# US 2018/0025797 A1 · Methods of forming structures and fissile fuel materials by additive manufacturing and related structures

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- Number: US 2018/0025797 A1
- Document ID: US20180025797A1
- Status: Published application
- Kind: A1
- Application number: 15/653,258
- Filed: 2017-07-18
- Published: 2018-01-25
- Earliest claimed: 2016-07-19
- Assignees: Battelle Energy Alliance, LLC
- Applicants: Battelle Energy Alliance, LLC
- Inventors: Isabella J. Van Rooyen; Sean R. Morrell
- Web page: https://patentgrep.com/patent/US20180025797A1

## CPC

- G21C 21/02: Manufacture of fuel elements or breeder elements contained in non-active casings
- B22F 10/28: Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
- B22F 10/36: of energy beam parameters
- B22F 10/38: to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
- B22F 12/53: Nozzles
- B28B 1/001: {Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material (selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00)}
- B29C 64/153: using layers of powder being selectively joined, e.g. by selective laser sintering or melting
- B29C 64/268: using laser beams; using electron beams [EB]
- B33Y 10/00: Processes of additive manufacturing
- B33Y 70/10: Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
- B33Y 80/00: Products made by additive manufacturing
- G21C 3/044: {Fuel elements with porous or capillary structure}
- G21C 3/16: Details of the construction within the casing
- G21C 3/62: Ceramic fuel
- G21C 3/623: {Oxide fuels}
- G21C 3/626: {Coated fuel particles}
- B22F 10/32: of the atmosphere, e.g. composition or pressure in a building chamber
- B22F 10/66: by mechanical means
- B22F 12/41: characterised by the type, e.g. laser or electron beam
- Y02E 30/30: Nuclear fission reactors
- Y02P 10/25: Process efficiency
- G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B28B: SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER (foundry moulding B22C; working stone or stone-like material B28D; shaping of substances in a plastic state, in general B29C; making layered products not composed wholly of these substances B32B)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method of forming one or more structures by additive manufacturing comprises introducing a first layer of a powder mixture comprising graphite and a fuel on a surface of a substrate. The first layer is at least partially compacted and then exposed to laser radiation to form a first layer of material comprising the fuel dispersed within a graphite matrix material. At least a second layer of the powder mixture is provided over the first layer of material and exposed to laser radiation to form inter-granular bonds between the second layer and the first layer. Related structures and methods of forming one or more structures are also disclosed.

## Claims

### Claim 1

A method of forming a fissile fuel structure by additive manufacturing, the method comprising:
introducing a first layer of a powder mixture comprising graphite and a fuel on a surface of a substrate;
at least partially compacting the first layer;
exposing the first layer of the powder mixture to laser radiation to form a first layer of material comprising the fuel dispersed within a graphite matrix material;
forming a second layer of the powder mixture over the first layer of material; and
exposing the second layer of the powder mixture to laser radiation to form a second layer of material comprising the fuel dispersed within a graphite matrix material and to form inter-granular bonds between the second layer and the first layer.

### Claim 2 (depends on 1)

The method of claim 1, further comprising selecting the powder mixture such that graphite constitutes between about 97.0 weight percent and about 99.9 weight percent of the powder mixture.

### Claim 3 (depends on 1)

The method of claim 1, further comprising selecting the powder mixture to comprise graphite and a uranium-containing material.

### Claim 4 (depends on 1)

The method of claim 1, further comprising selecting the powder mixture to consist essentially of graphite and a uranium oxide.

### Claim 5 (depends on 1)

The method of claim 1, further comprising selecting the fuel to comprise uranium oxide particles coated with graphite.

### Claim 6 (depends on 1)

The method of claim 1, further comprising selecting the powder mixture to comprise a graphite to total carbon ratio of about 1.0:1.0.

### Claim 7 (depends on 1)

The method of claim 1, wherein exposing the first layer and the second layer of the powder mixture to laser radiation comprises exposing at least one of the first layer and the second layer to defocused laser radiation.

### Claim 8 (depends on 1)

The method of claim 1, further comprising selecting the fuel to comprise uranium silicide, uranium carbide, or a combination thereof.

### Claim 9 (depends on 1)

The method of claim 1, further comprising providing a powder of a cladding material substantially around a circumference of at least one of the first layer of the powder mixture and the second layer of the powder mixture and exposing the powder of the cladding material to laser radiation.

### Claim 10 (depends on 1)

The method of claim 1, wherein exposing the first layer and the second layer of the powder mixture to laser radiation comprises exposing the first layer and the second layer to the laser radiation in an inert atmosphere.

### Claim 11 (depends on 1)

The method of claim 1, further comprising moving the substrate away from the laser prior to forming the second layer of the powder mixture over the first layer of material.

### Claim 12 (depends on 1)

The method of claim 1, wherein introducing a first layer of a powder mixture comprising graphite and a fuel on a surface of a substrate comprises forming the first layer of the powder mixture to a thickness between about 0.1 mm and about 5.0 mm.

### Claim 13 (depends on 1)

The method of claim 1, further comprising providing a dopant to the powder mixture at a concentration between about 1 ppb and about 1,000 ppb.

### Claim 14 (depends on 1)

The method of claim 1, wherein exposing the first layer to laser radiation comprises exposing the first layer to laser radiation after at least partially compacting the first layer of the powder mixture.

