LBE and Pb as Coolants for Generation IV Reactors: The Impurities Problem Available to Purchase

Pb and the eutectic alloy Pb 55.5Bi (LBE) have been chosen as possible reference coolants for Generation IV fast reactors. Originally, in the frame of ADS systems research activities, the LBE was considered to be the best possible choice as reference coolant, and, in that case, as spallation material, due to not only the very favourable thermal characteristics and low chemical reactivity of the alloy, but also due to the very low melting point (125°C), resulting in relatively low temperatures of the whole nuclear system. During the last years, the attention of the scientific community switched its attention to pure Pb. The formation of a large amount of Po, when Bi is irradiated, together with several technological issues were the major reasons for this switch. At ENEA Brasimone laboratories several years of experience both with LBE and with pure flowing Pb have been gathered, in the frame of the V, VI and the recently started VII framework Programmes of the EU. This paper focuses on this experience, highlighting the major issues and open points on the choice of pure Pb for Gen IV applications, focussing on the impurities control and filtering techniques.