Axial turbine and power plant

An axial-flow turbine comprising:

• turbine nozzles arranged to form a line in a circumferential direction of an annular flow channel formed between an outer diaphragm ring and an inner diaphragm ring, the turbine nozzles being arranged corresponding to each of turbine stages arranged along a central rotation axis;
• turbine rotor blades arranged downstream of the turbine nozzles and implanted, to form a line in the circumferential direction, in each of turbine rotor disks provided along the central rotation axis of a cylindrical flow channel formed by the inner diaphragm ring, the turbine rotor blades being arranged corresponding to each of the turbine stages arranged on the central rotation axis;
• a heat shield plate provided to form a space between the heat shield plate and an outer surface of the turbine rotor, between two rotor disks adjacent to each other along the central rotation axis;
• a first communication hole formed in the turbine rotor and connected to the space, to flow a cooling medium;
• a first opening formed in at least any one of the two adjacent rotor disks, to be connected to the space;
• a second communication hole connected to the space through the first opening, to communicate with an implant unit of the turbine rotor blade in the rotor disk;
• a third communication hole connected to the second communication hole, to communicate along an effective length of the turbine rotor blade;
• a second opening formed in a side face of the turbine rotor blade, to be connected to the third communication hole;
• and
• a third opening formed in an outer circumferential end face of the turbine rotor blade, to be connected to the third communication hole.