Container and system for handling damaged nuclear fuel, and method of making the same

Abstract

A container and system for handling damaged nuclear fuel, and a method of making the same. In one embodiment, the invention is a damaged fuel container having a specially designed top cap that can be detachably coupled to the elongated tubular wall by simply translating the top cap into proper position within the elongated tubular wall, wherein biased locking elements automatically lock the top cap to the elongated tubular wall. In another embodiment, the vent screens of the damaged fuel container are integrally formed rather than being separate components. In still other embodiments, the lower vent screens are arranged on an upstanding portion of the damaged fuel container. In an even further embodiment, the elongated tubular wall is formed by an extrusion process.

What is claimed is: 
     
         1 . A method of forming an elongated tubular container for receiving damaged nuclear fuel, the method comprising:
 a) extruding, from a material comprising a metal and a neutron absorber, an elongated tubular wall having a container cavity;   b) forming, from a material comprising a metal that is metallurgically compatible with the metal of the elongated tubular wall, a bottom cap comprising a first screen having a plurality of openings; and   c) autogenously welding the bottom cap to a bottom end of the elongated tubular wall, the plurality of openings of the first screen forming vent passageways to a bottom of the container cavity.   
     
     
         2 . The method according to  claim 1  wherein step b) further comprises:
 b-1) casting a body of the bottom cap; and 
 b-2) integrally forming the plurality of openings into the body of the bottom cap to form the first screen. 
 
     
     
         3 . The method according to  claim 2  wherein the plurality of openings are integrally formed by laser cutting the plurality of openings into the body of the bottom cap. 
     
     
         4 . The method according to  claim 1  wherein the elongated tubular wall is formed of a metal matrix composite having neutron absorbing particulate reinforcement. 
     
     
         5 . The method according to  claim 4  wherein the metal matrix composite having neutron absorbing particulate reinforcement is a boron carbide aluminum matrix composite material. 
     
     
         6 . The method according to  claim 1  wherein the bottom cap is formed of aluminum. 
     
     
         7 . The method according to  claim 1  wherein step c) further comprises:
 c-1) butt welding the bottom cap to the bottom end of the elongated tubular wall to produce a weld junction that is smooth with an outer surface of the elongated tubular wall. 
 
     
     
         8 . The method according to  claim 1  wherein the container cavity of the elongated tubular wall resulting from step a) has a substantially constant transverse cross-section. 
     
     
         9 . The method according to  claim 8  further comprises:
 expanding a portion of the transverse cross-section of the container cavity along a top portion of the elongated tubular wall. 
 
     
     
         10 . The method according to  claim 9  wherein the expanded portion of the transverse cross-section of the container cavity tapers moving away from a top edge of the elongated tubular wall. 
     
     
         11 . The method according to  claim 1  further comprising:
 d) forming a top cap having a second screen comprising a plurality of openings; and 
 e) detachably coupling the top cap to the elongated tubular wall, the plurality of openings of the first cap forming vent passageways into a top of the container cavity. 
 
     
     
         12 . The method according to  claim 11  wherein step e comprises:
 e-1) sliding the top cap into an open top end of the container cavity, wherein locking elements of the top cap that are normally biased into an extended state are forced into a retracted state due to contact with the elongated tubular wall during said sliding; and 
 e-2) upon the locking elements of the top cap becoming aligned with locking apertures of the elongated tubular container, the locking elements automatically returning to the extended state such that the locking elements protrude into the locking apertures. 
 
     
     
         13 . A system for storing and/or transporting nuclear fuel comprising:
 a vessel comprising defining a vessel cavity and extending along a vessel axis;   a fuel basket positioned within the vessel cavity, the fuel basket comprising a grid forming a plurality of elongated cells, each of the cells extending along a cell axis that is substantially parallel to the vessel axis; and   at least one elongated tubular container comprising a container cavity containing damaged nuclear fuel positioned within one of the cells, the elongated tubular container comprising:
 an extruded tubular wall forming a container cavity about a container axis, the extruded tubular wall formed of a metal matrix composite having neutron absorbing particulate reinforcement; 
 a bottom cap coupled to a bottom end of the extruded tubular wall; 
 a top cap detachably coupled to a top end of the extruded tubular wall; 
 a first screen comprising a plurality of openings that define lower vent passageways into a bottom of the container cavity; and 
 a second screen comprising a plurality of openings that define upper vent passageways into a top of the container cavity. 
   
     
     
         14 . The system according to  claim 13  wherein a top portion of the extruded tubular wall comprises locking apertures, and the top cap comprises locking elements that are alterable between a retracted state and an extended state, the locking elements biased into the extended state, and wherein the top cap is detachably coupled to the extruded tubular wall when the locking elements are in the extended state and protrude into the locking apertures. 
     
     
         15 . The system according to  claim 14  wherein contact between the extruded tubular wall and the locking elements forces the locking elements into the retracted state during insertion of the top cap into the container cavity until the locking elements become aligned with the locking apertures. 
     
     
         16 . The system according to  claim 14  wherein the bottom cap comprises the first screen and the top cap comprises the second screen. 
     
     
         17 . The system according to  claim 16  wherein the first screen is integrally formed into a body of the bottom cap and the second screen is integrally formed into a body of the top cap. 
     
     
         18 . The system according to  claim 13  wherein the bottom cap comprises a floor plate that forms a floor of the container cavity and an oblique wall plate extending upward from a perimeter of the floor plate, the oblique wall plate coupled to the bottom end of the extruded tubular wall, the first screen located on the oblique wall plate of the bottom cap. 
     
     
         19 . The system according to  claim 13  further comprising a floor of the container cavity, and wherein at least one of the plurality of openings of the first screen is located an axial distance above the floor of the container cavity. 
     
     
         20 . The system according to  claim 15 , wherein the locking elements are spring biased laterally outward towards the extended state.