Sheathed, annular metal nuclear fuel

Abstract

A sheathed, annular metal fuel system is described. A metal fuel pin system is described that includes an annular metal nuclear fuel alloy. A sheath may surround the metal nuclear fuel alloy, and a cladding may surround the sheath. A gas plenum may also be present. Mold arrangements and methods of fabrication of the sheathed, annular metal fuel are also described.

What is claimed is: 
     
         1 . A method of fabricating metal nuclear fuel, the method comprising:
 inserting a sheath into an annular mold;   bottom pouring a liquid metal nuclear fuel into the annular mold; and   allowing the liquid metal nuclear fuel alloy to form a sheathed, annular metal fuel wherein the sheathed, wherein the annular metal fuel has the sheath surrounding and tightly fitted to the metal nuclear fuel.   
     
     
         2 . The method of  claim 1 , wherein the sheath is a zirconium sheath or a refractory alloy sheath. 
     
     
         3 . The method of  claim 1 , wherein the mold block comprises graphite. 
     
     
         4 . The method of  claim 1 , wherein the annular mold comprises a rod in the approximate center of a hole, and the sheath within the hole. 
     
     
         5 . The method of  claim 4 , wherein the rod is a titanium nitride coated steel rod or a threaded solid graphite rod. 
     
     
         6 . The method of  claim 1 , further comprising placing the sheathed, annular metal fuel in a cladding with a gas plenum. 
     
     
         7 . The method of  claim 6 , wherein the gas plenum is filled with helium. 
     
     
         8 . The method of  claim 7 , further comprising using over pressure of helium in the gas plenum. 
     
     
         9 . The method of  claim 6 , wherein the cladding is steel. 
     
     
         10 . The method of  claim 1 , wherein the metal nuclear fuel and the sheath form a unitary product. 
     
     
         11 . The method of  claim 1 , wherein the metal nuclear fuel alloy comprises uranium-zirconium. 
     
     
         12 . The method of  claim 1 , wherein the metal nuclear fuel alloy comprises uranium-molybdenum. 
     
     
         13 . The method of  claim 1 , wherein the metal nuclear fuel alloy comprises transuranic elements. 
     
     
         14 . The method of  claim 1 , wherein the metal nuclear fuel alloy comprises thorium alloys. 
     
     
         15 . The method of  claim 1 , wherein a central hole in the sheathed, annular metal fuel provides for an effective fuel density of 75% or less upon irradiation. 
     
     
         16 . The method of  claim 1 , further comprising remote fabrication of reprocessed fuel. 
     
     
         17 . The method of  claim 1 , further comprising removing minor actinides from spent fuel and alloying the minor actinides with the metal nuclear fuel prior to bottom casting. 
     
     
         18 . The method of  claim 1 , further comprising placing a tube into a cladding then placing the sheathed, annular metal fuel into the tube. 
     
     
         19 . The method of  claim 18 , wherein the tube fits tightly within the cladding. 
     
     
         20 . The method of  claim 18 , wherein the tube is zirconium sheath or a refractory alloy.