Abstract: A reheater for a steam power plant generally comprises a tube plate, a header including a high-temperature chamber and a low-temperature chamber defined outwardly of the tube plate, and a number of heat-exchanger tubes bent into U-shapes, both ends of which are secured to the tube plate. The reheater further comprises nozzle members, each having a flange portion, inserted into the upstream ends of the heat-exchanger tubes, respectively, and a bellmouth plate having a number of holes, secured detachably to the tube plate such that the holes align with the nozzle members. The flange portions of the nozzle members are secured firmly between the bellmouth plate and the tube plate.