Patent Number: 055442102
Section: claims

1. Pressure vessel apparatus defining a pressure vessel interior for containing fluid under high temperature and pressure, said pressure vessel apparatus comprising, in combination: a vessel main body having a bottom and an outer peripheral wall extending upwardly from said bottom and defining a vessel main body top opening;  a vessel top body having an outer peripheral wall positioned on the outer peripheral wall of said vessel main body to form a joint therebetween and defining a vessel top body bottom opening communicating with said vessel main body top opening, and said vessel top body defining a top opening;  a vessel head positioned on said vessel top body and covering said top opening;  first securement means securing said vessel top body to said vessel main body; and  second securement means securing said vessel head to said vessel top body, said second securement means comprising a plurality of double-ended, elongated tendons under tension extending between and secured to said vessel top body and said vessel head. 2. The pressure vessel apparatus according to claim 1 wherein the outer peripheral walls of said vessel main body and said vessel top body define a plurality of spaced throughbores extending vertically alongside and spaced from said pressure vessel interior, said first securement means including a plurality of double-ended tendons under tension extending through said throughbores and secured to said vessel main body and said vessel top body. 3. The pressure vessel according to claim 2 wherein the tendons secured to said vessel main body and said vessel top body permit movement of said vessel top body away from said vessel main body due to a pressure surge within said pressure vessel interior before the tendons secured to said vessel top body and said vessel head permit movement of said vessel head away from said vessel top body due to a pressure surge within said pressure vessel interior. 4. The pressure vessel according to claim 2 additionally comprising damper means connected to at least some of the tendons extending through said throughbores and secured to said vessel main body and said vessel top body. 5. The pressure vessel according to claim 2 additionally comprising spring means connected to at least some of the tendons extending through said throughbores and secured to said vessel main body and said vessel top body. 6. The pressure vessel according to claim 2 additionally comprising protective sleeves surrounding said throughbores at the joint between said vessel main body and said vessel top body protecting and guiding the tendons extending through said throughbores. 7. The pressure vessel apparatus according to claim 2 additionally comprising bellows secured to said vessel main body and said vessel top body about said joint to form a seal about said joint. 8. The pressure vessel apparatus according to claim 7 additionally comprising elongated reinforcement members extending about said bellows and cooperable therewith to limit outward movement of said bellows. 9. The pressure vessel apparatus according to claim 1 additionally comprising elongated reinforcement elements under tension in engagement with and extending about the outer peripheral walls of said vessel main body and said vessel top body. 10. The pressure vessel apparatus according to claim 7 additionally comprising support means in the form of metallic cushions disposed inside the bellows for supporting the bellows during prestressing of the elongated reinforcement members. 11. The pressure vessel apparatus according to claim 1 comprising a nuclear reactor vessel, said pressure vessel interior accommodating a nuclear reactor core. 12. The pressure vessel apparatus according to claim 1 wherein said vessel top body has a steel lining welded to a steel lining inside said vessel main body at said joint, to form a weld which will fracture when pressure within said pressure vessel interior is increased beyond the yield capacity of said tendons secured to said main vessel body. 13. The pressure vessel according to claim 2 additionally comprising damper means connected to some of the tendons extending through said throughbores and secured to said vessel main body and said vessel top body and spring means connected to some of the tendons extending through said throughbores and secured to said vessel main body and said vessel top body, some of the tendons extending through said throughbores and secured to said vessel main body and said vessel top body being secured directly to said vessel main body and said vessel top body. 14. The pressure vessel according to claim 11 additionally comprising support means supporting said nuclear reactor core from said vessel top body.