Patent Number: 052895122
Section: claims

1. A Nuclear Propulsion reactor, comprising: a. a rector vessel enclosing two separate coaxial core regions;  b. an annular-shaped first core positioned inside said reactor vessel, said first core containing particle bed reactor nuclear fuel elements having inlet and exhaust ends that direct propellant axially therethrough;  c. beryllium hydride moderator material positioned between the fuel elements in said first core;  d. a cylindrical second core containing fissionable material positioned in the axial space encompassed by said first core and in fluid communication with the exhaust end of said first core for heating propellant to a higher temperature than said first core;  e. thermal insulation between said first and second cores; and  f. a propellant nozzle attached to one end of said reactor vessel and in fluid communication with said second core. 2. The reactor of claim 1, further comprising control drums positioned inside said reactor vessel. 3. The reactor of claim 1, wherein said second core is formed from a highly refractory fissionable carbide. 4. The reactor of claim 1, wherein said second core is formed from an open porosity carbide foam. 5. The reactor of claim 1, wherein said second core is formed from a plurality of conduits positioned axially in said core. 6. The reactor of claim 5, wherein fissionable material is incorporated into said conduits. 7. The reactor of claim 5, wherein a fissionable gas is contained in spaces between said conduits.