Patent Number: 
Section: claims

1. A fuel bundle for a nuclear reactor comprising:a first fuel element including thorium dioxide;a second fuel element including uranium having a first fissile content; anda third fuel element including uranium having a second fissile content different from the first fissile content,wherein the first fuel element, the second fuel element, and the third fuel element are arranged such that a common coolant flows over each of the first fuel element, the second fuel element, and the third fuel element. 2. The fuel bundle of claim 1, wherein the uranium having the first fissile content includes recycled uranium having a fissile content of approximately 0.72 wt % of 235U to approximately 1.2 wt % of 235U. 3. The fuel bundle of claim 2, wherein the uranium having the second fissile content includes recycled uranium having a fissile content of approximately 0.72 wt % of 235U to approximately 1.2 wt % of 235U. 4. The fuel bundle of claim 2, wherein the uranium having the second fissile content includes slightly enriched uranium having a fissile content of approximately 0.9 wt % of 235U to approximately 3 wt % of 235U. 5. The fuel bundle of claim 2, wherein the uranium having the second fissile content includes natural uranium having a fissile content of approximately 0.71 wt % of 235U. 6. The fuel bundle of claim 2, wherein the uranium having the second fissile content includes low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 7. The fuel bundle of claim 1, wherein the uranium having the first fissile content includes slightly enriched uranium having a fissile content of approximately 0.9 wt % of 235U to approximately 3 wt % of 235U. 8. The fuel bundle of claim 7, wherein the uranium having the second fissile content includes slightly enriched uranium having a fissile content of approximately 0.9 wt % of 235U to approximately 3 wt % of 235U. 9. The fuel bundle of claim 7, wherein the uranium having the second fissile content includes natural uranium having a fissile content of approximately 0.71 wt % of 235U. 10. The fuel bundle of claim 7, wherein the uranium having the second fissile content includes low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 11. The fuel bundle of claim 1, wherein the uranium having the first fissile content includes natural uranium having a fissile content of approximately 0.71 wt % of 235U. 12. The fuel bundle of claim 11, wherein the uranium having the second fissile content includes low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 13. The fuel bundle of claim 1, wherein the uranium having the first fissile content includes low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 14. The fuel bundle of claim 13, wherein the uranium having the second fissile content includes low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 15. The fuel bundle of claim 2, wherein the uranium included in at least one of the second fuel element and the third fuel element is included with at least one of recycled uranium having a fissile content of approximately 0.72 wt % of 235U to approximately 1.2 wt % of 235U, depleted uranium having a fissile content of approximately 0.2 wt % of 235U to approximately 0.5 wt % of 235U, slightly enriched uranium having a fissile content of approximately 0.9 wt % of 235U to approximately 3 wt % of 235U, natural uranium having a fissile content of approximately 0.71 wt % of 235U, and low enriched uranium having a fissile content of approximately 3 wt % of 235U to approximately 20 wt % of 235U. 16. The fuel bundle of claim 2, wherein the uranium included in at least one of second fuel element and the third fuel element is included with a burnable poison. 17. The fuel bundle of claim 2, wherein the thorium dioxide included in the first fuel element is included with a burnable poison. 18. The fuel bundle of claim 1, wherein the first fuel element includes a rod of thorium dioxide. 19. The fuel bundle of claim 1, wherein the second fuel element includes a rod of the uranium having the first fissile content. 20. The fuel bundle of claim 1, wherein the third fuel element includes a rod of the uranium having the second fissile content. 21. The fuel bundle of claim 1, wherein the first fuel element includes a tube containing the thorium dioxide. 22. The fuel bundle of claim 1, wherein the second fuel element includes a tube containing the uranium having the first fissile content. 23. The fuel bundle of claim 1, wherein the third fuel element includes a tube containing the uranium having the second fissile content. 24. The fuel bundle of claim 1, wherein the second fissile content is higher than the first fissile content. 25. A nuclear reactor comprising: a tube of pressurized fluid; and the fuel bundle of claim 1.