Patent Number: 043483569
Section: claims

1. In a nuclear reactor vessel support system including a nuclear reactor vessel having an outwardly extending support ring, a nuclear reactor containment structure surrounding the vessel, the containment structure having an inwardly extending support ledge aligned with and attached to the support ring whereby the vessel weight is transmitted to the support ledge, the improvement comprising a box ring interposed in load bearing relationship directly between the support ring and support ledge to transmit the vessel weight from the support ring to the support ledge, said box ring having rigid cylindrical side walls and flat rigid ring-shaped upper and lower walls to enclose and define an annular space directly between the support ledge and the support ring to limit heat flow therebetween. 2. The improvement of claim 1 wherein the top and bottom of the box ring are low alloy steel and the side walls thereof are of relatively thin Inconel. 3. The improvement of claim 1 including radial keys in the top and bottom of the box ring and mating keyways in the bottom of the reactor vessel support ring and in the top plate of the reactor vessel support ledge. 4. The improvement of claim 1 wherein holddown bolts are provided that extend through said support ring and support ledge. 5. The improvement of claim 1 including a coolant header defined by a seal collar spaced from the outside edge of the support ring and a coolant channel extending from the coolant header to the reactor containment cavity between the reactor vessel and the support ledge. 6. The improvement of claim 5 wherein said seal collar comprises a ring of metal plate having an angular cross-section with a horizontal and a vertical flange, said horizontal flange outer edge in sealing engagement with said support ring and said vertical flange outer edge in sealing engagement with said reactor containment. 7. The improvement of claim 5 wherein a plurality of radial keyways commuting with said coolant header are provided in the top surface of said support ledge for receiving radial keys also in keyway engagement with said box rings, said keys including channels in alignment with said keyway for passing coolant flow.