Methods of forming triuranium disilicide structures, and related fuel rods for light water reactors

1. A method of forming an U 3 Si 2 structure, comprising:

forming a mixture comprising uranium particles and silicon particles;

pressing the mixture to form a compact comprising the uranium particles and the silicon particles;

subjecting the compact to an arc melting process to form a preliminary U 3 Si 2 structure;

subjecting the preliminary U 3 Si 2 structure to a comminution process to form a fine U 3 Si 2 powder;

pressing the fine U 3 Si 2 powder to form a green U 3 Si 2 structure; and

sintering the green U 3 Si 2 structure.

2. The method of claim 1 , wherein forming a mixture comprises:

segmenting at least one larger uranium structure into smaller uranium structures;

subjecting the smaller uranium structures to at least one hydriding/dehydriding process to form the uranium particles; and

combining at least some of the uranium particles with the silicon particles to form the mixture, the mixture comprising from about 92.7 wt % uranium to about 92.5 wt % uranium and from about 7.3 wt % silicon to about 7.5 wt % silicon.

3. The method of claim 1 , wherein pressing the mixture to form a compact comprises:

providing at least a portion of the mixture into a cavity of a container; and

applying a pressure within a range of from about 150 MPa to about 300 MPa to the at least a portion of the mixture within the cavity.

4. The method of claim 1 , wherein subjecting the compact to an arc melting process comprises:

positioning the compact over a surface of a conductive structure;

positioning an electrode over the compact;

applying electric current to the electrode to form an arc between the electrode and the conductive structure and form a molten U 3 Si 2 structure; and

cooling the molten U 3 Si 2 structure to form the preliminary U 3 Si 2 structure.

5. The method of claim 4 , further comprising:

inverting the preliminary U 3 Si 2 structure;

positioning the inverted preliminary U 3 Si 2 structure over the surface of a conductive structure;

positioning an electrode over the inverted preliminary U 3 Si 2 structure;

applying additional electrical current to the electrode over the inverted preliminary U 3 Si 2 structure to form another arc between the electrode and the conductive structure over which the inverted preliminary U 3 Si 2 structure is positioned and form another molten U 3 Si 2 structure; and

cooling the another molten U 3 Si 2 structure to reform the preliminary U 3 Si 2 structure.

6. The method of claim 1 , further comprising heating the compact to a temperature within a range of from about 800° C. to about 1450° C. prior to subjecting the compact to the arc melting process.

7. The method of claim 1 , wherein subjecting the preliminary U 3 Si 2 structure to a comminution process comprises:

subjecting the preliminary U 3 Si 2 structure to an initial milling process to form an initial U 3 Si 2 powder comprising U 3 Si 2 particles each independently exhibiting a particle size less than or equal to about 5 mm; and

subjecting the initial U 3 Si 2 particles to an additional milling process to form the fine U 3 Si 2 powder, the fine U 3 Si 2 powder comprising fine U 3 Si 2 particles exhibiting an average particle size within a range of from about 0.5 μm to about 10 μm.

8. The method of claim 7 , wherein subjecting the preliminary U 3 Si 2 structure to an initial milling process to form an initial U 3 Si 2 powder comprises hammer milling the preliminary U 3 Si 2 structure.

9. The method of claim 7 , wherein subjecting the initial U 3 Si 2 particles to an additional milling process comprises:

subjecting the initial U 3 Si 2 particles to a first planetary milling process to form smaller U 3 Si 2 particles each independently exhibiting a particle size less than or equal to about 50 μm; and

subjecting the smaller U 3 Si 2 particles to at least one second planetary milling process to form the fine U 3 Si 2 particles.

10. The method of claim 9 , wherein subjecting the initial U 3 Si 2 particles to a first planetary milling process comprises:

introducing the initial U 3 Si 2 particles and a first milling media into a milling container; and

pulverizing the initial U 3 Si 2 particles using the first milling media and the milling container to form the smaller U 3 Si 2 particles.

11. The method of claim 10 , wherein subjecting the smaller U 3 Si 2 particles to at least one second planetary milling process comprises:

separating the smaller U 3 Si 2 particles from the first milling media;

providing the separated smaller U 3 Si 2 particles and a second milling media into a milling container, the second milling media having an average particle size less than that of the first milling media; and

pulverizing the smaller U 3 Si 2 particles using the second milling media and the milling container to form the fine U 3 Si 2 particles.

12. The method of claim 11 , further comprising:

selecting the first milling media to comprise hard material particles having an average particle size less than or equal to about 5 mm; and

selecting the second milling media to comprise additional hard material particles having an average particle size less than or equal to about 1 mm.

13. The method of claim 9 , further comprising combining the initial U 3 Si 2 particles with at least one lubricant prior to subjecting the initial U 3 Si 2 particles to the first planetary milling process.

14. The method of claim 13 , further comprising subjecting the fine U 3 Si 2 particles to a volatilization process to substantially remove remaining portions of the at least one lubricant from the fine U 3 Si 2 particles.

