Spacer grid using tubular cells with mixing vanes

Patent metadata

Field	Value
Publication number	US-10818402-B2
Application number	US-201715475186-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Mar 31, 2017
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

A spacer grid specifically designed for accident tolerant fuel utilizing fuel rods with SiC cladding for implementation in pressurized water reactors. The spacer grid has a generally square design that allows for ease of SiC fuel rod insertion during the fuel assembly fabrication process by providing a smooth contact geometry. The co-planar support allows the fuel rods to be rotated axially more freely at the grid location than a conventional six-point contact geometry used in existing fuel assembly designs.

First claim

What is claimed is:

1. A nuclear fuel assembly spacer grid having an axial dimension along a vertical axis of an elongated nuclear fuel assembly in which it is to be deployed, the nuclear fuel assembly spacer grid comprising:
a plurality of fuel rod support cells having four walls, generally square in cross section, having a length along the axial dimension that is longer than a width of the walls and corners that connect with adjacent fuel rod support cells or a control rod support cell, with an interior of each of the walls of the fuel rod support cells supporting a vertical spring; and
a mixing vane connected to an exterior of at least one of the fuel rod support cells, wherein each of the fuel rod support cell walls are bowed inwardly, along an entire length thereof, into an interior of the fuel rod support cell.

2. The nuclear fuel assembly spacer grid of claim 1 wherein the fuel rod support cell walls are bowed symmetrically around an axis parallel to the vertical axis.

3. The nuclear fuel assembly spacer grid of claim 2 wherein at least one of the vertical springs is formed from two vertical slits in a center portion of at least one of the walls of at least one of the fuel rod support cells.

4. The nuclear fuel assembly spacer grid of claim 1 wherein each vertical spring is formed from two vertical slits in a center portion of each of the walls of the fuel rod support cells.

5. The nuclear fuel assembly spacer grid of claim 1 wherein at least one of the vertical springs is coated with a material.

6. The nuclear fuel assembly spacer grid of claim 5 wherein the material is a carbon coating.

7. An elongated nuclear fuel assembly, comprising:
a spacer grid having an axial dimension along a vertical axis of the elongated nuclear fuel assembly, the spacer grid comprising:
a plurality of fuel rod support cells having four walls, generally square in cross section, having a length along the axial dimension that is longer than a width of the walls and corners that connect with adjacent fuel rod support cells or a control rod support cell, with an interior of each of the walls of the fuel rod support cells supporting a vertical spring; and
a mixing vane connected to an exterior of at least one of the fuel rod support cells, wherein each of the fuel rod support cell walls are bowed inwardly, along an entire length thereof, into an interior of the fuel rod support cell; and

a fuel rod positioned in contact with at least one of the vertical springs.

8. The elongated nuclear fuel assembly of claim 7 wherein the fuel rod support cell walls are bowed symmetrically around an axis parallel to the vertical axis.

9. The elongated nuclear fuel assembly of claim 7 wherein each vertical spring is formed from two vertical slits in a center portion of each of the walls of the fuel rod support cells.

10. The elongated nuclear fuel assembly of claim 7 wherein the at least one of the vertical springs is coated with a material having a hardness that is equal to or greater than the hardness of a SiC cladding on the fuel rod.

11. The nuclear fuel assembly of claim 10 wherein the material is a carbon coating.

12. The nuclear fuel assembly of claim 8 wherein the at least one of the vertical springs is formed from two vertical slits in a center portion of at least one of the walls of at least one of the fuel rod support cells.

Assignees

• Westinghouse Electric Co Llc

Inventors

• Choi Joonhyung
• Karoutas Zeses
• Evans Paul M

Classifications

• G21C3/322

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

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C3/344 Primary

  formed of assembled tubular elements · CPC title

• G21C3/3563 Primary

  Supporting members formed only by deformations in the strips · CPC title

• G21C3/34 Primary

  Spacer grids · CPC title