JP2544010B

A refueling mast for a reactor complex includes nested generally cylindrical tubes (132, 134). The inner tube has vertical grooved tracks formed therein. The outer tube has a guide roller (224) mounted thereon with grooves which mate with track grooves of a respective track on the adjacent inner tube. Track grooves are cold formed moving a roller die tool up and down the inner tube, while increasing pressure on the incorporated die rollers. This process flattens the inner tube where the tracks are being formed. The grooved tracks and the associated flattening provide the torsional rigidity required on the mast tubes for precise positioning and orientation of fuel elements.