Coated fuel pellets, methods of making and using same

1. A method of preparing a coated fuel pellet via atomic layer deposition (ALD), the method comprising:

providing a green compact consisting of a fission material powder selected from uranium silicide, uranium nitride, uranium carbide, and combinations thereof, and gas trapped in pores and/or channels of the green compact, in an atomic layer deposition chamber and pulling a vacuum within the chamber at a rate of about 1 Torr/min to about 10 Torr/min until the atomic layer deposition chamber has a pressure of about 0.1 Torr to about 1.0 Torr thereby releasing the gas trapped in pores and/or channels of the green compact;

depositing a protective coating on the green compact using atomic layer deposition such that the protective coating infiltrates into and coat the pores and/or channels of the green compact, to provide a protective-coated green compact, wherein the protective coating comprises a metal nitride, molybdenum, or a combination thereof;

depositing an oxide-based coating on the protective-coated green compact using atomic layer deposition such that the oxide-based coating infiltrates into and coat the protective coating coated pores and/or channels of the protective-coated green compact, thereby providing an oxidation diffusion barrier; and,

sintering the protective-coated green compact with the oxygen diffusion barrier, thereby providing the coated fuel pellet.

2. The method of claim 1 , wherein the metal nitride is selected from the group consisting of aluminum nitride (AlN), silicon nitride (Si 3 N 4 ), titanium nitride (TiN), zirconium nitride (ZrN), or any combination thereof.

3. The method of claim 1 , wherein the protective coating comprises molybdenum.

4. The method of claim 1 , wherein the oxide-based coating is selected from the group consisting of aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), zirconium (IV) silicate (ZrSiO 4 ), silicon dioxide (SiO 2 ), yttrium oxide (Y 2 O 3 ), chromium (II) oxide (CrO), chromium (III) oxide (Cr 2 O 3 ), chromium (IV) oxide (CrO 2 ), chromium (VI) oxide (CrO 3 ), and any combination thereof.

5. The method of claim 1 , wherein the protective coating and/or the oxide-based coating is deposited at a temperature of about 200° C. to about 250° C.

6. The method of claim 1 , wherein depositing the protective coating comprises alternately depositing two or more protective coating precursors on the green compact, wherein the two or more protective coating precursors are independently selected from the group consisting of tetrakis (dimethylamido) zirconium (IV) (TDMAZ), trimethylaluminum, tris (dimethylamido) aluminum (III), tetrakis (diethylamido) titanium (IV) (TDEAT), tris (dimethylamino) silane (TDMSi), disilane, molybdenum hexafluoride, ammonia, hydrazine, and any combination thereof.

7. The method of claim 6 , wherein depositing each of the protective coating precursors has a pulse time of about 1 second to about 10 seconds and a purge time of at least about 60 seconds.

8. The method of claim 1 , wherein depositing the oxide-based coating comprises alternately depositing two or more oxide-based coating precursors on the protective-coated green compact, wherein the two or more oxide-based coating precursors are independently selected from the group consisting of tetrakis (dimethylamido) zirconium (IV) (TDMAZ), bis (methyl-η 5 -cyclopentadienyl)methoxymethylzirconium (ZRCMMM), trimethylaluminum, tris (dimethylamido) aluminum (III), tetrakis (dimethylamido) titanium (IV) (TDMAT), tetrakis (diethylamido) titanium (IV) (TDEAT), titanium tetrachloride, tris (dimethylamino) silane (TDMAS), hexachlorodisilane, water, hydrogen peroxide, ozone, tris (cyclopentadienyl) yttrium (Cp 3 Y), tris (methylcyclopentadienyl) yttrium ((CpCH 3 ) 3 Y), bis (cyclopentadienyl) chromium (II), bis (pentamethylcyclopentadienyl) chromium (II), chromyl chloride, methanol, and any combination thereof.

9. The method of claim 8 , wherein depositing each of the oxide-based coating precursors has a pulse time of about 1 second to about 10 seconds and a purge time of at least about 60 seconds.

10. The method of claim 1 , wherein the coated fuel pellet comprises the protective coating and the oxide-based coating in an amount of about 2 wt % to about 10 wt %, based on the total weight of the coated fuel pellet.

11. The method of claim 1 , wherein the coated fuel pellet has an onset temperature for steam oxidation that is at least about 100° C. higher than an uncoated fuel pellet.

12. The method of claim 1 , wherein the fission material powder has a particle size of about 2 microns to about 8 microns.