Carbide-based fuel assembly for thermal propulsion applications

Patent metadata

Field	Value
Publication number	US-11728044-B2
Application number	US-202117399822-A
Country	US
Kind code	B2
Filing date	Aug 11, 2021
Priority date	Oct 12, 2020
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material, the interior surface of which is lined in higher temperature regions with an insulation layer of porous refractory ceramic material. Continuous insulation layer extends the length of the fuel assembly or separate insulation layer sections have a thickness increasing step-wise along the length of the fuel assembly from upper (inlet) section towards bottom (outlet) section. A fuel element positioned inward of the insulation layer and between support meshes has a fuel composition including HALEU and the form of a plurality of individual elongated fuel bodies or one or more fuel monolith bodies containing coolant flow channels. Fuel assemblies are distributively arranged in a moderator block, with upper end of the outer structural member attached to an inlet for propellant and lower end of the outer structural member operatively interfaced with a nozzle forming a nuclear thermal propulsion reactor.

First claim

What is claimed is:

1. A fuel assembly, comprising:
a fuel assembly outer structure;
a first fuel element contained within the fuel assembly outer structure; and
an insulation layer interposed between an inner surface of the fuel assembly outer structure and an outer envelope surface of the first fuel element,
wherein the fuel assembly outer structure is formed of a ceramic matrix composite material,
wherein the insulation layer is formed of a first refractory ceramic material,
wherein the insulation layer is spaced apart from the outer envelope surface of the first fuel element and extends parallel to the first fuel element from a first end surface of the first fuel element to a second end surface of the first fuel element, and
wherein the first refractory ceramic material is a zirconium carbide refractory ceramic material and is porous with 60 to 85% of the volume consisting of void spaces.

2. The fuel assembly according to claim 1 , wherein the first fuel element includes a plurality of elongated fuel bodies,
wherein the elongated fuel bodies contain a fuel composition, and
wherein the plurality of elongated fuel bodies are arranged in a fuel bundle.

3. The fuel assembly according to claim 2 , wherein each elongated fuel body longitudinally extends from a first end to a second end along a longitudinal axis of the respective elongated fuel body,
wherein, in the fuel bundle, the plurality of elongated fuel bodies are arranged in spaced-apart relationship relative to each other, and
wherein an empty space between the spaced-apart elongated fuel bodies in the fuel bundle is a coolant flow volume through which a coolant in a form of a propellant gas flows during operation of a reactor containing the fuel assembly.

4. The assembly according to claim 2 , wherein the fuel assembly is elongated and is tubular-shaped and has an axial centerline defining a longitudinal axis of the fuel assembly,
wherein the plurality of elongated fuel bodies of the first fuel element are located at positions that are axisymmetric about the longitudinal axis of the fuel assembly, as seen in cross-section in a plane perpendicular to the longitudinal axis of the fuel assembly.

5. The fuel assembly according to claim 4 , wherein, in a plane perpendicular to the longitudinal axis of the elongated fuel body, a cross-sectional shape of the elongated fuel body is a polygon, a circle, or an oval, preferably a regular polygon.

6. The fuel assembly according to claim 1 , wherein the first fuel element includes one or more fuel monolith bodies,
wherein each fuel monolith body contains a fuel composition, and wherein each fuel monolith body includes one or more coolant flow channels, and
wherein the one or more coolant flow channels is a coolant flow volume through which a coolant in a form of a propellant gas flows during operation of a reactor containing the fuel assembly.

7. The fuel assembly according to claim 6 , wherein the one or more fuel monolith bodies are in a form of a wafer, a layer, a pie-shaped section, or a cylinder.

8. The fuel assembly according to claim 2 , wherein the fuel composition includes uranium having a U-235 assay above 5 percent and below 20 percent.

9. The fuel assembly according to claim 2 , wherein the fuel composition includes a binary carbide containing uranium or a ternary carbide containing uranium.

