Method, use and device concerning cladding tubes for nuclear fuel and a fuel assembly for a nuclear boiling water reactor

The invention concerns a method of producing a cladding tube for nuclear fuel for a nuclear boiling water reactor. According to the method, a tube is formed which comprises an outer cylindrical component ( 10 ) mainly containing zirconium and an inner cylindrical component ( 20 ) metallurgically bonded to the outer component ( 10 ), wherein also the inner component ( 20 ) at least mainly contains zirconium. The inner component ( 20 ) has a lower recrystallization temperature than the outer component ( 10 ). The cladding tube is final annealed at a temperature and during a time such that the inner component ( 20 ) substantially completely recrystallizes and such that the outer component ( 10 ) partly recrystallizes but to a lower extent than the inner component ( 20 ). The invention also concerns a cladding tube, a fuel assembly for a boiling water reactor as well as the use of a cladding tube.