel assembly during the reactor unloading and draw the deformation distribution of the whole core fuel assembly by using ultrasonic ranging and post-image processing technology. The measurement results show that the deformation of the whole core fuel assembly of the same unit tends to be consistent at the end of the cycle, and the peripheral assemblies are deformed to the outside of the reactor to varying degrees at the end of the cycle. This technology can provide a basis for the optimization of refueling design and avoid the risk of rod drop test and the wear of peripheral fuel assembly grid.