Fuel channel box

Purpose: To improve the corrosion resistance at the welded portions of a fuel channel box by using special inserts comprising zirconium-based alloys of high strength. Constitution: In conventional fuel structural members, spotty gray-white corrosion products called as nodular corrosions are formed at the surface. Although these members have sufficient function under the operation condition of existent reactors, it is not sure whether they can withstand in the case of feature improvements to be made from economical point of views. In this invention, structural members comprising zirconium-based alloys containing 1 to 3 wt% of niobium, 0.5 to 0.15 wt% of oxygen are joined by welding using inserts comprising zirconium-based alloy containing 0.1 % Nb, 1 - 3 % Sn, 0.1 - 1.0 % Fe and 0.01 - 0.1 % Ni. As a result, reliability of fuel assemblies of high economical advantage can be improved. (Takahashi, M.)