Patent Number: 041705173
Section: claims

1. A nuclear reactor containment arrangement including: an open ended pressure vessel operable to expand and contract during cyclic operation of the reactor;  a structural wall spaced from and surrounding the peripheral wall of the pressure vessel defining an open annulus therebetween; and  a water tight flexible annular ring seal having a quarter-circular cross section permanently affixed to and extending between the peripheral wall of the vessel proximate the vessel opening and the structural wall, the seal being constructed to cyclicly contract and expand respectively with cyclic expansion and contraction of the vessel relative to the wall during reactor operation while maintaining the water-tight integrity of the seal. 2. The nuclear reactor containment arrangement of claim 1 wherein the quarter-circular arc of the annular ring is positioned to have a convex interface with the open annulus. 3. The nuclear reactor containment arrangement of claim 1 wherein the quarter-circular arc of the annular ring is formed with an eight inch radius. 4. The nuclear reactor containment arrangement of claim 1 wherein the seal has a quarter inch thickness. 5. The nuclear reactor containment arrangement of claim 1 wherein the wall of the pressure vessel adjacent the open end has an outwardly extending flange adapted to receive a head enclosure and wherein one end of the arc of the quarter-circular seal ring is permanently affixed and sealed to the outwardly extending end of the flange and the other end of the arc is affixed and sealed to the structural wall. 6. The nuclear reactor containment arrangement of claim 1 wherein the seal is constructed from stainless steel.