A reaction turbine has channels formed in the top surface of a disc to create nozzles. The channels can be covered by a membrane sealed to the disc or by the housing extended from a combustor. Each channel may have a first section extending radially outwardly from an inlet of the reaction turbine and a second curved section extending from the first section to a periphery of the disc. A reaction turbine may also receive input from an impulse turbine. Fluid flows through the impulse turbine and fluid from the impulse turbine enters an inlet of the reaction turbine. The reaction turbine may have cooling channels and cooling fins to lower the temperature of the disc during operation. In addition, magnets may provide bearing support and electricity generation. In addition, the reaction turbine may have a dual shaft construction, with each shaft connected to a reaction turbine. One reaction turbine powers a compressor, while the second reaction turbine powers a load through the second shaft.