Patent Number: 059498374
Section: claims

1. A nuclear reactor having a core including a plurality of seed-blanket units, each said seed-blanket unit comprising: a) a central seed region, said seed region containing plutonium seed fuel elements;  b) a blanket region surrounding said seed region and containing blanket fuel elements comprising predominantly thorium oxide;  c) moderator in said seed region in the volume ratio of moderator to fuel in the range of approximately 2.5 to 3.5; and  d) moderator in said blanket region in the volume ratio of moderator to fuel of approximately 1.5 and 2.0.  a) a central seed region, said seed region containing plutonium seed fuel elements, each of said seed fuel elements being comprised of plutonium-zirconium alloy;  b) a blanket region surrounding said seed region and containing blanket fuel elements comprising predominantly thorium oxide with approximately 1% or less plutonium oxide, and approximately 2-5% by volume uranium tailings;  c) moderator in said seed region in the volume ratio of moderator to fuel in the range of approximately 2.5 to 3.5; and  d) moderator in said blanket region in the volume ratio of moderator to fuel of between approximately 1.5 and 2.0. 2. The nuclear reactor of claim 1, wherein each of said seed fuel elements is comprised of plutonium-zirconium alloy. 3. The nuclear reactor of claim 1, wherein said seed region comprises between approximately 45 and 55% of the total volume of each said seed-blanket unit. 4. The nuclear reactor of claim 1, wherein said blanket fuel elements further include plutonium oxide in the amount of no more than approximately 1%. 5. The nuclear reactor of claim 1, wherein said blanket fuel elements comprise approximately 2-5% by volume uranium tailings. 6. The nuclear reactor of claim 1, wherein the volume ratio of moderator to fuel in said seed region is in the range of approximately 2.5 to 3.0. 7. The nuclear reactor of claim 1, wherein said central seed region further contains a plurality of burnable poison containing rods. 8. The nuclear reactor of claim 7, wherein said plurality of burnable poison containing rods includes WABA poison rods and gadolinium containing fuel rods. 9. A nuclear reactor having a core including a plurality of seed-blanket units, each said seed-blanket unit comprising: 10. The nuclear reactor of claim 9, wherein said seed region comprises between approximately 45 and 55% of the total volume of each said seed-blanket unit. 11. The nuclear reactor of claim 10, wherein the volume ratio of moderator to fuel in said seed region is in the range of approximately 2.5 to 3.0. 12. The nuclear reactor of claim 11, wherein said central seed region further contains a plurality of burnable poison containing rods. 13. The nuclear reactor of claim 12, wherein said plurality of burnable poison containing rods includes WABA poison rods and gadolinium containing fuel rods.