Exposing the DIN 1.4970 fuel cladding in static LBE at targeted oxygen concentrations

摘要

Fast reactor concepts using lead or lead-bismuth eutectic (LBE) as coolant are currently being developed. While providing many advantages (low neutron absorption, good thermal conductivity, natural cooling during shutdown etc.), lead or LBE are known to be corrosive environments for steels at elevated temperatures. Cladding tubes, encapsulating pellets of fissile material, are submitted to the highest temperature in the core making them the most sensitive part for corrosion damage. In contact with the liquid metal and given a sufficient temperature, steel elements (Fe, Cr, Ni) diffuse out, leading to the destabilisation of the steel structure and the penetration of the coolant into the steel. Adding oxygen in the lead/LBE slows down or stops this process by the formation of an oxide layer.