Induced nuclear reactions: processes – systems – and elements – Reactor structures – Circulating fluid within reactor
Reexamination Certificate
2000-12-01
2001-11-20
Carone, Michael J. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Reactor structures
Circulating fluid within reactor
C379S285000, C379S372000, C379S392000, C379S260000
Reexamination Certificate
active
06320923
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a device for maintaining a jet pump downcomer in contact with a restraining ring. More particularly, the invention relates to a locking device that will hold a wedge in tight engagement with the restraining ring, thus maintaining a frictional engagement between the restraining ring and the downcomer.
BACKGROUND OF THE INVENTION
A conventional downcomer may be used in distillation, absorption, extraction and other fluid contacting operations along with a fluid-contacting device. As illustrated in U.S. Pat. No. 3,784,175, a downcomer aids in the mixing or separation of fluids. A downcomer typically comprises a vertically extending structure similar to pipes or ducts.
When used in a boiling water reactor (BWR), the downcomer is associated with a fluid-contacting device. The downcomer typically connects an upper portion of the fluid-contacting device with a lower portion. The downcomer, thus, serves as a passageway for descending fluids. Often, fluid mixing occurs in the downcomer. For example, hot reactor fluids may be mixed with cool feedwater. Consequently, it is important to maintain proper vertical alignment between the downcomer and the upper and lower portions of the fluid-contacting device and any other components associated with the downcomer.
In conventional BWR systems, existing jet pump downcomers are generally held in place by only a restraining ring. The downcomer is typically located in the restraining ring by two adjustable screws and a wedge. Often the screws are tack welded in place. The wedge rides on a guide bolt, and is held in place mainly by gravity. The described arrangement can loosen under vibration, causing long and expensive fieldwork to eliminate gaps between the downcomer and the wedge and to readjust the screws.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a jet pump downcomer locking device that uses frictional forces to hold the downcomer in place.
It is a further object of this invention to provide a jet pump downcomer locking device that is easy to install and service.
The foregoing objects and other objects of the invention are obtained by providing a locking device including an upper jaw, a lower jaw, a connecting member movably supporting the upper jaw and the lower jaw, and a means for inducing a compressive force against the upper jaw and the lower jaw.
The means for inducing a pressure against the upper jaw and the lower jaw is a tightening screw extending therebetween. The tightening screw, when tightened, induces a compressive force on both the upper jaw and the lower jaw. One end of the upper jaw and a corresponding end of the lower jaw are moveably supported by a guide bolt.
The guide bolt is supported on the exterior surface of the downcomer by two guide blocks carried by and extending from the exterior surface of the downcomer.
The tightening screw and the guide bolt each support the upper jaw and lower jaw such that the upper jaw and the lower jaw may be moved toward or away from one another.
The locking device described herein may be used in a nuclear reactor to restrain a jet pump downcomer in a desired position. When so used, the assembly includes a restraining ring; a downcomer carried the restraining ring; a wedge supported by the restraining ring and the downcomer; a guide bolt extending in an axial direction in relation to the downcomer such that the wedge is movably supported by the guide bolt; a locking device including an upper jaw; a lower jaw placed in an opposing position below the upper jaw; and a tightening screw movably supporting the upper jaw and the lower jaw.
The wedge is interposed between the upper jaw and the lower jaw, and one end of the upper jaw and a corresponding end of the lower jaw are moveably supported by the guide bolt. Both the upper jaw and the lower jaw, respectively, include a hook-shaped member at the distal end thereof.
The tightening screw is retained within a housing that defines a recess. When the tightening screw is adjusted to cause the upper jaw and lower jaw to move toward one another, the bottom surface of the recess is brought into contact with the restraining ring. This action forces the wedge and restraining ring into frictional engagement, resulting in the wedge being firmly held against the downcomer. Thus, this frictional engagement causes the downcomer, wedge, and restraining ring to be secured in a desired position.
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Starnes Dwight E.
Wivagg Adrian P.
Carone Michael J.
Richardson John
Westinghouse Electric Company LLC
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