Functionally graded lattice cermet fuel structure with shape corresponding to a mathematically-based periodic solid, particularly for nuclear thermal propulsion applications

Patent metadata

Field	Value
Publication number	US-12159727-B2
Application number	US-202318378691-A
Country	US
Kind code	B2
Filing date	Oct 11, 2023
Priority date	Apr 1, 2019
Publication date	Dec 3, 2024
Grant date	Dec 3, 2024

Abstract

Nuclear propulsion fission reactor structure has an active core region including fuel element structures, a reflector with rotatable neutron absorber structures (such as drum absorbers), and a core former conformal mating the outer surface of the fuel element structures to the reflector. Fuel element structures are arranged abutting nearest neighbor fuel element structures in a tri-pitch design. Cladding bodies defining coolant channels are inserted into and joined to lower and upper core plates to from a continuous structure that is a first portion of the containment structure. The body of the fuel element has a structure with a shape corresponding to a mathematically-based periodic solid, such as a triply periodic minimal surface (TPMS) in a gyroid structure. The nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

First claim

What is claimed is:

1. A nuclear fuel lattice structure, comprising:
a body having a structure including a plurality of webbings having outer surfaces that define a network of interconnected channels located within an envelope surface of the body,
wherein a baseline of the webbings is an implicit surface of a mathematically-based periodic solid,
wherein the mathematically-based periodic solid is a triply periodic minimal surface (TPMS),
wherein at least a portion of the channels extend from a first outer surface of the body to a second outer surface of the body,
wherein the structure has a volumetric density of 35% to 85%, and
wherein a composition of the structure includes a nuclear fissionable fuel having an enrichment of up to 20%.

2. The nuclear fuel lattice structure according to claim 1 , wherein the triply periodic minimal surface (TPMS) is a gyroid structure, and wherein the implicit surface is defined by a gyroid equation (sin×cos y+sin y cos z+sin z cos x)=0.

3. The nuclear fuel lattice structure according to claim 2 , wherein each webbing has a thickness relative to the baseline, and, within the body, the thickness of the webbing varies in accordance with a vector field.

4. The nuclear fuel lattice structure according to claim 3 , wherein the thickness of the webbings is symmetric relative to the baseline.

5. The nuclear fuel lattice structure according to claim 3 , wherein the thickness of the webbings is asymmetric relative to the baseline.

6. The nuclear fuel lattice structure according to claim 1 , wherein a uranium content of the nuclear fissionable fuel varies by spatial location in the body.

7. The nuclear fuel lattice structure according to claim 6 , wherein the variation in uranium content by spatial location in the body includes increasing a content of U235 due to an increased density of the lattice.

8. The nuclear fuel lattice structure according to claim 1 , wherein the mathematically-based periodic solid is biased to effect a flow rate of a medium flowing through the network of interconnected channels.

9. The nuclear fuel lattice structure according to claim 1 , wherein the body is disc-shaped and occupies a volume that includes a radial side surface corresponding to a thickness of the body between the first outer surface and the second outer surface.

10. The nuclear fuel lattice structure according to claim 1 , wherein the triply periodic minimal surface (TPMS) is a Schwarz minimal surface.

11. The nuclear fuel lattice structure according to claim 1 , wherein the nuclear fissionable fuel is high-assay low-enriched uranium (HALEU) with a U 235 assay equal to or greater than 5 percent to equal to or lower than 20 percent.

12. The nuclear fuel lattice structure according to claim 1 , wherein the nuclear fissionable fuel includes uranium oxide that is less than 20% enriched, uranium with 10 wt. % molybdenum (U-10Mo), uranium nitride (UN), or a cermet thereof.

13. A nuclear fuel segment, comprising:
the nuclear fuel lattice structure according to claim 1 ; and
a cladding layer deposited on the outer surfaces of the plurality of webbings that define the network of interconnected channels.

14. The nuclear fuel segment according to claim 13 , wherein the cladding layer has a composition including molybdenum, tungsten, rhenium, tantalum, hafnium and alloys thereof, including carbides.

15. A nuclear reactor structure, comprising:
an active core region including a plurality of nuclear fuel segments according to claim 13 ,
wherein the plurality of nuclear fuel segments are arranged along an axial centerline defining a longitudinal axis of the nuclear reactor structure.

16. The nuclear reactor structure according to claim 15 , wherein the network of interconnected channels in the body of adjacent nuclear fuel segments are aligned to provide fluid communication from a first end surface of the active core to a second end surface of the active core.

17. A nuclear thermal propulsion engine, comprising:
the nuclear reactor structure according to claim 15 , wherein the nuclear reactor structure is housed within an interior volume of a hull;
shielding;
a reservoir for cryogenically storing propulsion gas;
turbomachinery; and
a nozzle,
wherein the shielding, the turbomachinery, and the reservoir are operatively mounted to a first end of the hull to provide a flow path from the reservoir to the nuclear reactor structure, and
wherein the nozzle is operatively mounted to a second end of the hull to provide a flow path for superheated propulsion gas exiting the nuclear thermal propulsion engine.

Assignees

• Bwxt Advanced Tech Llc

Inventors

• Fisher Benjamin D
• Salasin John R
• Gramlich Craig D
• Witter Jonathan K

Classifications

• Y10S376/909

  Mobile reactors · CPC title

• Y10S376/901

  Fuel · CPC title

• G21C7/24

  Selection of substances for use as neutron-absorbing material · CPC title

• G21C3/64

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

• G21C3/60

  Metallic fuel; Intermetallic dispersions · CPC title