Pressurized water reactor fuel assembly

Patent metadata

Field	Value
Publication number	US-9773573-B2
Application number	US-201414495957-A
Country	US
Kind code	B2
Filing date	Sep 25, 2014
Priority date	Sep 25, 2014
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

An elongated control rod guide thimble for a nuclear reactor having a tube-in-tube dashpot design that has circumferential slots in the dashpot walls that align with spaced openings in the guide thimble sheath. The dashpot tube has an end plug with a threaded opening extending axially therethrough which is captured by a thimble screw that extend through an opening in the bottom nozzle and sandwiches an end plug attached to the guide thimble sheath between the dashpot tube end plug and the bottom nozzle.

First claim

What is claimed is:

1. A nuclear fuel assembly comprising:
a top nozzle;
a bottom nozzle;
a plurality of elongated guide thimbles extending axially between and attached to the top nozzle and the bottom nozzle, at least some of the plurality of guide thimbles having a tubular sheath that extends a majority of the length of the corresponding guide thimble with a lower end of the sheath capped by a lower end plug having an aperture extending axially there through; and
a tube-in-tube dashpot having an axially extending sidewall disposed within a lower portion of the tubular sheath with an opening in the sidewall of the dashpot aligned with an opening in the tubular sheath, wherein the opening in one of the sidewall of the dashpot or the tubular sheath is oblong extending partially around a circumference of the one of the sidewall or the tubular sheath with a greater diameter of the oblong opening extending in the circumferential direction.

2. The nuclear fuel assembly of claim 1 wherein the tube-in-tube dashpot has a lower end cap with an aperture extending axially there through which aligns with the aperture in the lower end plug of the tubular sheath.

3. The nuclear fuel assembly of claim 2 including a fastener that extends through the bottom nozzle, through the lower end plug of the tubular sheath and into the lower end cap of the tube-in-tube dashpot, attaching the guide thimble and the tube-in-tube dashpot to the bottom nozzle.

4. The nuclear fuel assembly of claim 3 wherein the aperture in the lower end cap of the tube-in-tube dashpot is threaded and mates with a corresponding thread on the fastener.

5. The nuclear fuel assembly of claim 1 wherein the opening in the one of the sidewall or the tubular sheath comprises a plurality of circumferentially spaced oblong openings formed approximately at the same elevation.

6. The nuclear fuel assembly of claim 5 wherein the opening in the one of the sidewall or the tubular sheath comprises two circumferentially spaced oblong openings formed approximately at the same elevation.

7. The nuclear fuel assembly of claim 1 wherein the opening in the other of the tubular sheath or the sidewall is circular and overlaps a portion of the oblong opening in the one of the sidewall of the tube-in-tube dashpot or the tubular sheath.

8. A modular reactor having a primary circuit substantially contained within a pressure vessel that houses a core comprising fuel assemblies at least some of which include:
a top nozzle;
a bottom nozzle;
a plurality of elongated guide thimbles extending axially between and attached to the top nozzle and the bottom nozzle, at least some of the plurality of guide thimbles having a tubular sheath that extends a majority of the length of the corresponding guide thimble with a lower end of the sheath capped by a lower end plug having an aperture extending axially there through; and
a tube-in-tube dashpot having an axially extending sidewall disposed within a lower portion of the tubular sheath with an opening in the sidewall of the dashpot aligned with an opening in the tubular sheath, wherein the opening in one of the sidewall of the dashpot or the tubular sheath is oblong extending partially around a circumference of the one of the sidewall or the tubular sheath with a greater diameter of the oblong opening extending in the circumferential direction.

9. The modular reactor of claim 8 wherein the tube-in-tube dashpot has a lower end cap with a threaded aperture extending axially there through which aligns with the aperture in the lower end plug of the tubular sheath.

10. The modular reactor of claim 9 including a threaded fastener that extends through the bottom nozzle, through the lower end plug of the tubular sheath and into the lower end cap of the tube-in-tube dashpot, attaching the guide thimble and the tube-in-tube dashpot to the bottom nozzle.

11. The modular reactor of claim 10 wherein the aperture in the lower end cap of the tube-in-tube dashpot is threaded and mates with a corresponding thread on the fastener.

12. The modular reactor of claim 8 wherein the opening in the one of the sidewall or the tubular sheath comprises a plurality of circumferentially spaced oblong openings formed approximately at the same elevation.

13. The modular reactor of claim 11 wherein the opening in the one of the sidewall or the tubular sheath comprises two circumferentially spaced oblong openings formed approximately at the same elevation.

14. The modular reactor of claim 8 wherein the opening in the other of the tubular sheath or the sidewall is circular and overlaps a portion of the oblong opening in the one of the sidewall of the tube-in-tube dashpot or the tubular sheath.

Assignees

• Westinghouse Electric Co Llc

Inventors

• Liu Jin

Classifications

• G21C3/322 Primary

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

• G21C3/326 Primary

  comprising fuel elements of different composition; comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods · CPC title

• G21C7/117

  Clusters of control rods; Spider construction · CPC title

• G21C1/322

  wherein the heat exchanger is disposed above the core · CPC title

• G21C7/20 Primary

  Disposition of shock-absorbing devices (shock-absorbers in general F16F ){; Braking arrangements} · CPC title