Control rods

Purpose: To secure close fitting of a cadmium layer to inner and outer aluminum pipes, as well as to facilitate the confirmation for such close fitting during fabrication in control rods such as employed mainly in experimental reactors. Constitution: A cadmium plate is wound around while extended e.g., by rollers to the outer circumference of a cylindrical aluminum inner pipe whose inner and outer diameters are finished to specified dimensions with particular care for the finishing of the outer diameter to a specified allowance. Then an aluminum outer pipe with its inner diameter being finished to a predetermined dimension is fitted to the outside of the cadmium plate so as to closely fit the outer surface thereof. Thereafter, both ends of the cadmium plate are cut out by an appropriate length, an insertion pipe is inserted therein and then cap members are engaged and integrated by welding. (Horiuchi, T.)