Patent Number: 042382912
Section: summary

The invention relates to a device for coupling pipelines in nuclear reactor pressure vessels, especially in boiling water reactors, with a core flood line formed of a first line section extending sealingly through a housing wall of the reactor pressure vessel and secured to the latter, and second line section disposed in the interior of the pressure vessel and couplable sealingly to the first line section, the second line section extending through a cover of a nuclear core container and terminating in the core container. Such a device has become known heretofore, for example, from the article entitled: Steam-Water Separators and Steam Dryers, by G. Pollak in the periodical "Konstruktion," 1971, Book 11, Page 442, FIG. 1, wherein, however no particulars are otherwise provided or recognizable details presented concerning how the coupling of both line sections of the core spray or flood system is effected. In two heretofore known arrangements, the steam separators are fastened to the cover of the core container. A number of problems is produced thereby: a varying axial and radial thermal expansion of the pressure vessel, the built-ins or installations in the pressure vessel as well as the core flood line then exists. The line coupling of the core flood line must maintain the tightness or impermeability thereof to leaks. A reliable and rapid coupling operation for both core flood line sections with a minimum of tool outlay or expense is desired. As many sections or parts as possible, including sections of the core flood line, should be disassemblable so that an inspection of these disassembled parts or sections as well as also an inspection of the remaining reactor pressure vessel per se is afforded. During the operation of the reactor, oscillations or vibrations occur in the coolant circulatory loop (boiling water reactor) or in the primary coolant circulatory loop (pressurized water reactor); the coupling between the core flood line sections must therefore also be vibration-proof. It is accordingly an object of the invention to provide a device for coupling pipelines in nuclear reactor pressure vessels, especially in boiling water reactors, which meet the foregoing requirements which offer improvement over prior art devices of this general type. More specifically, it is an object of the invention to provide such a coupling device for a core flood line, especially for boiling water reactors which, with good sealing action, is thermally displaceable and vibration-proof, and which does not require actuation of threaded fasteners for engagement or releasing thereof. With the foregoing and other objects in view, there is provided, in accordance with the invention, for coupling pipelines in a nuclear reactor pressure vessel with a core flood line formed of a first line section extending sealingly through a housing wall of the reactor pressure vessel and secured thereto, and a second line section disposed in the interior of the pressure vessel and couplable sealingly to the first line section, the second line section extending through a cover of a core container and terminating in the core container, a device comprising means for forming the second line section and the core container cover into a structural unit so that the second line section together with the core container cover is liftable out of and insertable into the pressure vessel upon opening the latter for selectively inspecting, servicing and both inspecting and servicing the same, the first and second line sections having a mutual coupling location, means defining coaxial sealing surfaces disposed at the mutual coupling location for holding the first and second line sections in mutual engagement, the coaxial sealing surface having a contact pressure therebetween deriving from weight per se and bracing forces of the core container cover oriented in axial direction of the pressure vessel, the first and the second line sections being in mutual spring-biased engagement at the mutual coupling location thereof. The advantages attainable with the device of the invention are, primarily, that a thermally displaceable coupling location is provided which assures a virtually uniform contact pressure, under all operating conditions, and that the coupling and uncoupling operation occurs automatically without the use of special tools. In accordance with another feature of the invention, the coaxial sealing surfaces are engageable at a ball-and-socket seat. This produces, on the one hand, a linear sealing surface of high contact pressure and, on the other hand, produces a centering action of the line sections during the coupling operation. In accordance with a further feature of the invention, the first line section has an upwardly directed ball seat-mouthpiece forming the ball of the ball-and-socket seat, and the second line section has a downwardly directed cone seat-counter-support member forming the socket of the ball-and-socket seat, the counter-support member being formed as a pipe bushing mounted with spring bias and displaceable longitudinally on a guidance collar formed on the second line section, the spring bias being afforded by compression spring means disposed intermediate the pipe bushing and the guidance collar. The greatest part of the coupling is accordingly disassemblable and inspectable, and pre-assembly of the guidance collar, the compression springs and pipe bushing in a relatively simplified manner is possible. In accordance with an added feature of the invention, axially normal, inwardly directed pins are mounted on the counter-support member and guided, in axial direction of the counter-support member, in longitudinal grooves formed in the guidance collar, the longitudinal grooves having end flanks for limiting displacement of the counter-support member in opposite axial directions. In accordance with an additional feature of the invention, opposing end flanges formed, respectively, on the guidance collar and on the counter-support member are included and disposed in mutual alignment, the compression spring means comprising at least one helical compression spring mounted between the end flanges. In accordance with yet another feature of the invention, also included is a pipe apron disposed at the mutual coupling location radially inwardly of the compression spring means for shielding the compression spring means from the interior of the first and second line sections. In accordance with yet a further feature of the invention, included are means for introducing an initial flow of flood water to the core flood line forming the first and second line sections, the second line section at the mutual coupling location having surfaces subjectible to application of interior pressure from the pressure vessel and pressure of the flood water, the area of the surfaces having a mutual ratio effecting an increase in contact pressuere applied between the coaxial sealing surfaces upon introduction of the initial flow of flood water. In accordance with yet an additional feature of the invention, the steam separators in the reactor pressure vessel overlie and are connected to the interior of the core container through the cover thereof, and means are included for incorporating the steam separators into the structural unit formed of the second line section and the core container cover. In accordance with a concomitant feature of the invention, there are provided, in combination, a device for coupling pipelines and a pressure vessel, for example, for steam generators of pressurized water nuclear reactors having a first line section extending sealingly through a housing wall of the pressure vessel and secured thereto, and a second line section disposed in the interior of the pressure vessel and forming a structural unit with at least one installation within the pressure vessel, releasable bracing means for holding the installation in position, in closed condition of the pressure vessel, against stops provided in the pressure vessel, the coupling device holing the first and second line sections in engagement due to a force lock by the bracing means, the bracing means being releasable for removing the installation and simultaneously automatically uncoupling the coupling device, and the bracing means being lockable for holding an installation received in the pressure vessel and simultaneously automatically coupling the first and second line sections to one another with the coupling device. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in device for coupling pipelines in nuclear reactor pressure vessels, especially in boiling water reactors, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.