A reactor installation tool and method for installing reactor components in a reactor housing. A reactor installation tool can include a push unit having a central aperture traversing its entire length and a push rod, a housing gripper having a center open section traversing its entire length and an expandable bladder positioned adjacent the center open section for securing the housing gripper inside a reactor housing. Reactor components can be installed by first lowering reactor components into a reactor housing, then lowering the reactor installation tool into the reactor housing above the reactor components, and then inflating the expandable bladder such that the expandable bladder contacts an inside surface of the reactor housing to secure the housing gripper inside the reactor housing.