Provided are a range of ultrasonic cleaning assemblies that include radiating surfaces activated by corresponding arrays of planar transducers configured to increase the power applied to a reduced volume of fluid associated with a fuel assembly, thereby increasing that applied power density for improved cleaning. The individual ultrasonic cleaning assemblies may be arranged in a variety of modules that, in turn, may be combined to increase the length of the cleaning zone and provide variations in the power density applied to improve the cleaning uniformity.