15. The method of claim 1 , wherein pressing the fine U 3 Si 2 powder comprises:

providing the fine U 3 Si 2 powder into a die cavity; and

applying pressure to the fine U 3 Si 2 powder within the die cavity to form the green U 3 Si 2 structure, the green U 3 Si 2 structure having a density within a range of from about 7.32 g/cm 3 to about 7.93 g/cm 3 .

16. The method of claim 1 , further comprising combining the fine U 3 Si 2 powder with at least one binder material prior to pressing the fine U 3 Si 2 powder to form the green U 3 Si 2 structure.

17. The method of claim 1 , wherein sintering the green U 3 Si 2 structure comprises heating the green U 3 Si 2 structure to a temperature within a range of from about 1200° C. to about 1500° C. under negative pressure or in an inert atmosphere for a sufficient amount of time to form a sintered U 3 Si 2 structure having a density greater than or equal to about 11.47 g/cm 3 .

18. The method of claim 17 , further comprising subjecting at least one of the green U 3 Si 2 structure or the sintered U 3 Si 2 structure to at least one machining process to reduce at least one dimension thereof.

19. The method of claim 18 , wherein subjecting at least one of the green U 3 Si 2 structure or the sintered U 3 Si 2 structure to at least one machining process comprises subjecting the sintered U 3 Si 2 structure to a centerless grinding process.

20. A method of forming an U 3 Si 2 structure, comprising:

forming a compact comprising from about 92.5 wt % to about 92.7 wt % uranium particles each independently exhibiting a particle size less than or equal to about 300 μm and from about 7.3 wt % to about 7.5 wt % silicon particles each independently exhibiting a particle size less than or equal to about 150 μm;

subjecting the compact to an arc melting process to form a preliminary U 3 Si 2 structure;

subjecting the preliminary U 3 Si 2 structure to a hammer milling process to form an initial U 3 Si 2 powder comprising U 3 Si 2 particles each independently having a particle size less than or equal to about 5 mm;

subjecting the initial U 3 Si 2 powder to a planetary milling process to form a fine U 3 Si 2 powder comprising fine U 3 Si 2 particles exhibiting an average particle size less than or equal to about 4 μm;

combining the fine U 3 Si 2 particles with at least one binder material to form a substantially homogeneous mixture;

pressing the substantially homogeneous mixture at a pressure within a range of from about 124 MPa to about 156 MPa to form a green U 3 Si 2 structure exhibiting an aspect ratio less than or equal to about 1.0;

sintering the green U 3 Si 2 structure at a temperature within a range of from about 1200° C. to about 1550° C. under at least one of vacuum or an inert atmosphere to form a sintered U 3 Si 2 structure; and

subjecting the sintered U 3 Si 2 structure to a machining process to reduce at least one of a diameter of the sintered U 3 Si 2 structure or a height of the sintered U 3 Si 2 structure.

21. The method of claim 20 , wherein subjecting the compact to an arc melting process comprises:

arc melting the compact within a conductive crucible to form a first molten U 3 Si 2 structure;

cooling the first molten U 3 Si 2 structure to form a first solid U 3 Si 2 structure;

arc melting the first solid U 3 Si 2 structure to form a second molten U 3 Si 2 structure;

cooling the second molten U 3 Si 2 structure to form a second solid U 3 Si 2 structure exhibiting increased homogeneity relative to the first solid U 3 Si 2 structure;

arc melting the second solid U 3 Si 2 structure to form a third molten U 3 Si 2 structure; and

cooling the third molten U 3 Si 2 structure to form the preliminary U 3 Si 2 structure, the preliminary U 3 Si 2 structure exhibiting increased homogeneity relative to the second solid U 3 Si 2 structure.

22. The method of claim 20 , wherein subjecting the initial U 3 Si 2 powder to a planetary milling process comprises:

combining the initial U 3 Si 2 powder with a milling aid comprising at least one of oleic acid or polyethylene glycol to form a first mixture;

grinding the first mixture using a milling media comprising partially stabilized zirconia particles having an average particle size less than or equal to about 5 mm to form a second mixture comprising the milling aid and smaller U 3 Si 2 particles each independently exhibiting an average particle size less than or equal to about 50 μm;

grinding the second mixture using another milling media comprising additional partially stabilized zirconia particles having an average particle size less than or equal to about 1 mm to form a third mixture comprising the milling aid and the fine U 3 Si 2 particles; and

heating the third mixture above a decomposition temperature of the milling aid to substantially remove the milling aid from the fine U 3 Si 2 particles.

23. The method of claim 20 , wherein combining the fine U 3 Si 2 particles with at least one binder material comprises combining the fine U 3 Si 2 particles with poly(ethylene oxide) having a molecular weight greater than or equal to about 4,000,000 g/mol.

24. The method of claim 20 , wherein subjecting the sintered U 3 Si 2 structure to a machining process comprises centerlessly grinding the sintered U 3 Si 2 structure to reduce the diameter and the height of the sintered U 3 Si 2 structure.