Abstract: A stopper apparatus for use in blocking the unvalved nozzle of a cooling fluid filled nuclear reactor pressure vessel includes a plug, typically in the shape of a frusto-conical member having inflatable gaskets for sealing against a seat of generally unknown surface characteristics and means for positioning and urging the plug into position to seal the nozzle. The plug is typically positioned by suspension cables whereby the apparatus can be temporarily inserted and removed from the pressure vessel. The urging means is generally a two-way hydraulically driven jack controlled by remotely-actuated hydarulic lines. The apparatus is a tool which permits temporary sealing of a submerged outlet in a reactor vessel to permit maintenance on a fluid recirculation loop.

Abstract: A jet pump plug for a multi-nozzle jet pump is disclosed wherein the nozzles are accessible through a relatively small opening in the pump structure. The plug comprises a plurality of sections, each including a closure plate and a lever coupled thereto. Each plug section is constructed so as to allow that section to be separately introduced into the opening to the vicinity of the nozzles from a location which may be remote from the pump. The closure plates are manipulated through their attached levers from a remote location to the end of sealing the nozzles with them. The first plug section introduced through the opening includes means for alignment relative to the jet pump structure so as to orient its closure plate with respect to the nozzles. The remaining plug section is supported by the first plug section upon being introduced into the opening.