Tolerant metal fuel/cladding barrier and related method of installation

摘要

A multi-layer, rolled metal foil is laser tackwelded to form a tube which can be inserted in the intermediate space between the fuel body and cladding of a metal alloy fissionable fuel element. The rolled foil has at least three foil layers at the point of tack welding. The laser welding penetration is adjusted so that the foil weld is maintained at a thickness of at least two foil layers, but does not penetrate all of the layers. The weld is designed to fail in response to fuel or blanket alloy swelling during irradiation. After weld failure, the overlapping layers slip and the multi-layer foil unrolls as the fuel swells, providing a continuous, unbroken barrier between the fuel or blanket alloy and cladding which masks defects in the barrier due to weld failure.