Aerosol Retention Near the Tube Breach During Steam Generator Tube Rupture Sequences

Steam generator tube rupture sequences are identified as major contributors to the risk assessments of pressurized water reactors. Despite very low probability, they involve a direct pathway for radioactivity release into the environment. Nonetheless, fission products could be partially retained in the secondary side of the steam generator, even in the absence of water. This paper summarizes the main results of a bench-scale experimental program focused on the aerosol retention near the tube breach at the secondary side of a dry steam generator. The major variables investigated were the breach configuration (i.e., type, orientation, and location) and the gas mass flow rate. The results showed that near the breach, aerosol retention is low (<20%), and it generally decreases when the gas mass flow rate increases. Discussion of the experimental results suggested that certain phenomena, such as fragmentation and/or resuspension, as well as particle nature could have a large effect on the scenario studied, and they should be considered as potential issues and/or variables to be explored in future work.