Abstract: A barrier tube of non-circular cross section is arranged in the space between the stainless steel cladding and metal fuel slugs of a liquid metal reactor. The non-circular shape of this barrier design promotes improved thermal bonding in both the cladding/barrier and barrier/fuel interface regions. The non-circular barrier results in three areas with liquid metal thermal bond gaps having an angle which approaches that for a metal fuel pin without a barrier. Thus, the degree of circumferential unbonding will be less than that which results in localized fuel melting during radiation.

Abstract: 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.

Abstract: A method of inhibiting deleterious reactions between metallic fissionable fuel for nuclear reactors and stainless steel containers for housing such fuel comprising imposing an expendable body of alloying metal intermediate the fuel and container is disclosed. The disclosure also includes an improved nuclear fuel element comprising metal alloy fuel housed within stainless steel containers having a body of zirconium metal interposed between the fuel and containers.