Accurate prediction of the above-surface radiological effects resulting from a shallow underwater nuclear explosion requires a complete knowledge of the mechanisms by which the fission products are transported from the explosion bubble to the surface environment. A complete phenomenology for shallow underwater explosions is not currently available however, considerable progress has been made both theoretically and experimentally with high explosive in the area of hydrodynamics of the bubble and above-surface columns. This investigation is concerned with the explosion or fission product transfer mechanisms and their relation to the hydrodynamic processes of the bubble and columns. For small scale shallow underwater explosions, the traced explosion products were found to transfer into the column or plumes in three distinct modes or phases. Each of the transfer phases was related to a hydrodynamic process. Phase I is associated with the bubble top oscillation, phase II with the column walls, and phase III with the bubble bottom oscillation late emission process.