Method and apparatus for sizing nuclear fuel rod cladding tubes

Claim 1

A method for reducing a metal cladding tube of a nuclear fuel rod, to an inside diameter substantially precisely fitting pellets of nuclear fuel contained in the cladding tube, comprising the step of encircling said tube with a fluid pressure chamber that embraces a short length of said tube and with said length containing an internal support having substantially the diameter of said pellets and with said chamber filled with a compressible fluid, forcing more of said compressible fluid into said chamber to obtain a fluid pressure in the chamber providing a fluid pressure on said tube causing initial yielding of said tube inwardly, and holding said fluid in said chamber so that by expansion of said fluid and with said tube yielding, said tube plastically deforms inwardly onto said internal support to provide said tube with said inside diameter; said pressure being applied by a high-pressure hydraulic pump having a cylinder connected by a pipe to said chamber and containing a piston which moves forwardly in said cylinder, said cylinder and said pipe and said chamber being filled with a substantially constant volume of compressible hydraulic liquid, and said piston being moved forwardly to a position providing said pressure compressing said fluid and causing said initial yielding of said tube, and said piston being then held substantially at said position until said hydraulic liquid expands to plastically deform said tube inwardly onto said internal support.

Claim 2

A method for reducing a metal cladding tube of a nuclear fuel rod, to an inside diameter substantially precisely fitting pellets of nuclear fuel contained in the cladding tube, comprising the step of encircling said tube with a fluid pressure chamber that embraces a short length of said tube and with said length containing an internal support having substantially the diameter of said pellets and with said chamber filled with a compressible fluid, forcing more of said compressible fluid into said chamber to obtain a fluid pressure in the chamber providing a fluid pressure on said tube causing initial yielding of said tube inwardly, and holding said fluid in said chamber so that by expansion of said fluid and with said tube yielding, said tube plastically deforms inwardly onto said internal support to provide said tube with said inside diameter; said pressure being applied by a high-pressure hydraulic pump having a cylinder connected by a pipe to said chamber and containing a piston which moves forwardly in said cylinder, said cylinder and said pipe and said chamber being filled with a substantially constant volume of compressible hydraulic liquid, and said piston being moved forwardly to a position providing said pressure compressing said fluid and causing said initial yielding of said tube, and said piston being then held substantially at said position until said hydraulic liquid expands to plastically deform said tube inwardly onto said internal support.

Claim 4

An apparatus for reducing a metal cladding tube to an inside diameter substantially precisely fitting pellets of nuclear fuel contained in the cladding tube, comprising an annular pressure chamber having a passage surrounded by the chamber and through which a short length of said tube may be positioned with at least said length containing an internal support having substantially the diameter of said pellets, a non-metallic elastically-deformable annular seal inside of said chamber for surrounding and sealing said length relative to said pressure chamber, a high-pressure fluid pump having a cylinder with a solid-walled working portion and a pipe through which said working portion is connected to said chamber and a reciprocative piston in said working portion, reciprocating means for mechanically reciprocating said piston with a pause between forward and backward strokes, moving means for intermittently moving said tube length-by-length through said opening, and means for timing said moving means so that said reciprocating means reciprocates said piston for a forward stroke, as a result of which fluid pressure is placed on said tube causing initial yielding of said tube inwardly, and pause, during which said fluid expands and plastically deforms said tube inwardly onto said internal support, while said tube is stationary and the moving means moves said tube forwardly while said reciprocating means moves said piston backwardly, the cylinder's said working portion, said pipe and said chamber being filled with a substantially constant volume of compressible hydraulic liquid.

Claim 5

An apparatus for reducing a metal cladding tube to an inside diameter substantially precisely fitting pellets of nuclear fuel contained in the cladding tube, comprising an annular pressure chamber having a passage surrounded by the chamber and through which a short length of said tube may be positioned with at least said length containing an internal support having substantially the diameter of said pellets, a non-metallic elastically-deformable annular seal inside of said chamber for surrounding and sealing said length relative to said pressure chamber, a high-pressure fluid pump having a cylinder with a solid-walled working portion and a pipe through which said working portion is connected to said chamber and a reciprocative piston in said working portion, reciprocating means for mechanically reciprocating said piston with a pause between forward and backward strokes, moving means for intermittently moving said tube length-by-length through said opening, and means for timing said moving means so that said reciprocating means reciprocates said piston for a forward stroke, as a result of which fluid pressure is placed on said tube causing initial yielding of said tube inwardly, and pause, during which said fluid expands and plastically deforms said tube inwardly onto said internal support, while said tube is stationary and the moving means moves said tube forwardly while said reciprocating means moves said piston backwardly, the cylinder's said working portion, said pipe and said chamber being filled with a substantially constant volume of compressible hydraulic liquid.