Patent Number: 
Section: claims

1. A nuclear reactor core comprising:a plurality of moderator blocks;a nuclear fuel rod inserted into each moderator block, the nuclear fuel rod comprising a mixture of fissile material and hydrogen-containing glass microspheres coated with a burnable poison film; anda fertile material disposed about the nuclear fuel rod in each moderator block;wherein the hydrogen is stored in the glass microspheres as a moderator to control reactivity of the nuclear reactor core; andwherein the burnable poison film comprises a thermal neutron absorber selected for neutron capture in the fissile material. 2. The nuclear reactor core of claim 1, wherein depletion of the burnable poison shifts a neutron energy spectrum within the nuclear reactor core, such that neutron hydrogen collisions inside the hydrogen-containing glass microspheres improve utilization of additional fissile material generated from the neutron capture. 3. The nuclear reactor core of claim 1, further comprising a cladding material comprising zirconium on the nuclear fuel rods comprising the mixture of fissile material and hydrogen-containing glass microspheres, wherein hydrogen permeability of the glass microspheres increases with increasing temperature. 4. The nuclear reactor core of claim 1, wherein the fissile material comprises enriched uranium or plutonium. 5. The nuclear reactor core of claim 4, wherein the fertile material comprises thorium. 6. The nuclear reactor core of claim 1, wherein the fissile material is comprised within fuel microspheres mixed with the hydrogen-containing glass microspheres. 7. A nuclear reactor comprising the nuclear reactor core of claim 1, wherein the plurality of moderator blocks are disposed within a reactor shell. 8. The nuclear reactor of claim 7, wherein depletion of the burnable poison during operation of the nuclear reactor shifts a neutron energy spectrum within the nuclear reactor, such that neutron hydrogen collisions inside the hydrogen-containing glass microspheres improve utilization of additional fissile material generated from the neutron capture. 9. The nuclear reactor of claim 7, wherein the nuclear fuel rod comprises plutonium and the fertile material comprises thorium. 10. The nuclear reactor of claim 9, wherein the burnable poison comprises boron. 11. The nuclear reactor of claim 7, wherein the nuclear fuel rods comprise tri-structural isotropic fuel particles with uranium or plutonium fissile material. 12. The nuclear reactor of claim 11, further comprising a hydride distributed in the fissile material to provide a negative fuel temperature coefficient of reactivity. 13. The nuclear reactor of claim 7, further comprising holes provided in the moderator blocks, the holes configured for high temperature gas cooling. 14. A method of operating a nuclear reactor core, the method comprising:providing a plurality of moderator blocks;providing a nuclear fuel rod inserted into each moderator block, the nuclear fuel rod comprising a mixture of fissile material and hydrogen-containing glass microspheres coated with a burnable poison film; andproviding a fertile material disposed about the nuclear fuel rod in each moderator block;wherein the hydrogen is stored in the glass microspheres as a moderator and operates as a moderator to control reactivity of the nuclear reactor core during operation thereof; andwherein the burnable poison film comprises a thermal neutron absorber selected for neutron capture in the fissile material. 15. The method of claim 14, further comprising operating an electrical generator, wherein the nuclear reactor core serves as an energy source therefor. 16. The method of claim 14, further comprising heating the glass microspheres and filling the glass microspheres in a hydrogen gas environment, wherein a fill rate of the glass microspheres varies with a pressure of the hydrogen gas and a temperature at which the hydrogen gas is absorbed. 17. The method of claim 14, wherein providing the plurality of moderator blocks comprises dividing a graphite region into slices or leaves, and further comprising moving the slices or leaves in or out of an active core region of the nuclear reactor core to accommodate changes in a reactivity thereof. 18. The method of claim 14, wherein the fissile material comprises uranium or plutonium disposed within tri-structural isotropic fuel particles. 19. The method of claim 14, further comprising a hydride distributed in the fissile material to provide a negative fuel temperature coefficient of reactivity. 20. The method of claim 14, wherein the moderator blocks have holes configured for a cooling system and further comprising gas cooling of the nuclear reactor core thereby.