Abstract: A core barrel hole plug. A plug body sized to easily fit the hole to be plugged is slidably attached to a flange sized larger than the hole to limit the movement of the plug body into the hole. A rectangular bore at the inner end of the plug body has a pair of pawls pivotally mounted therein which are moveable between retracted and extended positions for releasing or locking the plug in position. An actuator screw is threadably engaged through a cylindrical bore in the plug body and in communication with the rectangular bore where a cam on the actuator screw causes movement of the pawls between the release and locking positions. The flange and screw are adapted to receive a remotely operated tool for remote operation of the assembly.

Abstract: A closure mechanism for closing a tubular opening and releasably securing articles therein is disclosed. The closure mechanism includes an axially movable actuator and a latching member which engages the tubular opening. Means are provided for axially moving the actuator.

Abstract: A surveillance assembly within a nuclear reactor contains representative reactor material specimens which are to be irradiated. The material specimens are contained within sealed capsules that are stacked end to end within a holder tube. Each capsule is designed with shaped end fittings which intermesh with the adjacent end of an abutting capsule, holder tube end plug or holder tube closure device. The capsules are restrained by axial loading imparted by the closure device. The holder tube is orthotropically supported within the reactor.