A method for manufacturing an axially-split radial turbine, the method comprising: joining a forward bladed ring to a forward disk to produce a forward turbine rotor; fabricating an aft turbine rotor; and disposing the forward turbine rotor and the aft turbine rotor in an axially-abutting, rotationally-fixed relationship to produce the axially-split radial turbine, wherein the forward bladed ring is fabricated utilizing a process comprising: casting a plurality of forward bladed pieces; arranging the plurality of forward bladed pieces in a ring formation; and metallurgically consolidating the plurality of forward bladed pieces included in the ring formation to yield the forward bladed ring; characterized in that the method further comprises: producing (114, 131, 138) the forward bladed ring to include a first plurality of blade cooling passages; and forming an inner disk cavity (68, 70) within the axially-split radial turbine, the inner disk cavity (68, 70) placed in fluid communication with the first plurality of blade cooling passages when the forward turbine rotor and the aft turbine rotor are disposed in the axially-abutting, rotationally-fixed relationship; and the forward bladed ring is produced to extend to and to partially define the inner disk cavity (68, 70), wherein the first plurality of blade cooling passages is formed entirely in forward bladed ring. joining a forward bladed ring to a forward disk to produce a forward turbine rotor; fabricating an aft turbine rotor; and disposing the forward turbine rotor and the aft turbine rotor in an axially-abutting, rotationally-fixed relationship to produce the axially-split radial turbine, wherein the forward bladed ring is fabricated utilizing a process comprising: casting a plurality of forward bladed pieces; arranging the plurality of forward bladed pieces in a ring formation; and metallurgically consolidating the plurality of forward bladed pieces included in the ring formation to yield the forward bladed ring; casting a plurality of forward bladed pieces; arranging the plurality of forward bladed pieces in a ring formation; and metallurgically consolidating the plurality of forward bladed pieces included in the ring formation to yield the forward bladed ring; characterized in that the method further comprises: producing (114, 131, 138) the forward bladed ring to include a first plurality of blade cooling passages; and forming an inner disk cavity (68, 70) within the axially-split radial turbine, the inner disk cavity (68, 70) placed in fluid communication with the first plurality of blade cooling passages when the forward turbine rotor and the aft turbine rotor are disposed in the axially-abutting, rotationally-fixed relationship; and producing (114, 131, 138) the forward bladed ring to include a first plurality of blade cooling passages; and forming an inner disk cavity (68, 70) within the axially-split radial turbine, the inner disk cavity (68, 70) placed in fluid communication with the first plurality of blade cooling passages when the forward turbine rotor and the aft turbine rotor are disposed in the axially-abutting, rotationally-fixed relationship; and the forward bladed ring is produced to extend to and to partially define the inner disk cavity (68, 70), wherein the first plurality of blade cooling passages is formed entirely in forward bladed ring.