Experiments on cover-gas phenomena of the European fast reactor

The European fast reactor is a common European project for a 1500-MW(electric) fast breeder reactor. According to the 1991 design, the primary sodium tank will contain a 17-m-diam sodium pool with 545[degree]C surface temperature, 0.85-m-high argon cover gas, and an air-cooled upper closure with the low temperature of 120[degree]C. Thus, a strong temperature gradient will exist across the cover gas, causing aerosol formation and related phenomena. For a better understanding of the conditions during normal reactor operation and in case of accidental release through a leak in the upper closure, it is necessary to study the aerosol system, including heat transfer across the cover gas, mass deposition on cover plate and other structures, enrichment of volatile fission products, and other radioactive materials in the aerosol. In addition, it is interesting to compare the sodium aerosol behavior in the helium cover gas with the argon case because fundamental differences occur. This paper provides an overview of Kernforschungszentrum Karlsruhe research related to this topic.