Patent Number: 052951650
Section: abstract

Self-locking plug for plugging a hole defined by a surrounding structure, which structure may be a nuclear power reactor pressure vessel core barrel flange. When the hole is plugged, transient hydraulic forces generated in the pressure vessel will tend to force the plug from the hole. The plug includes a plug body sized to be disposed in the hole and a locking member pivotally connected to the plug for locking the plug body to the flange, so that the plug is not inadvertently forced from the hole by the transient hydraulic forces. A cam, which is capable of engaging the locking mechanism for outwardly pivoting the locking mechanism, is slidably connected to the plug body. A movable piston is connected to the cam for driving the cam into engagement with the locking mechanism. Moreover, the locking mechanism pivots to engage the flange as the cam engages the locking member. A ram, which is also connected to the plug body, is provided to ram the plug body into the hole for snugly plugging the hole. In this manner, the plug is locked to the flange and resists being inadvertently dislodged from the hole, which may otherwise occur due to transient hydraulic forces generated in the pressure vessel during service operations to retrieve the detector.