Nuclear fuel assembly having a spacer grid with one or more seamless corners

Patent metadata

Field	Value
Publication number	US-9734923-B2
Application number	US-201313922629-A
Country	US
Kind code	B2
Filing date	Jun 20, 2013
Priority date	Jun 20, 2013
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A nuclear fuel assembly grid that has fuel rod support features that take up a substantial portion of the width of the corner fuel rod support cells. The nuclear fuel assembly grid has an outer strap that is joined around a corner of the grid to another outer strap segment and a mating inner strap end at the intersection with the inner strap. The juncture accommodates the width of the rod support feature, enables grid-to-grid anti-snag capabilities and facilitates the use of longitudinal feed materials and dies.

First claim

What is claimed is:

1. A fuel assembly for a nuclear reactor, the fuel assembly comprising:
a parallel, spaced array of a plurality of elongated nuclear fuel rods, supported between a lower nozzle and an upper nozzle, and having an axial length along the elongated dimension of the nuclear fuel rods;
a plurality of spaced support grids arranged in tandem along the axial length of the fuel rods, between the upper nozzle and the lower nozzle, at least partially enclosing an axial portion of a circumference of each fuel rod within a corresponding support cell of the support grids to maintain a lateral spacing between fuel rods, at least one of the support grids comprising:
a plurality of elongated, interior intersecting straps that define interior ones of the support cells at an intersection of each four adjacent, interior, intersecting straps that surround the nuclear fuel rods passing through the interior support cells, with a length of each strap along its elongated dimension, forming a wall of the corresponding support cell, with each side of the support grid having an outer wall of each of an outer row of support cells respectively on a first side, on a second side, on a third side and on a fourth side of the support grid, the outer walls formed from at least one bordering strap, each bordering strap having a first and a second end, the at least one bordering strap includes at least one extended bordering strap, each extended bordering strap having a continuous length extending completely over a length of at least one side of the support grid, the first end of an extended bordering strap extending along one side of the support grid, then around a corner of the support and, and then over at least one support cell of the outer row of support cells of an adjacent side of the support grid, the first end of the extended bordering strap overlapping a second end of a bordering strap on the adjacent side of the support grid, to form an overlapping section of bordering strap ends, the overlapping section mates with an end of one of the interior straps to which it is structurally joined.

2. The fuel assembly of claim 1 wherein the bordering strap covering the first side, the second side, the third side and the fourth side of the support grid is one continuous strap with the first and second end.

3. The fuel assembly of claim 1 wherein the bordering strap includes anti-snag projections that extend from the top and bottom of the bordering strap at regular intervals between fuel rod support features generally centered on a width of the outer wall of the outer row of support cells, except one of the first and second ends has no anti-snag projections in the overlapping section.

4. The fuel assembly of claim 1 wherein the first end is provided with two spaced lateral cuts that are spaced along a height of the first end that define three tabs with a center tab wider than an upper and a lower tab.

5. The fuel assembly of claim 4 wherein the upper and lower tabs are substantially of the same height.

6. The fuel assembly of claim 4 wherein each of the upper, lower and center tabs has a vertical bend line and the vertical bend line of the upper and lower tabs are substantially equidistant from an intersection of the interior strap closest to the first end and the vertical bend line of the center tab is further distant from the intersection than the upper and lower tabs.

7. The fuel assembly of claim 4 wherein the second end includes a generally “U”-shaped notch along its height that is substantially in-line with the center tab.

8. The fuel assembly of claim 7 wherein each of the upper, lower and center tabs has a vertical bend line and the vertical bend line of the upper and lower tabs are substantially equidistant from an intersection of the interior strap closest to the first end and the vertical bend line of the center tab is further distant from the intersection than the upper and lower tabs and the “U”-shaped notch in the second end has a lateral depth substantially equal to the width of the center tab from the first end to the bend line.

9. The fuel assembly of claim 1 wherein an upper and lower edge of a portion of the overlapping section at the second end adjacent where the bordering strap extends around the corner, has an upright and inverted generally “V” shaped cut that is substantially centered at the corner.

10. The fuel assembly of claim 1 wherein the bordering strap includes fuel rod support features generally centered on a width of the outer wall of the outer row of the support cells, except that the distance between the adjacent fuel rod support features at the one of the first and second end that is part of the overlapping section is smaller than the distance between other of the fuel rod support features.

11. A nuclear fuel assembly support grid structured to maintain a spacing between nuclear fuel rods in a parallel, spaced array of a plurality of elongated nuclear fuel rods supported within a nuclear fuel assembly, the nuclear fuel rods having an axial length along the elongated dimension of the nuclear fuel rods and the nuclear fuel assembly support grids being adapted to be supported along a portion of the axial length of the fuel rods, and at least partially enclosing the axial portion of a circumference of each fuel rod within a corresponding support cell of the nuclear fuel assembly support grid, the nuclear fuel assembly support grid comprising:
a plurality of elongated, interior intersecting straps that define interior ones of the support cells at an intersection of each four adjacent, interior, intersecting straps that surround the nuclear fuel rods passing through the interior support cells, with a length of each strap along its elongated dimension, forming a wall of the corresponding support cell, with each side of the support grid having an outer wall of each of an outer row of support cells respectively on a first side, on a second side, on a third side and on a fourth side of the support grid the outer walls formed from at least one bordering strap, each bordering strap having a first and a second end, the at least one bordering strap includes at least one extended bordering strap, each extended bordering strap having a continuous length extending completely over a length of at least one side of the support grid, the first end of an extended bordering strap extending along one side of the support grid, then around a corner of the support grid, and then over at least one support cell of the outer row of support cells of an adjacent side of the support grid, the first end of the extended bordering strap overlapping a second end of a bordering strap on the adjacent side of the support grid, to form an overlapping section of bordering strap ends, the overlapping section mates with an end of one of the interior straps to which it is structurally joined.

12. The fuel assembly support grid of claim 11 wherein the bordering strap covering the first side, the second side, the third side and the fourth side of the support grid is one continuous strap with the first and second end.

13. The fuel assembly support grid of claim 11 wherein the bordering strap includes anti-snag projections that extend from the top and bottom of the bordering strap at regular intervals between fuel rod support features generally centered on a width of the outer wall of the outer row of support cells, except one of the first and second ends has no anti-snag projections in the overlapping section.

14. The fuel assembly support grid of claim 11 wherein the first end is provided with two spaced lateral cuts that are spaced along a height of the first end that define t

Assignees

• Westinghouse Electric Co Llc

Inventors

• Walters Jason A

Classifications

• G21C3/356

  being provided with fuel element supporting members · CPC title

• G21C3/352 Primary

  formed of assembled intersecting strips · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• Y02E30/40

  Cross-Sectional Technologies · mapped topic