# US 9,437,335 B2 · Designed porosity materials in nuclear reactor components

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- Number: US 9,437,335 B2
- Document ID: US9437335B2
- Status: Granted
- Kind: B2
- Application number: 14/017,173
- Filed: 2013-09-03
- Published: 2015-03-05
- Granted: 2016-09-06
- Earliest claimed: 2013-09-03
- Assignees: Uchicago Argonne, LLC
- Applicants: A. M. Yacout; Michael J. Pellin; Marius Stan
- Inventors: A. M. Yacout; Michael J. Pellin; Marius Stan
- Web page: https://patentgrep.com/patent/US9437335B2

## CPC

- G21C 21/02: Manufacture of fuel elements or breeder elements contained in non-active casings
- G21C 3/044: {Fuel elements with porous or capillary structure}
- G21C 3/07: characterised by their material, e.g. alloys
- G21C 3/20: with coating on fuel or on inside of casing; with non-active interlayer between casing and active material {with multiple casings or multiple active layers}
- G21C 3/045: {Pellets}
- Y02E 30/30: Nuclear fission reactors
- G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A nuclear fuel pellet with a porous substrate, such as a carbon or tungsten aerogel, on which at least one layer of a fuel containing material is deposited via atomic layer deposition, and wherein the layer deposition is controlled to prevent agglomeration of defects. Further, a method of fabricating a nuclear fuel pellet, wherein the method features the steps of selecting a porous substrate, depositing at least one layer of a fuel containing material, and terminating the deposition when the desired porosity is achieved. Also provided is a nuclear reactor fuel cladding made of a porous substrate, such as silicon carbide aerogel or silicon carbide cloth, upon which layers of silicon carbide are deposited.

## Claims

### Claim 1

A nuclear fuel pellet, comprising:
a porous substrate; and
a plurality of layers of a fuel containing material deposited via atomic layer deposition upon said porous substrate, wherein the total porosity of the nuclear fuel pellet is between about 3 and 30 percent, wherein the porous substrate underlies the deposited layers of the fuel.

### Claim 2 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the fuel containing material is fissile material selected from the group consisting of uranium dioxide, plutonium dioxide, uranium-zirconium, uranium molybdenum and uranium nitride, and combinations thereof.

### Claim 3 (depends on 1)

The nuclear fuel pellet of claim 1, wherein said porous substrate is an aerogel which defines pores which extend through the substrate.

### Claim 4 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the fuel overlays substantially all of the surfaces of the substrate which define pores.

### Claim 5 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the porous substrate has a density less than the density of the fuel.

### Claim 6 (depends on 5)

The nuclear fuel pellet of claim 5, wherein the porous substrate is selected from the group consisting of carbon, tungsten, beryllium oxide, and aluminum nitride.

### Claim 7 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the fuel pellet has an overall density of about 90% of the density of the fuel material.

### Claim 8 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the pores within the pellet have a uniform size and distribution.

### Claim 9 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the pores at the surface of the pellet are smaller than the pores at the center of the pellet and wherein the size of the pores tapers between the center and the surface of the pellet.

### Claim 10 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the fuel pellet has closed pores.

### Claim 11 (depends on 1)

The nuclear fuel pellet of claim 1, wherein the pores are uniformly distributed throughout the pellet and wherein the pores are spaced between about 0.02 mm and about 0.2 mm apart from each other.

### Claim 12 (depends on 1)

The nuclear fuel pellet of claim 1 wherein the porosity of the pellet is between about 15 and 30 percent.

### Claim 13

A nuclear reactor fuel cladding, said cladding comprising:
a porous substrate of silicon carbide, wherein the substrate is substantially a hollow tube, and wherein the porous substrate surrounds nuclear fuel without an underlying liner between said fuel and said porous substrate; and
at least one layer of silicon carbide deposited on the substrate via atomic layer deposition.

### Claim 14 (depends on 13)

The nuclear reactor fuel cladding of claim 13, wherein the porous substrate is a silicon carbide aerogel.

### Claim 15 (depends on 13)

The nuclear reactor fuel cladding of claim 13, wherein the porous substrate is a silicon carbide cloth.

### Claim 16 (depends on 13)

The nuclear reactor fuel cladding of claim 13, wherein the at least one layer of silicon carbide deposition is one atom thick.

### Claim 17 (depends on 13)

The nuclear reactor fuel cladding of claim 13, wherein the coating of silicon carbide is conformal and substantially defect free.