A shaft interlock system may have an a interlocking piston that translates a movable locking apparatus configured to interface with a turbine shaft having a fixed locking apparatus. The movable locking apparatus may engage and disengage the fixed locking apparatus. When the movable locking apparatus is engaged with the fixed locking apparatus, the turbine shaft is only able to turn in one direction. When the movable locking apparatus is disengaged from the fixed locking apparatus, the turbine shaft is able to turn in both directions. In this way, a turbine shaft can be prevented from reverse rotation.