Abstract: A clamp assembly prevents separation of a thermal sleeve penetrating a nuclear reactor pressure vessel wall and a jet pump riser elbow welded one to the other and lying within an annular space between the pressure vessel wall and core shroud. The clamp assembly includes a pair of heads having semi-cylindrical recesses. Pins project inwardly from each of the heads in the semi-cylindrical recesses and have axes which lie parallel to one another. By using actuators mounting multiple electrodes, holes may be formed in situ in the adjoining ends of the thermal sleeve and elbow. Once the holes are formed, the heads can be applied in situ with the pins being received through the holes and the heads clamped to one another. Thug, the pins in each of the sleeve and elbow prevent separating movement of the sleeve and elbow in the event of failure of the welded joint therebetween.

Abstract: Apparatus for supporting the lower elbow assembly of a jet pump in a reactor pressure vessel (RPV) of a nuclear reactor are described. The clamp apparatus includes a lower clamp element and an upper clamp element. The upper and lower elements are configured to be positioned at the interface between the thermal sleeve and the jet pump riser elbow. The upper and lower elements include extended ridges that are configured to fit in circumferential grooves precisely machined into the sleeve-elbow assembly on opposing sides of the interface.