10. The fuel assembly according to claim 2 , wherein the fuel composition includes UC—ZrC.

11. The fuel assembly according to claim 2 , wherein the fuel composition includes UC—ZrC—NbC.

12. The fuel assembly according to claim 6 , wherein the fuel monolith body includes a carbide matrix in which the fuel composition is distributed.

13. The fuel assembly according to claim 12 , wherein the fuel composition includes a binary carbide containing uranium or uranium nitride.

14. The fuel assembly according to claim 9 , wherein the first fuel element is refractory carbide coated.

15. The fuel assembly according to claim 6 , wherein the fuel monolith body includes a refractory metal matrix in which the fuel composition is distributed.

16. The fuel assembly according to claim 15 , wherein the fuel composition includes uranium nitride.

17. The fuel assembly according to claim 15 , wherein the fuel monolith body is refractory metal coated.

18. The fuel assembly according to claim 2 , wherein the fuel composition is carbide-based and wherein the first fuel element is refractory carbide coated.

19. The fuel assembly according to claim 1 , wherein the ceramic matrix composite material is a SiC—SiC composite.

20. The fuel assembly according to claim 1 , wherein the first refractory ceramic material is porous with 72-76% or 78-82% of the volume consisting of void spaces.

21. The fuel assembly according to claim 1 , further comprising a first support mesh located at the first end surface of the first fuel element and a second support mesh located at the second end surface of the first fuel element.

22. The fuel assembly according to claim 21 , wherein each support mesh includes a first region having a plurality of openings, and wherein the plurality of openings are interconnected internally within the first region and form a flow path from a first side to a second side of the support mesh.

23. The fuel assembly according to claim 22 , wherein each support mesh includes an outer region enclosing a perimeter of the first region.

24. The fuel assembly according to claim 23 , wherein the outer region has a lower porosity than the first region.

25. The fuel assembly according to claim 23 , wherein the outer region is devoid of openings.

26. The fuel assembly according to claim 21 , wherein each support mesh is formed of a second refractory ceramic material.

27. The fuel assembly according to claim 26 , wherein the second refractory ceramic material is porous with 30 to 70% of the volume consisting of void spaces.

28. The fuel assembly according to claim 27 , wherein the second refractory ceramic material is a zirconium carbide refractory ceramic material or a niobium carbide refractory ceramic material.

29. The fuel assembly according to claim 26 , wherein the second refractory ceramic material is 90% to 99.999% zirconium carbide or 90% to 99.999% niobium carbide, and wherein the second refractory ceramic material has an open-cell foam structure.

30. The fuel assembly according to claim 21 , wherein a first end surface of the insulation layer abuts an outer region of the first support mesh and a second end surface of the insulation layer abuts an outer region of the second support mesh.

31. The fuel assembly according to claim 21 , further comprising a second fuel element, wherein the second fuel element is separated from the first fuel element in a longitudinal direction by one of the first support mesh and the second support mesh.

32. The fuel assembly according to claim 31 , further comprising a third support mesh, wherein the third support mesh is located at an opposite end of the second fuel element from the one first or second support mesh separating the second fuel element from the first fuel element.

33. The fuel assembly according to claim 31 , wherein the insulation layer interposed between the inner surface of the fuel assembly outer structure and the first fue

Assignees

• Bwxt Advanced Tech Llc
• Bwxt Nuclear Energy Inc

Inventors

• Barringer Eric A
• Jensen Russell R
• Gustafson Jeremy L
• Ales Matt
• Bergman Joshua J
• Swanson Ryan T
• Witter Jonathan K
• Galicki Danny
• Inman James B
• Krecicki Matt
• Ridgeway Roger

Classifications

• G21C11/081

  consisting of a non-metallic layer of insulating material · CPC title

• G21C3/64

  Ceramic dispersion fuel, e.g. cermet · CPC title

• G21C5/02

  Details · CPC title

• G21C3/07 Primary

  characterised by their material, e.g. alloys · CPC title

• G21D5/02 Primary

  Reactor and engine structurally combined, e.g. portable · CPC title