Wash-down tests of silver aerosol from stainless steel and painted surfaces

In this work results from wash-down experiments of insoluble silver aerosol from different containment typical surfaces are presented. The test series include surfaces coated with decontamination paint and stainless steel surfaces, surface inclinations of 2°, 10°, 20° and 90°, three different aerosol loadings, a variation in size distribution of the aerosol and water flow rates ranging from 1 g/s to 12 g/s. The laboratory scale experiments are performed to support and develop measurement strategies to quantify the aerosol wash-down in large scale experiments e.g. in the THAI test facility and to provide validation data for model development of severe accident simulation tools, like COCOSYS or ASTEC. A two phase test procedure was developed which consists of a separate aerosol loading phase and a subsequent aerosol wash-down phase. The test results have been evaluated in order to quantify the main influencing parameters of the wash-down. As a result it was found that the wash-off generally occurs by rivulets instead of closed water films and that an enlarged water flow rate does not necessarily accelerate or increase the wash-down behavior. (author)