Two-step process for bonding the elements of a three-layer cladding tube

摘要

A method is provided for preparing a cladding tube having an outer substrate, an intermediate zirconium barrier layer, and an inner liner. The method includes the following steps: (a) bonding an inner liner alloy sheath exterior circumferential surface to a zirconium sheath interior circumferential surface to form a barrier/inner liner sheath, and (b) bonding the exterior surface of the zirconium sheath on the barrier/inner liner sheath to the interior circumferential surface of an outer substrate alloy tube to form the cladding tube. Alternatively, the method includes the following steps: (a) bonding the zirconium sheath exterior circumferential surface to the outer substrate alloy tube interior circumferential surface to form a substrate tube/barrier sheath, and (b) bonding the exterior circumferential surface of the inner liner alloy sheath to the interior circumferential surface of the zirconium sheath of the substrate tube/barrier sheath to form said cladding tube. In either approach the tube produced by step (a) is heat treated before step (b) is performed. The bonding steps are performed by extrusion and sometimes hot isostatic pressing.