| 摘要 |
PROBLEM TO BE SOLVED: To provide excellent corrosion resistance in hightemperature water and to improve wear resistance by forming an anode oxide film on the surface of metal hafnium as the step of integrating metal hafnium into a control rod frame. SOLUTION: Each piece end of a cross tie rod 5 has a groove form, a sheath 3 worked into U-shaped section is welded to each piece of the tie rod 5, metal hafnium 4 having an elliptic section is housed in the internal space formed thereby by two each per blade. The elliptic tube form of the hafnium 4 is formed by forming the 12 form of the elliptic form from a hafnium metal plate by bending as members 4-1 and 4-2, and mutually fixing the members 4-1, 4-2 by butt weld. A surface oxide film layer 4' is formed on the surface of the elliptic hafnium 4 by anode oxidation. An electrolytic cell is filled with electrolyte, and the anode oxidation is performed by using platinum as a cathode and a hafnium bar as an anode. According to the above, a reactivity control material excellent in corrosion resistance and wear resistance can be provided without having a significant influence on the manufacturing process.
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