Method for welding of fuel rod
AssigneeMitsubishi Nuclear Fuel Co.
InventorEiji Yoneda
Life of this patent
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Abstract
A resistance welding method for a fuel rod is presented in which the gas seal opening is closed with a sealing material of the same composition as the end plug material. The method enable to perform welding stably in a pressurized welding chamber, and the process is amenable to automation. The sealing material body is made of a wire, and is pressed against the conical shaped opening provided on the end plug. The welding method avoids contaminating the weld with undesirable impurities from the electrode material, and the welding operations is designed so that there is no need to reshape the end of the electrode or adjust the gap between the sealing material and the seal opening.
Claims20
A method for resistance welding of a gas seal opening provided on an end plug of a fuel rod, comprising the steps of:
- (a) providing a fuel rod comprising a metal tube which houses pellets and a coil spring, and a pair of end plugs fixed in both ends of said metal tube, one of said end plugs having a gas seal opening formed through said end plug, and said gas seal opening containing a conical opening formed in an end thereof so as to enlarge its inner diameter as it extends outward away from said metal tube;
- (b) providing a sealing material body having a constant diameter being smaller than a maximum diameter of said conical opening and being larger then a minimum diameter of said conical opening;
- (c) pressing the sealing material body against said conical opening coaxially to each other;
- (d) passing a current through contact electrodes disposed on said sealing material body and on said metal tube so as to heat a joint between said sealing material body and said end plug, to cause resistance welding of said joint;
- and
- (e) cutting said sealing material body perpendicularly to center axis thereof.
A system for resistance welding of a gas seal opening provided on an end plug of a fuel rod, comprising:
- a fuel rod comprising a metal tube which houses pellets and a coil spring, and a pair of end plugs fixed in both ends of said metal tube, one of said end plugs having a gas seal opening formed through said end plug, and said gas seal opening containing a conical opening formed in an end thereof so as to enlarge its inner diameter as it extends outward away from said metal tube;
- a sealing material body having a constant diameter being smaller than a maximum diameter of said conical opening and being larger then a minimum diameter of said conical opening, wherein the sealing material body is pressed against said conical opening coaxially to each other;
- a current passing through contact electrodes disposed on said sealing material body and on said metal tube so as to heat a joint between said sealing material body and said end plug, to cause resistance welding of said joint.
Dependencies are inferred from the claim text.