Characterization of the washout of aerosols by spraying water for thermal hydraulic conditions representative of a severe accident in nuclear reactor containment
Denis MARCHAND, Emmanuel PORCHERON, Pascal LEMAITRE (IRSN) et Gérard GREHAN (CORIA) - Congrès ICLASS-10 (International Conference on Liquid Atomization and Spray Systems), 27/08/06 – 01/09/06, Kyoto, Japon;
Aerosol washout using water sprays is one of the most common techniques for aerosol removal in the containment building during severe accident of Pressurized Water Reactors (PWR). This work lies within the general framework of studies and researches on the safety of PWR containment. In order to study the physical phenomena involved in the washout of aerosols by spraying water for thermal hydraulic conditions representative of a severe accident, the Institute for Radiological Protection and Nuclear Safety (IRSN) has developed the TOSQAN facility. Measurements of aerosol characteristics in gas such as aerosols concentration and aerosols size, coupled with measurements of spray characteristics such as droplets size and droplets velocity will provide detailed information for better understanding collection mechanisms. To date, all previous studies described in the literature were based on old technologies of measurements and few experiments were interested in these phenomena under well-controlled thermodynamic conditions. This paper presents a bibliographical review exposing the phenomenology of the severe accident and the basic phenomena controlling the collection of aerosols. Then, the experimental facility TOSQAN is presented with diagnostics associates used for aerosols washout characterization under severe conditions. Finally the first results are discussed and compared to the calculations performed with the integral code ASTEC (Accident Source Term Evaluation Code).