Validation Matrix for Pool Scrubbing Models

The removal of aerosol particles and vapors in gas bubbles moving through a water pool is known to be an efficient means to reduce source term to the environment during severe accidents, as happened in Fukushima Daiichi. This trapping, called pool scrubbing, entails a complex phenomenology in which hydrodynamics, thermal hydraulics, and aerosol physics strongly affect each other and determine the net transfer of radioactivity coming out from the aqueous pond. More than 20 experimental programs have addressed this issue since the early 1980s, but few of them did it in a systematic and representative way. This paper thoroughly reviews the entire pool scrubbing database until 2016 and assesses the adequacy of the experimental setup, representativeness of boundary conditions, weaknesses in decontamination factor derivation, data uncertainties, and some other aspects to finally synthesize a reduced number of experiments that could be used as an experimental matrix for the validation of pool scrubbing models. More than 500 tests were reviewed and classified as Qualified for Validation, Useful for Understanding, or Not Useful; less than 15% of these experiments are considered in the proposed validation matrix due to different reasons. Major insights and remaining needs are also highlighted. This work was conducted under the framework of the Integration of Pool Scrubbing Research to Enhance Source-Term Calculations, or the IPRESCA project, led by Becker Technologies, in the framework of the Sustainable Nuclear Energy Technology Platform/Nuclear Generation II & III Alliance/Technical Area 2.