Control rod

The object of this invention is to reduce the weight and improve the neutron absorbing performance and corrosion resistance of a nuclear reactor control rod to a sufficiently practical level. The control rod comprises an alloy containing, on the weight base, at least one of 0.1 to 5% Fe, 0.1 to 5% Ni, 0.1 to 3% Cr, 0.1 to 2% Nb and 0.1 to 2% Mo, 5 to 50% Hf and the substantial balance of Zr. Further, at least one of 0.1 to 3% Sn and 0.05 to 1% Si may be incorporated into the alloy. As a result of the experiment using the alloy according to this invention and B4C powder together, it has been found that they have excellent property both in the neutron absorbance and corrosion resistance. It has also been found, as the result of the experiment not using B4C together, that they have excellent corrosion resistance and stable property for a long period of time although the neutron absorbance is somewhat reduced. Accordingly, it is possible to reduce the weight of the control rod while keeping practically sufficient neutron absorbance and excellent corrosion resistance. (I.S.)