A power plant which operationally combines a downstream turbine unit (7) and an upstream grating assembly (8), includes a grating (16), a supporting structure (17), and an element (18) for associating the grating (16), which has a structure that enables movement of at least the upper portion of the grating (16) between an upright position for the debris-stopping function and a folded-down position for discharging the floating debris stopped by the grating (16).