Carbide-based fuel assembly for thermal propulsion applications

Patent metadata

Field	Value
Publication number	US-12249435-B2
Application number	US-202318206302-A
Country	US
Kind code	B2
Filing date	Jun 6, 2023
Priority date	Oct 12, 2020
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material (e.g., SiC—SiC composite), insulation layer of porous refractory ceramic material (e.g., zirconium carbide with open-cell foam structure or fibrous zirconium carbide), and interior structural member of refractory ceramic-graphite composite material (e.g., zirconium carbide-graphite or niobium carbide-graphite). Spacer structures between various layers provide a defined and controlled spacing relationship. A fuel element bundle positioned between support meshes includes a plurality of distributively arranged fuel elements or a solid, unitary fuel element with coolant channels, each having a fuel composition including high assay, low enriched uranium (HALEU). Fuel assemblies are distributively arranged in a moderator block and the upper end of the outer structural member is attached to a metallic inlet tube for hydrogen propellant and the lower end of the outer structural member is interfaced with a support plate, forming a nuclear thermal propulsion reactor.

First claim

What is claimed is:

1. A fuel assembly, comprising:
a fuel assembly outer structure;
a fuel assembly intermediate structure;
a fuel element contained within the fuel assembly intermediate structure, wherein the fuel element includes one or more fuel bodies containing a uranium-based fuel composition, wherein the fuel assembly intermediate structure is spaced apart from an outer envelope surface of the fuel element and extends parallel to the fuel element from a first end surface of the fuel element to a second end surface of the fuel element, an inner surface of the fuel assembly intermediate structure is oriented toward the fuel element, and an outer surface of the fuel assembly intermediate structure is oriented away from the fuel element;
an insulation layer interposed between an inner surface of the fuel assembly outer structure and the outer surface of the fuel assembly intermediate structure;
a first void space between an outer surface of the insulation layer and the inner surface of the fuel assembly outer structure; and
a second void space between an inner surface of the insulation layer and the outer surface of the fuel assembly intermediate structure,
wherein the fuel assembly intermediate structure is formed of a refractory ceramic-graphite composite material.

2. The fuel assembly according to claim 1 , wherein the one or more fuel bodies are in the form of a plurality of elongated fuel bodies,
wherein each of the elongated fuel bodies contains the uranium-based fuel composition, and
wherein the plurality of elongated fuel bodies are arranged in a fuel bundle,
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 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 plurality of elongated fuel bodies in the fuel bundle forms at least part of a coolant flow volume through which a coolant in a form of a propellant gas is able to flow during operation of a reactor containing the fuel assembly.

3. The fuel 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 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.

4. The fuel assembly according to claim 3 , 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.

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

6. The fuel assembly according to claim 5 , wherein the fuel element is refractory carbide coated.

7. The fuel assembly according to claim 2 , wherein the uranium-based fuel composition includes UC-ZrC.

8. The fuel assembly according to claim 2 , wherein the uranium-based fuel composition includes UC-ZrC-NbC.

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

10. The fuel assembly according to claim 2 , wherein the insulation layer extends between a first end surface of a first fuel element bundle and a second end surface of the first fuel element bundle.

11. The fuel assembly according to claim 10 , further comprising a first support mesh located at the first end surface of the first fuel element bundle and a second support mesh located at the second end surface of the first fuel element bundle.

12. The fuel assembly according to claim 11 , 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.

13. The fuel assembly according to claim 12 , wherein each support mesh is formed of a third refractory ceramic material, and wherein the third refractory ceramic material is a zirconium-carbide refractory ceramic material or a niobium-carbide refractory ceramic material.

14. The fuel assembly according to claim 11 , wherein a first end surface of the fuel assembly intermediate structure abuts an outer region of the first support mesh and a second end surface of the fuel assembly intermediate structure abuts an outer region of the second support mesh.

15. The fuel assembly according to claim 11 , further comprising a second fuel element bundle, wherein, in a direction of the longitudinal axis of the fuel assembly, the second fuel element bundle is separated from the first fuel element bundle by one of the first support mesh and the second support mesh.

16. The fuel assembly according to claim 15 , further comprising a third support mesh, wherein the third support mesh is located at an opposite end of the second fuel element bundle from the one first or second support mesh separating the second fuel element bundle from the first fuel element bundle.

17. The fuel assembly according to claim 16 , wherein the fuel assembly intermediate structure spaced apart from the envelope surface of the first fuel element bundle is a first fuel assembly intermediate structure, and
the fuel assembly further comprises a second fuel assembly intermediate structure, wherein the second fuel assembly intermediate structure is spaced apart from an envelope surface of the second fuel element bundle.

18. The fuel assembly according to claim 17 , wherein a first end surface of the second fuel assembly intermediate structure abuts an outer region of the one first or second support mesh separating the second fuel element bundle from the first fuel element bundle and a second end surface of the second fuel assembly intermediate structure abuts an outer region of the third support mesh.

19. The fuel assembly according to claim 1 , wherein the one or more fuel bodies are in the form of one or more fuel monolith bodies,
wherein each fuel monolith body contains the uranium-based fuel composition, and wherein each fuel monolith body includes one or more coolant flow channels, and
wherein the one or more coolant flow channels forms at least part of a coolant flow volume through which a coolant in a form of a propellant gas is able to flow during operation of a reactor containing the fuel assembly.

20. The fuel assembly according to claim 19 , wherein the one or more fuel monolith bodies are in a form of a wafer, a layer, a pie-shaped section, or a cylinder.

21. The fuel assembly according to claim 19 , wherein the fuel monolith body includes a carbide matrix in which the uranium-based fuel composition is distributed.

22. The fuel assembly according to claim 21 , wherein the uranium-based fuel composition includes a binary carbide containing uranium or uranium nitride.

23. The fuel assembly according to claim 22 , wherein the fuel element is refractory carbide coated.

24. The fuel assembly according to claim 22 , wherein the binary carbide containing uranium includes (U,Zr) C.

25. The fuel assembly according to claim 21 , w

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

• G21C3/62

  Ceramic fuel · CPC title

• G21C3/322

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

• G21D5/02 Primary

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

• B64G1/408

  Nuclear spacecraft propulsion · CPC title

• G21C3/3432

  Grids designed to influence the coolant, i.e. coolant mixing function · CPC title