| 摘要 |
PROBLEM TO BE SOLVED: To provide a control rod which makes it possible to restrain crevice corrosion on the inner surface of a sheath from appearing and a method for manufacturing it. SOLUTION: A control rod for a BWR has four blades extending in four directions from a tie rod located in a shaft. A handle and a lower supporting member are mounted on the upper and lower ends of the tie rod respectively. Each of the blades is composed by laying out hafnium members, flat cylinders, in the sheath with its U-shaped cross section. An oxide film is formed beforehand on the inner surface of the sheath. The formation of the oxide film is conducted as follows: A tubular nozzle 24 of a preparatory oxidation treatment device 21 is inserted into the U-shaped sheath 6 at one end in the longitudinal direction and moves in the sheath 6 in the longitudinal direction with the migration of a running gear 23. High-temperature steam generated by a heater 26 is supplied into the tubular nozzle 24 and is spouted from blast nozzles 25. The oxide film is formed on the inner surface of the sheath 6 by the spouted steam. COPYRIGHT: (C)2009,JPO&INPIT
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