CONTROL ROD FOR NUCLEAR REACTOR

PURPOSE:To prevent corrosion products from being formed between a sheath and a diluted alloy plate by preventing the diluted alloy plate and the sheath which covers it from coming into surface contact with each other, and holding the gap between the diluted alloy plate and sheath constant at the same time and allowing a reactor cooling material to flow. CONSTITUTION:The diluted alloy plate 9a of a long-lived neutron absorbing material does not come into surface contact with the internal surface of the sheath 3a between wings 4a of the control rod, and a flow passage for reactor cooling water is secured between the diluted alloy plate 9a and sheath 3a. Consequently, corrosion products are prevented from being deposited on the gap between the diluted alloy plate 9a and sheath 3a and oxygen which is decomposed with radiation never stays in the gap, thereby improving the corrosion resistance of the sheath. Further, the gap between the diluted alloy plate and sheath is held constant, so even if the corrosion products are deposited on the gap, no press spreading force resulting from wedge operation operates on the sheath and large bending stress is not generated.