Performance of the Barrier between the Metallic Fuel and the Clad Material in Sodium-cooled Fast Reactor

Metallic fuel has been considered as one of the most probable candidates of the fuel system in the Sodium-cooled Fast Reactor (SFR) in that it has high thermal conductivity, proliferation resistance, and good compatibility between sodium. Addition of the alloying element such as chromium, molybdenum, zirconium and titanium was applied in order to increase the solidus temperature of the uranium-plutonium alloy. Among these, uranium-plutonium alloys with the addition of 10-20% zirconium have been considered in the design of the metallic fuel in SFR. However, actinide elements in metallic fuel like uranium and plutonium react with stainless steel at a temperature above 650 .deg. C to form eutectic compounds. Such eutectic reaction reduces cladding thickness so that mechanical integrity of the cladding gradually decreases as the fuel burnup proceeds. To mitigate such a circumstance, barrier layer, which prevents both fuel and clad elements from diffusing each other, has been developed. Metallic foil made of pure metal has been suggested as a barrier and its feasibility test has been carried out. The objectives in this study are to propose several kinds of the barrier material and to verify its performance under a fuel-clad interaction situation