| 摘要 |
PURPOSE:To obtain nuclear fuel for a nuclear reactor with the high quality by allowing an electric current to flow to a prescribed number of welding electrodes alternately in a chamber with a high-pressure helium atmosphere and reducing consumption of the welding electrodes. CONSTITUTION:The two welding electrodes 15a and 15b are connected with an electrode holder of a welding torch 15 and the electric current flowing to the electrodes 15a and 15b is made on and off by a switching control unit incorporated in a welding controller. As a welding process, the head of a coated pipe 1 filled up with pellets, etc., from a fuel element storage vessel 12 is inserted into the welding chamber 8 which is roughly exhausted by a rotary pump 29 etc., of an evacuation system 20 and afterward, moreover, the inside of the welding chamber 8 is formed to a high vacuum by an oil diffusion pump 25. Next, the helium with the prescribed pressure is supplied from a helium supply system 22 to the chamber 8 and an end plug 5 is installed on the coated pipe 1 and the positioning of the electrodes 15a and 15b and a gap between the electrodes and the coated pipe are set. Next, the electric current, the welding time and the pulse width are set by the welding controller 10 and an arc is started while turning the coated pipe 1 by a turning driving motor 11.
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