### Claim 15 (depends on 1)

The method of claim 1, further comprising heating the substrate prior to introducing the first layer of the powder mixture on the surface of the substrate.

### Claim 16

A method of additively manufacturing a structure, the method comprising:
disposing a first layer of a powder onto a surface of a substrate;
compacting the first layer of the powder on the surface of the substrate;
exposing the first layer of the powder to defocused laser radiation to form a first layer of a structure comprising inter-granular bonds between particles of the powder;
disposing a second layer of another powder on the first layer of the structure; and
exposing the second layer of the another powder to defocused laser radiation to form a second layer of the structure.

### Claim 17 (depends on 16)

The method of claim 16, further comprising selecting the powder and the another powder to comprise a different material.

### Claim 18 (depends on 17)

The method of claim 17, further comprising selecting the powder to comprise one of a metal and a ceramic material and selecting the another powder to comprise the other of the metal and the ceramic material.

### Claim 19 (depends on 16)

The method of claim 16, further comprising selecting the powder and the another powder to comprise graphite.

### Claim 20 (depends on 16)

The method of claim 16, further comprising selecting the powder and the another powder to comprise a uranium-containing material.

### Claim 21 (depends on 16)

The method of claim 16, further comprising selecting the powder to comprise a matrix material and the another powder to comprise a fuel material.

### Claim 22 (depends on 16)

The method of claim 16, wherein exposing the first layer of the powder to defocused laser radiation comprises exposing the first layer of the powder to defocused laser radiation having a spot size between about 1 mm and about 10 mm.

### Claim 23 (depends on 16)

The method of claim 16, further comprising forming a third layer of a powder over the second layer of the structure, the third layer of the powder having a same composition as the first layer of the powder.

### Claim 24

A method of forming a structure, the method comprising:
providing a substrate within an enclosure;
disposing a powder on the substrate;
exposing the powder on the substrate to defocused laser radiation to form a first layer of a structure;
disposing additional powder over the first layer; and
exposing the additional powder over the first layer to defocused laser radiation.

### Claim 25 (depends on 24)

The method of claim 24, further comprising selecting the powder to comprise a matrix material and at least another material.

### Claim 26 (depends on 25)

The method of claim 25, further comprising selecting the matrix material to comprise graphite.

### Claim 27 (depends on 26)

The method of claim 26, further comprising selecting the at least another material to comprise particles of a uranium-containing material coated with graphite.

### Claim 28 (depends on 25)

The method of claim 25, further comprising selecting the powder to comprise a carbon to uranium ratio between about 700:1 and about 10,000:1.

### Claim 29 (depends on 24)

The method of claim 24, further comprising adding at least one dopant selected from the group consisting of nanotubes and zirconium to the powder.

### Claim 30 (depends on 24)

The method of claim 24, wherein disposing a powder on the substrate comprises disposing the powder on the substrate from a single powder delivery nozzle.

### Claim 31 (depends on 24)

The method of claim 24, wherein disposing a powder on the substrate comprises disposing a matrix material from a first powder delivery nozzle and disposing at least another material from a second powder delivery nozzle on the substrate.

### Claim 32 (depends on 24)

The method of claim 24, further comprising selecting a duration of time that the powder is exposed to the defocused laser radiation based on one or more of a particle size of the powder, a composition of the powder, or a spot size of the defocused laser radiation.

### Claim 33 (depends on 24)

The method of claim 24, wherein disposing a powder on the substrate comprises forming a powder layer comprising a varying composition at different cross-sectional locations of the powder layer on the substrate.

### Claim 34 (depends on 33)

The method of claim 33, wherein forming a powder layer comprising a varying composition at different cross-sectional locations of the powder layer comprises forming a first composition at internal locations of the powder layer and a second composition around a circumference of the first composition.

### Claim 35 (depends on 34)

The method of claim 34, further comprising selecting the first composition to comprise a fuel material and selecting the second composition to comprise a cladding material.

### Claim 36

A structure including a fissile fuel material, comprising:
at least a first layer comprising a fuel material dispersed in a graphite matrix material, wherein particles of the fuel material are directly bonded to adjacent particles of the graphite matrix material,
the fissile fuel material exhibiting a graphite to total carbon ratio equal to about 1.0:1.0; and
at least a second layer of another material bonded to the first layer.

### Claim 37 (depends on 36)

The structure of claim 36, wherein the fuel material comprises at least one of uranium dioxide, uranium silicide, or uranium carbide.

### Claim 38 (depends on 36)

The structure of claim 36, wherein the fissile fuel material comprises at least a portion of a fuel block or at least a portion of a fuel rod.

### Claim 39 (depends on 36)

The structure of claim 36, wherein the fissile fuel material exhibits a porosity between about 0.01 and about 0.05.

### Claim 40 (depends on 36)

The structure of claim 36, wherein the fissile fuel material comprises a carbon to uranium ratio between about 700:1 and about 10,000:1

### Claim 41 (depends on 36)

The structure of claim 36, wherein the graphite matrix material constitutes between about 97.0 weight percent and about 99.9 weight percent of the fissile fuel material.

### Claim 42 (depends on 36)

The structure of claim 36, wherein the at least a first layer and the at least a second layer comprise the same material.