Abstract: An open-vane regenerative turbine pump includes a housing, an impeller rotatably supported on the housing having a plurality of paddle-like open-vane type vanes thereon, an annular pump channel in the housing around the periphery of the impeller and around the vanes, a stripper in the pump channel between an inlet port of the latter and a discharge port thereof, and a pair of bosses on the housing in the pump channel on opposite sides of the impeller about midway between the inlet and discharge ports. The bosses each have an edge obstructing a radially inner fraction of the pump channel to intercept inertially separated vapor in the inner fraction having a velocity component in the direction of rotation of the impeller. A pair of notches are formed in the housing adjacent respective ones of the bosses in flow communication with a vapor collection chamber and with a radially innermost extremity of the pump channel.