Instrumentation tube features for reduction of coolant flow-induced vibration of flux thimble tube
AssigneeWestinghouse Electric Corp.
InventorJohn A. Rylatt
Life of this patent
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Abstract
A nuclear fuel assembly has mechanical elements which constrain the flux thimble tube within the instrumentation tube to maintain physical contact with the interior surface of the instrumentation tube at a plurality of points staggered on a single-diametral plane and spaced substantially throughout the length of the instrumentation tube. The staggered mechanical elements induce a controlled elastic sinuous deflection of the inner thimble tube. The mechanical elements can take several different forms, for example, dimples or cantilevered spring fingers formed in the wall of the instrumentation tube and projecting radially inwardly therefrom.
Claims15
In a fuel assembly having a instrumentation tube with a hollow interior and a flux thimble tube inserted in said hollow interior of said instrumentation tube for taking flux measurements, said flux thimble tube radially spaced inwardly at its exterior surface from an interior surface of said instrumentation tube so as to define a coolant flow annulus therebetween, means for reducing coolant flow-inducing vibration of said thimble tube, comprising:
- a plurality of mechanical elements defined on said interior surface of said instrumentation tube in said hollow interior of said instrumentation tube at a plurality of axially spaced points therealong for engaging said exterior surface of said flux thimble tube within said instrumentation tube and inducing a controlled elastic sinuous deflection of said thimble tube to reduce vibration thereof induced by coolant flow in said annulus between said instrumentation and thimble tubes.
In a fuel assembly having a skeleton including a plurality of fuel rod-supporting grids being spaced apart from one another along an axis of said skeleton, a instrumentation tube extending through said grids and having a hollow interior, and a flux thimble tue inserted in said hollow interior of said instrumentation tube for taking flux measurements, said flux thimble tube radially spaced inwardly at its exterior surface from an interior surface of said instrumentation tube so as to define a coolant flow annulus therebetween, means for reducing coolant flow-inducing vibration of said thimble tube, comprising:
- a plurality of mechanical elements defined on said interior surface of said instrumentation tube in said hollow interior of said instrumentation tube at a plurality of axially spaced points therealong for engaging said exterior surface of said flux thimble tube within said instrumentation tube and inducing a controlled elastic sinuous deflection of said thimble tube to reduce vibration thereof induced by coolant flow in said annulus between said instrumentation and thimble tubes, said elements being disposed at the elevations of said grids along said instrumentation tube.
Dependencies are inferred from the claim text.