JPH0634058B

An apparatus and process for control rod assembly and construction for a nuclear reactor is disclosed wherein the control rod (Fig. 2a) is of cruciform configuration having a plurality of, preferably four, flat planar members (S) each made up with an assembly of square cross sectioned tubular members (T). Each square cross sectioned tubular member includes a defined cylindrical center (40) and a surrounding tubular metallic shell (30) of constant thickness (36) defining a cylindrically shaped pressure vessel for containing neutron absorbing materials. The constant thickness surrounding tubular shell has four corner sections (31-34) added to generate a modified square exterior profile having additional thickness at its corners. The square cross sectioned tubular members are welded together to extend axially and longitudinally the length of the control rod in the direction of control rod movement and fluid flow. The square cross sectioned tubular members (T) are filled with a neutron absorbing material, plugged at both ends.