Low pressure drop nuclear fuel assembly bottom nozzle

Patent metadata

Field	Value
Publication number	US-9847144-B1
Application number	US-201414243954-A
Country	US
Kind code	B1
Filing date	Apr 3, 2014
Priority date	Apr 3, 2014
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A nuclear fuel assembly having a bottom nozzle with protrusions that extend from the upstream (lower or fluid entry) and downstream (upper or fluid exit) side of a horizontally supported perforated flow plate. The protrusions have a funnel-like shape that gradually decreases the lateral flow area on the upstream side of the perforated flow plate and gradually increases the lateral flow area on the downstream side of the perforated plate. The protrusions on the downstream side are preferably recessed to accommodate the ends of the fuel rods.

First claim

What is claimed is:

1. A nuclear fuel assembly including:
a plurality of elongated nuclear fuel rods having an extended axial length;
at least a lowermost grid supporting said fuel rods in an organized array and having unoccupied spaces defined therein adapted to allow flow of fluid coolant therethrough and past said fuel rods when said fuel assembly is installed in a nuclear reactor;
a plurality of guide thimbles extending along said fuel rods through and supporting said grid;
a bottom nozzle disposed below said grid, below lower ends of said fuel rods, supporting said guide thimbles and having openings therethrough to allow the flow of fluid coolant into said fuel assembly, the bottom nozzle comprising:
a substantially horizontal plate, orthogonal to the axis of the fuel rods, having an upper face directed substantially toward the lowermost grid and a lower face on an underside of said horizontal plate with said openings extending therethrough for the flow of coolant, at least some of said openings in at least one of either the upper face or the lower face having a funnel-like first appendage respectively extending above the upper face or below the lower face, as the case may be, around at least some of the openings in the one of the upper face or the lower face with an opening at the first appendage's substantially highest extent, in the case of the upper face or lowest extent, in the case of the lower face, having a larger diameter than a diameter of the opening in the one of the upper face or the lower face, an internal wall of the first appendage substantially gradually decreasing in diameter from the opening at the first appendage's substantially highest extent in the case of the upper face or substantially lowest extent in the case of the lower face, until the wall of the first appendage transitions to the opening in the upper face or lower face, as the case may be and wherein a lip of at least some of the openings at the first appendage's substantially highest extent in the case of the upper face or lowest extent in the case of the lower face, has a scalloped contour.

2. The nuclear fuel assembly of claim 1 wherein the scalloped lip has four substantially equally spaced depressions, resembling the contour of an egg receptacle in an egg carton.

3. The nuclear fuel assembly of claim 1 wherein the substantially horizontal plate has a plurality of such openings extending therethrough and substantially all of the lips of the openings at the first appendages' substantially highest extents in the case of the upper face or lowest extents in the case of the lower face, have a scalloped contour.

4. The nuclear fuel assembly of claim 1 including a funnel-like second appendage extending outwardly from at least some of the openings in another of the upper face or the lower face with an opening at the second appendages' substantially highest extent in the case of the upper face or lowest extent in the case of the lower face, having a larger diameter than a diameter of the opening in the another of the upper face or the lower face, an internal wall of the second appendage substantially gradually decreases in diameter from the opening at the second appendages' substantially highest extent in the case of the upper face or lowest extent in the case of the lower face until the wall of the second appendage transitions to the opening in the another of the upper face or the lower face.

5. The nuclear fuel assembly of claim 4 wherein a lip of at least some of the openings at the second appendages' substantially highest extent in the case of the upper face or lowest extent in the case of the lower face, has a scalloped contour.

6. The nuclear fuel assembly of claim 5 wherein the scalloped lip has four substantially equally spaced depressions resembling the contour of an egg receptacle in an egg carton.

7. The nuclear fuel assembly of claim 6 wherein the appendage to the upper face is at least partially recessed within a corresponding one of the openings in the upper face.

8. The nuclear fuel assembly of claim 4 wherein substantially all of the lips of the appendages' substantially highest extent, on the upper face have a scalloped contour.

9. The nuclear fuel assembly of claim 4 wherein the appendages to the upper face terminate below the lower ends of the fuel rods.

10. The nuclear fuel assembly of claim 9 wherein the highest extent of the appendages to the upper face is smaller than the lowest extent of the appendages to the lower face.

11. The nuclear fuel assembly of claim 1 wherein at least some of the openings in the bottom nozzle substantially align with the unoccupied spaces in the lowermost grid.

12. A nuclear fuel assembly including:
a plurality of elongated nuclear fuel rods having an extended axial length;
at least a lowermost grid supporting said fuel rods in an organized array and having unoccupied spaces defined therein adapted to allow flow of fluid coolant therethrough and past said fuel rods when said fuel assembly is installed in a nuclear reactor;
a plurality of guide thimbles extending along said fuel rods through and supporting said grid;
a bottom nozzle disposed below said grid, below lower ends of said fuel rods, supporting said guide thimbles and having openings therethrough to allow the flow of fluid coolant into said fuel assembly, the bottom nozzle comprising:
a substantially horizontal plate, orthogonal to the axis of the fuel rods, having an upper face directed substantially toward the lower most grid and a lower face on an underside of said horizontal plate with said openings extending therethrough for the flow of coolant, at least some of said openings in at least one of either the upper face or the lower face having a funnel-like first appendage respectively extending above the upper face or below the lower face, as the case may be, around at least some of the openings in the at least one of the upper face or the lower face with an opening at the first appendage's substantially highest extent, in the case of the upper face or lowest extent, in the case of the lower face, having a larger diameter than a diameter of the opening in the at least one of the upper face the lower face, an internal wall of the first appendage substantially gradually decreasing the lateral flow area axially through the first appendage as the first appendage transitions from the opening at the first appendage's substantially highest extent, in the case of the upper face or lowest extent, in the case of the lower face, to the opening in upper face or the lower face, as the case may be, wherein a lip of at least some of the openings at the first appendage's substantially highest extent in the case of the upper face or lowest extent in the case of the lower face, has a scalloped contour.

13. The nuclear fuel assembly of claim 12 including a funnel-like second appendage extending up from at least some of the openings in another of the upper face or the lower face with an opening at the second appendage's substantially highest extent, in the case of the upper face, or lowest extent, in the case of the lower face, having a larger diameter than a diameter of the opening in the another of the upper face or the lower face, an internal wall of the second appendage substantially gradually decreases the lateral flow area axially through the second appendage as the second appendage transitions from the opening at the second appendage's substantially highest extent in the case of the upper face or lowest extent in the case of the lower face to the opening in the another of the upper face or the lower face, as the case may be.

14. The nuclear fuel assembly of

Assignees

• Westinghouse Electric Co Llc

Inventors

• Broach Kirkland D
• Lewis Michael L
• Peterson Mark W
• Huegel David S
• Frick Peyton M

Classifications

• Y02E30/40

  Cross-Sectional Technologies · mapped topic

• G21C3/3305 Primary

  Lower nozzle · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C3/322

  Means to influence the coolant flow through or around the bundles · CPC title